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000
FXUS63 KLOT 230301
AFDLOT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
1001 PM CDT WED OCT 22 2014

.DISCUSSION...
310 PM CDT

SHORT TERM...THIS AFTERNOON THROUGH TONIGHT...FOR THE REMAINDER OF
THE AFTERNOON AND TONIGHT...MOSTLY CLEAR SKIES AND SLIGHTLY HIGHER
TEMPERATURES ARE MAKING FOR A TRANSITION DAY TODAY BEFORE A MORE
NOTABLE WARMING TREND EXPECTED FOR THE NEXT FEW DAYS. UNDER THE
CLEAR SKIES AND LIGHT WINDS...TEMPERATURES THIS AFTERNOON ARE
CLIMBING INTO THE LOW 50S NEAR LAKE MICHIGAN TO AROUND 60F WELL
INLAND.  A RIDGE OF HIGH PRESSURE MOVING ACROSS THE WESTERN GREAT
LAKES HAS SET UP LIGHT ONSHORE FLOW NEAR THE LAKE...PREVENTING THE
WARMER CONDITIONS NEAR THE LAKE.  FOR TONIGHT...UNDER CLEAR
SKIES...LIGHT WINDS AND WITH A RELATIVELY DRY AIRMASS IN
PLACE...TEMPERATURES WILL ONCE AGAIN HAVE AN OPPORTUNITY TO RADIATE
DOWN INTO THE MIDDLE TO UPPER 30S.  THE HIGHLY URBANIZED AREAS OF
THE CHICAGO METRO AREA SHOULD REMAIN A BIT WARMER...WITH LOWS ONLY
IN THE LOWER 40S.  EVEN THOUGH THE AIRMASS IS EXPECTED TO BE
RELATIVELY DRY...DEWPOINTS SHOULD BE THE LOWER TO MIDDLE 30S...SO
TEMPERATURES WILL LIKELY RADIATE CLOSE TO THE DEWPOINTS.  DO NOT
ANTICIPATE WIDESPREAD DENSE FOG...BUT RATHER THERE COULD MORE LIKELY
BE SOME PATCHY...SHALLOW GROUND FOG IN LOW-LYING...SHELTERED...RURAL
LOCATIONS.

LONGER TERM...THURSDAY THROUGH WEDNESDAY...AS THE HIGH SLIDES OFF TO
THE EAST AND A SFC TROUGH AND ASSOCIATED COLD FRONT CROSS THE
CENTRAL PLAINS...A RETURN FLOW OF SLIGHTLY WARMER...MOISTER AIR WILL
SET UP.  WHILE THE NORTHERN PORTION OF THE SFC HIGH WILL PUSH WELL
EAST OF THE AREA...THE MIDWEST WILL REMAIN CUT OFF FROM THE RICHER
GULF MOISTURE AS A RIDGE AXIS EXTENDS SWWD THROUGH ERN TX.  THIS
COMBINATION WILL AFFECT BOTH MAX TEMP POTENTIAL FOR THE DAY AS WELL
AS PCPN POTENTIAL WITH THE PASSAGE OF THE COLD FRONT.  WHILE
INCREASING CLOUD COVER WILL SOMEWHAT TEMPER THE POTENTIAL MAX TEMPS
FOR THE DAY...HIGHS THURSDAY SHOULD RANGE FROM THE UPPER 50S TO
AROUND 60F.  AS FOR PCPN POTENTIAL...THERE SHOULD BE ADEQUATE SFC
FORCING WITH THE COLD FRONT AS WELL AS MID LEVEL FORCING FROM A NRN
STREAM SHORTWAVE TRACKING ACROSS THE UPPER MISSISSIPPI VALLEY AND
WRN GREAT LAKES AS WELL AS SOME PHASING WITH A SRN STREAM SHORTWAVE
PASSING ACROSS THE MIDDLE MISSISSIPPI VALLEY.  EVEN THOUGH THE
SURFACE LAYER WILL BE SOMEWHAT CUT OFF FROM THE RICHEST LOW LEVEL
GULF MOISTURE...THE SRN STREAM SHORT WAVE WILL BRING SOME ENHANCED
MID LEVEL MOISTURE...SO THE OVERALL MOISTURE PROFILE WILL STILL BE
RELATIVELY MOIST WITH THE MODELS INDICATING PWATS OF AROUND 1 INCH
WITH THE FROPA.  SO...EXPECT THAT ENTIRE CWA SHOULD SEE WETTING
RAINFALL THROUGH THE DAY TOMORROW...POSSIBLY LINGERING INTO TOMORROW
EVENING OVER THE FAR ERN PORTIONS OF THE CWA...THE STEADILY
PROGRESSIVE NATURE OF THE SYSTEM SHOULD LIMIT RAINFALL AMOUNTS TO
ARND A TENTH TO A QUARTER OF AN INCH WITH SOME OF THE HEAVIER
SHOWERS.  MODELS SOUNDINGS INDICATE LITTLE OR NO CAPE...SO THUNDER
SHOULD NOT BE AN ISSUE.

FOLLOWING THE PASSAGE OF THE FRONT...THE REAL WARMING TREND WILL
BEGIN IN EARNEST ON FRIDAY AS UPPER RIDGING BUILDS ACROSS THE
ROCKIES AND INTO THE WESTERN PLAINS...WHILE THE UPPER TROUGH AND
COLD FRONT MOVE TO THE EAST COAST.  BY FRIDAY...850MB TEMPS ARND 15C
WILL MOVE ACROSS THE AREA AND EXPECT THAT TEMPS SHOULD REACH INTO
THE MIDDLE TO UPPER 60S.  BY SATURDAY...THE THERMAL AXIS WILL SHIFT
TO THE SOUTH...ACROSS CNTRL/SRN IL/IN WHILE A DEEP UPPER LOW TRACKS
ACROSS THE UPPER GREAT LAKES.  THIS WILL LEAD TO MORE NWLY FLOW
ACROSS THE UPPER MIDWEST...AND POSSIBLY LIMITING WARMING ACROSS THE
NRN PORTIONS OF THE AREA...SO...WILL CARRY TEMPS IN THE LOWER TO
MIDDLE 60S NORTH OF THE I-80 CORRIDOR WITH TEMPS IN THE UPPER 60S
ACROSS THE SRN PORTIONS OF THE CWA.  WITH ENOUGH SUNSHINE...SOME 70F
MAX TEMPS ARE NOT OUT OF THE QUESTION FOR LOCATIONS SOUTH OF A
PONTIAC TO REMINGTON LINE.  THE RELATIVELY WARM AND DRY WEATHER WILL
PERSIST THROUGH THE WEEKEND AS THE UPPER RIDGE SLOWLY PROGRESSES
ACROSS THE CENTRAL CONUS.

THE NEXT SIGNIFICANT CHANCE FOR PCPN WILL NOT BE UNTIL EARLY NEXT
WEEK WHEN THE UPPER RIDGE BUILDS TO THE EAST COAST AND A STRONG
PACIFIC SHORTWAVE DROPS FROM THE PACIFIC NORTHWEST TO THE FOUR
CORNERS AREA BY MONDAY AFTERNOON.  THIS WILL SET UP STRONG SWLY FLOW
ALOFT...WITH A TRAIN OF SOUTHERN STREAM SHORTWAVE ENERGY...WHILE AN
OPEN GULF OF MEXICO EVOLVES AT THE SURFACE.  INCREASED LOW LEVEL
MOISTURE AND MID LEVEL SHORT WAVE ENERGY WILL BRING A CHANCE FOR
SHOWERS AND POSSIBLY SOME THUNDERSTORMS FOR MONDAY NIGHT AND INTO
TUESDAY.  THE UNSEASONABLY HIGH TEMPERATURES WILL COME TO AN END BY
EARLY NEXT WEEK AS ANOTHER COLD FRONT IS EXPECTED TO CROSS THE
REGION.  THE LATEST LONG RANGE GUIDANCE SUGGESTS THAT THIS FRONT
SHOULD PUSH THROUGH THE AREA BY TUESDAY NIGHT OR WEDNESDAY...
BRINGING MAX TEMPS BACK INTO THE 50S.

KREIN

&&

.AVIATION...

//ORD AND MDW CONCERNS...UPDATED 030Z...

* -SHRA EXPECTED LATE THURSDAY AFTERNOON AND MVFR CIGS ARE PSBL
  WITH AND AFTER -SHRA PASSES

KMD

//DISCUSSION...UPDATED 00Z...

QUIET CONDITIONS EXPECTED OVERNIGHT WITH LIGHT WINDS IN SLOWLY
INCREASING HIGH CLOUDS. WINDS INCREASE DURING THE DAY AHEAD OF
SLOW MOVING FRONTAL SYSTEM. SW WINDS INCREASE TO AROUND 10 KT
THROUGH THE DAY. THERE MAY BE  HIGHER SW WINDS AHEAD OF THE FRONT
IN THE 18Z-22Z TIME FRAME THAN THE CURRENT TAFS INDICATE...BUT THE
GRADIENT WILL BE WEAKENING DURING THIS TIME AHEAD OF RAIN/SHOWER
ACTIVITY. EXPECT A PERIOD OF MVFR AT SOME POINT WITH THE LIGHT
SHOWERS...WITH A BETTER CHANCE TOWARD THE TAIL END OF THE MAIN
RAINFALL ACTIVITY DURING THE EVENING HOURS. THERE MAY EVEN BE SOME
LINGERING DRIZZLE BEHIND THE SHOWERS AS LOW LEVEL SATURATION
INCREASES WHICH COULD LOWER CIGS/VSBYS AS WELL.

KMD

//ORD AND MDW CONFIDENCE...UPDATED 03Z...

* MEDIUM CONFIDENCE IN TIMING AND COVERAGE OF -SHRA THURSDAY.

* MEDIUM-LOW CONFIDENCE IN TIMING AND OCCURRENCE OF MVFR CIGS
  THURSDAY/THURSDAY NIGHT.

KMD

//OUTLOOK FOR ORD/MDW FOR 12Z FRIDAY-12Z WEDNESDAY...UPDATED 00Z...

* FRIDAY...DRY/VFR. SOUTHWEST WINDS.
* SATURDAY...DRY/VFR. GUSTY NORTHWEST WINDS.
* SUNDAY...DRY/VFR. SOUTH/SOUTHEAST WINDS.
* MONDAY...SLIGHT CHANCE OF SHRA. GUSTY SOUTH WINDS.
* TUESDAY...CHANCE OF SHRA. STRONG/GUSTY WESTERLY WINDS.

KMD

&&

.MARINE...
158 PM CDT

THE WEATHER PATTERN ACROSS THE WESTERN GREAT LAKES REGION WILL
REMAIN FAIRLY PROGRESSIVE THROUGH THE WEEKEND AND INTO EARLY NEXT
WEEK...WITH SEVERAL FRONTAL PASSAGES ALTERNATING WITH WEAK HIGH
PRESSURE RIDGES.

HIGH PRESSURE WAS SITUATED OVER THE WESTERN LAKES THIS AFTERNOON...
BUT THE RIDGE WILL MOVE SLOWLY EAST TONIGHT WITH SOUTH WINDS
BECOMING STRONGER THURSDAY AS A TROUGH OF LOW PRESSURE MOVES INTO
THE UPPER MIDWEST. PRESSURE FALLS AHEAD OF THIS SYSTEM WILL LIKELY
LEAD TO SOUTH WINDS GUSTING TO 20-25 KT ESPECIALLY ACROSS THE
NORTHERN PART LAKE MICHIGAN THURSDAY AFTERNOON AND EVENING. THE COLD
FRONT ASSOCIATED WITH THIS TROUGH WILL WEAKEN AS IT MOVES THROUGH
THE REGION EARLY FRIDAY...WITH WINDS BACKING SOUTH AGAIN AHEAD OF
ANOTHER DISTURBANCE EMERGING FROM THE NORTHERN PLAINS. THIS NEXT
TROUGH AND COLD FRONT WILL PASS LATE FRIDAY NIGHT...WITH WINDS
VEERING TO THE WEST AND AGAIN GUSTING AS HIGH AS 30 KT INTO SATURDAY
AND SATURDAY NIGHT. A FEW GUSTS NEAR GALE FORCE MAY BE POSSIBLE
SATURDAY NIGHT AS COLDER AIR STEEPENS THE LOW LEVEL LAPSE RATES OVER
THE LAKE AND ALLOWS DEEPER MIXING OF THE HIGHER MOMENTUM AIR FROM
ABOVE. WINDS WILL THEN EASE SUNDAY AS ANOTHER WEAK HIGH PRESSURE
RIDGE MOVES ACROSS THE LAKE LATE IN THE DAY.

A DEEPER LOW PRESSURE SYSTEM IS FORECAST TO DEVELOP OVER THE PLAINS
AND LIFT NORTHEAST ACROSS THE UPPER MIDWEST SUNDAY NIGHT THROUGH
TUESDAY. SURFACE PRESSURE FALLS AND A RESULTING TIGHTENING OF THE
SURFACE PRESSURE GRADIENT WILL RESULT IN WINDS BACK TO THE
SOUTH-SOUTHEAST BY EARLY MONDAY...WITH SPEEDS INCREASING INTO THE
20-30 KT RANGE AGAIN.

RATZER

&&

.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...NONE.
&&

$$

VISIT US AT HTTP://WEATHER.GOV/CHICAGO (ALL LOWERCASE)

FOLLOW US ON FACEBOOK...TWITTER...AND YOUTUBE AT:
WWW.FACEBOOK.COM/NWSCHICAGO
WWW.TWITTER.COM/NWSCHICAGO
WWW.YOUTUBE.COM/NWSCHICAGO







000
FXUS63 KLOT 222357
AFDLOT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
657 PM CDT WED OCT 22 2014

.DISCUSSION...
310 PM CDT

SHORT TERM...THIS AFTERNOON THROUGH TONIGHT...FOR THE REMAINDER OF
THE AFTERNOON AND TONIGHT...MOSTLY CLEAR SKIES AND SLIGHTLY HIGHER
TEMPERATURES ARE MAKING FOR A TRANSITION DAY TODAY BEFORE A MORE
NOTABLE WARMING TREND EXPECTED FOR THE NEXT FEW DAYS. UNDER THE
CLEAR SKIES AND LIGHT WINDS...TEMPERATURES THIS AFTERNOON ARE
CLIMBING INTO THE LOW 50S NEAR LAKE MICHIGAN TO AROUND 60F WELL
INLAND.  A RIDGE OF HIGH PRESSURE MOVING ACROSS THE WESTERN GREAT
LAKES HAS SET UP LIGHT ONSHORE FLOW NEAR THE LAKE...PREVENTING THE
WARMER CONDITIONS NEAR THE LAKE.  FOR TONIGHT...UNDER CLEAR
SKIES...LIGHT WINDS AND WITH A RELATIVELY DRY AIRMASS IN
PLACE...TEMPERATURES WILL ONCE AGAIN HAVE AN OPPORTUNITY TO RADIATE
DOWN INTO THE MIDDLE TO UPPER 30S.  THE HIGHLY URBANIZED AREAS OF
THE CHICAGO METRO AREA SHOULD REMAIN A BIT WARMER...WITH LOWS ONLY
IN THE LOWER 40S.  EVEN THOUGH THE AIRMASS IS EXPECTED TO BE
RELATIVELY DRY...DEWPOINTS SHOULD BE THE LOWER TO MIDDLE 30S...SO
TEMPERATURES WILL LIKELY RADIATE CLOSE TO THE DEWPOINTS.  DO NOT
ANTICIPATE WIDESPREAD DENSE FOG...BUT RATHER THERE COULD MORE LIKELY
BE SOME PATCHY...SHALLOW GROUND FOG IN LOW-LYING...SHELTERED...RURAL
LOCATIONS.

LONGER TERM...THURSDAY THROUGH WEDNESDAY...AS THE HIGH SLIDES OFF TO
THE EAST AND A SFC TROUGH AND ASSOCIATED COLD FRONT CROSS THE
CENTRAL PLAINS...A RETURN FLOW OF SLIGHTLY WARMER...MOISTER AIR WILL
SET UP.  WHILE THE NORTHERN PORTION OF THE SFC HIGH WILL PUSH WELL
EAST OF THE AREA...THE MIDWEST WILL REMAIN CUT OFF FROM THE RICHER
GULF MOISTURE AS A RIDGE AXIS EXTENDS SWWD THROUGH ERN TX.  THIS
COMBINATION WILL AFFECT BOTH MAX TEMP POTENTIAL FOR THE DAY AS WELL
AS PCPN POTENTIAL WITH THE PASSAGE OF THE COLD FRONT.  WHILE
INCREASING CLOUD COVER WILL SOMEWHAT TEMPER THE POTENTIAL MAX TEMPS
FOR THE DAY...HIGHS THURSDAY SHOULD RANGE FROM THE UPPER 50S TO
AROUND 60F.  AS FOR PCPN POTENTIAL...THERE SHOULD BE ADEQUATE SFC
FORCING WITH THE COLD FRONT AS WELL AS MID LEVEL FORCING FROM A NRN
STREAM SHORTWAVE TRACKING ACROSS THE UPPER MISSISSIPPI VALLEY AND
WRN GREAT LAKES AS WELL AS SOME PHASING WITH A SRN STREAM SHORTWAVE
PASSING ACROSS THE MIDDLE MISSISSIPPI VALLEY.  EVEN THOUGH THE
SURFACE LAYER WILL BE SOMEWHAT CUT OFF FROM THE RICHEST LOW LEVEL
GULF MOISTURE...THE SRN STREAM SHORT WAVE WILL BRING SOME ENHANCED
MID LEVEL MOISTURE...SO THE OVERALL MOISTURE PROFILE WILL STILL BE
RELATIVELY MOIST WITH THE MODELS INDICATING PWATS OF AROUND 1 INCH
WITH THE FROPA.  SO...EXPECT THAT ENTIRE CWA SHOULD SEE WETTING
RAINFALL THROUGH THE DAY TOMORROW...POSSIBLY LINGERING INTO TOMORROW
EVENING OVER THE FAR ERN PORTIONS OF THE CWA...THE STEADILY
PROGRESSIVE NATURE OF THE SYSTEM SHOULD LIMIT RAINFALL AMOUNTS TO
ARND A TENTH TO A QUARTER OF AN INCH WITH SOME OF THE HEAVIER
SHOWERS.  MODELS SOUNDINGS INDICATE LITTLE OR NO CAPE...SO THUNDER
SHOULD NOT BE AN ISSUE.

FOLLOWING THE PASSAGE OF THE FRONT...THE REAL WARMING TREND WILL
BEGIN IN EARNEST ON FRIDAY AS UPPER RIDGING BUILDS ACROSS THE
ROCKIES AND INTO THE WESTERN PLAINS...WHILE THE UPPER TROUGH AND
COLD FRONT MOVE TO THE EAST COAST.  BY FRIDAY...850MB TEMPS ARND 15C
WILL MOVE ACROSS THE AREA AND EXPECT THAT TEMPS SHOULD REACH INTO
THE MIDDLE TO UPPER 60S.  BY SATURDAY...THE THERMAL AXIS WILL SHIFT
TO THE SOUTH...ACROSS CNTRL/SRN IL/IN WHILE A DEEP UPPER LOW TRACKS
ACROSS THE UPPER GREAT LAKES.  THIS WILL LEAD TO MORE NWLY FLOW
ACROSS THE UPPER MIDWEST...AND POSSIBLY LIMITING WARMING ACROSS THE
NRN PORTIONS OF THE AREA...SO...WILL CARRY TEMPS IN THE LOWER TO
MIDDLE 60S NORTH OF THE I-80 CORRIDOR WITH TEMPS IN THE UPPER 60S
ACROSS THE SRN PORTIONS OF THE CWA.  WITH ENOUGH SUNSHINE...SOME 70F
MAX TEMPS ARE NOT OUT OF THE QUESTION FOR LOCATIONS SOUTH OF A
PONTIAC TO REMINGTON LINE.  THE RELATIVELY WARM AND DRY WEATHER WILL
PERSIST THROUGH THE WEEKEND AS THE UPPER RIDGE SLOWLY PROGRESSES
ACROSS THE CENTRAL CONUS.

THE NEXT SIGNIFICANT CHANCE FOR PCPN WILL NOT BE UNTIL EARLY NEXT
WEEK WHEN THE UPPER RIDGE BUILDS TO THE EAST COAST AND A STRONG
PACIFIC SHORTWAVE DROPS FROM THE PACIFIC NORTHWEST TO THE FOUR
CORNERS AREA BY MONDAY AFTERNOON.  THIS WILL SET UP STRONG SWLY FLOW
ALOFT...WITH A TRAIN OF SOUTHERN STREAM SHORTWAVE ENERGY...WHILE AN
OPEN GULF OF MEXICO EVOLVES AT THE SURFACE.  INCREASED LOW LEVEL
MOISTURE AND MID LEVEL SHORT WAVE ENERGY WILL BRING A CHANCE FOR
SHOWERS AND POSSIBLY SOME THUNDERSTORMS FOR MONDAY NIGHT AND INTO
TUESDAY.  THE UNSEASONABLY HIGH TEMPERATURES WILL COME TO AN END BY
EARLY NEXT WEEK AS ANOTHER COLD FRONT IS EXPECTED TO CROSS THE
REGION.  THE LATEST LONG RANGE GUIDANCE SUGGESTS THAT THIS FRONT
SHOULD PUSH THROUGH THE AREA BY TUESDAY NIGHT OR WEDNESDAY...
BRINGING MAX TEMPS BACK INTO THE 50S.

KREIN

&&

.AVIATION...

//ORD AND MDW CONCERNS...UPDATED 00Z...

* -SHRA EXPECTED LATE THURSDAY AFTERNOON AND MVFR CIGS ARE PSBL
  WITH AND AFTER -SHRA PASSES

KMD

//DISCUSSION...UPDATED 00Z...

QUIET CONDITIONS EXPECTED OVERNIGHT WITH LIGHT WINDS IN SLOWLY
INCREASING HIGH CLOUDS. WINDS INCREASE DURING THE DAY AHEAD OF
SLOW MOVING FRONTAL SYSTEM. SW WINDS INCREASE TO AROUND 10 KT
THROUGH THE DAY. THERE MAY BE  HIGHER SW WINDS AHEAD OF THE FRONT
IN THE 18Z-22Z TIME FRAME THAN THE CURRENT TAFS INDICATE...BUT THE
GRADIENT WILL BE WEAKENING DURING THIS TIME AHEAD OF RAIN/SHOWER
ACTIVITY. EXPECT A PERIOD OF MVFR AT SOME POINT WITH THE LIGHT
SHOWERS...WITH A BETTER CHANCE TOWARD THE TAIL END OF THE MAIN
RAINFALL ACTIVITY DURING THE EVENING HOURS. THERE MAY EVEN BE SOME
LINGERING DRIZZLE BEHIND THE SHOWERS AS LOW LEVEL SATURATION
INCREASES WHICH COULD LOWER CIGS/VSBYS AS WELL.

KMD


//ORD AND MDW CONFIDENCE...UPDATED 00Z...

* MEDIUM CONFIDENCE IN TIMING AND COVERAGE OF -SHRA THURSDAY.

* MEDIUM-LOW CONFIDENCE IN TIMING AND OCCURRENCE OF MVFR CIGS
  THURSDAY/THURSDAY NIGHT.

KMD

//OUTLOOK FOR ORD/MDW FOR 12Z FRIDAY-12Z WEDNESDAY...UPDATED 00Z...

* FRIDAY...DRY/VFR. SOUTHWEST WINDS.
* SATURDAY...DRY/VFR. GUSTY NORTHWEST WINDS.
* SUNDAY...DRY/VFR. SOUTH/SOUTHEAST WINDS.
* MONDAY...SLIGHT CHANCE OF SHRA. GUSTY SOUTH WINDS.
* TUESDAY...CHANCE OF SHRA. STRONG/GUSTY WESTERLY WINDS.

KMD

&&

.MARINE...
158 PM CDT

THE WEATHER PATTERN ACROSS THE WESTERN GREAT LAKES REGION WILL
REMAIN FAIRLY PROGRESSIVE THROUGH THE WEEKEND AND INTO EARLY NEXT
WEEK...WITH SEVERAL FRONTAL PASSAGES ALTERNATING WITH WEAK HIGH
PRESSURE RIDGES.

HIGH PRESSURE WAS SITUATED OVER THE WESTERN LAKES THIS AFTERNOON...
BUT THE RIDGE WILL MOVE SLOWLY EAST TONIGHT WITH SOUTH WINDS
BECOMING STRONGER THURSDAY AS A TROUGH OF LOW PRESSURE MOVES INTO
THE UPPER MIDWEST. PRESSURE FALLS AHEAD OF THIS SYSTEM WILL LIKELY
LEAD TO SOUTH WINDS GUSTING TO 20-25 KT ESPECIALLY ACROSS THE
NORTHERN PART LAKE MICHIGAN THURSDAY AFTERNOON AND EVENING. THE COLD
FRONT ASSOCIATED WITH THIS TROUGH WILL WEAKEN AS IT MOVES THROUGH
THE REGION EARLY FRIDAY...WITH WINDS BACKING SOUTH AGAIN AHEAD OF
ANOTHER DISTURBANCE EMERGING FROM THE NORTHERN PLAINS. THIS NEXT
TROUGH AND COLD FRONT WILL PASS LATE FRIDAY NIGHT...WITH WINDS
VEERING TO THE WEST AND AGAIN GUSTING AS HIGH AS 30 KT INTO SATURDAY
AND SATURDAY NIGHT. A FEW GUSTS NEAR GALE FORCE MAY BE POSSIBLE
SATURDAY NIGHT AS COLDER AIR STEEPENS THE LOW LEVEL LAPSE RATES OVER
THE LAKE AND ALLOWS DEEPER MIXING OF THE HIGHER MOMENTUM AIR FROM
ABOVE. WINDS WILL THEN EASE SUNDAY AS ANOTHER WEAK HIGH PRESSURE
RIDGE MOVES ACROSS THE LAKE LATE IN THE DAY.

A DEEPER LOW PRESSURE SYSTEM IS FORECAST TO DEVELOP OVER THE PLAINS
AND LIFT NORTHEAST ACROSS THE UPPER MIDWEST SUNDAY NIGHT THROUGH
TUESDAY. SURFACE PRESSURE FALLS AND A RESULTING TIGHTENING OF THE
SURFACE PRESSURE GRADIENT WILL RESULT IN WINDS BACK TO THE
SOUTH-SOUTHEAST BY EARLY MONDAY...WITH SPEEDS INCREASING INTO THE
20-30 KT RANGE AGAIN.

RATZER

&&

.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...NONE.
&&

$$

VISIT US AT HTTP://WEATHER.GOV/CHICAGO (ALL LOWERCASE)

FOLLOW US ON FACEBOOK...TWITTER...AND YOUTUBE AT:
WWW.FACEBOOK.COM/NWSCHICAGO
WWW.TWITTER.COM/NWSCHICAGO
WWW.YOUTUBE.COM/NWSCHICAGO







000
FXUS63 KLOT 222357
AFDLOT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
657 PM CDT WED OCT 22 2014

.DISCUSSION...
310 PM CDT

SHORT TERM...THIS AFTERNOON THROUGH TONIGHT...FOR THE REMAINDER OF
THE AFTERNOON AND TONIGHT...MOSTLY CLEAR SKIES AND SLIGHTLY HIGHER
TEMPERATURES ARE MAKING FOR A TRANSITION DAY TODAY BEFORE A MORE
NOTABLE WARMING TREND EXPECTED FOR THE NEXT FEW DAYS. UNDER THE
CLEAR SKIES AND LIGHT WINDS...TEMPERATURES THIS AFTERNOON ARE
CLIMBING INTO THE LOW 50S NEAR LAKE MICHIGAN TO AROUND 60F WELL
INLAND.  A RIDGE OF HIGH PRESSURE MOVING ACROSS THE WESTERN GREAT
LAKES HAS SET UP LIGHT ONSHORE FLOW NEAR THE LAKE...PREVENTING THE
WARMER CONDITIONS NEAR THE LAKE.  FOR TONIGHT...UNDER CLEAR
SKIES...LIGHT WINDS AND WITH A RELATIVELY DRY AIRMASS IN
PLACE...TEMPERATURES WILL ONCE AGAIN HAVE AN OPPORTUNITY TO RADIATE
DOWN INTO THE MIDDLE TO UPPER 30S.  THE HIGHLY URBANIZED AREAS OF
THE CHICAGO METRO AREA SHOULD REMAIN A BIT WARMER...WITH LOWS ONLY
IN THE LOWER 40S.  EVEN THOUGH THE AIRMASS IS EXPECTED TO BE
RELATIVELY DRY...DEWPOINTS SHOULD BE THE LOWER TO MIDDLE 30S...SO
TEMPERATURES WILL LIKELY RADIATE CLOSE TO THE DEWPOINTS.  DO NOT
ANTICIPATE WIDESPREAD DENSE FOG...BUT RATHER THERE COULD MORE LIKELY
BE SOME PATCHY...SHALLOW GROUND FOG IN LOW-LYING...SHELTERED...RURAL
LOCATIONS.

LONGER TERM...THURSDAY THROUGH WEDNESDAY...AS THE HIGH SLIDES OFF TO
THE EAST AND A SFC TROUGH AND ASSOCIATED COLD FRONT CROSS THE
CENTRAL PLAINS...A RETURN FLOW OF SLIGHTLY WARMER...MOISTER AIR WILL
SET UP.  WHILE THE NORTHERN PORTION OF THE SFC HIGH WILL PUSH WELL
EAST OF THE AREA...THE MIDWEST WILL REMAIN CUT OFF FROM THE RICHER
GULF MOISTURE AS A RIDGE AXIS EXTENDS SWWD THROUGH ERN TX.  THIS
COMBINATION WILL AFFECT BOTH MAX TEMP POTENTIAL FOR THE DAY AS WELL
AS PCPN POTENTIAL WITH THE PASSAGE OF THE COLD FRONT.  WHILE
INCREASING CLOUD COVER WILL SOMEWHAT TEMPER THE POTENTIAL MAX TEMPS
FOR THE DAY...HIGHS THURSDAY SHOULD RANGE FROM THE UPPER 50S TO
AROUND 60F.  AS FOR PCPN POTENTIAL...THERE SHOULD BE ADEQUATE SFC
FORCING WITH THE COLD FRONT AS WELL AS MID LEVEL FORCING FROM A NRN
STREAM SHORTWAVE TRACKING ACROSS THE UPPER MISSISSIPPI VALLEY AND
WRN GREAT LAKES AS WELL AS SOME PHASING WITH A SRN STREAM SHORTWAVE
PASSING ACROSS THE MIDDLE MISSISSIPPI VALLEY.  EVEN THOUGH THE
SURFACE LAYER WILL BE SOMEWHAT CUT OFF FROM THE RICHEST LOW LEVEL
GULF MOISTURE...THE SRN STREAM SHORT WAVE WILL BRING SOME ENHANCED
MID LEVEL MOISTURE...SO THE OVERALL MOISTURE PROFILE WILL STILL BE
RELATIVELY MOIST WITH THE MODELS INDICATING PWATS OF AROUND 1 INCH
WITH THE FROPA.  SO...EXPECT THAT ENTIRE CWA SHOULD SEE WETTING
RAINFALL THROUGH THE DAY TOMORROW...POSSIBLY LINGERING INTO TOMORROW
EVENING OVER THE FAR ERN PORTIONS OF THE CWA...THE STEADILY
PROGRESSIVE NATURE OF THE SYSTEM SHOULD LIMIT RAINFALL AMOUNTS TO
ARND A TENTH TO A QUARTER OF AN INCH WITH SOME OF THE HEAVIER
SHOWERS.  MODELS SOUNDINGS INDICATE LITTLE OR NO CAPE...SO THUNDER
SHOULD NOT BE AN ISSUE.

FOLLOWING THE PASSAGE OF THE FRONT...THE REAL WARMING TREND WILL
BEGIN IN EARNEST ON FRIDAY AS UPPER RIDGING BUILDS ACROSS THE
ROCKIES AND INTO THE WESTERN PLAINS...WHILE THE UPPER TROUGH AND
COLD FRONT MOVE TO THE EAST COAST.  BY FRIDAY...850MB TEMPS ARND 15C
WILL MOVE ACROSS THE AREA AND EXPECT THAT TEMPS SHOULD REACH INTO
THE MIDDLE TO UPPER 60S.  BY SATURDAY...THE THERMAL AXIS WILL SHIFT
TO THE SOUTH...ACROSS CNTRL/SRN IL/IN WHILE A DEEP UPPER LOW TRACKS
ACROSS THE UPPER GREAT LAKES.  THIS WILL LEAD TO MORE NWLY FLOW
ACROSS THE UPPER MIDWEST...AND POSSIBLY LIMITING WARMING ACROSS THE
NRN PORTIONS OF THE AREA...SO...WILL CARRY TEMPS IN THE LOWER TO
MIDDLE 60S NORTH OF THE I-80 CORRIDOR WITH TEMPS IN THE UPPER 60S
ACROSS THE SRN PORTIONS OF THE CWA.  WITH ENOUGH SUNSHINE...SOME 70F
MAX TEMPS ARE NOT OUT OF THE QUESTION FOR LOCATIONS SOUTH OF A
PONTIAC TO REMINGTON LINE.  THE RELATIVELY WARM AND DRY WEATHER WILL
PERSIST THROUGH THE WEEKEND AS THE UPPER RIDGE SLOWLY PROGRESSES
ACROSS THE CENTRAL CONUS.

THE NEXT SIGNIFICANT CHANCE FOR PCPN WILL NOT BE UNTIL EARLY NEXT
WEEK WHEN THE UPPER RIDGE BUILDS TO THE EAST COAST AND A STRONG
PACIFIC SHORTWAVE DROPS FROM THE PACIFIC NORTHWEST TO THE FOUR
CORNERS AREA BY MONDAY AFTERNOON.  THIS WILL SET UP STRONG SWLY FLOW
ALOFT...WITH A TRAIN OF SOUTHERN STREAM SHORTWAVE ENERGY...WHILE AN
OPEN GULF OF MEXICO EVOLVES AT THE SURFACE.  INCREASED LOW LEVEL
MOISTURE AND MID LEVEL SHORT WAVE ENERGY WILL BRING A CHANCE FOR
SHOWERS AND POSSIBLY SOME THUNDERSTORMS FOR MONDAY NIGHT AND INTO
TUESDAY.  THE UNSEASONABLY HIGH TEMPERATURES WILL COME TO AN END BY
EARLY NEXT WEEK AS ANOTHER COLD FRONT IS EXPECTED TO CROSS THE
REGION.  THE LATEST LONG RANGE GUIDANCE SUGGESTS THAT THIS FRONT
SHOULD PUSH THROUGH THE AREA BY TUESDAY NIGHT OR WEDNESDAY...
BRINGING MAX TEMPS BACK INTO THE 50S.

KREIN

&&

.AVIATION...

//ORD AND MDW CONCERNS...UPDATED 00Z...

* -SHRA EXPECTED LATE THURSDAY AFTERNOON AND MVFR CIGS ARE PSBL
  WITH AND AFTER -SHRA PASSES

KMD

//DISCUSSION...UPDATED 00Z...

QUIET CONDITIONS EXPECTED OVERNIGHT WITH LIGHT WINDS IN SLOWLY
INCREASING HIGH CLOUDS. WINDS INCREASE DURING THE DAY AHEAD OF
SLOW MOVING FRONTAL SYSTEM. SW WINDS INCREASE TO AROUND 10 KT
THROUGH THE DAY. THERE MAY BE  HIGHER SW WINDS AHEAD OF THE FRONT
IN THE 18Z-22Z TIME FRAME THAN THE CURRENT TAFS INDICATE...BUT THE
GRADIENT WILL BE WEAKENING DURING THIS TIME AHEAD OF RAIN/SHOWER
ACTIVITY. EXPECT A PERIOD OF MVFR AT SOME POINT WITH THE LIGHT
SHOWERS...WITH A BETTER CHANCE TOWARD THE TAIL END OF THE MAIN
RAINFALL ACTIVITY DURING THE EVENING HOURS. THERE MAY EVEN BE SOME
LINGERING DRIZZLE BEHIND THE SHOWERS AS LOW LEVEL SATURATION
INCREASES WHICH COULD LOWER CIGS/VSBYS AS WELL.

KMD


//ORD AND MDW CONFIDENCE...UPDATED 00Z...

* MEDIUM CONFIDENCE IN TIMING AND COVERAGE OF -SHRA THURSDAY.

* MEDIUM-LOW CONFIDENCE IN TIMING AND OCCURRENCE OF MVFR CIGS
  THURSDAY/THURSDAY NIGHT.

KMD

//OUTLOOK FOR ORD/MDW FOR 12Z FRIDAY-12Z WEDNESDAY...UPDATED 00Z...

* FRIDAY...DRY/VFR. SOUTHWEST WINDS.
* SATURDAY...DRY/VFR. GUSTY NORTHWEST WINDS.
* SUNDAY...DRY/VFR. SOUTH/SOUTHEAST WINDS.
* MONDAY...SLIGHT CHANCE OF SHRA. GUSTY SOUTH WINDS.
* TUESDAY...CHANCE OF SHRA. STRONG/GUSTY WESTERLY WINDS.

KMD

&&

.MARINE...
158 PM CDT

THE WEATHER PATTERN ACROSS THE WESTERN GREAT LAKES REGION WILL
REMAIN FAIRLY PROGRESSIVE THROUGH THE WEEKEND AND INTO EARLY NEXT
WEEK...WITH SEVERAL FRONTAL PASSAGES ALTERNATING WITH WEAK HIGH
PRESSURE RIDGES.

HIGH PRESSURE WAS SITUATED OVER THE WESTERN LAKES THIS AFTERNOON...
BUT THE RIDGE WILL MOVE SLOWLY EAST TONIGHT WITH SOUTH WINDS
BECOMING STRONGER THURSDAY AS A TROUGH OF LOW PRESSURE MOVES INTO
THE UPPER MIDWEST. PRESSURE FALLS AHEAD OF THIS SYSTEM WILL LIKELY
LEAD TO SOUTH WINDS GUSTING TO 20-25 KT ESPECIALLY ACROSS THE
NORTHERN PART LAKE MICHIGAN THURSDAY AFTERNOON AND EVENING. THE COLD
FRONT ASSOCIATED WITH THIS TROUGH WILL WEAKEN AS IT MOVES THROUGH
THE REGION EARLY FRIDAY...WITH WINDS BACKING SOUTH AGAIN AHEAD OF
ANOTHER DISTURBANCE EMERGING FROM THE NORTHERN PLAINS. THIS NEXT
TROUGH AND COLD FRONT WILL PASS LATE FRIDAY NIGHT...WITH WINDS
VEERING TO THE WEST AND AGAIN GUSTING AS HIGH AS 30 KT INTO SATURDAY
AND SATURDAY NIGHT. A FEW GUSTS NEAR GALE FORCE MAY BE POSSIBLE
SATURDAY NIGHT AS COLDER AIR STEEPENS THE LOW LEVEL LAPSE RATES OVER
THE LAKE AND ALLOWS DEEPER MIXING OF THE HIGHER MOMENTUM AIR FROM
ABOVE. WINDS WILL THEN EASE SUNDAY AS ANOTHER WEAK HIGH PRESSURE
RIDGE MOVES ACROSS THE LAKE LATE IN THE DAY.

A DEEPER LOW PRESSURE SYSTEM IS FORECAST TO DEVELOP OVER THE PLAINS
AND LIFT NORTHEAST ACROSS THE UPPER MIDWEST SUNDAY NIGHT THROUGH
TUESDAY. SURFACE PRESSURE FALLS AND A RESULTING TIGHTENING OF THE
SURFACE PRESSURE GRADIENT WILL RESULT IN WINDS BACK TO THE
SOUTH-SOUTHEAST BY EARLY MONDAY...WITH SPEEDS INCREASING INTO THE
20-30 KT RANGE AGAIN.

RATZER

&&

.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...NONE.
&&

$$

VISIT US AT HTTP://WEATHER.GOV/CHICAGO (ALL LOWERCASE)

FOLLOW US ON FACEBOOK...TWITTER...AND YOUTUBE AT:
WWW.FACEBOOK.COM/NWSCHICAGO
WWW.TWITTER.COM/NWSCHICAGO
WWW.YOUTUBE.COM/NWSCHICAGO







000
FXUS63 KLOT 222010
AFDLOT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
310 PM CDT WED OCT 22 2014

.DISCUSSION...
310 PM CDT

SHORT TERM...THIS AFTERNOON THROUGH TONIGHT...FOR THE REMAINDER OF
THE AFTERNOON AND TONIGHT...MOSTLY CLEAR SKIES AND SLIGHTLY HIGHER
TEMPERATURES ARE MAKING FOR A TRANSITION DAY TODAY BEFORE A MORE
NOTABLE WARMING TREND EXPECTED FOR THE NEXT FEW DAYS. UNDER THE
CLEAR SKIES AND LIGHT WINDS...TEMPERATURES THIS AFTERNOON ARE
CLIMBING INTO THE LOW 50S NEAR LAKE MICHIGAN TO AROUND 60F WELL
INLAND.  A RIDGE OF HIGH PRESSURE MOVING ACROSS THE WESTERN GREAT
LAKES HAS SET UP LIGHT ONSHORE FLOW NEAR THE LAKE...PREVENTING THE
WARMER CONDITIONS NEAR THE LAKE.  FOR TONIGHT...UNDER CLEAR
SKIES...LIGHT WINDS AND WITH A RELATIVELY DRY AIRMASS IN
PLACE...TEMPERATURES WILL ONCE AGAIN HAVE AN OPPORTUNITY TO RADIATE
DOWN INTO THE MIDDLE TO UPPER 30S.  THE HIGHLY URBANIZED AREAS OF
THE CHICAGO METRO AREA SHOULD REMAIN A BIT WARMER...WITH LOWS ONLY
IN THE LOWER 40S.  EVEN THOUGH THE AIRMASS IS EXPECTED TO BE
RELATIVELY DRY...DEWPOINTS SHOULD BE THE LOWER TO MIDDLE 30S...SO
TEMPERATURES WILL LIKELY RADIATE CLOSE TO THE DEWPOINTS.  DO NOT
ANTICIPATE WIDESPREAD DENSE FOG...BUT RATHER THERE COULD MORE LIKELY
BE SOME PATCHY...SHALLOW GROUND FOG IN LOW-LYING...SHELTERED...RURAL
LOCATIONS.

LONGER TERM...THURSDAY THROUGH WEDNESDAY...AS THE HIGH SLIDES OFF TO
THE EAST AND A SFC TROUGH AND ASSOCIATED COLD FRONT CROSS THE
CENTRAL PLAINS...A RETURN FLOW OF SLIGHTLY WARMER...MOISTER AIR WILL
SET UP.  WHILE THE NORTHERN PORTION OF THE SFC HIGH WILL PUSH WELL
EAST OF THE AREA...THE MIDWEST WILL REMAIN CUT OFF FROM THE RICHER
GULF MOISTURE AS A RIDGE AXIS EXTENDS SWWD THROUGH ERN TX.  THIS
COMBINATION WILL AFFECT BOTH MAX TEMP POTENTIAL FOR THE DAY AS WELL
AS PCPN POTENTIAL WITH THE PASSAGE OF THE COLD FRONT.  WHILE
INCREASING CLOUD COVER WILL SOMEWHAT TEMPER THE POTENTIAL MAX TEMPS
FOR THE DAY...HIGHS THURSDAY SHOULD RANGE FROM THE UPPER 50S TO
AROUND 60F.  AS FOR PCPN POTENTIAL...THERE SHOULD BE ADEQUATE SFC
FORCING WITH THE COLD FRONT AS WELL AS MID LEVEL FORCING FROM A NRN
STREAM SHORTWAVE TRACKING ACROSS THE UPPER MISSISSIPPI VALLEY AND
WRN GREAT LAKES AS WELL AS SOME PHASING WITH A SRN STREAM SHORTWAVE
PASSING ACROSS THE MIDDLE MISSISSIPPI VALLEY.  EVEN THOUGH THE
SURFACE LAYER WILL BE SOMEWHAT CUT OFF FROM THE RICHEST LOW LEVEL
GULF MOISTURE...THE SRN STREAM SHORT WAVE WILL BRING SOME ENHANCED
MID LEVEL MOISTURE...SO THE OVERALL MOISTURE PROFILE WILL STILL BE
RELATIVELY MOIST WITH THE MODELS INDICATING PWATS OF AROUND 1 INCH
WITH THE FROPA.  SO...EXPECT THAT ENTIRE CWA SHOULD SEE WETTING
RAINFALL THROUGH THE DAY TOMORROW...POSSIBLY LINGERING INTO TOMORROW
EVENING OVER THE FAR ERN PORTIONS OF THE CWA...THE STEADILY
PROGRESSIVE NATURE OF THE SYSTEM SHOULD LIMIT RAINFALL AMOUNTS TO
ARND A TENTH TO A QUARTER OF AN INCH WITH SOME OF THE HEAVIER
SHOWERS.  MODELS SOUNDINGS INDICATE LITTLE OR NO CAPE...SO THUNDER
SHOULD NOT BE AN ISSUE.

FOLLOWING THE PASSAGE OF THE FRONT...THE REAL WARMING TREND WILL
BEGIN IN EARNEST ON FRIDAY AS UPPER RIDGING BUILDS ACROSS THE
ROCKIES AND INTO THE WESTERN PLAINS...WHILE THE UPPER TROUGH AND
COLD FRONT MOVE TO THE EAST COAST.  BY FRIDAY...850MB TEMPS ARND 15C
WILL MOVE ACROSS THE AREA AND EXPECT THAT TEMPS SHOULD REACH INTO
THE MIDDLE TO UPPER 60S.  BY SATURDAY...THE THERMAL AXIS WILL SHIFT
TO THE SOUTH...ACROSS CNTRL/SRN IL/IN WHILE A DEEP UPPER LOW TRACKS
ACROSS THE UPPER GREAT LAKES.  THIS WILL LEAD TO MORE NWLY FLOW
ACROSS THE UPPER MIDWEST...AND POSSIBLY LIMITING WARMING ACROSS THE
NRN PORTIONS OF THE AREA...SO...WILL CARRY TEMPS IN THE LOWER TO
MIDDLE 60S NORTH OF THE I-80 CORRIDOR WITH TEMPS IN THE UPPER 60S
ACROSS THE SRN PORTIONS OF THE CWA.  WITH ENOUGH SUNSHINE...SOME 70F
MAX TEMPS ARE NOT OUT OF THE QUESTION FOR LOCATIONS SOUTH OF A
PONTIAC TO REMINGTON LINE.  THE RELATIVELY WARM AND DRY WEATHER WILL
PERSIST THROUGH THE WEEKEND AS THE UPPER RIDGE SLOWLY PROGRESSES
ACROSS THE CENTRAL CONUS.

THE NEXT SIGNIFICANT CHANCE FOR PCPN WILL NOT BE UNTIL EARLY NEXT
WEEK WHEN THE UPPER RIDGE BUILDS TO THE EAST COAST AND A STRONG
PACIFIC SHORTWAVE DROPS FROM THE PACIFIC NORTHWEST TO THE FOUR
CORNERS AREA BY MONDAY AFTERNOON.  THIS WILL SET UP STRONG SWLY FLOW
ALOFT...WITH A TRAIN OF SOUTHERN STREAM SHORTWAVE ENERGY...WHILE AN
OPEN GULF OF MEXICO EVOLVES AT THE SURFACE.  INCREASED LOW LEVEL
MOISTURE AND MID LEVEL SHORT WAVE ENERGY WILL BRING A CHANCE FOR
SHOWERS AND POSSIBLY SOME THUNDERSTORMS FOR MONDAY NIGHT AND INTO
TUESDAY.  THE UNSEASONABLY HIGH TEMPERATURES WILL COME TO AN END BY
EARLY NEXT WEEK AS ANOTHER COLD FRONT IS EXPECTED TO CROSS THE
REGION.  THE LATEST LONG RANGE GUIDANCE SUGGESTS THAT THIS FRONT
SHOULD PUSH THROUGH THE AREA BY TUESDAY NIGHT OR WEDNESDAY...
BRINGING MAX TEMPS BACK INTO THE 50S.

KREIN

&&

.AVIATION...

//ORD AND MDW CONCERNS...UPDATED 20Z...

* -SHRA EXPECTED LATE THURSDAY AFTERNOON AND MVFR CIGS ARE PSBL.

JEE

//DISCUSSION...UPDATED 18Z...

QUIET HIGH PRESSURE IS OVERHEAD LEADING TO CONTINUED VFR
CONDITIONS OVERNIGHT. THE HIGH SHIFTS EAST TOMORROW AS A WEAK
SURFACE LOW OVER MANITOBA APPROACHES. THE MAIN LOW WILL REMAIN
OVER SOUTHERN CANADA AND WEAKEN AS IT MOVES INTO WESTERN ONTARIO.
AN UPPER LEVEL DISTURBANCE ASSOCIATED WITH THE LOWS WARM FRONT
PASSES OVERHEAD TOMORROW AFTERNOON AND THIS WILL BE THE TRIGGER
FOR PRECIP. THE DISTURBANCE AND FRONT WILL BE WEAKENING AS THEY
MOVE OVERHEAD SO HAVE LIMITED CONFIDENCE IN HOW LONG THE BAND OF
PRECIP WILL HOLD TOGETHER. MODELS ARE ALSO SLOWING THE SYSTEM SO
THE ONSET OF PRECIP MAY BE LATER THAN CURRENTLY INDICATED.

AS SUCH ONLY HAVE PRECIP MENTIONED AT ORD. COULD SEE PRECIP
REACHING RFD ARND 18Z...BUT GIVEN THE SLOWING TREND...OPTED TO
KEEP -SHRA OUT OF THE RFD TAF FOR NOW.

GUIDANCE DIFFERS ON CIGS WITH THE PRECIP AS WELL...WITH ONE MODEL
INDICATING MFVR OR LOWER CIGS. GIVEN THE DIFFERENCES AND WEAKENING
TREND...WENT WITH LOW END VFR CIGS WITH A SCT LATER OF MVFR.

LASTLY...WINDS TURN SSW TOMORROW MORNING AND WILL BE ARND 10 KT.

JEE

//ORD AND MDW CONFIDENCE...UPDATED 20Z...

* MEDIUM CONFIDENCE IN TIMING AND COVERAGE OF -SHRA THURSDAY.

* MEDIUM-LOW CONFIDENCE IN TIMING AND OCCURRENCE OF MVFR CIGS
  THURSDAY.

* HIGH CONFIDENCE IN ALL OTHER FORECAST ELEMENTS.

JEE

//OUTLOOK FOR ORD/MDW FOR 00Z FRIDAY-12Z WEDNESDAY...UPDATED 12Z...

* THURSDAY NIGHT...CHANCE OF SHRA. MVFR POSSIBLE.
* FRIDAY...DRY/VFR. SOUTHWEST WINDS.
* SATURDAY...DRY/VFR. GUSTY NORTHWEST WINDS.
* SUNDAY...DRY/VFR. SOUTH/SOUTHEAST WINDS.
* MONDAY...SLIGHT CHANCE OF SHRA. GUSTY SOUTH/SOUTHWEST WINDS.
* TUESDAY...CHANCE OF SHRA. STRONG/GUSTY WESTERLY WINDS.

&&

.MARINE...
158 PM CDT

THE WEATHER PATTERN ACROSS THE WESTERN GREAT LAKES REGION WILL
REMAIN FAIRLY PROGRESSIVE THROUGH THE WEEKEND AND INTO EARLY NEXT
WEEK...WITH SEVERAL FRONTAL PASSAGES ALTERNATING WITH WEAK HIGH
PRESSURE RIDGES.

HIGH PRESSURE WAS SITUATED OVER THE WESTERN LAKES THIS AFTERNOON...
BUT THE RIDGE WILL MOVE SLOWLY EAST TONIGHT WITH SOUTH WINDS
BECOMING STRONGER THURSDAY AS A TROUGH OF LOW PRESSURE MOVES INTO
THE UPPER MIDWEST. PRESSURE FALLS AHEAD OF THIS SYSTEM WILL LIKELY
LEAD TO SOUTH WINDS GUSTING TO 20-25 KT ESPECIALLY ACROSS THE
NORTHERN PART LAKE MICHIGAN THURSDAY AFTERNOON AND EVENING. THE COLD
FRONT ASSOCIATED WITH THIS TROUGH WILL WEAKEN AS IT MOVES THROUGH
THE REGION EARLY FRIDAY...WITH WINDS BACKING SOUTH AGAIN AHEAD OF
ANOTHER DISTURBANCE EMERGING FROM THE NORTHERN PLAINS. THIS NEXT
TROUGH AND COLD FRONT WILL PASS LATE FRIDAY NIGHT...WITH WINDS
VEERING TO THE WEST AND AGAIN GUSTING AS HIGH AS 30 KT INTO SATURDAY
AND SATURDAY NIGHT. A FEW GUSTS NEAR GALE FORCE MAY BE POSSIBLE
SATURDAY NIGHT AS COLDER AIR STEEPENS THE LOW LEVEL LAPSE RATES OVER
THE LAKE AND ALLOWS DEEPER MIXING OF THE HIGHER MOMENTUM AIR FROM
ABOVE. WINDS WILL THEN EASE SUNDAY AS ANOTHER WEAK HIGH PRESSURE
RIDGE MOVES ACROSS THE LAKE LATE IN THE DAY.

A DEEPER LOW PRESSURE SYSTEM IS FORECAST TO DEVELOP OVER THE PLAINS
AND LIFT NORTHEAST ACROSS THE UPPER MIDWEST SUNDAY NIGHT THROUGH
TUESDAY. SURFACE PRESSURE FALLS AND A RESULTING TIGHTENING OF THE
SURFACE PRESSURE GRADIENT WILL RESULT IN WINDS BACK TO THE
SOUTH-SOUTHEAST BY EARLY MONDAY...WITH SPEEDS INCREASING INTO THE
20-30 KT RANGE AGAIN.

RATZER

&&

.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...NONE.
&&

$$

VISIT US AT HTTP://WEATHER.GOV/CHICAGO (ALL LOWERCASE)

FOLLOW US ON FACEBOOK...TWITTER...AND YOUTUBE AT:
WWW.FACEBOOK.COM/NWSCHICAGO
WWW.TWITTER.COM/NWSCHICAGO
WWW.YOUTUBE.COM/NWSCHICAGO







000
FXUS63 KLOT 221955
AFDLOT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
255 PM CDT WED OCT 22 2014

.DISCUSSION...
310 AM CDT

TRANSITION AWAY FROM THE BELOW AVERAGE TEMPS OF LATE TO WARMER THAN
AVERAGE TEMPS BY THIS WEEKEND INTO EARLY NEXT WEEK STILL ON
TRACK...WITH A COUPLE SHOTS OF RAIN POSSIBLE.

ANY LINGERING LAKE CLOUDINESS IN NE IL EARLY THIS MORNING WILL FADE
WITH 100% SUNSHINE LOOKING LIKELY TODAY. TEMPERATURES SHOULD
MODERATE SEVERAL DEGREES OVER YESTERDAY MOST AREAS...THOUGH LAKE
ADJACENT AREAS OF NE IL WILL STILL FACE ONSHORE WINDS AND COOLER
TEMPS THAN THE REMAINDER OF THE CWA. MAINLY CLEAR SKIES AND LIGHT
WINDS SHOULD ALLOW FOR ANOTHER CHILLY NIGHT TONIGHT.

SKIES WILL CLOUD OVER THURSDAY LEAVING OUR PROSPECTS FOR SEEING THE
SOLAR ECLIPSE THURSDAY AFTERNOON DIM. SHARP UPPER TROUGH WILL
APPROACH FROM THE WEST THURSDAY AND DESPITE RELATIVE LACK OF
MOISTURE...FORCING LOOKS TO BE STRONG ENOUGH TO PROVIDE FOR A DECENT
SHOT OF SHOWERS SPREADING FROM WEST TO EAST THURSDAY AND ENDING
EASTERN CWA THURSDAY EVENING. SOUTHERN EXTENT OF THIS SHORTWAVE WILL
BE WEAKENING AS IT RUNS INTO THE NARROW RIDGE BEHIND THE LARGE
EASTERN CONUS UPPER LOW. THE ANTICIPATED GRADUAL WEAKENING OF THE
TROUGH IN OUR NECK OF THE WOODS IS REASONING FOR HIGHEST POPS WEST
AND LOWER POPS EAST...THOUGH GUIDANCE OFTEN WEAKENS THESE SYSTEMS
TOO QUICKLY AND HAVE GENERALLY GONE WITH HIGHER MOS POPS FOR THIS
SYSTEM.

WARM ADVECTION WILL RAMP UP BEHIND THIS SYSTEM AS UPPER RIDGING
BRIEFLY BUILDS INTO THE AREA FRIDAY ALLOWING FOR MODERATING TEMPS.
THE 00Z WRF-NAM DID HAVE A STRONGER TROUGH MOVING THROUGH ON FRIDAY
WITH SOME LIGHT QPF...BUT GIVEN THE GLOBAL MODELS ALL MUCH MORE
MUTED WITH THIS TROUGH WITH NO PRECIP HAVE BUMPED UP SKY COVER A BIT
AND POPS UP TO 10% BUT KEPT FORECAST DRY FOR NOW.

PATTERN WILL REMAIN QUITE AMPLIFIED THROUGH THE WEEKEND WITH DEEP
TROUGH TO OUR NE AND UPPER RIDGE BUILDING INTO THE CENTRAL CONUS.
GUIDANCE HAS TRENDED A BIT FARTHER WEST WITH THE NE CONUS UPPER
TROUGH THIS WEEKEND PLACING OUR CWA A BIT CLOSER TO THE COOLER AIR
MASS...BUT STILL EXPECT HIGHS TO MAKE IT INTO THE 60S. IT NOW
APPEARS THE GFS...ECMWF...AND GEM HAVE MONDAY AS OUR WARMEST DAY
WITH 850MB TEMPS PROGGED TO BE AROUND 1.5 STANDARD DEVIATIONS ABOVE
AVERAGE. GIVEN THE INCREASING SOUTHERLY WINDS THINK MOST OF THE CWA
STANDS A DECENT SHOT TO TAG 70F WITH ENSEMBLE MAX TEMPS AS WARM AS
THE MID TO UPPER 70S. COLD FRONT LOOKS TO END OUR BRIEF STINT OF
INDIAN SUMMER MONDAY NIGHT OR TUESDAY WITH SHOWERS AND POSSIBLY SOME
THUNDERSTORMS ACCOMPANYING THE FRONT.

IZZI

&&

.AVIATION...

//ORD AND MDW CONCERNS...UPDATED 20Z...

* -SHRA EXPECTED LATE THURSDAY AFTERNOON AND MVFR CIGS ARE PSBL.

JEE

//DISCUSSION...UPDATED 18Z...

QUIET HIGH PRESSURE IS OVERHEAD LEADING TO CONTINUED VFR
CONDITIONS OVERNIGHT. THE HIGH SHIFTS EAST TOMORROW AS A WEAK
SURFACE LOW OVER MANITOBA APPROACHES. THE MAIN LOW WILL REMAIN
OVER SOUTHERN CANADA AND WEAKEN AS IT MOVES INTO WESTERN ONTARIO.
AN UPPER LEVEL DISTURBANCE ASSOCIATED WITH THE LOWS WARM FRONT
PASSES OVERHEAD TOMORROW AFTERNOON AND THIS WILL BE THE TRIGGER
FOR PRECIP. THE DISTURBANCE AND FRONT WILL BE WEAKENING AS THEY
MOVE OVERHEAD SO HAVE LIMITED CONFIDENCE IN HOW LONG THE BAND OF
PRECIP WILL HOLD TOGETHER. MODELS ARE ALSO SLOWING THE SYSTEM SO
THE ONSET OF PRECIP MAY BE LATER THAN CURRENTLY INDICATED.

AS SUCH ONLY HAVE PRECIP MENTIONED AT ORD. COULD SEE PRECIP
REACHING RFD ARND 18Z...BUT GIVEN THE SLOWING TREND...OPTED TO
KEEP -SHRA OUT OF THE RFD TAF FOR NOW.

GUIDANCE DIFFERS ON CIGS WITH THE PRECIP AS WELL...WITH ONE MODEL
INDICATING MFVR OR LOWER CIGS. GIVEN THE DIFFERENCES AND WEAKENING
TREND...WENT WITH LOW END VFR CIGS WITH A SCT LATER OF MVFR.

LASTLY...WINDS TURN SSW TOMORROW MORNING AND WILL BE ARND 10 KT.

JEE

//ORD AND MDW CONFIDENCE...UPDATED 20Z...

* MEDIUM CONFIDENCE IN TIMING AND COVERAGE OF -SHRA THURSDAY.

* MEDIUM-LOW CONFIDENCE IN TIMING AND OCCURRENCE OF MVFR CIGS
  THURSDAY.

* HIGH CONFIDENCE IN ALL OTHER FORECAST ELEMENTS.

JEE

//OUTLOOK FOR ORD/MDW FOR 00Z FRIDAY-12Z WEDNESDAY...UPDATED 12Z...

* THURSDAY NIGHT...CHANCE OF SHRA. MVFR POSSIBLE.
* FRIDAY...DRY/VFR. SOUTHWEST WINDS.
* SATURDAY...DRY/VFR. GUSTY NORTHWEST WINDS.
* SUNDAY...DRY/VFR. SOUTH/SOUTHEAST WINDS.
* MONDAY...SLIGHT CHANCE OF SHRA. GUSTY SOUTH/SOUTHWEST WINDS.
* TUESDAY...CHANCE OF SHRA. STRONG/GUSTY WESTERLY WINDS.

&&

.MARINE...
158 PM CDT

THE WEATHER PATTERN ACROSS THE WESTERN GREAT LAKES REGION WILL
REMAIN FAIRLY PROGRESSIVE THROUGH THE WEEKEND AND INTO EARLY NEXT
WEEK...WITH SEVERAL FRONTAL PASSAGES ALTERNATING WITH WEAK HIGH
PRESSURE RIDGES.

HIGH PRESSURE WAS SITUATED OVER THE WESTERN LAKES THIS AFTERNOON...
BUT THE RIDGE WILL MOVE SLOWLY EAST TONIGHT WITH SOUTH WINDS
BECOMING STRONGER THURSDAY AS A TROUGH OF LOW PRESSURE MOVES INTO
THE UPPER MIDWEST. PRESSURE FALLS AHEAD OF THIS SYSTEM WILL LIKELY
LEAD TO SOUTH WINDS GUSTING TO 20-25 KT ESPECIALLY ACROSS THE
NORTHERN PART LAKE MICHIGAN THURSDAY AFTERNOON AND EVENING. THE COLD
FRONT ASSOCIATED WITH THIS TROUGH WILL WEAKEN AS IT MOVES THROUGH
THE REGION EARLY FRIDAY...WITH WINDS BACKING SOUTH AGAIN AHEAD OF
ANOTHER DISTURBANCE EMERGING FROM THE NORTHERN PLAINS. THIS NEXT
TROUGH AND COLD FRONT WILL PASS LATE FRIDAY NIGHT...WITH WINDS
VEERING TO THE WEST AND AGAIN GUSTING AS HIGH AS 30 KT INTO SATURDAY
AND SATURDAY NIGHT. A FEW GUSTS NEAR GALE FORCE MAY BE POSSIBLE
SATURDAY NIGHT AS COLDER AIR STEEPENS THE LOW LEVEL LAPSE RATES OVER
THE LAKE AND ALLOWS DEEPER MIXING OF THE HIGHER MOMENTUM AIR FROM
ABOVE. WINDS WILL THEN EASE SUNDAY AS ANOTHER WEAK HIGH PRESSURE
RIDGE MOVES ACROSS THE LAKE LATE IN THE DAY.

A DEEPER LOW PRESSURE SYSTEM IS FORECAST TO DEVELOP OVER THE PLAINS
AND LIFT NORTHEAST ACROSS THE UPPER MIDWEST SUNDAY NIGHT THROUGH
TUESDAY. SURFACE PRESSURE FALLS AND A RESULTING TIGHTENING OF THE
SURFACE PRESSURE GRADIENT WILL RESULT IN WINDS BACK TO THE
SOUTH-SOUTHEAST BY EARLY MONDAY...WITH SPEEDS INCREASING INTO THE
20-30 KT RANGE AGAIN.

RATZER

&&

.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...NONE.
&&

$$

VISIT US AT HTTP://WEATHER.GOV/CHICAGO (ALL LOWERCASE)

FOLLOW US ON FACEBOOK...TWITTER...AND YOUTUBE AT:
WWW.FACEBOOK.COM/NWSCHICAGO
WWW.TWITTER.COM/NWSCHICAGO
WWW.YOUTUBE.COM/NWSCHICAGO







000
FXUS63 KLOT 221859
AFDLOT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
159 PM CDT WED OCT 22 2014

.DISCUSSION...
310 AM CDT

TRANSITION AWAY FROM THE BELOW AVERAGE TEMPS OF LATE TO WARMER THAN
AVERAGE TEMPS BY THIS WEEKEND INTO EARLY NEXT WEEK STILL ON
TRACK...WITH A COUPLE SHOTS OF RAIN POSSIBLE.

ANY LINGERING LAKE CLOUDINESS IN NE IL EARLY THIS MORNING WILL FADE
WITH 100% SUNSHINE LOOKING LIKELY TODAY. TEMPERATURES SHOULD
MODERATE SEVERAL DEGREES OVER YESTERDAY MOST AREAS...THOUGH LAKE
ADJACENT AREAS OF NE IL WILL STILL FACE ONSHORE WINDS AND COOLER
TEMPS THAN THE REMAINDER OF THE CWA. MAINLY CLEAR SKIES AND LIGHT
WINDS SHOULD ALLOW FOR ANOTHER CHILLY NIGHT TONIGHT.

SKIES WILL CLOUD OVER THURSDAY LEAVING OUR PROSPECTS FOR SEEING THE
SOLAR ECLIPSE THURSDAY AFTERNOON DIM. SHARP UPPER TROUGH WILL
APPROACH FROM THE WEST THURSDAY AND DESPITE RELATIVE LACK OF
MOISTURE...FORCING LOOKS TO BE STRONG ENOUGH TO PROVIDE FOR A DECENT
SHOT OF SHOWERS SPREADING FROM WEST TO EAST THURSDAY AND ENDING
EASTERN CWA THURSDAY EVENING. SOUTHERN EXTENT OF THIS SHORTWAVE WILL
BE WEAKENING AS IT RUNS INTO THE NARROW RIDGE BEHIND THE LARGE
EASTERN CONUS UPPER LOW. THE ANTICIPATED GRADUAL WEAKENING OF THE
TROUGH IN OUR NECK OF THE WOODS IS REASONING FOR HIGHEST POPS WEST
AND LOWER POPS EAST...THOUGH GUIDANCE OFTEN WEAKENS THESE SYSTEMS
TOO QUICKLY AND HAVE GENERALLY GONE WITH HIGHER MOS POPS FOR THIS
SYSTEM.

WARM ADVECTION WILL RAMP UP BEHIND THIS SYSTEM AS UPPER RIDGING
BRIEFLY BUILDS INTO THE AREA FRIDAY ALLOWING FOR MODERATING TEMPS.
THE 00Z WRF-NAM DID HAVE A STRONGER TROUGH MOVING THROUGH ON FRIDAY
WITH SOME LIGHT QPF...BUT GIVEN THE GLOBAL MODELS ALL MUCH MORE
MUTED WITH THIS TROUGH WITH NO PRECIP HAVE BUMPED UP SKY COVER A BIT
AND POPS UP TO 10% BUT KEPT FORECAST DRY FOR NOW.

PATTERN WILL REMAIN QUITE AMPLIFIED THROUGH THE WEEKEND WITH DEEP
TROUGH TO OUR NE AND UPPER RIDGE BUILDING INTO THE CENTRAL CONUS.
GUIDANCE HAS TRENDED A BIT FARTHER WEST WITH THE NE CONUS UPPER
TROUGH THIS WEEKEND PLACING OUR CWA A BIT CLOSER TO THE COOLER AIR
MASS...BUT STILL EXPECT HIGHS TO MAKE IT INTO THE 60S. IT NOW
APPEARS THE GFS...ECMWF...AND GEM HAVE MONDAY AS OUR WARMEST DAY
WITH 850MB TEMPS PROGGED TO BE AROUND 1.5 STANDARD DEVIATIONS ABOVE
AVERAGE. GIVEN THE INCREASING SOUTHERLY WINDS THINK MOST OF THE CWA
STANDS A DECENT SHOT TO TAG 70F WITH ENSEMBLE MAX TEMPS AS WARM AS
THE MID TO UPPER 70S. COLD FRONT LOOKS TO END OUR BRIEF STINT OF
INDIAN SUMMER MONDAY NIGHT OR TUESDAY WITH SHOWERS AND POSSIBLY SOME
THUNDERSTORMS ACCOMPANYING THE FRONT.

IZZI

&&

.AVIATION...

//ORD AND MDW CONCERNS...UPDATED 18Z...

* -SHRA EXPECTED LATE THURSDAY AFTERNOON AND MVFR CIGS ARE PSBL.

JEE

//DISCUSSION...UPDATED 18Z...

QUIET HIGH PRESSURE IS OVERHEAD LEADING TO CONTINUED VFR
CONDITIONS OVERNIGHT. THE HIGH SHIFTS EAST TOMORROW AS A WEAK
SURFACE LOW OVER MANITOBA APPROACHES. THE MAIN LOW WILL REMAIN
OVER SOUTHERN CANADA AND WEAKEN AS IT MOVES INTO WESTERN ONTARIO.
AN UPPER LEVEL DISTURBANCE ASSOCIATED WITH THE LOWS WARM FRONT
PASSES OVERHEAD TOMORROW AFTERNOON AND THIS WILL BE THE TRIGGER
FOR PRECIP. THE DISTURBANCE AND FRONT WILL BE WEAKENING AS THEY
MOVE OVERHEAD SO HAVE LIMITED CONFIDENCE IN HOW LONG THE BAND OF
PRECIP WILL HOLD TOGETHER. MODELS ARE ALSO SLOWING THE SYSTEM SO
THE ONSET OF PRECIP MAY BE LATER THAN CURRENTLY INDICATED.

AS SUCH ONLY HAVE PRECIP MENTIONED AT ORD. COULD SEE PRECIP
REACHING RFD ARND 18Z...BUT GIVEN THE SLOWING TREND...OPTED TO
KEEP -SHRA OUT OF THE RFD TAF FOR NOW.

GUIDANCE DIFFERS ON CIGS WITH THE PRECIP AS WELL...WITH ONE MODEL
INDICATING MFVR OR LOWER CIGS. GIVEN THE DIFFERENCES AND WEAKENING
TREND...WENT WITH LOW END VFR CIGS WITH A SCT LATER OF MVFR.

LASTLY...WINDS TURN SSW TOMORROW MORNING AND WILL BE ARND 10 KT.

JEE

//ORD AND MDW CONFIDENCE...UPDATED 18Z...

* MEDIUM CONFIDENCE IN TIMING AND COVERAGE OF -SHRA THURSDAY.

* MEDIUM-LOW CONFIDENCE IN TIMING AND OCCURRENCE OF MVFR CIGS
  THURSDAY.

* HIGH CONFIDENCE IN ALL OTHER FORECAST ELEMENTS.

JEE

//OUTLOOK FOR ORD/MDW FOR 00Z FRIDAY-12Z WEDNESDAY...UPDATED 12Z...

* THURSDAY NIGHT...CHANCE OF SHRA. MVFR POSSIBLE.
* FRIDAY...DRY/VFR. SOUTHWEST WINDS.
* SATURDAY...DRY/VFR. GUSTY NORTHWEST WINDS.
* SUNDAY...DRY/VFR. SOUTH/SOUTHEAST WINDS.
* MONDAY...SLIGHT CHANCE OF SHRA. GUSTY SOUTH/SOUTHWEST WINDS.
* TUESDAY...CHANCE OF SHRA. STRONG/GUSTY WESTERLY WINDS.

&&

.MARINE...
158 PM CDT

THE WEATHER PATTERN ACROSS THE WESTERN GREAT LAKES REGION WILL
REMAIN FAIRLY PROGRESSIVE THROUGH THE WEEKEND AND INTO EARLY NEXT
WEEK...WITH SEVERAL FRONTAL PASSAGES ALTERNATING WITH WEAK HIGH
PRESSURE RIDGES.

HIGH PRESSURE WAS SITUATED OVER THE WESTERN LAKES THIS AFTERNOON...
BUT THE RIDGE WILL MOVE SLOWLY EAST TONIGHT WITH SOUTH WINDS
BECOMING STRONGER THURSDAY AS A TROUGH OF LOW PRESSURE MOVES INTO
THE UPPER MIDWEST. PRESSURE FALLS AHEAD OF THIS SYSTEM WILL LIKELY
LEAD TO SOUTH WINDS GUSTING TO 20-25 KT ESPECIALLY ACROSS THE
NORTHERN PART LAKE MICHIGAN THURSDAY AFTERNOON AND EVENING. THE COLD
FRONT ASSOCIATED WITH THIS TROUGH WILL WEAKEN AS IT MOVES THROUGH
THE REGION EARLY FRIDAY...WITH WINDS BACKING SOUTH AGAIN AHEAD OF
ANOTHER DISTURBANCE EMERGING FROM THE NORTHERN PLAINS. THIS NEXT
TROUGH AND COLD FRONT WILL PASS LATE FRIDAY NIGHT...WITH WINDS
VEERING TO THE WEST AND AGAIN GUSTING AS HIGH AS 30 KT INTO SATURDAY
AND SATURDAY NIGHT. A FEW GUSTS NEAR GALE FORCE MAY BE POSSIBLE
SATURDAY NIGHT AS COLDER AIR STEEPENS THE LOW LEVEL LAPSE RATES OVER
THE LAKE AND ALLOWS DEEPER MIXING OF THE HIGHER MOMENTUM AIR FROM
ABOVE. WINDS WILL THEN EASE SUNDAY AS ANOTHER WEAK HIGH PRESSURE
RIDGE MOVES ACROSS THE LAKE LATE IN THE DAY.

A DEEPER LOW PRESSURE SYSTEM IS FORECAST TO DEVELOP OVER THE PLAINS
AND LIFT NORTHEAST ACROSS THE UPPER MIDWEST SUNDAY NIGHT THROUGH
TUESDAY. SURFACE PRESSURE FALLS AND A RESULTING TIGHTENING OF THE
SURFACE PRESSURE GRADIENT WILL RESULT IN WINDS BACK TO THE
SOUTH-SOUTHEAST BY EARLY MONDAY...WITH SPEEDS INCREASING INTO THE
20-30 KT RANGE AGAIN.

RATZER

&&

.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...NONE.
&&

$$

VISIT US AT HTTP://WEATHER.GOV/CHICAGO (ALL LOWERCASE)

FOLLOW US ON FACEBOOK...TWITTER...AND YOUTUBE AT:
WWW.FACEBOOK.COM/NWSCHICAGO
WWW.TWITTER.COM/NWSCHICAGO
WWW.YOUTUBE.COM/NWSCHICAGO







000
FXUS63 KLOT 221742
AFDLOT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
1242 PM CDT WED OCT 22 2014

.DISCUSSION...
310 AM CDT

TRANSITION AWAY FROM THE BELOW AVERAGE TEMPS OF LATE TO WARMER THAN
AVERAGE TEMPS BY THIS WEEKEND INTO EARLY NEXT WEEK STILL ON
TRACK...WITH A COUPLE SHOTS OF RAIN POSSIBLE.

ANY LINGERING LAKE CLOUDINESS IN NE IL EARLY THIS MORNING WILL FADE
WITH 100% SUNSHINE LOOKING LIKELY TODAY. TEMPERATURES SHOULD
MODERATE SEVERAL DEGREES OVER YESTERDAY MOST AREAS...THOUGH LAKE
ADJACENT AREAS OF NE IL WILL STILL FACE ONSHORE WINDS AND COOLER
TEMPS THAN THE REMAINDER OF THE CWA. MAINLY CLEAR SKIES AND LIGHT
WINDS SHOULD ALLOW FOR ANOTHER CHILLY NIGHT TONIGHT.

SKIES WILL CLOUD OVER THURSDAY LEAVING OUR PROSPECTS FOR SEEING THE
SOLAR ECLIPSE THURSDAY AFTERNOON DIM. SHARP UPPER TROUGH WILL
APPROACH FROM THE WEST THURSDAY AND DESPITE RELATIVE LACK OF
MOISTURE...FORCING LOOKS TO BE STRONG ENOUGH TO PROVIDE FOR A DECENT
SHOT OF SHOWERS SPREADING FROM WEST TO EAST THURSDAY AND ENDING
EASTERN CWA THURSDAY EVENING. SOUTHERN EXTENT OF THIS SHORTWAVE WILL
BE WEAKENING AS IT RUNS INTO THE NARROW RIDGE BEHIND THE LARGE
EASTERN CONUS UPPER LOW. THE ANTICIPATED GRADUAL WEAKENING OF THE
TROUGH IN OUR NECK OF THE WOODS IS REASONING FOR HIGHEST POPS WEST
AND LOWER POPS EAST...THOUGH GUIDANCE OFTEN WEAKENS THESE SYSTEMS
TOO QUICKLY AND HAVE GENERALLY GONE WITH HIGHER MOS POPS FOR THIS
SYSTEM.

WARM ADVECTION WILL RAMP UP BEHIND THIS SYSTEM AS UPPER RIDGING
BRIEFLY BUILDS INTO THE AREA FRIDAY ALLOWING FOR MODERATING TEMPS.
THE 00Z WRF-NAM DID HAVE A STRONGER TROUGH MOVING THROUGH ON FRIDAY
WITH SOME LIGHT QPF...BUT GIVEN THE GLOBAL MODELS ALL MUCH MORE
MUTED WITH THIS TROUGH WITH NO PRECIP HAVE BUMPED UP SKY COVER A BIT
AND POPS UP TO 10% BUT KEPT FORECAST DRY FOR NOW.

PATTERN WILL REMAIN QUITE AMPLIFIED THROUGH THE WEEKEND WITH DEEP
TROUGH TO OUR NE AND UPPER RIDGE BUILDING INTO THE CENTRAL CONUS.
GUIDANCE HAS TRENDED A BIT FARTHER WEST WITH THE NE CONUS UPPER
TROUGH THIS WEEKEND PLACING OUR CWA A BIT CLOSER TO THE COOLER AIR
MASS...BUT STILL EXPECT HIGHS TO MAKE IT INTO THE 60S. IT NOW
APPEARS THE GFS...ECMWF...AND GEM HAVE MONDAY AS OUR WARMEST DAY
WITH 850MB TEMPS PROGGED TO BE AROUND 1.5 STANDARD DEVIATIONS ABOVE
AVERAGE. GIVEN THE INCREASING SOUTHERLY WINDS THINK MOST OF THE CWA
STANDS A DECENT SHOT TO TAG 70F WITH ENSEMBLE MAX TEMPS AS WARM AS
THE MID TO UPPER 70S. COLD FRONT LOOKS TO END OUR BRIEF STINT OF
INDIAN SUMMER MONDAY NIGHT OR TUESDAY WITH SHOWERS AND POSSIBLY SOME
THUNDERSTORMS ACCOMPANYING THE FRONT.

IZZI

&&

.AVIATION...

//ORD AND MDW CONCERNS...UPDATED 18Z...

* -SHRA EXPECTED LATE THURSDAY AFTERNOON AND MVFR CIGS ARE PSBL.

JEE

//DISCUSSION...UPDATED 18Z...

QUIET HIGH PRESSURE IS OVERHEAD LEADING TO CONTINUED VFR
CONDITIONS OVERNIGHT. THE HIGH SHIFTS EAST TOMORROW AS A WEAK
SURFACE LOW OVER MANITOBA APPROACHES. THE MAIN LOW WILL REMAIN
OVER SOUTHERN CANADA AND WEAKEN AS IT MOVES INTO WESTERN ONTARIO.
AN UPPER LEVEL DISTURBANCE ASSOCIATED WITH THE LOWS WARM FRONT
PASSES OVERHEAD TOMORROW AFTERNOON AND THIS WILL BE THE TRIGGER
FOR PRECIP. THE DISTURBANCE AND FRONT WILL BE WEAKENING AS THEY
MOVE OVERHEAD SO HAVE LIMITED CONFIDENCE IN HOW LONG THE BAND OF
PRECIP WILL HOLD TOGETHER. MODELS ARE ALSO SLOWING THE SYSTEM SO
THE ONSET OF PRECIP MAY BE LATER THAN CURRENTLY INDICATED.

AS SUCH ONLY HAVE PRECIP MENTIONED AT ORD. COULD SEE PRECIP
REACHING RFD ARND 18Z...BUT GIVEN THE SLOWING TREND...OPTED TO
KEEP -SHRA OUT OF THE RFD TAF FOR NOW.

GUIDANCE DIFFERS ON CIGS WITH THE PRECIP AS WELL...WITH ONE MODEL
INDICATING MFVR OR LOWER CIGS. GIVEN THE DIFFERENCES AND WEAKENING
TREND...WENT WITH LOW END VFR CIGS WITH A SCT LATER OF MVFR.

LASTLY...WINDS TURN SSW TOMORROW MORNING AND WILL BE ARND 10 KT.

JEE


//ORD AND MDW CONFIDENCE...UPDATED 18Z...

* MEDIUM CONFIDENCE IN TIMING AND COVERAGE OF -SHRA THURSDAY.

* MEDIUM-LOW CONFIDENCE IN TIMING AND OCCURRENCE OF MVFR CIGS
  THURSDAY.

* HIGH CONFIDENCE IN ALL OTHER FORECAST ELEMENTS.

JEE

//OUTLOOK FOR ORD/MDW FOR 00Z FRIDAY-12Z WEDNESDAY...UPDATED 12Z...

* THURSDAY NIGHT...CHANCE OF SHRA. MVFR POSSIBLE.
* FRIDAY...DRY/VFR. SOUTHWEST WINDS.
* SATURDAY...DRY/VFR. GUSTY NORTHWEST WINDS.
* SUNDAY...DRY/VFR. SOUTH/SOUTHEAST WINDS.
* MONDAY...SLIGHT CHANCE OF SHRA. GUSTY SOUTH/SOUTHWEST WINDS.
* TUESDAY...CHANCE OF SHRA. STRONG/GUSTY WESTERLY WINDS.

&&

.MARINE...

324 AM...A LARGE RIDGE OF HIGH PRESSURE EXTENDS FROM QUEBEC INTO
THE WESTERN LAKES. THIS RIDGE WILL MOVE EAST TODAY AND TONIGHT AND
SLOWLY WEAKEN. EASTERLY WINDS WILL CONTINUE TO DIMINISH THIS
MORNING BUT WAVE ACTION...ESPECIALLY ACROSS THE SOUTHWESTERN PART
OF THE LAKE WILL SLOWLY SUBSIDE THIS MORNING. WINDS WILL TURN BACK
SOUTHERLY TONIGHT AND INCREASE ON THURSDAY AS THE GRADIENT
TIGHTENS AHEAD OF AN APPROACHING COLD FRONT WHICH WILL THEN MOVE
ACROSS THE LAKE THURSDAY NIGHT AS IT DISSIPATES. THE FLOW WILL
TURN BACK SOUTHWESTERLY FRIDAY AHEAD OF ANOTHER COLD FRONT WHICH
WILL MOVE ACROSS THE LAKE FRIDAY NIGHT INTO SATURDAY MORNING.
WINDS BEHIND THIS FRONT WILL INCREASE TO 15-25 KTS WITH HIGHER
WINDS POSSIBLE OVER THE NORTHERN PART OF THE LAKE. CMS

&&

.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...NONE.
&&

$$

VISIT US AT HTTP://WEATHER.GOV/CHICAGO (ALL LOWERCASE)

FOLLOW US ON FACEBOOK...TWITTER...AND YOUTUBE AT:
WWW.FACEBOOK.COM/NWSCHICAGO
WWW.TWITTER.COM/NWSCHICAGO
WWW.YOUTUBE.COM/NWSCHICAGO







000
FXUS63 KLOT 221742
AFDLOT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
1242 PM CDT WED OCT 22 2014

.DISCUSSION...
310 AM CDT

TRANSITION AWAY FROM THE BELOW AVERAGE TEMPS OF LATE TO WARMER THAN
AVERAGE TEMPS BY THIS WEEKEND INTO EARLY NEXT WEEK STILL ON
TRACK...WITH A COUPLE SHOTS OF RAIN POSSIBLE.

ANY LINGERING LAKE CLOUDINESS IN NE IL EARLY THIS MORNING WILL FADE
WITH 100% SUNSHINE LOOKING LIKELY TODAY. TEMPERATURES SHOULD
MODERATE SEVERAL DEGREES OVER YESTERDAY MOST AREAS...THOUGH LAKE
ADJACENT AREAS OF NE IL WILL STILL FACE ONSHORE WINDS AND COOLER
TEMPS THAN THE REMAINDER OF THE CWA. MAINLY CLEAR SKIES AND LIGHT
WINDS SHOULD ALLOW FOR ANOTHER CHILLY NIGHT TONIGHT.

SKIES WILL CLOUD OVER THURSDAY LEAVING OUR PROSPECTS FOR SEEING THE
SOLAR ECLIPSE THURSDAY AFTERNOON DIM. SHARP UPPER TROUGH WILL
APPROACH FROM THE WEST THURSDAY AND DESPITE RELATIVE LACK OF
MOISTURE...FORCING LOOKS TO BE STRONG ENOUGH TO PROVIDE FOR A DECENT
SHOT OF SHOWERS SPREADING FROM WEST TO EAST THURSDAY AND ENDING
EASTERN CWA THURSDAY EVENING. SOUTHERN EXTENT OF THIS SHORTWAVE WILL
BE WEAKENING AS IT RUNS INTO THE NARROW RIDGE BEHIND THE LARGE
EASTERN CONUS UPPER LOW. THE ANTICIPATED GRADUAL WEAKENING OF THE
TROUGH IN OUR NECK OF THE WOODS IS REASONING FOR HIGHEST POPS WEST
AND LOWER POPS EAST...THOUGH GUIDANCE OFTEN WEAKENS THESE SYSTEMS
TOO QUICKLY AND HAVE GENERALLY GONE WITH HIGHER MOS POPS FOR THIS
SYSTEM.

WARM ADVECTION WILL RAMP UP BEHIND THIS SYSTEM AS UPPER RIDGING
BRIEFLY BUILDS INTO THE AREA FRIDAY ALLOWING FOR MODERATING TEMPS.
THE 00Z WRF-NAM DID HAVE A STRONGER TROUGH MOVING THROUGH ON FRIDAY
WITH SOME LIGHT QPF...BUT GIVEN THE GLOBAL MODELS ALL MUCH MORE
MUTED WITH THIS TROUGH WITH NO PRECIP HAVE BUMPED UP SKY COVER A BIT
AND POPS UP TO 10% BUT KEPT FORECAST DRY FOR NOW.

PATTERN WILL REMAIN QUITE AMPLIFIED THROUGH THE WEEKEND WITH DEEP
TROUGH TO OUR NE AND UPPER RIDGE BUILDING INTO THE CENTRAL CONUS.
GUIDANCE HAS TRENDED A BIT FARTHER WEST WITH THE NE CONUS UPPER
TROUGH THIS WEEKEND PLACING OUR CWA A BIT CLOSER TO THE COOLER AIR
MASS...BUT STILL EXPECT HIGHS TO MAKE IT INTO THE 60S. IT NOW
APPEARS THE GFS...ECMWF...AND GEM HAVE MONDAY AS OUR WARMEST DAY
WITH 850MB TEMPS PROGGED TO BE AROUND 1.5 STANDARD DEVIATIONS ABOVE
AVERAGE. GIVEN THE INCREASING SOUTHERLY WINDS THINK MOST OF THE CWA
STANDS A DECENT SHOT TO TAG 70F WITH ENSEMBLE MAX TEMPS AS WARM AS
THE MID TO UPPER 70S. COLD FRONT LOOKS TO END OUR BRIEF STINT OF
INDIAN SUMMER MONDAY NIGHT OR TUESDAY WITH SHOWERS AND POSSIBLY SOME
THUNDERSTORMS ACCOMPANYING THE FRONT.

IZZI

&&

.AVIATION...

//ORD AND MDW CONCERNS...UPDATED 18Z...

* -SHRA EXPECTED LATE THURSDAY AFTERNOON AND MVFR CIGS ARE PSBL.

JEE

//DISCUSSION...UPDATED 18Z...

QUIET HIGH PRESSURE IS OVERHEAD LEADING TO CONTINUED VFR
CONDITIONS OVERNIGHT. THE HIGH SHIFTS EAST TOMORROW AS A WEAK
SURFACE LOW OVER MANITOBA APPROACHES. THE MAIN LOW WILL REMAIN
OVER SOUTHERN CANADA AND WEAKEN AS IT MOVES INTO WESTERN ONTARIO.
AN UPPER LEVEL DISTURBANCE ASSOCIATED WITH THE LOWS WARM FRONT
PASSES OVERHEAD TOMORROW AFTERNOON AND THIS WILL BE THE TRIGGER
FOR PRECIP. THE DISTURBANCE AND FRONT WILL BE WEAKENING AS THEY
MOVE OVERHEAD SO HAVE LIMITED CONFIDENCE IN HOW LONG THE BAND OF
PRECIP WILL HOLD TOGETHER. MODELS ARE ALSO SLOWING THE SYSTEM SO
THE ONSET OF PRECIP MAY BE LATER THAN CURRENTLY INDICATED.

AS SUCH ONLY HAVE PRECIP MENTIONED AT ORD. COULD SEE PRECIP
REACHING RFD ARND 18Z...BUT GIVEN THE SLOWING TREND...OPTED TO
KEEP -SHRA OUT OF THE RFD TAF FOR NOW.

GUIDANCE DIFFERS ON CIGS WITH THE PRECIP AS WELL...WITH ONE MODEL
INDICATING MFVR OR LOWER CIGS. GIVEN THE DIFFERENCES AND WEAKENING
TREND...WENT WITH LOW END VFR CIGS WITH A SCT LATER OF MVFR.

LASTLY...WINDS TURN SSW TOMORROW MORNING AND WILL BE ARND 10 KT.

JEE


//ORD AND MDW CONFIDENCE...UPDATED 18Z...

* MEDIUM CONFIDENCE IN TIMING AND COVERAGE OF -SHRA THURSDAY.

* MEDIUM-LOW CONFIDENCE IN TIMING AND OCCURRENCE OF MVFR CIGS
  THURSDAY.

* HIGH CONFIDENCE IN ALL OTHER FORECAST ELEMENTS.

JEE

//OUTLOOK FOR ORD/MDW FOR 00Z FRIDAY-12Z WEDNESDAY...UPDATED 12Z...

* THURSDAY NIGHT...CHANCE OF SHRA. MVFR POSSIBLE.
* FRIDAY...DRY/VFR. SOUTHWEST WINDS.
* SATURDAY...DRY/VFR. GUSTY NORTHWEST WINDS.
* SUNDAY...DRY/VFR. SOUTH/SOUTHEAST WINDS.
* MONDAY...SLIGHT CHANCE OF SHRA. GUSTY SOUTH/SOUTHWEST WINDS.
* TUESDAY...CHANCE OF SHRA. STRONG/GUSTY WESTERLY WINDS.

&&

.MARINE...

324 AM...A LARGE RIDGE OF HIGH PRESSURE EXTENDS FROM QUEBEC INTO
THE WESTERN LAKES. THIS RIDGE WILL MOVE EAST TODAY AND TONIGHT AND
SLOWLY WEAKEN. EASTERLY WINDS WILL CONTINUE TO DIMINISH THIS
MORNING BUT WAVE ACTION...ESPECIALLY ACROSS THE SOUTHWESTERN PART
OF THE LAKE WILL SLOWLY SUBSIDE THIS MORNING. WINDS WILL TURN BACK
SOUTHERLY TONIGHT AND INCREASE ON THURSDAY AS THE GRADIENT
TIGHTENS AHEAD OF AN APPROACHING COLD FRONT WHICH WILL THEN MOVE
ACROSS THE LAKE THURSDAY NIGHT AS IT DISSIPATES. THE FLOW WILL
TURN BACK SOUTHWESTERLY FRIDAY AHEAD OF ANOTHER COLD FRONT WHICH
WILL MOVE ACROSS THE LAKE FRIDAY NIGHT INTO SATURDAY MORNING.
WINDS BEHIND THIS FRONT WILL INCREASE TO 15-25 KTS WITH HIGHER
WINDS POSSIBLE OVER THE NORTHERN PART OF THE LAKE. CMS

&&

.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...NONE.
&&

$$

VISIT US AT HTTP://WEATHER.GOV/CHICAGO (ALL LOWERCASE)

FOLLOW US ON FACEBOOK...TWITTER...AND YOUTUBE AT:
WWW.FACEBOOK.COM/NWSCHICAGO
WWW.TWITTER.COM/NWSCHICAGO
WWW.YOUTUBE.COM/NWSCHICAGO







000
FXUS63 KLOT 221400
AFDLOT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
900 AM CDT WED OCT 22 2014

.DISCUSSION...
310 AM CDT

TRANSITION AWAY FROM THE BELOW AVERAGE TEMPS OF LATE TO WARMER THAN
AVERAGE TEMPS BY THIS WEEKEND INTO EARLY NEXT WEEK STILL ON
TRACK...WITH A COUPLE SHOTS OF RAIN POSSIBLE.

ANY LINGERING LAKE CLOUDINESS IN NE IL EARLY THIS MORNING WILL FADE
WITH 100% SUNSHINE LOOKING LIKELY TODAY. TEMPERATURES SHOULD
MODERATE SEVERAL DEGREES OVER YESTERDAY MOST AREAS...THOUGH LAKE
ADJACENT AREAS OF NE IL WILL STILL FACE ONSHORE WINDS AND COOLER
TEMPS THAN THE REMAINDER OF THE CWA. MAINLY CLEAR SKIES AND LIGHT
WINDS SHOULD ALLOW FOR ANOTHER CHILLY NIGHT TONIGHT.

SKIES WILL CLOUD OVER THURSDAY LEAVING OUR PROSPECTS FOR SEEING THE
SOLAR ECLIPSE THURSDAY AFTERNOON DIM. SHARP UPPER TROUGH WILL
APPROACH FROM THE WEST THURSDAY AND DESPITE RELATIVE LACK OF
MOISTURE...FORCING LOOKS TO BE STRONG ENOUGH TO PROVIDE FOR A DECENT
SHOT OF SHOWERS SPREADING FROM WEST TO EAST THURSDAY AND ENDING
EASTERN CWA THURSDAY EVENING. SOUTHERN EXTENT OF THIS SHORTWAVE WILL
BE WEAKENING AS IT RUNS INTO THE NARROW RIDGE BEHIND THE LARGE
EASTERN CONUS UPPER LOW. THE ANTICIPATED GRADUAL WEAKENING OF THE
TROUGH IN OUR NECK OF THE WOODS IS REASONING FOR HIGHEST POPS WEST
AND LOWER POPS EAST...THOUGH GUIDANCE OFTEN WEAKENS THESE SYSTEMS
TOO QUICKLY AND HAVE GENERALLY GONE WITH HIGHER MOS POPS FOR THIS
SYSTEM.

WARM ADVECTION WILL RAMP UP BEHIND THIS SYSTEM AS UPPER RIDGING
BRIEFLY BUILDS INTO THE AREA FRIDAY ALLOWING FOR MODERATING TEMPS.
THE 00Z WRF-NAM DID HAVE A STRONGER TROUGH MOVING THROUGH ON FRIDAY
WITH SOME LIGHT QPF...BUT GIVEN THE GLOBAL MODELS ALL MUCH MORE
MUTED WITH THIS TROUGH WITH NO PRECIP HAVE BUMPED UP SKY COVER A BIT
AND POPS UP TO 10% BUT KEPT FORECAST DRY FOR NOW.

PATTERN WILL REMAIN QUITE AMPLIFIED THROUGH THE WEEKEND WITH DEEP
TROUGH TO OUR NE AND UPPER RIDGE BUILDING INTO THE CENTRAL CONUS.
GUIDANCE HAS TRENDED A BIT FARTHER WEST WITH THE NE CONUS UPPER
TROUGH THIS WEEKEND PLACING OUR CWA A BIT CLOSER TO THE COOLER AIR
MASS...BUT STILL EXPECT HIGHS TO MAKE IT INTO THE 60S. IT NOW
APPEARS THE GFS...ECMWF...AND GEM HAVE MONDAY AS OUR WARMEST DAY
WITH 850MB TEMPS PROGGED TO BE AROUND 1.5 STANDARD DEVIATIONS ABOVE
AVERAGE. GIVEN THE INCREASING SOUTHERLY WINDS THINK MOST OF THE CWA
STANDS A DECENT SHOT TO TAG 70F WITH ENSEMBLE MAX TEMPS AS WARM AS
THE MID TO UPPER 70S. COLD FRONT LOOKS TO END OUR BRIEF STINT OF
INDIAN SUMMER MONDAY NIGHT OR TUESDAY WITH SHOWERS AND POSSIBLY SOME
THUNDERSTORMS ACCOMPANYING THE FRONT.

IZZI

&&

.AVIATION...

//ORD AND MDW CONCERNS...UPDATED 14Z...

* NONE.

JEE

//DISCUSSION...UPDATED 12Z...

3KFT CIGS CONTINUE TO SLOWLY DISSIPATE AS THEY SPREAD NORTH.
MAINTAINED CIGS FOR A FEW MORE HOURS AT ORD/MDW BUT SCATTERING
SHOULD CONTINUE OVER THE NEXT FEW HOURS.

NO CHANGE TO THE WINDS...STARTING CALM IN MANY LOCATIONS AND LIGHT
NORTHWESTERLY AT ORD/MDW. THESE SHOULD SHIFT TO THE EAST/SOUTHEAST
BY MID MORNING THEN TURN MORE EASTERLY THIS AFTERNOON WITH A
POSSIBLE LAKE BREEZE. PREVAILING SPEEDS SHOULD REMAIN BELOW 10KTS.
WINDS TURN LIGHT SOUTHEASTERLY THIS EVENING THEN SOUTHERLY
OVERNIGHT. CMS

//ORD AND MDW CONFIDENCE...UPDATED 14Z...

* HIGH CONFIDENCE IN ALL FORECAST ELEMENTS.

JEE

//OUTLOOK FOR ORD/MDW FOR 00Z FRIDAY-12Z WEDNESDAY...UPDATED 12Z...

* THURSDAY NIGHT...CHANCE OF SHRA. MVFR POSSIBLE.
* FRIDAY...DRY/VFR. SOUTHWEST WINDS.
* SATURDAY...DRY/VFR. GUSTY NORTHWEST WINDS.
* SUNDAY...DRY/VFR. SOUTH/SOUTHEAST WINDS.
* MONDAY...SLIGHT CHANCE OF SHRA. GUSTY SOUTH/SOUTHWEST WINDS.
* TUESDAY...CHANCE OF SHRA. STRONG/GUSTY WESTERLY WINDS.

&&

.MARINE...

324 AM...A LARGE RIDGE OF HIGH PRESSURE EXTENDS FROM QUEBEC INTO
THE WESTERN LAKES. THIS RIDGE WILL MOVE EAST TODAY AND TONIGHT AND
SLOWLY WEAKEN. EASTERLY WINDS WILL CONTINUE TO DIMINISH THIS
MORNING BUT WAVE ACTION...ESPECIALLY ACROSS THE SOUTHWESTERN PART
OF THE LAKE WILL SLOWLY SUBSIDE THIS MORNING. WINDS WILL TURN BACK
SOUTHERLY TONIGHT AND INCREASE ON THURSDAY AS THE GRADIENT
TIGHTENS AHEAD OF AN APPROACHING COLD FRONT WHICH WILL THEN MOVE
ACROSS THE LAKE THURSDAY NIGHT AS IT DISSIPATES. THE FLOW WILL
TURN BACK SOUTHWESTERLY FRIDAY AHEAD OF ANOTHER COLD FRONT WHICH
WILL MOVE ACROSS THE LAKE FRIDAY NIGHT INTO SATURDAY MORNING.
WINDS BEHIND THIS FRONT WILL INCREASE TO 15-25 KTS WITH HIGHER
WINDS POSSIBLE OVER THE NORTHERN PART OF THE LAKE. CMS

&&

.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...NONE.
&&

$$

VISIT US AT HTTP://WEATHER.GOV/CHICAGO (ALL LOWERCASE)

FOLLOW US ON FACEBOOK...TWITTER...AND YOUTUBE AT:
WWW.FACEBOOK.COM/NWSCHICAGO
WWW.TWITTER.COM/NWSCHICAGO
WWW.YOUTUBE.COM/NWSCHICAGO







000
FXUS63 KLOT 221139
AFDLOT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
639 AM CDT WED OCT 22 2014

.DISCUSSION...
310 AM CDT

TRANSITION AWAY FROM THE BELOW AVERAGE TEMPS OF LATE TO WARMER THAN
AVERAGE TEMPS BY THIS WEEKEND INTO EARLY NEXT WEEK STILL ON
TRACK...WITH A COUPLE SHOTS OF RAIN POSSIBLE.

ANY LINGERING LAKE CLOUDINESS IN NE IL EARLY THIS MORNING WILL FADE
WITH 100% SUNSHINE LOOKING LIKELY TODAY. TEMPERATURES SHOULD
MODERATE SEVERAL DEGREES OVER YESTERDAY MOST AREAS...THOUGH LAKE
ADJACENT AREAS OF NE IL WILL STILL FACE ONSHORE WINDS AND COOLER
TEMPS THAN THE REMAINDER OF THE CWA. MAINLY CLEAR SKIES AND LIGHT
WINDS SHOULD ALLOW FOR ANOTHER CHILLY NIGHT TONIGHT.

SKIES WILL CLOUD OVER THURSDAY LEAVING OUR PROSPECTS FOR SEEING THE
SOLAR ECLIPSE THURSDAY AFTERNOON DIM. SHARP UPPER TROUGH WILL
APPROACH FROM THE WEST THURSDAY AND DESPITE RELATIVE LACK OF
MOISTURE...FORCING LOOKS TO BE STRONG ENOUGH TO PROVIDE FOR A DECENT
SHOT OF SHOWERS SPREADING FROM WEST TO EAST THURSDAY AND ENDING
EASTERN CWA THURSDAY EVENING. SOUTHERN EXTENT OF THIS SHORTWAVE WILL
BE WEAKENING AS IT RUNS INTO THE NARROW RIDGE BEHIND THE LARGE
EASTERN CONUS UPPER LOW. THE ANTICIPATED GRADUAL WEAKENING OF THE
TROUGH IN OUR NECK OF THE WOODS IS REASONING FOR HIGHEST POPS WEST
AND LOWER POPS EAST...THOUGH GUIDANCE OFTEN WEAKENS THESE SYSTEMS
TOO QUICKLY AND HAVE GENERALLY GONE WITH HIGHER MOS POPS FOR THIS
SYSTEM.

WARM ADVECTION WILL RAMP UP BEHIND THIS SYSTEM AS UPPER RIDGING
BRIEFLY BUILDS INTO THE AREA FRIDAY ALLOWING FOR MODERATING TEMPS.
THE 00Z WRF-NAM DID HAVE A STRONGER TROUGH MOVING THROUGH ON FRIDAY
WITH SOME LIGHT QPF...BUT GIVEN THE GLOBAL MODELS ALL MUCH MORE
MUTED WITH THIS TROUGH WITH NO PRECIP HAVE BUMPED UP SKY COVER A BIT
AND POPS UP TO 10% BUT KEPT FORECAST DRY FOR NOW.

PATTERN WILL REMAIN QUITE AMPLIFIED THROUGH THE WEEKEND WITH DEEP
TROUGH TO OUR NE AND UPPER RIDGE BUILDING INTO THE CENTRAL CONUS.
GUIDANCE HAS TRENDED A BIT FARTHER WEST WITH THE NE CONUS UPPER
TROUGH THIS WEEKEND PLACING OUR CWA A BIT CLOSER TO THE COOLER AIR
MASS...BUT STILL EXPECT HIGHS TO MAKE IT INTO THE 60S. IT NOW
APPEARS THE GFS...ECMWF...AND GEM HAVE MONDAY AS OUR WARMEST DAY
WITH 850MB TEMPS PROGGED TO BE AROUND 1.5 STANDARD DEVIATIONS ABOVE
AVERAGE. GIVEN THE INCREASING SOUTHERLY WINDS THINK MOST OF THE CWA
STANDS A DECENT SHOT TO TAG 70F WITH ENSEMBLE MAX TEMPS AS WARM AS
THE MID TO UPPER 70S. COLD FRONT LOOKS TO END OUR BRIEF STINT OF
INDIAN SUMMER MONDAY NIGHT OR TUESDAY WITH SHOWERS AND POSSIBLY SOME
THUNDERSTORMS ACCOMPANYING THE FRONT.

IZZI

&&

.AVIATION...

//ORD AND MDW CONCERNS...UPDATED 12Z...

* MVFR CIGS THIS MORNING.
* EAST WINDS MID MORNING THRU EARLY EVENING. CMS

//DISCUSSION...UPDATED 12Z...

3KFT CIGS CONTINUE TO SLOWLY DISSIPATE AS THEY SPREAD NORTH.
MAINTAINED CIGS FOR A FEW MORE HOURS AT ORD/MDW BUT SCATTERING
SHOULD CONTINUE OVER THE NEXT FEW HOURS.

NO CHANGE TO THE WINDS...STARTING CALM IN MANY LOCATIONS AND LIGHT
NORTHWESTERLY AT ORD/MDW. THESE SHOULD SHIFT TO THE EAST/SOUTHEAST
BY MID MORNING THEN TURN MORE EASTERLY THIS AFTERNOON WITH A
POSSIBLE LAKE BREEZE. PREVAILING SPEEDS SHOULD REMAIN BELOW 10KTS.
WINDS TURN LIGHT SOUTHEASTERLY THIS EVENING THEN SOUTHERLY
OVERNIGHT. CMS

//ORD AND MDW CONFIDENCE...UPDATED 12Z...

* HIGH FOR MVFR CIGS THIS MORNING...MEDIUM FOR CLEARING TIMING.
* HIGH FOR WINDS THRU THE PERIOD. CMS

//OUTLOOK FOR ORD/MDW FOR 00Z FRIDAY-12Z WEDNESDAY...UPDATED 12Z...

* THURSDAY NIGHT...CHANCE OF SHRA. MVFR POSSIBLE.
* FRIDAY...DRY/VFR. SOUTHWEST WINDS.
* SATURDAY...DRY/VFR. GUSTY NORTHWEST WINDS.
* SUNDAY...DRY/VFR. SOUTH/SOUTHEAST WINDS.
* MONDAY...SLIGHT CHANCE OF SHRA. GUSTY SOUTH/SOUTHWEST WINDS.
* TUESDAY...CHANCE OF SHRA. STRONG/GUSTY WESTERLY WINDS.

&&

.MARINE...

324 AM...A LARGE RIDGE OF HIGH PRESSURE EXTENDS FROM QUEBEC INTO
THE WESTERN LAKES. THIS RIDGE WILL MOVE EAST TODAY AND TONIGHT AND
SLOWLY WEAKEN. EASTERLY WINDS WILL CONTINUE TO DIMINISH THIS
MORNING BUT WAVE ACTION...ESPECIALLY ACROSS THE SOUTHWESTERN PART
OF THE LAKE WILL SLOWLY SUBSIDE THIS MORNING. WINDS WILL TURN BACK
SOUTHERLY TONIGHT AND INCREASE ON THURSDAY AS THE GRADIENT
TIGHTENS AHEAD OF AN APPROACHING COLD FRONT WHICH WILL THEN MOVE
ACROSS THE LAKE THURSDAY NIGHT AS IT DISSIPATES. THE FLOW WILL
TURN BACK SOUTHWESTERLY FRIDAY AHEAD OF ANOTHER COLD FRONT WHICH
WILL MOVE ACROSS THE LAKE FRIDAY NIGHT INTO SATURDAY MORNING.
WINDS BEHIND THIS FRONT WILL INCREASE TO 15-25 KTS WITH HIGHER
WINDS POSSIBLE OVER THE NORTHERN PART OF THE LAKE. CMS

&&

.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...SMALL CRAFT ADVISORY...ILLINOIS NEARSHORE WATERS UNTIL 7 AM
     WEDNESDAY.

&&

$$

VISIT US AT HTTP://WEATHER.GOV/CHICAGO (ALL LOWERCASE)

FOLLOW US ON FACEBOOK...TWITTER...AND YOUTUBE AT:
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WWW.TWITTER.COM/NWSCHICAGO
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000
FXUS63 KLOT 220910
AFDLOT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
410 AM CDT WED OCT 22 2014

.DISCUSSION...
310 AM CDT

TRANSITION AWAY FROM THE BELOW AVERAGE TEMPS OF LATE TO WARMER THAN
AVERAGE TEMPS BY THIS WEEKEND INTO EARLY NEXT WEEK STILL ON
TRACK...WITH A COUPLE SHOTS OF RAIN POSSIBLE.

ANY LINGERING LAKE CLOUDINESS IN NE IL EARLY THIS MORNING WILL FADE
WITH 100% SUNSHINE LOOKING LIKELY TODAY. TEMPERATURES SHOULD
MODERATE SEVERAL DEGREES OVER YESTERDAY MOST AREAS...THOUGH LAKE
ADJACENT AREAS OF NE IL WILL STILL FACE ONSHORE WINDS AND COOLER
TEMPS THAN THE REMAINDER OF THE CWA. MAINLY CLEAR SKIES AND LIGHT
WINDS SHOULD ALLOW FOR ANOTHER CHILLY NIGHT TONIGHT.

SKIES WILL CLOUD OVER THURSDAY LEAVING OUR PROSPECTS FOR SEEING THE
SOLAR ECLIPSE THURSDAY AFTERNOON DIM. SHARP UPPER TROUGH WILL
APPROACH FROM THE WEST THURSDAY AND DESPITE RELATIVE LACK OF
MOISTURE...FORCING LOOKS TO BE STRONG ENOUGH TO PROVIDE FOR A DECENT
SHOT OF SHOWERS SPREADING FROM WEST TO EAST THURSDAY AND ENDING
EASTERN CWA THURSDAY EVENING. SOUTHERN EXTENT OF THIS SHORTWAVE WILL
BE WEAKENING AS IT RUNS INTO THE NARROW RIDGE BEHIND THE LARGE
EASTERN CONUS UPPER LOW. THE ANTICIPATED GRADUAL WEAKENING OF THE
TROUGH IN OUR NECK OF THE WOODS IS REASONING FOR HIGHEST POPS WEST
AND LOWER POPS EAST...THOUGH GUIDANCE OFTEN WEAKENS THESE SYSTEMS
TOO QUICKLY AND HAVE GENERALLY GONE WITH HIGHER MOS POPS FOR THIS
SYSTEM.

WARM ADVECTION WILL RAMP UP BEHIND THIS SYSTEM AS UPPER RIDGING
BRIEFLY BUILDS INTO THE AREA FRIDAY ALLOWING FOR MODERATING TEMPS.
THE 00Z WRF-NAM DID HAVE A STRONGER TROUGH MOVING THROUGH ON FRIDAY
WITH SOME LIGHT QPF...BUT GIVEN THE GLOBAL MODELS ALL MUCH MORE
MUTED WITH THIS TROUGH WITH NO PRECIP HAVE BUMPED UP SKY COVER A BIT
AND POPS UP TO 10% BUT KEPT FORECAST DRY FOR NOW.

PATTERN WILL REMAIN QUITE AMPLIFIED THROUGH THE WEEKEND WITH DEEP
TROUGH TO OUR NE AND UPPER RIDGE BUILDING INTO THE CENTRAL CONUS.
GUIDANCE HAS TRENDED A BIT FARTHER WEST WITH THE NE CONUS UPPER
TROUGH THIS WEEKEND PLACING OUR CWA A BIT CLOSER TO THE COOLER AIR
MASS...BUT STILL EXPECT HIGHS TO MAKE IT INTO THE 60S. IT NOW
APPEARS THE GFS...ECMWF...AND GEM HAVE MONDAY AS OUR WARMEST DAY
WITH 850MB TEMPS PROGGED TO BE AROUND 1.5 STANDARD DEVIATIONS ABOVE
AVERAGE. GIVEN THE INCREASING SOUTHERLY WINDS THINK MOST OF THE CWA
STANDS A DECENT SHOT TO TAG 70F WITH ENSEMBLE MAX TEMPS AS WARM AS
THE MID TO UPPER 70S. COLD FRONT LOOKS TO END OUR BRIEF STINT OF
INDIAN SUMMER MONDAY NIGHT OR TUESDAY WITH SHOWERS AND POSSIBLY SOME
THUNDERSTORMS ACCOMPANYING THE FRONT.

IZZI

&&

.AVIATION...

//ORD AND MDW CONCERNS...UPDATED 09Z...

* MVFR CIGS EARLY THIS MORNING.
* EAST WINDS MID MORNING THRU EARLY EVENING. CMS

//DISCUSSION...UPDATED 09Z...

CIGS AROUND 3KFT CONTINUE ACROSS NORTHEAST IL AND CONFIDENCE AS TO
WHEN THESE WILL SCATTER AND DISSIPATE IS LOW AND TRENDS WILL NEED
TO BE MONITORED. OUTSIDE THIS AREA OF CLOUDS...LIGHT/CALM WINDS
WILL ALLOW SOME PATCHY FOG TO FORM. CMS

PREVIOUS 09Z DISCUSSION...

HIGH PRESSURE WILL MOVE SOUTHEAST ACROSS THE REGION TODAY. LIGHT
EAST/NORTHEAST WINDS WILL SHIFT SOUTHEAST LATER THIS MORNING...
THEN TURN BACK EAST/NORTHEAST THIS AFTERNOON WITH A POSSIBLE LAKE
BREEZE. PREVAILING SPEEDS WILL LIKELY REMAIN UNDER 10KTS.

HIGH MVFR CIGS AROUND 3KFT WILL SLOWLY SCATTER OUT AND DISSIPATE
EARLY THIS MORNING WITH SKC EXPECTED LATER TODAY WITH INCREASING
HIGH CLOUDS TONIGHT. CMS

//ORD AND MDW CONFIDENCE...UPDATED 09Z...

* HIGH FOR MVFR CIGS EARLY THIS MORNING...LOW FOR CLEARING TIMING.
* HIGH FOR WIND THRU THE PERIOD. CMS

//OUTLOOK FOR ORD/MDW FOR 12Z THURSDAY-12Z TUESDAY...UPDATED 00Z...

* THURSDAY...CHANCE OF AFTERNOON SHRA. SOUTH WINDS.
* FRIDAY AND SATURDAY...DRY/VFR. WEST/SOUTHWEST WINDS.
* SUNDAY...DRY/VFR. SOUTH WINDS.
* MONDAY...SLIGHT CHANCE OF SHRA. GUSTY SOUTHWEST WINDS.

KJB

&&

.MARINE...

324 AM...A LARGE RIDGE OF HIGH PRESSURE EXTENDS FROM QUEBEC INTO
THE WESTERN LAKES. THIS RIDGE WILL MOVE EAST TODAY AND TONIGHT AND
SLOWLY WEAKEN. EASTERLY WINDS WILL CONTINUE TO DIMINISH THIS
MORNING BUT WAVE ACTION...ESPECIALLY ACROSS THE SOUTHWESTERN PART
OF THE LAKE WILL SLOWLY SUBSIDE THIS MORNING. WINDS WILL TURN BACK
SOUTHERLY TONIGHT AND INCREASE ON THURSDAY AS THE GRADIENT
TIGHTENS AHEAD OF AN APPROACHING COLD FRONT WHICH WILL THEN MOVE
ACROSS THE LAKE THURSDAY NIGHT AS IT DISSIPATES. THE FLOW WILL
TURN BACK SOUTHWESTERLY FRIDAY AHEAD OF ANOTHER COLD FRONT WHICH
WILL MOVE ACROSS THE LAKE FRIDAY NIGHT INTO SATURDAY MORNING.
WINDS BEHIND THIS FRONT WILL INCREASE TO 15-25 KTS WITH HIGHER
WINDS POSSIBLE OVER THE NORTHERN PART OF THE LAKE. CMS

&&

.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...SMALL CRAFT ADVISORY...ILLINOIS NEARSHORE WATERS UNTIL 7 AM
     WEDNESDAY.

&&

$$

VISIT US AT HTTP://WEATHER.GOV/CHICAGO (ALL LOWERCASE)

FOLLOW US ON FACEBOOK...TWITTER...AND YOUTUBE AT:
WWW.FACEBOOK.COM/NWSCHICAGO
WWW.TWITTER.COM/NWSCHICAGO
WWW.YOUTUBE.COM/NWSCHICAGO







000
FXUS63 KLOT 220824
AFDLOT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
324 AM CDT WED OCT 22 2014

.DISCUSSION...
310 AM CDT

TRANSITION AWAY FROM THE BELOW AVERAGE TEMPS OF LATE TO WARMER THAN
AVERAGE TEMPS BY THIS WEEKEND INTO EARLY NEXT WEEK STILL ON
TRACK...WITH A COUPLE SHOTS OF RAIN POSSIBLE.

ANY LINGERING LAKE CLOUDINESS IN NE IL EARLY THIS MORNING WILL FADE
WITH 100% SUNSHINE LOOKING LIKELY TODAY. TEMPERATURES SHOULD
MODERATE SEVERAL DEGREES OVER YESTERDAY MOST AREAS...THOUGH LAKE
ADJACENT AREAS OF NE IL WILL STILL FACE ONSHORE WINDS AND COOLER
TEMPS THAN THE REMAINDER OF THE CWA. MAINLY CLEAR SKIES AND LIGHT
WINDS SHOULD ALLOW FOR ANOTHER CHILLY NIGHT TONIGHT.

SKIES WILL CLOUD OVER THURSDAY LEAVING OUR PROSPECTS FOR SEEING THE
SOLAR ECLIPSE THURSDAY AFTERNOON DIM. SHARP UPPER TROUGH WILL
APPROACH FROM THE WEST THURSDAY AND DESPITE RELATIVE LACK OF
MOISTURE...FORCING LOOKS TO BE STRONG ENOUGH TO PROVIDE FOR A DECENT
SHOT OF SHOWERS SPREADING FROM WEST TO EAST THURSDAY AND ENDING
EASTERN CWA THURSDAY EVENING. SOUTHERN EXTENT OF THIS SHORTWAVE WILL
BE WEAKENING AS IT RUNS INTO THE NARROW RIDGE BEHIND THE LARGE
EASTERN CONUS UPPER LOW. THE ANTICIPATED GRADUAL WEAKENING OF THE
TROUGH IN OUR NECK OF THE WOODS IS REASONING FOR HIGHEST POPS WEST
AND LOWER POPS EAST...THOUGH GUIDANCE OFTEN WEAKENS THESE SYSTEMS
TOO QUICKLY AND HAVE GENERALLY GONE WITH HIGHER MOS POPS FOR THIS
SYSTEM.

WARM ADVECTION WILL RAMP UP BEHIND THIS SYSTEM AS UPPER RIDGING
BRIEFLY BUILDS INTO THE AREA FRIDAY ALLOWING FOR MODERATING TEMPS.
THE 00Z WRF-NAM DID HAVE A STRONGER TROUGH MOVING THROUGH ON FRIDAY
WITH SOME LIGHT QPF...BUT GIVEN THE GLOBAL MODELS ALL MUCH MORE
MUTED WITH THIS TROUGH WITH NO PRECIP HAVE BUMPED UP SKY COVER A BIT
AND POPS UP TO 10% BUT KEPT FORECAST DRY FOR NOW.

PATTERN WILL REMAIN QUITE AMPLIFIED THROUGH THE WEEKEND WITH DEEP
TROUGH TO OUR NE AND UPPER RIDGE BUILDING INTO THE CENTRAL CONUS.
GUIDANCE HAS TRENDED A BIT FARTHER WEST WITH THE NE CONUS UPPER
TROUGH THIS WEEKEND PLACING OUR CWA A BIT CLOSER TO THE COOLER AIR
MASS...BUT STILL EXPECT HIGHS TO MAKE IT INTO THE 60S. IT NOW
APPEARS THE GFS...ECMWF...AND GEM HAVE MONDAY AS OUR WARMEST DAY
WITH 850MB TEMPS PROGGED TO BE AROUND 1.5 STANDARD DEVIATIONS ABOVE
AVERAGE. GIVEN THE INCREASING SOUTHERLY WINDS THINK MOST OF THE CWA
STANDS A DECENT SHOT TO TAG 70F WITH ENSEMBLE MAX TEMPS AS WARM AS
THE MID TO UPPER 70S. COLD FRONT LOOKS TO END OUR BRIEF STINT OF
INDIAN SUMMER MONDAY NIGHT OR TUESDAY WITH SHOWERS AND POSSIBLY SOME
THUNDERSTORMS ACCOMPANYING THE FRONT.

IZZI

&&

.AVIATION...

//ORD AND MDW CONCERNS...UPDATED 06Z...

* MVFR CIGS EARLY THIS MORNING.
* EAST WINDS MID MORNING THRU EARLY EVENING. CMS

//DISCUSSION...UPDATED 06Z...

HIGH PRESSURE WILL MOVE SOUTHEAST ACROSS THE REGION TODAY. LIGHT
EAST/NORTHEAST WINDS WILL SHIFT SOUTHEAST LATER THIS MORNING...
THEN TURN BACK EAST/NORTHEAST THIS AFTERNOON WITH A POSSIBLE LAKE
BREEZE. PREVAILING SPEEDS WILL LIKELY REMAIN UNDER 10KTS.

HIGH MVFR CIGS AROUND 3KFT WILL SLOWLY SCATTER OUT AND DISSIPATE
EARLY THIS MORNING WITH SKC EXPECTED LATER TODAY WITH INCREASING
HIGH CLOUDS TONIGHT. CMS

//ORD AND MDW CONFIDENCE...UPDATED 06Z...

* MEDIUM FOR MVFR CIGS EARLY THIS MORNING.
* HIGH FOR WIND THRU THE PERIOD. CMS

//OUTLOOK FOR ORD/MDW FOR 12Z THURSDAY-12Z TUESDAY...UPDATED 00Z...

* THURSDAY...CHANCE OF AFTERNOON SHRA. SOUTH WINDS.
* FRIDAY AND SATURDAY...DRY/VFR. WEST/SOUTHWEST WINDS.
* SUNDAY...DRY/VFR. SOUTH WINDS.
* MONDAY...SLIGHT CHANCE OF SHRA. GUSTY SOUTHWEST WINDS.

KJB

&&

.MARINE...

324 AM...A LARGE RIDGE OF HIGH PRESSURE EXTENDS FROM QUEBEC INTO
THE WESTERN LAKES. THIS RIDGE WILL MOVE EAST TODAY AND TONIGHT AND
SLOWLY WEAKEN. EASTERLY WINDS WILL CONTINUE TO DIMINISH THIS
MORNING BUT WAVE ACTION...ESPECIALLY ACROSS THE SOUTHWESTERN PART
OF THE LAKE WILL SLOWLY SUBSIDE THIS MORNING. WINDS WILL TURN BACK
SOUTHERLY TONIGHT AND INCREASE ON THURSDAY AS THE GRADIENT
TIGHTENS AHEAD OF AN APPROACHING COLD FRONT WHICH WILL THEN MOVE
ACROSS THE LAKE THURSDAY NIGHT AS IT DISSIPATES. THE FLOW WILL
TURN BACK SOUTHWESTERLY FRIDAY AHEAD OF ANOTHER COLD FRONT WHICH
WILL MOVE ACROSS THE LAKE FRIDAY NIGHT INTO SATURDAY MORNING.
WINDS BEHIND THIS FRONT WILL INCREASE TO 15-25 KTS WITH HIGHER
WINDS POSSIBLE OVER THE NORTHERN PART OF THE LAKE. CMS

&&

.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...SMALL CRAFT ADVISORY...INDIANA NEARSHORE WATERS UNTIL 4 AM WEDNESDAY.

     SMALL CRAFT ADVISORY...ILLINOIS NEARSHORE WATERS UNTIL 7 AM WEDNESDAY.

&&

$$

VISIT US AT HTTP://WEATHER.GOV/CHICAGO (ALL LOWERCASE)

FOLLOW US ON FACEBOOK...TWITTER...AND YOUTUBE AT:
WWW.FACEBOOK.COM/NWSCHICAGO
WWW.TWITTER.COM/NWSCHICAGO
WWW.YOUTUBE.COM/NWSCHICAGO







000
FXUS63 KLOT 220811
AFDLOT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
311 AM CDT WED OCT 22 2014

.DISCUSSION...
310 AM CDT

TRANSITION AWAY FROM THE BELOW AVERAGE TEMPS OF LATE TO WARMER THAN
AVERAGE TEMPS BY THIS WEEKEND INTO EARLY NEXT WEEK STILL ON
TRACK...WITH A COUPLE SHOTS OF RAIN POSSIBLE.

ANY LINGERING LAKE CLOUDINESS IN NE IL EARLY THIS MORNING WILL FADE
WITH 100% SUNSHINE LOOKING LIKELY TODAY. TEMPERATURES SHOULD
MODERATE SEVERAL DEGREES OVER YESTERDAY MOST AREAS...THOUGH LAKE
ADJACENT AREAS OF NE IL WILL STILL FACE ONSHORE WINDS AND COOLER
TEMPS THAN THE REMAINDER OF THE CWA. MAINLY CLEAR SKIES AND LIGHT
WINDS SHOULD ALLOW FOR ANOTHER CHILLY NIGHT TONIGHT.

SKIES WILL CLOUD OVER THURSDAY LEAVING OUR PROSPECTS FOR SEEING THE
SOLAR ECLIPSE THURSDAY AFTERNOON DIM. SHARP UPPER TROUGH WILL
APPROACH FROM THE WEST THURSDAY AND DESPITE RELATIVE LACK OF
MOISTURE...FORCING LOOKS TO BE STRONG ENOUGH TO PROVIDE FOR A DECENT
SHOT OF SHOWERS SPREADING FROM WEST TO EAST THURSDAY AND ENDING
EASTERN CWA THURSDAY EVENING. SOUTHERN EXTENT OF THIS SHORTWAVE WILL
BE WEAKENING AS IT RUNS INTO THE NARROW RIDGE BEHIND THE LARGE
EASTERN CONUS UPPER LOW. THE ANTICIPATED GRADUAL WEAKENING OF THE
TROUGH IN OUR NECK OF THE WOODS IS REASONING FOR HIGHEST POPS WEST
AND LOWER POPS EAST...THOUGH GUIDANCE OFTEN WEAKENS THESE SYSTEMS
TOO QUICKLY AND HAVE GENERALLY GONE WITH HIGHER MOS POPS FOR THIS
SYSTEM.

WARM ADVECTION WILL RAMP UP BEHIND THIS SYSTEM AS UPPER RIDGING
BRIEFLY BUILDS INTO THE AREA FRIDAY ALLOWING FOR MODERATING TEMPS.
THE 00Z WRF-NAM DID HAVE A STRONGER TROUGH MOVING THROUGH ON FRIDAY
WITH SOME LIGHT QPF...BUT GIVEN THE GLOBAL MODELS ALL MUCH MORE
MUTED WITH THIS TROUGH WITH NO PRECIP HAVE BUMPED UP SKY COVER A BIT
AND POPS UP TO 10% BUT KEPT FORECAST DRY FOR NOW.

PATTERN WILL REMAIN QUITE AMPLIFIED THROUGH THE WEEKEND WITH DEEP
TROUGH TO OUR NE AND UPPER RIDGE BUILDING INTO THE CENTRAL CONUS.
GUIDANCE HAS TRENDED A BIT FARTHER WEST WITH THE NE CONUS UPPER
TROUGH THIS WEEKEND PLACING OUR CWA A BIT CLOSER TO THE COOLER AIR
MASS...BUT STILL EXPECT HIGHS TO MAKE IT INTO THE 60S. IT NOW
APPEARS THE GFS...ECMWF...AND GEM HAVE MONDAY AS OUR WARMEST DAY
WITH 850MB TEMPS PROGGED TO BE AROUND 1.5 STANDARD DEVIATIONS ABOVE
AVERAGE. GIVEN THE INCREASING SOUTHERLY WINDS THINK MOST OF THE CWA
STANDS A DECENT SHOT TO TAG 70F WITH ENSEMBLE MAX TEMPS AS WARM AS
THE MID TO UPPER 70S. COLD FRONT LOOKS TO END OUR BRIEF STINT OF
INDIAN SUMMER MONDAY NIGHT OR TUESDAY WITH SHOWERS AND POSSIBLY SOME
THUNDERSTORMS ACCOMPANYING THE FRONT.

IZZI

&&

.AVIATION...

//ORD AND MDW CONCERNS...UPDATED 06Z...

* MVFR CIGS EARLY THIS MORNING.
* EAST WINDS MID MORNING THRU EARLY EVENING. CMS

//DISCUSSION...UPDATED 06Z...

HIGH PRESSURE WILL MOVE SOUTHEAST ACROSS THE REGION TODAY. LIGHT
EAST/NORTHEAST WINDS WILL SHIFT SOUTHEAST LATER THIS MORNING...
THEN TURN BACK EAST/NORTHEAST THIS AFTERNOON WITH A POSSIBLE LAKE
BREEZE. PREVAILING SPEEDS WILL LIKELY REMAIN UNDER 10KTS.

HIGH MVFR CIGS AROUND 3KFT WILL SLOWLY SCATTER OUT AND DISSIPATE
EARLY THIS MORNING WITH SKC EXPECTED LATER TODAY WITH INCREASING
HIGH CLOUDS TONIGHT. CMS

//ORD AND MDW CONFIDENCE...UPDATED 06Z...

* MEDIUM FOR MVFR CIGS EARLY THIS MORNING.
* HIGH FOR WIND THRU THE PERIOD. CMS

//OUTLOOK FOR ORD/MDW FOR 12Z THURSDAY-12Z TUESDAY...UPDATED 00Z...

* THURSDAY...CHANCE OF AFTERNOON SHRA. SOUTH WINDS.
* FRIDAY AND SATURDAY...DRY/VFR. WEST/SOUTHWEST WINDS.
* SUNDAY...DRY/VFR. SOUTH WINDS.
* MONDAY...SLIGHT CHANCE OF SHRA. GUSTY SOUTHWEST WINDS.

KJB

&&

.MARINE...

215 PM...LOW PRESSURE OVER WESTERN NEW YORK WILL MERGE WITH ANOTHER
LOW OVER NEAR THE DELMARVA AREA TONIGHT...AND RAPIDLY DEEPEN
WEDNESDAY NIGHT AND THURSDAY JUST SOUTH OF CAPE COD. THIS LOW WILL
THEN TRACK NORTHEAST TO NOVA SCOTIA BY SATURDAY MORNING.
MEANWHILE...HIGH PRESSURE CENTERED OVER THE SOUTHERN TIP OF JAMES
BAY...WITH HIGH PRESSURE RIDGING EXTENDING THROUGH THE MIDDLE
MISSISSIPPI VALLEY...WILL SLOWLY BUILD EAST. THE BRISK
NORTHEASTERLY WINDS CURRENTLY OVER THE LAKE WILL DIMINISH AND
BECOME LIGHT AND VARIABLE LATE TONIGHT AND EARLY WEDNESDAY AS THE
RIDGE AXIS CROSSES THE LAKE. WHILE WINDS SHOULD DROP BELOW SMALL
CRAFT ADVISORY LEVELS DURG THE AFTERNOON AND EARLY THIS
EVENING...RESIDUAL WAVE ACTION WILL BE SLOWER TO DAMPEN AND STILL
EXPECT THAT WAVES WILL REMAIN...ABOVE SMALL CRAFT ADVISORY LEVELS
THROUGH MUCH OF THE NIGHT. AS THE RIDGE MOVES TO THE EAST OF THE
LAKE WEDNESDAY NIGHT...A TROUGH OF LOW PRESSURE WILL CROSS THE
CENTRAL PLAINS...REACHING THE UPPER MISSISSIPPI VALLEY BY THURSDAY
MORNING. THIS WILL SET UP A STRENGTHENING SOUTHERLY GRADIENT OVER
THE LAKE WITH WINDS INCREASING TO ARND 20-25KT THURSDAY AFTERNOON.
WINDS WILL REMAIN SOUTHERLY UNTIL AN ASSOCIATED WEAK COLD FRONT
PUSHES ACROSS THE LAKE THURSDAY NIGHT.

KREIN

&&

.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...SMALL CRAFT ADVISORY...INDIANA NEARSHORE WATERS UNTIL 4 AM WEDNESDAY.

     SMALL CRAFT ADVISORY...ILLINOIS NEARSHORE WATERS UNTIL 7 AM WEDNESDAY.

&&

$$

VISIT US AT HTTP://WEATHER.GOV/CHICAGO (ALL LOWERCASE)

FOLLOW US ON FACEBOOK...TWITTER...AND YOUTUBE AT:
WWW.FACEBOOK.COM/NWSCHICAGO
WWW.TWITTER.COM/NWSCHICAGO
WWW.YOUTUBE.COM/NWSCHICAGO







000
FXUS63 KLOT 220532
AFDLOT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
1232 AM CDT WED OCT 22 2014

.DISCUSSION...
749 PM CDT

FOR AN EVENING UPDATE HAVE HELD ON TO FORECAST CLOUD COVER LONGER
TONIGHT...NAMELY FOR THE CENTRAL AND SOUTHERN PARTS OF THE
CHICAGO METRO AND SOUTH AND SOUTHWEST FROM THERE.

SURFACE RIDGING IS BUILDING SOUTHWARD THIS EVENING INTO NORTHERN
ILLINOIS AND WIND SPEEDS HAVE COME DOWN QUITE A BIT OUTSIDE OF THE
IMMEDIATE LAKE SHORE. SUBSIDENCE ALOFT IS CONTINUING AS WELL PER
WATER VAPOR AND DIAGNOSTIC MODEL SOUNDINGS...BUT CLOUDS HAVE
SLOWED THEIR RATE OF DIMINISHING...POSSIBLY DUE TO NO MORE CLOUD
TOP WARMING FROM THE SUN.

WHILE THE CLOUD LAYER IS VERY THIN IN DEPTH AS INDICATED BY
REGIONAL AMDAR DATA...FORESEE CLOUDS HANGING ON A WHILE LONGER
WITH NIGHTFALL. THE LOCAL 8KM ARW...AND RAP TO SOME DEGREE...INDICATE
LITTLE MOVEMENT IN THE MOST SOLID SATURATION ALONG AND EAST OF
INTERSTATE 55 THROUGH MIDNIGHT...AND THEN AS CLOUD-BEARING FLOW
TURNS EASTERLY THE MOISTURE ADVECTS WITH IT AND GRADUALLY THINS.
THIS WAS GENERALLY DEPICTED IN THE PREVIOUS FORECAST BUT JUST
HAVE SHIFTED BACK IN TIMING SEVERAL HOURS.

MADE SOME ADJUSTMENTS TO HOURLY TEMPERATURES TO BETTER FIT THIS
REASONING AND THAT DID LEAD TO AN INCREASE IN MIN TEMPS IN A FEW
PLACES...BUT OTHERWISE NO CHANGES MADE.

MTF

//PREV DISCUSSION...
309 PM CDT

MAIN FORECAST CONCERNS FOCUS ON PRECIPITATION CHANCES AND TIMING
WITH A COUPLE OF SYSTEMS WHICH WILL AFFECT THE REGION THURSDAY AND
NEXT MONDAY. ALSO...IT APPEARS THAT SOME 70 DEGREE TEMPERATURES ARE
POSSIBLE FOR PARTS OF THE FORECAST AREA OVER THE WEEKEND AS WELL AS
ON MONDAY.

TONIGHT THROUGH WEDNESDAY NIGHT...

GOES WATER VAPOR IMAGERY DEPICTS A STRONG MID-LEVEL SHORT WAVE
TROUGH WHICH HAD DUG SOUTH ACROSS THE REGION TODAY IS NOW EXITING
THE AREA ACROSS THE OHIO VALLEY TO THE SOUTHEAST. SUBSIDENCE IN THE
WAKE OF THIS FEATURE WAS EVIDENT BOTH IN RISING SURFACE PRESSURE
ACROSS THE CWA...AND IN VISIBLE SATELLITE IMAGERY AS EXTENSIVE AREA
OF STRATOCU ACROSS THE REGION ERODES FROM THE NORTH ACROSS WI/MI AND
LAKE MICHIGAN. EARLIER LAKE-INDUCED SHOWERS HAVE WEAKENED AND FADED
AS EXPECTED DUE TO LOWERING SUBSIDENCE INVERSION AND ASSOCIATED
WARMING ALOFT. CLOUD COVER IS EXPECTED TO CONTINUE TO DECREASE IN
COVERAGE INTO THE EVENING HOURS...WITH PERHAPS JUST SOME PATCHY THIN
SHALLOW STRATOCU LINGERING OFF THE LAKE BY LATE EVENING. LOOKING AT
THE BIGGER PICTURE...HIGH-AMPLITUDE UPPER RIDGE ANALYZED OVER THE
CENTRAL PORTION OF THE NATION WILL MOVE ACROSS THE MISSISSIPPI
VALLEY AND WESTERN/NORTHERN GREAT LAKES REGION THROUGH WEDNESDAY
MORNING...MAINTAINING SUBSIDENCE WHICH SHOULD FURTHER ERODE
LINGERING CLOUDS AND ALLOW SURFACE HIGH PRESSURE RIDGE TO MOVE
ACROSS THE AREA TONIGHT AND WEDNESDAY. WITH CLEARING SKIES AND
DECREASING WINDS ASSOCIATED WITH THE SURFACE RIDGE AXIS TONIGHT...
TEMPS ARE EXPECTED TO DROP OFF INTO THE 30S IN MANY AREAS AWAY FROM
THE IMMEDIATE LAKE MICHIGAN SHORE AND CORE OF CHICAGO. LATE NIGHT
MINS IN THE MID 30S AWAY FROM THE METRO AREA WILL LIKELY ALLOW AREAS
OF FROST TO DEVELOP WHERE WINDS DECOUPLE BECOME LIGHT/VARIABLE.
UPPER AND LOW LEVEL HIGH PRESSURE RIDGES REMAIN OVER THE AREA
WEDNESDAY ALLOWING PLENTIFUL SUNSHINE...THOUGH WITH ONLY MODEST
WARMING DUE TO EASTERLY WIND COMPONENT OFF LAKE AND COOLER UPSTREAM
AIR MASS. A BLEND OF MOS GUIDANCE APPEARS REASONABLE BASED ON RAW
MODEL LOW LEVEL THERMAL FIELDS...WITH WEDNESDAY AFTERNOON MAXES
EXPECTED TO RANGE FROM THE LOW 50S ALONG THE LAKE TO THE UPPER 50S
ACROSS THE FAR WESTERN/SOUTHERN COUNTIES OF THE CWA. ATTENTION THEN
TURNS BACK TOWARD THE NORTHWEST WEDNESDAY NIGHT...AS A WELL-DEFINED
SHORT WAVE TROUGH TRACKS ACROSS THE SOUTHERN CANADIAN PRAIRIES AND
DAKOTAS BEFORE APPROACHING THE UPPER MISSISSIPPI VALLEY WEDNESDAY
EVENING. HEIGHT/PRESSURE FALLS ACROSS THE UPPER MIDWEST NUDGES THE
SURFACE RIDGE AWAY TO OUR EAST AND INDUCES INCREASING
SOUTH-SOUTHEAST WINDS AHEAD OF THE APPROACHING SURFACE TROUGH
OVERNIGHT. CLEAR-PARTLY CLOUDY CONDITIONS AND LIGHT WINDS WILL
LIKELY ALLOW FOR QUICK DECOUPLING OF BOUNDARY LAYER WINDS EARLY
WEDNESDAY EVENING WITH TEMPS DROPPING INTO THE 30S AGAIN IN OUTLYING
AREAS...THOUGH SOME INCREASE IN HIGH CLOUDS AND THE INCREASE IN
WINDS OVERNIGHT WILL LIKELY LIMIT FROST SOMEWHAT.

THURSDAY THROUGH FRIDAY...

THE UPPER MIDWEST SHORT WAVE CONTINUES TO MOVE EAST-SOUTHEAST INTO
THE GREAT LAKES REGION THURSDAY...WITH THE BEST ORGANIZED DEEP LIFT
GENERALLY NORTH OF THE WFO CHICAGO CWA. THE MID-LEVEL TROUGH AXIS
DOES SHIFT ACROSS THE AREA LATER IN THE DAY AND OVERNIGHT HOWEVER...
THOUGH WITH MOISTURE RETURN FROM THE GULF INITIALLY BLOCKED BY THE
SURFACE HIGH PRESSURE RIDGE WHICH EXTENDS SOUTHWEST ACROSS THE
ARKLATEX REGION FOR MUCH OF THE PERIOD. THUS MOISTURE RETURN IS NOT
OVERLY IMPRESSIVE WITH THIS SYSTEM...THOUGH A PERIOD OF SHOWERS DOES
LOOK FAIRLY LIKELY THURSDAY INTO THURSDAY NIGHT. PRECIP POTENTIAL
LOOKS TO INCREASE AHEAD OF THE MID-LEVEL TROUGH AS IT MOVES INTO
NORTH CENTRAL IL DURING THE MID-LATE MORNING HOURS AND SPREADING
INTO NORTHEAST IL DURING THE AFTERNOON. FORCING WEAKENS THURSDAY
EVENING AS THE TROUGH RUNS INTO THE WEAKENING UPPER RIDGE...WITH
PRECIP EXPECTED TO BECOME MORE SPOTTY THURSDAY NIGHT AS IT MOVES
ACROSS THE EASTERN HALF OF THE FORECAST AREA. MID-LEVEL TROUGH AND
WEAKENING SURFACE TROUGH/COLD FRONT OF PACIFIC ORIGIN PASS EAST OF
THE AREA FRIDAY MORNING...WITH WEAK HIGH PRESSURE BUILDING IN DURING
THE DAY. TEMPERATURES ACTUALLY WARM IN THE WAKE OF THIS SYSTEM AS
THE SURFACE RIDGE DRIFTS EAST DURING THE DAY AND WESTERLY FLOW ALOFT
AROUND REBUILDING UPPER RIDGE OVER THE PLAINS ALLOWS WARM ADVECTION
BY AFTERNOON. MODEL THERMAL PROGS INDICATE SOME LOW-MID 60S ACROSS
NORTHERN IL FRIDAY AFTERNOON.

FRIDAY NIGHT THROUGH TUESDAY...

LONGER RANGE MODEL GUIDANCE IN GOOD AGREEMENT IN SPREADING BROAD
UPPER RIDGE EASTWARD FROM THE PLAINS AND ACROSS THE MIDWEST AND
GREAT LAKES REGION THROUGH THE WEEKEND...WHILE DEEP UPPER TROUGH
MOVES INTO THE WESTERN CONUS. MODELS DEPICT STRONG SOUTHERLY FLOW
AND WARM ADVECTION DEVELOPING AS SURFACE LOW PRESSURE DEVELOPS AND
LIFTS NORTHEAST ACROSS THE PLAINS AND THE UPPER MIDWEST SUNDAY...
THOUGH AGAIN WITH LIMITED MOISTURE RETURN FOR THE MAGNITUDE OF THE
FLOW. THIS ALLOWS US TO WARM UP SIGNIFICANTLY HOWEVER...WITH HIGHS
LIKELY GETTING ABOVE 70 DEGREES SATURDAY AND SUNDAY ACROSS PORTIONS
OF THE CWA...AND OVER MOST OF IT MONDAY. SURFACE TROUGH/COLD FRONT
APPROACHES MONDAY WITH AN ATTENDANT CHANCE OF RAIN AND INCREASED
CLOUD COVER. A SECOND LOW IS DEPICTED LIFTING ACROSS THE AREA MONDAY
NIGHT-TUESDAY MAINTAINING RAIN THREAT...AND ALSO LEADING TO MUCH
COOLER WEATHER AGAIN TUESDAY BEHIND THE SYSTEM COLD FRONT.

RATZER

&&

.AVIATION...

//ORD AND MDW CONCERNS...UPDATED 06Z...

* MVFR CIGS EARLY THIS MORNING.
* EAST WINDS MID MORNING THRU EARLY EVENING. CMS

//DISCUSSION...UPDATED 06Z...

HIGH PRESSURE WILL MOVE SOUTHEAST ACROSS THE REGION TODAY. LIGHT
EAST/NORTHEAST WINDS WILL SHIFT SOUTHEAST LATER THIS MORNING...
THEN TURN BACK EAST/NORTHEAST THIS AFTERNOON WITH A POSSIBLE LAKE
BREEZE. PREVAILING SPEEDS WILL LIKELY REMAIN UNDER 10KTS.

HIGH MVFR CIGS AROUND 3KFT WILL SLOWLY SCATTER OUT AND DISSIPATE
EARLY THIS MORNING WITH SKC EXPECTED LATER TODAY WITH INCREASING
HIGH CLOUDS TONIGHT. CMS

//ORD AND MDW CONFIDENCE...UPDATED 06Z...

* MEDIUM FOR MVFR CIGS EARLY THIS MORNING.
* HIGH FOR WIND THRU THE PERIOD. CMS

//OUTLOOK FOR ORD/MDW FOR 12Z THURSDAY-12Z TUESDAY...UPDATED 00Z...

* THURSDAY...CHANCE OF AFTERNOON SHRA. SOUTH WINDS.
* FRIDAY AND SATURDAY...DRY/VFR. WEST/SOUTHWEST WINDS.
* SUNDAY...DRY/VFR. SOUTH WINDS.
* MONDAY...SLIGHT CHANCE OF SHRA. GUSTY SOUTHWEST WINDS.

KJB

&&

.MARINE...

215 PM...LOW PRESSURE OVER WESTERN NEW YORK WILL MERGE WITH ANOTHER
LOW OVER NEAR THE DELMARVA AREA TONIGHT...AND RAPIDLY DEEPEN
WEDNESDAY NIGHT AND THURSDAY JUST SOUTH OF CAPE COD. THIS LOW WILL
THEN TRACK NORTHEAST TO NOVA SCOTIA BY SATURDAY MORNING.
MEANWHILE...HIGH PRESSURE CENTERED OVER THE SOUTHERN TIP OF JAMES
BAY...WITH HIGH PRESSURE RIDGING EXTENDING THROUGH THE MIDDLE
MISSISSIPPI VALLEY...WILL SLOWLY BUILD EAST. THE BRISK
NORTHEASTERLY WINDS CURRENTLY OVER THE LAKE WILL DIMINISH AND
BECOME LIGHT AND VARIABLE LATE TONIGHT AND EARLY WEDNESDAY AS THE
RIDGE AXIS CROSSES THE LAKE. WHILE WINDS SHOULD DROP BELOW SMALL
CRAFT ADVISORY LEVELS DURG THE AFTERNOON AND EARLY THIS
EVENING...RESIDUAL WAVE ACTION WILL BE SLOWER TO DAMPEN AND STILL
EXPECT THAT WAVES WILL REMAIN...ABOVE SMALL CRAFT ADVISORY LEVELS
THROUGH MUCH OF THE NIGHT. AS THE RIDGE MOVES TO THE EAST OF THE
LAKE WEDNESDAY NIGHT...A TROUGH OF LOW PRESSURE WILL CROSS THE
CENTRAL PLAINS...REACHING THE UPPER MISSISSIPPI VALLEY BY THURSDAY
MORNING. THIS WILL SET UP A STRENGTHENING SOUTHERLY GRADIENT OVER
THE LAKE WITH WINDS INCREASING TO ARND 20-25KT THURSDAY AFTERNOON.
WINDS WILL REMAIN SOUTHERLY UNTIL AN ASSOCIATED WEAK COLD FRONT
PUSHES ACROSS THE LAKE THURSDAY NIGHT.

KREIN

&&

.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...SMALL CRAFT ADVISORY...INDIANA NEARSHORE WATERS UNTIL 4 AM WEDNESDAY.

     SMALL CRAFT ADVISORY...ILLINOIS NEARSHORE WATERS UNTIL 7 AM WEDNESDAY.

&&

$$

VISIT US AT HTTP://WEATHER.GOV/CHICAGO (ALL LOWERCASE)

FOLLOW US ON FACEBOOK...TWITTER...AND YOUTUBE AT:
WWW.FACEBOOK.COM/NWSCHICAGO
WWW.TWITTER.COM/NWSCHICAGO
WWW.YOUTUBE.COM/NWSCHICAGO







000
FXUS63 KLOT 220532
AFDLOT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
1232 AM CDT WED OCT 22 2014

.DISCUSSION...
749 PM CDT

FOR AN EVENING UPDATE HAVE HELD ON TO FORECAST CLOUD COVER LONGER
TONIGHT...NAMELY FOR THE CENTRAL AND SOUTHERN PARTS OF THE
CHICAGO METRO AND SOUTH AND SOUTHWEST FROM THERE.

SURFACE RIDGING IS BUILDING SOUTHWARD THIS EVENING INTO NORTHERN
ILLINOIS AND WIND SPEEDS HAVE COME DOWN QUITE A BIT OUTSIDE OF THE
IMMEDIATE LAKE SHORE. SUBSIDENCE ALOFT IS CONTINUING AS WELL PER
WATER VAPOR AND DIAGNOSTIC MODEL SOUNDINGS...BUT CLOUDS HAVE
SLOWED THEIR RATE OF DIMINISHING...POSSIBLY DUE TO NO MORE CLOUD
TOP WARMING FROM THE SUN.

WHILE THE CLOUD LAYER IS VERY THIN IN DEPTH AS INDICATED BY
REGIONAL AMDAR DATA...FORESEE CLOUDS HANGING ON A WHILE LONGER
WITH NIGHTFALL. THE LOCAL 8KM ARW...AND RAP TO SOME DEGREE...INDICATE
LITTLE MOVEMENT IN THE MOST SOLID SATURATION ALONG AND EAST OF
INTERSTATE 55 THROUGH MIDNIGHT...AND THEN AS CLOUD-BEARING FLOW
TURNS EASTERLY THE MOISTURE ADVECTS WITH IT AND GRADUALLY THINS.
THIS WAS GENERALLY DEPICTED IN THE PREVIOUS FORECAST BUT JUST
HAVE SHIFTED BACK IN TIMING SEVERAL HOURS.

MADE SOME ADJUSTMENTS TO HOURLY TEMPERATURES TO BETTER FIT THIS
REASONING AND THAT DID LEAD TO AN INCREASE IN MIN TEMPS IN A FEW
PLACES...BUT OTHERWISE NO CHANGES MADE.

MTF

//PREV DISCUSSION...
309 PM CDT

MAIN FORECAST CONCERNS FOCUS ON PRECIPITATION CHANCES AND TIMING
WITH A COUPLE OF SYSTEMS WHICH WILL AFFECT THE REGION THURSDAY AND
NEXT MONDAY. ALSO...IT APPEARS THAT SOME 70 DEGREE TEMPERATURES ARE
POSSIBLE FOR PARTS OF THE FORECAST AREA OVER THE WEEKEND AS WELL AS
ON MONDAY.

TONIGHT THROUGH WEDNESDAY NIGHT...

GOES WATER VAPOR IMAGERY DEPICTS A STRONG MID-LEVEL SHORT WAVE
TROUGH WHICH HAD DUG SOUTH ACROSS THE REGION TODAY IS NOW EXITING
THE AREA ACROSS THE OHIO VALLEY TO THE SOUTHEAST. SUBSIDENCE IN THE
WAKE OF THIS FEATURE WAS EVIDENT BOTH IN RISING SURFACE PRESSURE
ACROSS THE CWA...AND IN VISIBLE SATELLITE IMAGERY AS EXTENSIVE AREA
OF STRATOCU ACROSS THE REGION ERODES FROM THE NORTH ACROSS WI/MI AND
LAKE MICHIGAN. EARLIER LAKE-INDUCED SHOWERS HAVE WEAKENED AND FADED
AS EXPECTED DUE TO LOWERING SUBSIDENCE INVERSION AND ASSOCIATED
WARMING ALOFT. CLOUD COVER IS EXPECTED TO CONTINUE TO DECREASE IN
COVERAGE INTO THE EVENING HOURS...WITH PERHAPS JUST SOME PATCHY THIN
SHALLOW STRATOCU LINGERING OFF THE LAKE BY LATE EVENING. LOOKING AT
THE BIGGER PICTURE...HIGH-AMPLITUDE UPPER RIDGE ANALYZED OVER THE
CENTRAL PORTION OF THE NATION WILL MOVE ACROSS THE MISSISSIPPI
VALLEY AND WESTERN/NORTHERN GREAT LAKES REGION THROUGH WEDNESDAY
MORNING...MAINTAINING SUBSIDENCE WHICH SHOULD FURTHER ERODE
LINGERING CLOUDS AND ALLOW SURFACE HIGH PRESSURE RIDGE TO MOVE
ACROSS THE AREA TONIGHT AND WEDNESDAY. WITH CLEARING SKIES AND
DECREASING WINDS ASSOCIATED WITH THE SURFACE RIDGE AXIS TONIGHT...
TEMPS ARE EXPECTED TO DROP OFF INTO THE 30S IN MANY AREAS AWAY FROM
THE IMMEDIATE LAKE MICHIGAN SHORE AND CORE OF CHICAGO. LATE NIGHT
MINS IN THE MID 30S AWAY FROM THE METRO AREA WILL LIKELY ALLOW AREAS
OF FROST TO DEVELOP WHERE WINDS DECOUPLE BECOME LIGHT/VARIABLE.
UPPER AND LOW LEVEL HIGH PRESSURE RIDGES REMAIN OVER THE AREA
WEDNESDAY ALLOWING PLENTIFUL SUNSHINE...THOUGH WITH ONLY MODEST
WARMING DUE TO EASTERLY WIND COMPONENT OFF LAKE AND COOLER UPSTREAM
AIR MASS. A BLEND OF MOS GUIDANCE APPEARS REASONABLE BASED ON RAW
MODEL LOW LEVEL THERMAL FIELDS...WITH WEDNESDAY AFTERNOON MAXES
EXPECTED TO RANGE FROM THE LOW 50S ALONG THE LAKE TO THE UPPER 50S
ACROSS THE FAR WESTERN/SOUTHERN COUNTIES OF THE CWA. ATTENTION THEN
TURNS BACK TOWARD THE NORTHWEST WEDNESDAY NIGHT...AS A WELL-DEFINED
SHORT WAVE TROUGH TRACKS ACROSS THE SOUTHERN CANADIAN PRAIRIES AND
DAKOTAS BEFORE APPROACHING THE UPPER MISSISSIPPI VALLEY WEDNESDAY
EVENING. HEIGHT/PRESSURE FALLS ACROSS THE UPPER MIDWEST NUDGES THE
SURFACE RIDGE AWAY TO OUR EAST AND INDUCES INCREASING
SOUTH-SOUTHEAST WINDS AHEAD OF THE APPROACHING SURFACE TROUGH
OVERNIGHT. CLEAR-PARTLY CLOUDY CONDITIONS AND LIGHT WINDS WILL
LIKELY ALLOW FOR QUICK DECOUPLING OF BOUNDARY LAYER WINDS EARLY
WEDNESDAY EVENING WITH TEMPS DROPPING INTO THE 30S AGAIN IN OUTLYING
AREAS...THOUGH SOME INCREASE IN HIGH CLOUDS AND THE INCREASE IN
WINDS OVERNIGHT WILL LIKELY LIMIT FROST SOMEWHAT.

THURSDAY THROUGH FRIDAY...

THE UPPER MIDWEST SHORT WAVE CONTINUES TO MOVE EAST-SOUTHEAST INTO
THE GREAT LAKES REGION THURSDAY...WITH THE BEST ORGANIZED DEEP LIFT
GENERALLY NORTH OF THE WFO CHICAGO CWA. THE MID-LEVEL TROUGH AXIS
DOES SHIFT ACROSS THE AREA LATER IN THE DAY AND OVERNIGHT HOWEVER...
THOUGH WITH MOISTURE RETURN FROM THE GULF INITIALLY BLOCKED BY THE
SURFACE HIGH PRESSURE RIDGE WHICH EXTENDS SOUTHWEST ACROSS THE
ARKLATEX REGION FOR MUCH OF THE PERIOD. THUS MOISTURE RETURN IS NOT
OVERLY IMPRESSIVE WITH THIS SYSTEM...THOUGH A PERIOD OF SHOWERS DOES
LOOK FAIRLY LIKELY THURSDAY INTO THURSDAY NIGHT. PRECIP POTENTIAL
LOOKS TO INCREASE AHEAD OF THE MID-LEVEL TROUGH AS IT MOVES INTO
NORTH CENTRAL IL DURING THE MID-LATE MORNING HOURS AND SPREADING
INTO NORTHEAST IL DURING THE AFTERNOON. FORCING WEAKENS THURSDAY
EVENING AS THE TROUGH RUNS INTO THE WEAKENING UPPER RIDGE...WITH
PRECIP EXPECTED TO BECOME MORE SPOTTY THURSDAY NIGHT AS IT MOVES
ACROSS THE EASTERN HALF OF THE FORECAST AREA. MID-LEVEL TROUGH AND
WEAKENING SURFACE TROUGH/COLD FRONT OF PACIFIC ORIGIN PASS EAST OF
THE AREA FRIDAY MORNING...WITH WEAK HIGH PRESSURE BUILDING IN DURING
THE DAY. TEMPERATURES ACTUALLY WARM IN THE WAKE OF THIS SYSTEM AS
THE SURFACE RIDGE DRIFTS EAST DURING THE DAY AND WESTERLY FLOW ALOFT
AROUND REBUILDING UPPER RIDGE OVER THE PLAINS ALLOWS WARM ADVECTION
BY AFTERNOON. MODEL THERMAL PROGS INDICATE SOME LOW-MID 60S ACROSS
NORTHERN IL FRIDAY AFTERNOON.

FRIDAY NIGHT THROUGH TUESDAY...

LONGER RANGE MODEL GUIDANCE IN GOOD AGREEMENT IN SPREADING BROAD
UPPER RIDGE EASTWARD FROM THE PLAINS AND ACROSS THE MIDWEST AND
GREAT LAKES REGION THROUGH THE WEEKEND...WHILE DEEP UPPER TROUGH
MOVES INTO THE WESTERN CONUS. MODELS DEPICT STRONG SOUTHERLY FLOW
AND WARM ADVECTION DEVELOPING AS SURFACE LOW PRESSURE DEVELOPS AND
LIFTS NORTHEAST ACROSS THE PLAINS AND THE UPPER MIDWEST SUNDAY...
THOUGH AGAIN WITH LIMITED MOISTURE RETURN FOR THE MAGNITUDE OF THE
FLOW. THIS ALLOWS US TO WARM UP SIGNIFICANTLY HOWEVER...WITH HIGHS
LIKELY GETTING ABOVE 70 DEGREES SATURDAY AND SUNDAY ACROSS PORTIONS
OF THE CWA...AND OVER MOST OF IT MONDAY. SURFACE TROUGH/COLD FRONT
APPROACHES MONDAY WITH AN ATTENDANT CHANCE OF RAIN AND INCREASED
CLOUD COVER. A SECOND LOW IS DEPICTED LIFTING ACROSS THE AREA MONDAY
NIGHT-TUESDAY MAINTAINING RAIN THREAT...AND ALSO LEADING TO MUCH
COOLER WEATHER AGAIN TUESDAY BEHIND THE SYSTEM COLD FRONT.

RATZER

&&

.AVIATION...

//ORD AND MDW CONCERNS...UPDATED 06Z...

* MVFR CIGS EARLY THIS MORNING.
* EAST WINDS MID MORNING THRU EARLY EVENING. CMS

//DISCUSSION...UPDATED 06Z...

HIGH PRESSURE WILL MOVE SOUTHEAST ACROSS THE REGION TODAY. LIGHT
EAST/NORTHEAST WINDS WILL SHIFT SOUTHEAST LATER THIS MORNING...
THEN TURN BACK EAST/NORTHEAST THIS AFTERNOON WITH A POSSIBLE LAKE
BREEZE. PREVAILING SPEEDS WILL LIKELY REMAIN UNDER 10KTS.

HIGH MVFR CIGS AROUND 3KFT WILL SLOWLY SCATTER OUT AND DISSIPATE
EARLY THIS MORNING WITH SKC EXPECTED LATER TODAY WITH INCREASING
HIGH CLOUDS TONIGHT. CMS

//ORD AND MDW CONFIDENCE...UPDATED 06Z...

* MEDIUM FOR MVFR CIGS EARLY THIS MORNING.
* HIGH FOR WIND THRU THE PERIOD. CMS

//OUTLOOK FOR ORD/MDW FOR 12Z THURSDAY-12Z TUESDAY...UPDATED 00Z...

* THURSDAY...CHANCE OF AFTERNOON SHRA. SOUTH WINDS.
* FRIDAY AND SATURDAY...DRY/VFR. WEST/SOUTHWEST WINDS.
* SUNDAY...DRY/VFR. SOUTH WINDS.
* MONDAY...SLIGHT CHANCE OF SHRA. GUSTY SOUTHWEST WINDS.

KJB

&&

.MARINE...

215 PM...LOW PRESSURE OVER WESTERN NEW YORK WILL MERGE WITH ANOTHER
LOW OVER NEAR THE DELMARVA AREA TONIGHT...AND RAPIDLY DEEPEN
WEDNESDAY NIGHT AND THURSDAY JUST SOUTH OF CAPE COD. THIS LOW WILL
THEN TRACK NORTHEAST TO NOVA SCOTIA BY SATURDAY MORNING.
MEANWHILE...HIGH PRESSURE CENTERED OVER THE SOUTHERN TIP OF JAMES
BAY...WITH HIGH PRESSURE RIDGING EXTENDING THROUGH THE MIDDLE
MISSISSIPPI VALLEY...WILL SLOWLY BUILD EAST. THE BRISK
NORTHEASTERLY WINDS CURRENTLY OVER THE LAKE WILL DIMINISH AND
BECOME LIGHT AND VARIABLE LATE TONIGHT AND EARLY WEDNESDAY AS THE
RIDGE AXIS CROSSES THE LAKE. WHILE WINDS SHOULD DROP BELOW SMALL
CRAFT ADVISORY LEVELS DURG THE AFTERNOON AND EARLY THIS
EVENING...RESIDUAL WAVE ACTION WILL BE SLOWER TO DAMPEN AND STILL
EXPECT THAT WAVES WILL REMAIN...ABOVE SMALL CRAFT ADVISORY LEVELS
THROUGH MUCH OF THE NIGHT. AS THE RIDGE MOVES TO THE EAST OF THE
LAKE WEDNESDAY NIGHT...A TROUGH OF LOW PRESSURE WILL CROSS THE
CENTRAL PLAINS...REACHING THE UPPER MISSISSIPPI VALLEY BY THURSDAY
MORNING. THIS WILL SET UP A STRENGTHENING SOUTHERLY GRADIENT OVER
THE LAKE WITH WINDS INCREASING TO ARND 20-25KT THURSDAY AFTERNOON.
WINDS WILL REMAIN SOUTHERLY UNTIL AN ASSOCIATED WEAK COLD FRONT
PUSHES ACROSS THE LAKE THURSDAY NIGHT.

KREIN

&&

.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...SMALL CRAFT ADVISORY...INDIANA NEARSHORE WATERS UNTIL 4 AM WEDNESDAY.

     SMALL CRAFT ADVISORY...ILLINOIS NEARSHORE WATERS UNTIL 7 AM WEDNESDAY.

&&

$$

VISIT US AT HTTP://WEATHER.GOV/CHICAGO (ALL LOWERCASE)

FOLLOW US ON FACEBOOK...TWITTER...AND YOUTUBE AT:
WWW.FACEBOOK.COM/NWSCHICAGO
WWW.TWITTER.COM/NWSCHICAGO
WWW.YOUTUBE.COM/NWSCHICAGO







000
FXUS63 KLOT 220239
AFDLOT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
939 PM CDT TUE OCT 21 2014

.DISCUSSION...
749 PM CDT

FOR AN EVENING UPDATE HAVE HELD ON TO FORECAST CLOUD COVER LONGER
TONIGHT...NAMELY FOR THE CENTRAL AND SOUTHERN PARTS OF THE
CHICAGO METRO AND SOUTH AND SOUTHWEST FROM THERE.

SURFACE RIDGING IS BUILDING SOUTHWARD THIS EVENING INTO NORTHERN
ILLINOIS AND WIND SPEEDS HAVE COME DOWN QUITE A BIT OUTSIDE OF THE
IMMEDIATE LAKE SHORE. SUBSIDENCE ALOFT IS CONTINUING AS WELL PER
WATER VAPOR AND DIAGNOSTIC MODEL SOUNDINGS...BUT CLOUDS HAVE
SLOWED THEIR RATE OF DIMINISHING...POSSIBLY DUE TO NO MORE CLOUD
TOP WARMING FROM THE SUN.

WHILE THE CLOUD LAYER IS VERY THIN IN DEPTH AS INDICATED BY
REGIONAL AMDAR DATA...FORESEE CLOUDS HANGING ON A WHILE LONGER
WITH NIGHTFALL. THE LOCAL 8KM ARW...AND RAP TO SOME DEGREE...INDICATE
LITTLE MOVEMENT IN THE MOST SOLID SATURATION ALONG AND EAST OF
INTERSTATE 55 THROUGH MIDNIGHT...AND THEN AS CLOUD-BEARING FLOW
TURNS EASTERLY THE MOISTURE ADVECTS WITH IT AND GRADUALLY THINS.
THIS WAS GENERALLY DEPICTED IN THE PREVIOUS FORECAST BUT JUST
HAVE SHIFTED BACK IN TIMING SEVERAL HOURS.

MADE SOME ADJUSTMENTS TO HOURLY TEMPERATURES TO BETTER FIT THIS
REASONING AND THAT DID LEAD TO AN INCREASE IN MIN TEMPS IN A FEW
PLACES...BUT OTHERWISE NO CHANGES MADE.

MTF

//PREV DISCUSSION...
309 PM CDT

MAIN FORECAST CONCERNS FOCUS ON PRECIPITATION CHANCES AND TIMING
WITH A COUPLE OF SYSTEMS WHICH WILL AFFECT THE REGION THURSDAY AND
NEXT MONDAY. ALSO...IT APPEARS THAT SOME 70 DEGREE TEMPERATURES ARE
POSSIBLE FOR PARTS OF THE FORECAST AREA OVER THE WEEKEND AS WELL AS
ON MONDAY.

TONIGHT THROUGH WEDNESDAY NIGHT...

GOES WATER VAPOR IMAGERY DEPICTS A STRONG MID-LEVEL SHORT WAVE
TROUGH WHICH HAD DUG SOUTH ACROSS THE REGION TODAY IS NOW EXITING
THE AREA ACROSS THE OHIO VALLEY TO THE SOUTHEAST. SUBSIDENCE IN THE
WAKE OF THIS FEATURE WAS EVIDENT BOTH IN RISING SURFACE PRESSURE
ACROSS THE CWA...AND IN VISIBLE SATELLITE IMAGERY AS EXTENSIVE AREA
OF STRATOCU ACROSS THE REGION ERODES FROM THE NORTH ACROSS WI/MI AND
LAKE MICHIGAN. EARLIER LAKE-INDUCED SHOWERS HAVE WEAKENED AND FADED
AS EXPECTED DUE TO LOWERING SUBSIDENCE INVERSION AND ASSOCIATED
WARMING ALOFT. CLOUD COVER IS EXPECTED TO CONTINUE TO DECREASE IN
COVERAGE INTO THE EVENING HOURS...WITH PERHAPS JUST SOME PATCHY THIN
SHALLOW STRATOCU LINGERING OFF THE LAKE BY LATE EVENING. LOOKING AT
THE BIGGER PICTURE...HIGH-AMPLITUDE UPPER RIDGE ANALYZED OVER THE
CENTRAL PORTION OF THE NATION WILL MOVE ACROSS THE MISSISSIPPI
VALLEY AND WESTERN/NORTHERN GREAT LAKES REGION THROUGH WEDNESDAY
MORNING...MAINTAINING SUBSIDENCE WHICH SHOULD FURTHER ERODE
LINGERING CLOUDS AND ALLOW SURFACE HIGH PRESSURE RIDGE TO MOVE
ACROSS THE AREA TONIGHT AND WEDNESDAY. WITH CLEARING SKIES AND
DECREASING WINDS ASSOCIATED WITH THE SURFACE RIDGE AXIS TONIGHT...
TEMPS ARE EXPECTED TO DROP OFF INTO THE 30S IN MANY AREAS AWAY FROM
THE IMMEDIATE LAKE MICHIGAN SHORE AND CORE OF CHICAGO. LATE NIGHT
MINS IN THE MID 30S AWAY FROM THE METRO AREA WILL LIKELY ALLOW AREAS
OF FROST TO DEVELOP WHERE WINDS DECOUPLE BECOME LIGHT/VARIABLE.
UPPER AND LOW LEVEL HIGH PRESSURE RIDGES REMAIN OVER THE AREA
WEDNESDAY ALLOWING PLENTIFUL SUNSHINE...THOUGH WITH ONLY MODEST
WARMING DUE TO EASTERLY WIND COMPONENT OFF LAKE AND COOLER UPSTREAM
AIR MASS. A BLEND OF MOS GUIDANCE APPEARS REASONABLE BASED ON RAW
MODEL LOW LEVEL THERMAL FIELDS...WITH WEDNESDAY AFTERNOON MAXES
EXPECTED TO RANGE FROM THE LOW 50S ALONG THE LAKE TO THE UPPER 50S
ACROSS THE FAR WESTERN/SOUTHERN COUNTIES OF THE CWA. ATTENTION THEN
TURNS BACK TOWARD THE NORTHWEST WEDNESDAY NIGHT...AS A WELL-DEFINED
SHORT WAVE TROUGH TRACKS ACROSS THE SOUTHERN CANADIAN PRAIRIES AND
DAKOTAS BEFORE APPROACHING THE UPPER MISSISSIPPI VALLEY WEDNESDAY
EVENING. HEIGHT/PRESSURE FALLS ACROSS THE UPPER MIDWEST NUDGES THE
SURFACE RIDGE AWAY TO OUR EAST AND INDUCES INCREASING
SOUTH-SOUTHEAST WINDS AHEAD OF THE APPROACHING SURFACE TROUGH
OVERNIGHT. CLEAR-PARTLY CLOUDY CONDITIONS AND LIGHT WINDS WILL
LIKELY ALLOW FOR QUICK DECOUPLING OF BOUNDARY LAYER WINDS EARLY
WEDNESDAY EVENING WITH TEMPS DROPPING INTO THE 30S AGAIN IN OUTLYING
AREAS...THOUGH SOME INCREASE IN HIGH CLOUDS AND THE INCREASE IN
WINDS OVERNIGHT WILL LIKELY LIMIT FROST SOMEWHAT.

THURSDAY THROUGH FRIDAY...

THE UPPER MIDWEST SHORT WAVE CONTINUES TO MOVE EAST-SOUTHEAST INTO
THE GREAT LAKES REGION THURSDAY...WITH THE BEST ORGANIZED DEEP LIFT
GENERALLY NORTH OF THE WFO CHICAGO CWA. THE MID-LEVEL TROUGH AXIS
DOES SHIFT ACROSS THE AREA LATER IN THE DAY AND OVERNIGHT HOWEVER...
THOUGH WITH MOISTURE RETURN FROM THE GULF INITIALLY BLOCKED BY THE
SURFACE HIGH PRESSURE RIDGE WHICH EXTENDS SOUTHWEST ACROSS THE
ARKLATEX REGION FOR MUCH OF THE PERIOD. THUS MOISTURE RETURN IS NOT
OVERLY IMPRESSIVE WITH THIS SYSTEM...THOUGH A PERIOD OF SHOWERS DOES
LOOK FAIRLY LIKELY THURSDAY INTO THURSDAY NIGHT. PRECIP POTENTIAL
LOOKS TO INCREASE AHEAD OF THE MID-LEVEL TROUGH AS IT MOVES INTO
NORTH CENTRAL IL DURING THE MID-LATE MORNING HOURS AND SPREADING
INTO NORTHEAST IL DURING THE AFTERNOON. FORCING WEAKENS THURSDAY
EVENING AS THE TROUGH RUNS INTO THE WEAKENING UPPER RIDGE...WITH
PRECIP EXPECTED TO BECOME MORE SPOTTY THURSDAY NIGHT AS IT MOVES
ACROSS THE EASTERN HALF OF THE FORECAST AREA. MID-LEVEL TROUGH AND
WEAKENING SURFACE TROUGH/COLD FRONT OF PACIFIC ORIGIN PASS EAST OF
THE AREA FRIDAY MORNING...WITH WEAK HIGH PRESSURE BUILDING IN DURING
THE DAY. TEMPERATURES ACTUALLY WARM IN THE WAKE OF THIS SYSTEM AS
THE SURFACE RIDGE DRIFTS EAST DURING THE DAY AND WESTERLY FLOW ALOFT
AROUND REBUILDING UPPER RIDGE OVER THE PLAINS ALLOWS WARM ADVECTION
BY AFTERNOON. MODEL THERMAL PROGS INDICATE SOME LOW-MID 60S ACROSS
NORTHERN IL FRIDAY AFTERNOON.

FRIDAY NIGHT THROUGH TUESDAY...

LONGER RANGE MODEL GUIDANCE IN GOOD AGREEMENT IN SPREADING BROAD
UPPER RIDGE EASTWARD FROM THE PLAINS AND ACROSS THE MIDWEST AND
GREAT LAKES REGION THROUGH THE WEEKEND...WHILE DEEP UPPER TROUGH
MOVES INTO THE WESTERN CONUS. MODELS DEPICT STRONG SOUTHERLY FLOW
AND WARM ADVECTION DEVELOPING AS SURFACE LOW PRESSURE DEVELOPS AND
LIFTS NORTHEAST ACROSS THE PLAINS AND THE UPPER MIDWEST SUNDAY...
THOUGH AGAIN WITH LIMITED MOISTURE RETURN FOR THE MAGNITUDE OF THE
FLOW. THIS ALLOWS US TO WARM UP SIGNIFICANTLY HOWEVER...WITH HIGHS
LIKELY GETTING ABOVE 70 DEGREES SATURDAY AND SUNDAY ACROSS PORTIONS
OF THE CWA...AND OVER MOST OF IT MONDAY. SURFACE TROUGH/COLD FRONT
APPROACHES MONDAY WITH AN ATTENDANT CHANCE OF RAIN AND INCREASED
CLOUD COVER. A SECOND LOW IS DEPICTED LIFTING ACROSS THE AREA MONDAY
NIGHT-TUESDAY MAINTAINING RAIN THREAT...AND ALSO LEADING TO MUCH
COOLER WEATHER AGAIN TUESDAY BEHIND THE SYSTEM COLD FRONT.

RATZER

&&

.AVIATION...

//ORD AND MDW CONCERNS...UPDATED 03Z...

* MVFR CIGS AROUND 2,800 FEET AGL HOLDING THROUGH LATER TONIGHT.

KJB

//DISCUSSION...UPDATED 00Z...

MVFR CIGS CONTINUE TO MOVE IN OFF THE LAKE EARLY THIS EVENING VIA A
NORTH-NORTHEASTERLY LOWER LEVEL WIND TRAJECTORY ASSOCIATED WITH A
SURFACE RIDGE OF HIGH PRESSURE BUILDING EASTWARD ACROSS THE UPPER
GREAT LAKES AND OVER EASTERN ONTARIO. IT APPEARS THESE LOW CLOUDS
WILL TRY TO GRADUALLY SCATTERED OUT OVER THE NEXT 2 TO 3 HOURS.
HOWEVER...SOME OF THESE CLOUDS COULD BE A LITTLE SLOWER TO SCATTER
OUT ACROSS THE EASTERN TERMINALS NEAR THE LAKE AS CONDITIONS LOOK
TO REMAIN FAVORABLE FOR SOME CLOUD COVER OVER SOUTHERN LAKE
MICHIGAN. THEREFORE...IT IS POSSIBLE THAT AS THE LOWER LEVEL WINDS
VEER MORE NORTHEASTERLY THIS EVENING...SOME CLOUDS WILL CONTINUE
TO STREAM OFF THE LAKE AND OVER NORTHEASTERN ILLINOIS AND
NORTHWESTERN INDIANA DURING THE EVENING HOURS. I WILL CONTINUE TO
WATCH TRENDS WITH THIS AS THE EXACT TIMING OF SCATTERING IS A BIT
LOWER THAN PREVIOUSLY THOUGHT. THE GOOD NEWS IS THAT CIG HEIGHTS
SHOULD GENERALLY REMAIN AT OR ABOVE 2500 FEET AGL...SO AVIATION
IMPACTS SHOULD BE MINIMAL.

OTHERWISE...THE REMAINDER OF THE PERIOD LOOKS TO BE MAINLY VFR WITH
LIGHT EASTERLY WINDS.

KJB

//ORD AND MDW CONFIDENCE...UPDATED 03Z...

* LOW-MEDIUM WITH EXACT TIMING OF IMPROVING CEILINGS TONIGHT.

* HIGH WITH OTHER FORECAST ELEMENTS.

KJB

//OUTLOOK FOR ORD/MDW FOR 12Z THURSDAY-12Z TUESDAY...UPDATED 00Z...

* THURSDAY...CHANCE OF AFTERNOON SHRA. SOUTH WINDS.
* FRIDAY AND SATURDAY...DRY/VFR. WEST/SOUTHWEST WINDS.
* SUNDAY...DRY/VFR. SOUTH WINDS.
* MONDAY...SLIGHT CHANCE OF SHRA. GUSTY SOUTHWEST WINDS.

KJB

&&

.MARINE...

215 PM...LOW PRESSURE OVER WESTERN NEW YORK WILL MERGE WITH ANOTHER
LOW OVER NEAR THE DELMARVA AREA TONIGHT...AND RAPIDLY DEEPEN
WEDNESDAY NIGHT AND THURSDAY JUST SOUTH OF CAPE COD. THIS LOW WILL
THEN TRACK NORTHEAST TO NOVA SCOTIA BY SATURDAY MORNING.
MEANWHILE...HIGH PRESSURE CENTERED OVER THE SOUTHERN TIP OF JAMES
BAY...WITH HIGH PRESSURE RIDGING EXTENDING THROUGH THE MIDDLE
MISSISSIPPI VALLEY...WILL SLOWLY BUILD EAST. THE BRISK
NORTHEASTERLY WINDS CURRENTLY OVER THE LAKE WILL DIMINISH AND
BECOME LIGHT AND VARIABLE LATE TONIGHT AND EARLY WEDNESDAY AS THE
RIDGE AXIS CROSSES THE LAKE. WHILE WINDS SHOULD DROP BELOW SMALL
CRAFT ADVISORY LEVELS DURG THE AFTERNOON AND EARLY THIS
EVENING...RESIDUAL WAVE ACTION WILL BE SLOWER TO DAMPEN AND STILL
EXPECT THAT WAVES WILL REMAIN...ABOVE SMALL CRAFT ADVISORY LEVELS
THROUGH MUCH OF THE NIGHT. AS THE RIDGE MOVES TO THE EAST OF THE
LAKE WEDNESDAY NIGHT...A TROUGH OF LOW PRESSURE WILL CROSS THE
CENTRAL PLAINS...REACHING THE UPPER MISSISSIPPI VALLEY BY THURSDAY
MORNING. THIS WILL SET UP A STRENGTHENING SOUTHERLY GRADIENT OVER
THE LAKE WITH WINDS INCREASING TO ARND 20-25KT THURSDAY AFTERNOON.
WINDS WILL REMAIN SOUTHERLY UNTIL AN ASSOCIATED WEAK COLD FRONT
PUSHES ACROSS THE LAKE THURSDAY NIGHT.

KREIN

&&

.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...SMALL CRAFT ADVISORY...INDIANA NEARSHORE WATERS UNTIL 4 AM WEDNESDAY.

     SMALL CRAFT ADVISORY...ILLINOIS NEARSHORE WATERS UNTIL 7 AM WEDNESDAY.

&&

$$

VISIT US AT HTTP://WEATHER.GOV/CHICAGO (ALL LOWERCASE)

FOLLOW US ON FACEBOOK...TWITTER...AND YOUTUBE AT:
WWW.FACEBOOK.COM/NWSCHICAGO
WWW.TWITTER.COM/NWSCHICAGO
WWW.YOUTUBE.COM/NWSCHICAGO







000
FXUS63 KLOT 220049 AAA
AFDLOT

AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
749 PM CDT TUE OCT 21 2014

.DISCUSSION...
749 PM CDT

FOR AN EVENING UPDATE HAVE HELD ON TO FORECAST CLOUD COVER LONGER
TONIGHT...NAMELY FOR THE CENTRAL AND SOUTHERN PARTS OF THE
CHICAGO METRO AND SOUTH AND SOUTHWEST FROM THERE.

SURFACE RIDGING IS BUILDING SOUTHWARD THIS EVENING INTO NORTHERN
ILLINOIS AND WIND SPEEDS HAVE COME DOWN QUITE A BIT OUTSIDE OF THE
IMMEDIATE LAKE SHORE. SUBSIDENCE ALOFT IS CONTINUING AS WELL PER
WATER VAPOR AND DIAGNOSTIC MODEL SOUNDINGS...BUT CLOUDS HAVE
SLOWED THEIR RATE OF DIMINISHING...POSSIBLY DUE TO NO MORE CLOUD
TOP WARMING FROM THE SUN.

WHILE THE CLOUD LAYER IS VERY THIN IN DEPTH AS INDICATED BY
REGIONAL AMDAR DATA...FORESEE CLOUDS HANGING ON A WHILE LONGER
WITH NIGHTFALL. THE LOCAL 8KM ARW...AND RAP TO SOME DEGREE...INDICATE
LITTLE MOVEMENT IN THE MOST SOLID SATURATION ALONG AND EAST OF
INTERSTATE 55 THROUGH MIDNIGHT...AND THEN AS CLOUD-BEARING FLOW
TURNS EASTERLY THE MOISTURE ADVECTS WITH IT AND GRADUALLY THINS.
THIS WAS GENERALLY DEPICTED IN THE PREVIOUS FORECAST BUT JUST
HAVE SHIFTED BACK IN TIMING SEVERAL HOURS.

MADE SOME ADJUSTMENTS TO HOURLY TEMPERATURES TO BETTER FIT THIS
REASONING AND THAT DID LEAD TO AN INCREASE IN MIN TEMPS IN A FEW
PLACES...BUT OTHERWISE NO CHANGES MADE.

MTF

&&

.PREV DISCUSSION...
309 PM CDT

MAIN FORECAST CONCERNS FOCUS ON PRECIPITATION CHANCES AND TIMING
WITH A COUPLE OF SYSTEMS WHICH WILL AFFECT THE REGION THURSDAY AND
NEXT MONDAY. ALSO...IT APPEARS THAT SOME 70 DEGREE TEMPERATURES ARE
POSSIBLE FOR PARTS OF THE FORECAST AREA OVER THE WEEKEND AS WELL AS
ON MONDAY.

TONIGHT THROUGH WEDNESDAY NIGHT...

GOES WATER VAPOR IMAGERY DEPICTS A STRONG MID-LEVEL SHORT WAVE
TROUGH WHICH HAD DUG SOUTH ACROSS THE REGION TODAY IS NOW EXITING
THE AREA ACROSS THE OHIO VALLEY TO THE SOUTHEAST. SUBSIDENCE IN THE
WAKE OF THIS FEATURE WAS EVIDENT BOTH IN RISING SURFACE PRESSURE
ACROSS THE CWA...AND IN VISIBLE SATELLITE IMAGERY AS EXTENSIVE AREA
OF STRATOCU ACROSS THE REGION ERODES FROM THE NORTH ACROSS WI/MI AND
LAKE MICHIGAN. EARLIER LAKE-INDUCED SHOWERS HAVE WEAKENED AND FADED
AS EXPECTED DUE TO LOWERING SUBSIDENCE INVERSION AND ASSOCIATED
WARMING ALOFT. CLOUD COVER IS EXPECTED TO CONTINUE TO DECREASE IN
COVERAGE INTO THE EVENING HOURS...WITH PERHAPS JUST SOME PATCHY THIN
SHALLOW STRATOCU LINGERING OFF THE LAKE BY LATE EVENING. LOOKING AT
THE BIGGER PICTURE...HIGH-AMPLITUDE UPPER RIDGE ANALYZED OVER THE
CENTRAL PORTION OF THE NATION WILL MOVE ACROSS THE MISSISSIPPI
VALLEY AND WESTERN/NORTHERN GREAT LAKES REGION THROUGH WEDNESDAY
MORNING...MAINTAINING SUBSIDENCE WHICH SHOULD FURTHER ERODE
LINGERING CLOUDS AND ALLOW SURFACE HIGH PRESSURE RIDGE TO MOVE
ACROSS THE AREA TONIGHT AND WEDNESDAY. WITH CLEARING SKIES AND
DECREASING WINDS ASSOCIATED WITH THE SURFACE RIDGE AXIS TONIGHT...
TEMPS ARE EXPECTED TO DROP OFF INTO THE 30S IN MANY AREAS AWAY FROM
THE IMMEDIATE LAKE MICHIGAN SHORE AND CORE OF CHICAGO. LATE NIGHT
MINS IN THE MID 30S AWAY FROM THE METRO AREA WILL LIKELY ALLOW AREAS
OF FROST TO DEVELOP WHERE WINDS DECOUPLE BECOME LIGHT/VARIABLE.
UPPER AND LOW LEVEL HIGH PRESSURE RIDGES REMAIN OVER THE AREA
WEDNESDAY ALLOWING PLENTIFUL SUNSHINE...THOUGH WITH ONLY MODEST
WARMING DUE TO EASTERLY WIND COMPONENT OFF LAKE AND COOLER UPSTREAM
AIR MASS. A BLEND OF MOS GUIDANCE APPEARS REASONABLE BASED ON RAW
MODEL LOW LEVEL THERMAL FIELDS...WITH WEDNESDAY AFTERNOON MAXES
EXPECTED TO RANGE FROM THE LOW 50S ALONG THE LAKE TO THE UPPER 50S
ACROSS THE FAR WESTERN/SOUTHERN COUNTIES OF THE CWA. ATTENTION THEN
TURNS BACK TOWARD THE NORTHWEST WEDNESDAY NIGHT...AS A WELL-DEFINED
SHORT WAVE TROUGH TRACKS ACROSS THE SOUTHERN CANADIAN PRAIRIES AND
DAKOTAS BEFORE APPROACHING THE UPPER MISSISSIPPI VALLEY WEDNESDAY
EVENING. HEIGHT/PRESSURE FALLS ACROSS THE UPPER MIDWEST NUDGES THE
SURFACE RIDGE AWAY TO OUR EAST AND INDUCES INCREASING
SOUTH-SOUTHEAST WINDS AHEAD OF THE APPROACHING SURFACE TROUGH
OVERNIGHT. CLEAR-PARTLY CLOUDY CONDITIONS AND LIGHT WINDS WILL
LIKELY ALLOW FOR QUICK DECOUPLING OF BOUNDARY LAYER WINDS EARLY
WEDNESDAY EVENING WITH TEMPS DROPPING INTO THE 30S AGAIN IN OUTLYING
AREAS...THOUGH SOME INCREASE IN HIGH CLOUDS AND THE INCREASE IN
WINDS OVERNIGHT WILL LIKELY LIMIT FROST SOMEWHAT.

THURSDAY THROUGH FRIDAY...

THE UPPER MIDWEST SHORT WAVE CONTINUES TO MOVE EAST-SOUTHEAST INTO
THE GREAT LAKES REGION THURSDAY...WITH THE BEST ORGANIZED DEEP LIFT
GENERALLY NORTH OF THE WFO CHICAGO CWA. THE MID-LEVEL TROUGH AXIS
DOES SHIFT ACROSS THE AREA LATER IN THE DAY AND OVERNIGHT HOWEVER...
THOUGH WITH MOISTURE RETURN FROM THE GULF INITIALLY BLOCKED BY THE
SURFACE HIGH PRESSURE RIDGE WHICH EXTENDS SOUTHWEST ACROSS THE
ARKLATEX REGION FOR MUCH OF THE PERIOD. THUS MOISTURE RETURN IS NOT
OVERLY IMPRESSIVE WITH THIS SYSTEM...THOUGH A PERIOD OF SHOWERS DOES
LOOK FAIRLY LIKELY THURSDAY INTO THURSDAY NIGHT. PRECIP POTENTIAL
LOOKS TO INCREASE AHEAD OF THE MID-LEVEL TROUGH AS IT MOVES INTO
NORTH CENTRAL IL DURING THE MID-LATE MORNING HOURS AND SPREADING
INTO NORTHEAST IL DURING THE AFTERNOON. FORCING WEAKENS THURSDAY
EVENING AS THE TROUGH RUNS INTO THE WEAKENING UPPER RIDGE...WITH
PRECIP EXPECTED TO BECOME MORE SPOTTY THURSDAY NIGHT AS IT MOVES
ACROSS THE EASTERN HALF OF THE FORECAST AREA. MID-LEVEL TROUGH AND
WEAKENING SURFACE TROUGH/COLD FRONT OF PACIFIC ORIGIN PASS EAST OF
THE AREA FRIDAY MORNING...WITH WEAK HIGH PRESSURE BUILDING IN DURING
THE DAY. TEMPERATURES ACTUALLY WARM IN THE WAKE OF THIS SYSTEM AS
THE SURFACE RIDGE DRIFTS EAST DURING THE DAY AND WESTERLY FLOW ALOFT
AROUND REBUILDING UPPER RIDGE OVER THE PLAINS ALLOWS WARM ADVECTION
BY AFTERNOON. MODEL THERMAL PROGS INDICATE SOME LOW-MID 60S ACROSS
NORTHERN IL FRIDAY AFTERNOON.

FRIDAY NIGHT THROUGH TUESDAY...

LONGER RANGE MODEL GUIDANCE IN GOOD AGREEMENT IN SPREADING BROAD
UPPER RIDGE EASTWARD FROM THE PLAINS AND ACROSS THE MIDWEST AND
GREAT LAKES REGION THROUGH THE WEEKEND...WHILE DEEP UPPER TROUGH
MOVES INTO THE WESTERN CONUS. MODELS DEPICT STRONG SOUTHERLY FLOW
AND WARM ADVECTION DEVELOPING AS SURFACE LOW PRESSURE DEVELOPS AND
LIFTS NORTHEAST ACROSS THE PLAINS AND THE UPPER MIDWEST SUNDAY...
THOUGH AGAIN WITH LIMITED MOISTURE RETURN FOR THE MAGNITUDE OF THE
FLOW. THIS ALLOWS US TO WARM UP SIGNIFICANTLY HOWEVER...WITH HIGHS
LIKELY GETTING ABOVE 70 DEGREES SATURDAY AND SUNDAY ACROSS PORTIONS
OF THE CWA...AND OVER MOST OF IT MONDAY. SURFACE TROUGH/COLD FRONT
APPROACHES MONDAY WITH AN ATTENDANT CHANCE OF RAIN AND INCREASED
CLOUD COVER. A SECOND LOW IS DEPICTED LIFTING ACROSS THE AREA MONDAY
NIGHT-TUESDAY MAINTAINING RAIN THREAT...AND ALSO LEADING TO MUCH
COOLER WEATHER AGAIN TUESDAY BEHIND THE SYSTEM COLD FRONT.

RATZER

&&

.AVIATION...

//ORD AND MDW CONCERNS...UPDATED 00Z...

* NORTH/NORTHEAST WINDS GRADUALLY DROPPING BELOW 10 KT EARLY THIS
  EVENING.

* MVFR CEILINGS HOLDING ON POSSIBLY THROUGH MID EVENING.

KJB

//DISCUSSION...UPDATED 00Z...

MVFR CIGS CONTINUE TO MOVE IN OFF THE LAKE EARLY THIS EVENING VIA A
NORTH-NORTHEASTERLY LOWER LEVEL WIND TRAJECTORY ASSOCIATED WITH A
SURFACE RIDGE OF HIGH PRESSURE BUILDING EASTWARD ACROSS THE UPPER
GREAT LAKES AND OVER EASTERN ONTARIO. IT APPEARS THESE LOW CLOUDS
WILL TRY TO GRADUALLY SCATTERED OUT OVER THE NEXT 2 TO 3 HOURS.
HOWEVER...SOME OF THESE CLOUDS COULD BE A LITTLE SLOWER TO SCATTER
OUT ACROSS THE EASTERN TERMINALS NEAR THE LAKE AS CONDITIONS LOOK
TO REMAIN FAVORABLE FOR SOME CLOUD COVER OVER SOUTHERN LAKE
MICHIGAN. THEREFORE...IT IS POSSIBLE THAT AS THE LOWER LEVEL WINDS
VEER MORE NORTHEASTERLY THIS EVENING...SOME CLOUDS WILL CONTINUE
TO STREAM OFF THE LAKE AND OVER NORTHEASTERN ILLINOIS AND
NORTHWESTERN INDIANA DURING THE EVENING HOURS. I WILL CONTINUE TO
WATCH TRENDS WITH THIS AS THE EXACT TIMING OF SCATTERING IS A BIT
LOWER THAN PREVIOUSLY THOUGHT. THE GOOD NEWS IS THAT CIG HEIGHTS
SHOULD GENERALLY REMAIN AT OR ABOVE 2500 FEET AGL...SO AVIATION
IMPACTS SHOULD BE MINIMAL.

OTHERWISE...THE REMAINDER OF THE PERIOD LOOKS TO BE MAINLY VFR WITH
LIGHT EASTERLY WINDS.

KJB

//ORD AND MDW CONFIDENCE...UPDATED 00Z...

* MEDIUM-HIGH CONFIDENCE WITH WIND SPEED/DIRECTION.

* LOW-MEDIUM CONFIDENCE WITH EXACT TIMING OF IMPROVING CEILINGS
  THIS EVENING.

KJB

//OUTLOOK FOR ORD/MDW FOR 12Z THURSDAY-12Z TUESDAY...UPDATED 00Z...

* THURSDAY...CHANCE OF AFTERNOON SHRA. SOUTH WINDS.
* FRIDAY AND SATURDAY...DRY/VFR. WEST/SOUTHWEST WINDS.
* SUNDAY...DRY/VFR. SOUTH WINDS.
* MONDAY...SLIGHT CHANCE OF SHRA. GUSTY SOUTHWEST WINDS.

KJB

&&

.MARINE...

215 PM...LOW PRESSURE OVER WESTERN NEW YORK WILL MERGE WITH ANOTHER
LOW OVER NEAR THE DELMARVA AREA TONIGHT...AND RAPIDLY DEEPEN
WEDNESDAY NIGHT AND THURSDAY JUST SOUTH OF CAPE COD. THIS LOW WILL
THEN TRACK NORTHEAST TO NOVA SCOTIA BY SATURDAY MORNING.
MEANWHILE...HIGH PRESSURE CENTERED OVER THE SOUTHERN TIP OF JAMES
BAY...WITH HIGH PRESSURE RIDGING EXTENDING THROUGH THE MIDDLE
MISSISSIPPI VALLEY...WILL SLOWLY BUILD EAST. THE BRISK
NORTHEASTERLY WINDS CURRENTLY OVER THE LAKE WILL DIMINISH AND
BECOME LIGHT AND VARIABLE LATE TONIGHT AND EARLY WEDNESDAY AS THE
RIDGE AXIS CROSSES THE LAKE. WHILE WINDS SHOULD DROP BELOW SMALL
CRAFT ADVISORY LEVELS DURG THE AFTERNOON AND EARLY THIS
EVENING...RESIDUAL WAVE ACTION WILL BE SLOWER TO DAMPEN AND STILL
EXPECT THAT WAVES WILL REMAIN...ABOVE SMALL CRAFT ADVISORY LEVELS
THROUGH MUCH OF THE NIGHT. AS THE RIDGE MOVES TO THE EAST OF THE
LAKE WEDNESDAY NIGHT...A TROUGH OF LOW PRESSURE WILL CROSS THE
CENTRAL PLAINS...REACHING THE UPPER MISSISSIPPI VALLEY BY THURSDAY
MORNING. THIS WILL SET UP A STRENGTHENING SOUTHERLY GRADIENT OVER
THE LAKE WITH WINDS INCREASING TO ARND 20-25KT THURSDAY AFTERNOON.
WINDS WILL REMAIN SOUTHERLY UNTIL AN ASSOCIATED WEAK COLD FRONT
PUSHES ACROSS THE LAKE THURSDAY NIGHT.

KREIN

&&

.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...SMALL CRAFT ADVISORY...NEARSHORE WATERS
     UNTIL 7 AM WEDNESDAY.

&&

$$

VISIT US AT HTTP://WEATHER.GOV/CHICAGO (ALL LOWERCASE)

FOLLOW US ON FACEBOOK...TWITTER...AND YOUTUBE AT:
WWW.FACEBOOK.COM/NWSCHICAGO
WWW.TWITTER.COM/NWSCHICAGO
WWW.YOUTUBE.COM/NWSCHICAGO








000
FXUS63 KLOT 212329
AFDLOT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
629 PM CDT TUE OCT 21 2014

.DISCUSSION...
309 PM CDT

MAIN FORECAST CONCERNS FOCUS ON PRECIPITATION CHANCES AND TIMING
WITH A COUPLE OF SYSTEMS WHICH WILL AFFECT THE REGION THURSDAY AND
NEXT MONDAY. ALSO...IT APPEARS THAT SOME 70 DEGREE TEMPERATURES ARE
POSSIBLE FOR PARTS OF THE FORECAST AREA OVER THE WEEKEND AS WELL AS
ON MONDAY.

TONIGHT THROUGH WEDNESDAY NIGHT...

GOES WATER VAPOR IMAGERY DEPICTS A STRONG MID-LEVEL SHORT WAVE
TROUGH WHICH HAD DUG SOUTH ACROSS THE REGION TODAY IS NOW EXITING
THE AREA ACROSS THE OHIO VALLEY TO THE SOUTHEAST. SUBSIDENCE IN THE
WAKE OF THIS FEATURE WAS EVIDENT BOTH IN RISING SURFACE PRESSURE
ACROSS THE CWA...AND IN VISIBLE SATELLITE IMAGERY AS EXTENSIVE AREA
OF STRATOCU ACROSS THE REGION ERODES FROM THE NORTH ACROSS WI/MI AND
LAKE MICHIGAN. EARLIER LAKE-INDUCED SHOWERS HAVE WEAKENED AND FADED
AS EXPECTED DUE TO LOWERING SUBSIDENCE INVERSION AND ASSOCIATED
WARMING ALOFT. CLOUD COVER IS EXPECTED TO CONTINUE TO DECREASE IN
COVERAGE INTO THE EVENING HOURS...WITH PERHAPS JUST SOME PATCHY THIN
SHALLOW STRATOCU LINGERING OFF THE LAKE BY LATE EVENING. LOOKING AT
THE BIGGER PICTURE...HIGH-AMPLITUDE UPPER RIDGE ANALYZED OVER THE
CENTRAL PORTION OF THE NATION WILL MOVE ACROSS THE MISSISSIPPI
VALLEY AND WESTERN/NORTHERN GREAT LAKES REGION THROUGH WEDNESDAY
MORNING...MAINTAINING SUBSIDENCE WHICH SHOULD FURTHER ERODE
LINGERING CLOUDS AND ALLOW SURFACE HIGH PRESSURE RIDGE TO MOVE
ACROSS THE AREA TONIGHT AND WEDNESDAY. WITH CLEARING SKIES AND
DECREASING WINDS ASSOCIATED WITH THE SURFACE RIDGE AXIS TONIGHT...
TEMPS ARE EXPECTED TO DROP OFF INTO THE 30S IN MANY AREAS AWAY FROM
THE IMMEDIATE LAKE MICHIGAN SHORE AND CORE OF CHICAGO. LATE NIGHT
MINS IN THE MID 30S AWAY FROM THE METRO AREA WILL LIKELY ALLOW AREAS
OF FROST TO DEVELOP WHERE WINDS DECOUPLE BECOME LIGHT/VARIABLE.
UPPER AND LOW LEVEL HIGH PRESSURE RIDGES REMAIN OVER THE AREA
WEDNESDAY ALLOWING PLENTIFUL SUNSHINE...THOUGH WITH ONLY MODEST
WARMING DUE TO EASTERLY WIND COMPONENT OFF LAKE AND COOLER UPSTREAM
AIR MASS. A BLEND OF MOS GUIDANCE APPEARS REASONABLE BASED ON RAW
MODEL LOW LEVEL THERMAL FIELDS...WITH WEDNESDAY AFTERNOON MAXES
EXPECTED TO RANGE FROM THE LOW 50S ALONG THE LAKE TO THE UPPER 50S
ACROSS THE FAR WESTERN/SOUTHERN COUNTIES OF THE CWA. ATTENTION THEN
TURNS BACK TOWARD THE NORTHWEST WEDNESDAY NIGHT...AS A WELL-DEFINED
SHORT WAVE TROUGH TRACKS ACROSS THE SOUTHERN CANADIAN PRAIRIES AND
DAKOTAS BEFORE APPROACHING THE UPPER MISSISSIPPI VALLEY WEDNESDAY
EVENING. HEIGHT/PRESSURE FALLS ACROSS THE UPPER MIDWEST NUDGES THE
SURFACE RIDGE AWAY TO OUR EAST AND INDUCES INCREASING
SOUTH-SOUTHEAST WINDS AHEAD OF THE APPROACHING SURFACE TROUGH
OVERNIGHT. CLEAR-PARTLY CLOUDY CONDITIONS AND LIGHT WINDS WILL
LIKELY ALLOW FOR QUICK DECOUPLING OF BOUNDARY LAYER WINDS EARLY
WEDNESDAY EVENING WITH TEMPS DROPPING INTO THE 30S AGAIN IN OUTLYING
AREAS...THOUGH SOME INCREASE IN HIGH CLOUDS AND THE INCREASE IN
WINDS OVERNIGHT WILL LIKELY LIMIT FROST SOMEWHAT.

THURSDAY THROUGH FRIDAY...

THE UPPER MIDWEST SHORT WAVE CONTINUES TO MOVE EAST-SOUTHEAST INTO
THE GREAT LAKES REGION THURSDAY...WITH THE BEST ORGANIZED DEEP LIFT
GENERALLY NORTH OF THE WFO CHICAGO CWA. THE MID-LEVEL TROUGH AXIS
DOES SHIFT ACROSS THE AREA LATER IN THE DAY AND OVERNIGHT HOWEVER...
THOUGH WITH MOISTURE RETURN FROM THE GULF INITIALLY BLOCKED BY THE
SURFACE HIGH PRESSURE RIDGE WHICH EXTENDS SOUTHWEST ACROSS THE
ARKLATEX REGION FOR MUCH OF THE PERIOD. THUS MOISTURE RETURN IS NOT
OVERLY IMPRESSIVE WITH THIS SYSTEM...THOUGH A PERIOD OF SHOWERS DOES
LOOK FAIRLY LIKELY THURSDAY INTO THURSDAY NIGHT. PRECIP POTENTIAL
LOOKS TO INCREASE AHEAD OF THE MID-LEVEL TROUGH AS IT MOVES INTO
NORTH CENTRAL IL DURING THE MID-LATE MORNING HOURS AND SPREADING
INTO NORTHEAST IL DURING THE AFTERNOON. FORCING WEAKENS THURSDAY
EVENING AS THE TROUGH RUNS INTO THE WEAKENING UPPER RIDGE...WITH
PRECIP EXPECTED TO BECOME MORE SPOTTY THURSDAY NIGHT AS IT MOVES
ACROSS THE EASTERN HALF OF THE FORECAST AREA. MID-LEVEL TROUGH AND
WEAKENING SURFACE TROUGH/COLD FRONT OF PACIFIC ORIGIN PASS EAST OF
THE AREA FRIDAY MORNING...WITH WEAK HIGH PRESSURE BUILDING IN DURING
THE DAY. TEMPERATURES ACTUALLY WARM IN THE WAKE OF THIS SYSTEM AS
THE SURFACE RIDGE DRIFTS EAST DURING THE DAY AND WESTERLY FLOW ALOFT
AROUND REBUILDING UPPER RIDGE OVER THE PLAINS ALLOWS WARM ADVECTION
BY AFTERNOON. MODEL THERMAL PROGS INDICATE SOME LOW-MID 60S ACROSS
NORTHERN IL FRIDAY AFTERNOON.

FRIDAY NIGHT THROUGH TUESDAY...

LONGER RANGE MODEL GUIDANCE IN GOOD AGREEMENT IN SPREADING BROAD
UPPER RIDGE EASTWARD FROM THE PLAINS AND ACROSS THE MIDWEST AND
GREAT LAKES REGION THROUGH THE WEEKEND...WHILE DEEP UPPER TROUGH
MOVES INTO THE WESTERN CONUS. MODELS DEPICT STRONG SOUTHERLY FLOW
AND WARM ADVECTION DEVELOPING AS SURFACE LOW PRESSURE DEVELOPS AND
LIFTS NORTHEAST ACROSS THE PLAINS AND THE UPPER MIDWEST SUNDAY...
THOUGH AGAIN WITH LIMITED MOISTURE RETURN FOR THE MAGNITUDE OF THE
FLOW. THIS ALLOWS US TO WARM UP SIGNIFICANTLY HOWEVER...WITH HIGHS
LIKELY GETTING ABOVE 70 DEGREES SATURDAY AND SUNDAY ACROSS PORTIONS
OF THE CWA...AND OVER MOST OF IT MONDAY. SURFACE TROUGH/COLD FRONT
APPROACHES MONDAY WITH AN ATTENDANT CHANCE OF RAIN AND INCREASED
CLOUD COVER. A SECOND LOW IS DEPICTED LIFTING ACROSS THE AREA MONDAY
NIGHT-TUESDAY MAINTAINING RAIN THREAT...AND ALSO LEADING TO MUCH
COOLER WEATHER AGAIN TUESDAY BEHIND THE SYSTEM COLD FRONT.

RATZER

&&

.AVIATION...

//ORD AND MDW CONCERNS...UPDATED 00Z...

* NORTH/NORTHEAST WINDS GRADUALLY DROPPING BELOW 10 KT EARLY THIS
  EVENING.

* MVFR CEILINGS HOLDING ON POSSIBLY THROUGH MID EVENING.

KJB

//DISCUSSION...UPDATED 00Z...

MVFR CIGS CONTINUE TO MOVE IN OFF THE LAKE EARLY THIS EVENING VIA A
NORTH-NORTHEASTERLY LOWER LEVEL WIND TRAJECTORY ASSOCIATED WITH A
SURFACE RIDGE OF HIGH PRESSURE BUILDING EASTWARD ACROSS THE UPPER
GREAT LAKES AND OVER EASTERN ONTARIO. IT APPEARS THESE LOW CLOUDS
WILL TRY TO GRADUALLY SCATTERED OUT OVER THE NEXT 2 TO 3 HOURS.
HOWEVER...SOME OF THESE CLOUDS COULD BE A LITTLE SLOWER TO SCATTER
OUT ACROSS THE EASTERN TERMINALS NEAR THE LAKE AS CONDITIONS LOOK
TO REMAIN FAVORABLE FOR SOME CLOUD COVER OVER SOUTHERN LAKE
MICHIGAN. THEREFORE...IT IS POSSIBLE THAT AS THE LOWER LEVEL WINDS
VEER MORE NORTHEASTERLY THIS EVENING...SOME CLOUDS WILL CONTINUE
TO STREAM OFF THE LAKE AND OVER NORTHEASTERN ILLINOIS AND
NORTHWESTERN INDIANA DURING THE EVENING HOURS. I WILL CONTINUE TO
WATCH TRENDS WITH THIS AS THE EXACT TIMING OF SCATTERING IS A BIT
LOWER THAN PREVIOUSLY THOUGHT. THE GOOD NEWS IS THAT CIG HEIGHTS
SHOULD GENERALLY REMAIN AT OR ABOVE 2500 FEET AGL...SO AVIATION
IMPACTS SHOULD BE MINIMAL.

OTHERWISE...THE REMAINDER OF THE PERIOD LOOKS TO BE MAINLY VFR WITH
LIGHT EASTERLY WINDS.

KJB


//ORD AND MDW CONFIDENCE...UPDATED 00Z...

* MEDIUM-HIGH CONFIDENCE WITH WIND SPEED/DIRECTION.

* LOW-MEDIUM CONFIDENCE WITH EXACT TIMING OF IMPROVING CEILINGS
  THIS EVENING.

KJB

//OUTLOOK FOR ORD/MDW FOR 12Z THURSDAY-12Z TUESDAY...UPDATED 00Z...

* THURSDAY...CHANCE OF AFTERNOON SHRA. SOUTH WINDS.
* FRIDAY AND SATURDAY...DRY/VFR. WEST/SOUTHWEST WINDS.
* SUNDAY...DRY/VFR. SOUTH WINDS.
* MONDAY...SLIGHT CHANCE OF SHRA. GUSTY SOUTHWEST WINDS.

KJB

&&

.MARINE...

215 PM...LOW PRESSURE OVER WESTERN NEW YORK WILL MERGE WITH ANOTHER
LOW OVER NEAR THE DELMARVA AREA TONIGHT...AND RAPIDLY DEEPEN
WEDNESDAY NIGHT AND THURSDAY JUST SOUTH OF CAPE COD. THIS LOW WILL
THEN TRACK NORTHEAST TO NOVA SCOTIA BY SATURDAY MORNING.
MEANWHILE...HIGH PRESSURE CENTERED OVER THE SOUTHERN TIP OF JAMES
BAY...WITH HIGH PRESSURE RIDGING EXTENDING THROUGH THE MIDDLE
MISSISSIPPI VALLEY...WILL SLOWLY BUILD EAST. THE BRISK
NORTHEASTERLY WINDS CURRENTLY OVER THE LAKE WILL DIMINISH AND
BECOME LIGHT AND VARIABLE LATE TONIGHT AND EARLY WEDNESDAY AS THE
RIDGE AXIS CROSSES THE LAKE. WHILE WINDS SHOULD DROP BELOW SMALL
CRAFT ADVISORY LEVELS DURG THE AFTERNOON AND EARLY THIS
EVENING...RESIDUAL WAVE ACTION WILL BE SLOWER TO DAMPEN AND STILL
EXPECT THAT WAVES WILL REMAIN...ABOVE SMALL CRAFT ADVISORY LEVELS
THROUGH MUCH OF THE NIGHT. AS THE RIDGE MOVES TO THE EAST OF THE
LAKE WEDNESDAY NIGHT...A TROUGH OF LOW PRESSURE WILL CROSS THE
CENTRAL PLAINS...REACHING THE UPPER MISSISSIPPI VALLEY BY THURSDAY
MORNING. THIS WILL SET UP A STRENGTHENING SOUTHERLY GRADIENT OVER
THE LAKE WITH WINDS INCREASING TO ARND 20-25KT THURSDAY AFTERNOON.
WINDS WILL REMAIN SOUTHERLY UNTIL AN ASSOCIATED WEAK COLD FRONT
PUSHES ACROSS THE LAKE THURSDAY NIGHT.

KREIN

&&

.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...SMALL CRAFT ADVISORY...NEARSHORE WATERS
     UNTIL 7 AM WEDNESDAY.

&&

$$

VISIT US AT HTTP://WEATHER.GOV/CHICAGO (ALL LOWERCASE)

FOLLOW US ON FACEBOOK...TWITTER...AND YOUTUBE AT:
WWW.FACEBOOK.COM/NWSCHICAGO
WWW.TWITTER.COM/NWSCHICAGO
WWW.YOUTUBE.COM/NWSCHICAGO







000
FXUS63 KLOT 212155
AFDLOT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
455 PM CDT TUE OCT 21 2014

.DISCUSSION...
309 PM CDT

MAIN FORECAST CONCERNS FOCUS ON PRECIPITATION CHANCES AND TIMING
WITH A COUPLE OF SYSTEMS WHICH WILL AFFECT THE REGION THURSDAY AND
NEXT MONDAY. ALSO...IT APPEARS THAT SOME 70 DEGREE TEMPERATURES ARE
POSSIBLE FOR PARTS OF THE FORECAST AREA OVER THE WEEKEND AS WELL AS
ON MONDAY.

TONIGHT THROUGH WEDNESDAY NIGHT...

GOES WATER VAPOR IMAGERY DEPICTS A STRONG MID-LEVEL SHORT WAVE
TROUGH WHICH HAD DUG SOUTH ACROSS THE REGION TODAY IS NOW EXITING
THE AREA ACROSS THE OHIO VALLEY TO THE SOUTHEAST. SUBSIDENCE IN THE
WAKE OF THIS FEATURE WAS EVIDENT BOTH IN RISING SURFACE PRESSURE
ACROSS THE CWA...AND IN VISIBLE SATELLITE IMAGERY AS EXTENSIVE AREA
OF STRATOCU ACROSS THE REGION ERODES FROM THE NORTH ACROSS WI/MI AND
LAKE MICHIGAN. EARLIER LAKE-INDUCED SHOWERS HAVE WEAKENED AND FADED
AS EXPECTED DUE TO LOWERING SUBSIDENCE INVERSION AND ASSOCIATED
WARMING ALOFT. CLOUD COVER IS EXPECTED TO CONTINUE TO DECREASE IN
COVERAGE INTO THE EVENING HOURS...WITH PERHAPS JUST SOME PATCHY THIN
SHALLOW STRATOCU LINGERING OFF THE LAKE BY LATE EVENING. LOOKING AT
THE BIGGER PICTURE...HIGH-AMPLITUDE UPPER RIDGE ANALYZED OVER THE
CENTRAL PORTION OF THE NATION WILL MOVE ACROSS THE MISSISSIPPI
VALLEY AND WESTERN/NORTHERN GREAT LAKES REGION THROUGH WEDNESDAY
MORNING...MAINTAINING SUBSIDENCE WHICH SHOULD FURTHER ERODE
LINGERING CLOUDS AND ALLOW SURFACE HIGH PRESSURE RIDGE TO MOVE
ACROSS THE AREA TONIGHT AND WEDNESDAY. WITH CLEARING SKIES AND
DECREASING WINDS ASSOCIATED WITH THE SURFACE RIDGE AXIS TONIGHT...
TEMPS ARE EXPECTED TO DROP OFF INTO THE 30S IN MANY AREAS AWAY FROM
THE IMMEDIATE LAKE MICHIGAN SHORE AND CORE OF CHICAGO. LATE NIGHT
MINS IN THE MID 30S AWAY FROM THE METRO AREA WILL LIKELY ALLOW AREAS
OF FROST TO DEVELOP WHERE WINDS DECOUPLE BECOME LIGHT/VARIABLE.
UPPER AND LOW LEVEL HIGH PRESSURE RIDGES REMAIN OVER THE AREA
WEDNESDAY ALLOWING PLENTIFUL SUNSHINE...THOUGH WITH ONLY MODEST
WARMING DUE TO EASTERLY WIND COMPONENT OFF LAKE AND COOLER UPSTREAM
AIR MASS. A BLEND OF MOS GUIDANCE APPEARS REASONABLE BASED ON RAW
MODEL LOW LEVEL THERMAL FIELDS...WITH WEDNESDAY AFTERNOON MAXES
EXPECTED TO RANGE FROM THE LOW 50S ALONG THE LAKE TO THE UPPER 50S
ACROSS THE FAR WESTERN/SOUTHERN COUNTIES OF THE CWA. ATTENTION THEN
TURNS BACK TOWARD THE NORTHWEST WEDNESDAY NIGHT...AS A WELL-DEFINED
SHORT WAVE TROUGH TRACKS ACROSS THE SOUTHERN CANADIAN PRAIRIES AND
DAKOTAS BEFORE APPROACHING THE UPPER MISSISSIPPI VALLEY WEDNESDAY
EVENING. HEIGHT/PRESSURE FALLS ACROSS THE UPPER MIDWEST NUDGES THE
SURFACE RIDGE AWAY TO OUR EAST AND INDUCES INCREASING
SOUTH-SOUTHEAST WINDS AHEAD OF THE APPROACHING SURFACE TROUGH
OVERNIGHT. CLEAR-PARTLY CLOUDY CONDITIONS AND LIGHT WINDS WILL
LIKELY ALLOW FOR QUICK DECOUPLING OF BOUNDARY LAYER WINDS EARLY
WEDNESDAY EVENING WITH TEMPS DROPPING INTO THE 30S AGAIN IN OUTLYING
AREAS...THOUGH SOME INCREASE IN HIGH CLOUDS AND THE INCREASE IN
WINDS OVERNIGHT WILL LIKELY LIMIT FROST SOMEWHAT.

THURSDAY THROUGH FRIDAY...

THE UPPER MIDWEST SHORT WAVE CONTINUES TO MOVE EAST-SOUTHEAST INTO
THE GREAT LAKES REGION THURSDAY...WITH THE BEST ORGANIZED DEEP LIFT
GENERALLY NORTH OF THE WFO CHICAGO CWA. THE MID-LEVEL TROUGH AXIS
DOES SHIFT ACROSS THE AREA LATER IN THE DAY AND OVERNIGHT HOWEVER...
THOUGH WITH MOISTURE RETURN FROM THE GULF INITIALLY BLOCKED BY THE
SURFACE HIGH PRESSURE RIDGE WHICH EXTENDS SOUTHWEST ACROSS THE
ARKLATEX REGION FOR MUCH OF THE PERIOD. THUS MOISTURE RETURN IS NOT
OVERLY IMPRESSIVE WITH THIS SYSTEM...THOUGH A PERIOD OF SHOWERS DOES
LOOK FAIRLY LIKELY THURSDAY INTO THURSDAY NIGHT. PRECIP POTENTIAL
LOOKS TO INCREASE AHEAD OF THE MID-LEVEL TROUGH AS IT MOVES INTO
NORTH CENTRAL IL DURING THE MID-LATE MORNING HOURS AND SPREADING
INTO NORTHEAST IL DURING THE AFTERNOON. FORCING WEAKENS THURSDAY
EVENING AS THE TROUGH RUNS INTO THE WEAKENING UPPER RIDGE...WITH
PRECIP EXPECTED TO BECOME MORE SPOTTY THURSDAY NIGHT AS IT MOVES
ACROSS THE EASTERN HALF OF THE FORECAST AREA. MID-LEVEL TROUGH AND
WEAKENING SURFACE TROUGH/COLD FRONT OF PACIFIC ORIGIN PASS EAST OF
THE AREA FRIDAY MORNING...WITH WEAK HIGH PRESSURE BUILDING IN DURING
THE DAY. TEMPERATURES ACTUALLY WARM IN THE WAKE OF THIS SYSTEM AS
THE SURFACE RIDGE DRIFTS EAST DURING THE DAY AND WESTERLY FLOW ALOFT
AROUND REBUILDING UPPER RIDGE OVER THE PLAINS ALLOWS WARM ADVECTION
BY AFTERNOON. MODEL THERMAL PROGS INDICATE SOME LOW-MID 60S ACROSS
NORTHERN IL FRIDAY AFTERNOON.

FRIDAY NIGHT THROUGH TUESDAY...

LONGER RANGE MODEL GUIDANCE IN GOOD AGREEMENT IN SPREADING BROAD
UPPER RIDGE EASTWARD FROM THE PLAINS AND ACROSS THE MIDWEST AND
GREAT LAKES REGION THROUGH THE WEEKEND...WHILE DEEP UPPER TROUGH
MOVES INTO THE WESTERN CONUS. MODELS DEPICT STRONG SOUTHERLY FLOW
AND WARM ADVECTION DEVELOPING AS SURFACE LOW PRESSURE DEVELOPS AND
LIFTS NORTHEAST ACROSS THE PLAINS AND THE UPPER MIDWEST SUNDAY...
THOUGH AGAIN WITH LIMITED MOISTURE RETURN FOR THE MAGNITUDE OF THE
FLOW. THIS ALLOWS US TO WARM UP SIGNIFICANTLY HOWEVER...WITH HIGHS
LIKELY GETTING ABOVE 70 DEGREES SATURDAY AND SUNDAY ACROSS PORTIONS
OF THE CWA...AND OVER MOST OF IT MONDAY. SURFACE TROUGH/COLD FRONT
APPROACHES MONDAY WITH AN ATTENDANT CHANCE OF RAIN AND INCREASED
CLOUD COVER. A SECOND LOW IS DEPICTED LIFTING ACROSS THE AREA MONDAY
NIGHT-TUESDAY MAINTAINING RAIN THREAT...AND ALSO LEADING TO MUCH
COOLER WEATHER AGAIN TUESDAY BEHIND THE SYSTEM COLD FRONT.

RATZER

&&

.AVIATION...

//ORD AND MDW CONCERNS...UPDATED 22Z...

* NORTH/NORTHEAST WINDS 10-14 KT THROUGH EARLY EVENING...THEN
  GRADUALLY ABATING.

* MVFR CEILINGS HOLDING ON THROUGH AROUND 01 TO 02 UTC.

RODRIGUEZ/KB

//DISCUSSION...UPDATED 18Z...

DESPITE HIGH PRESSURE BUILDING ACROSS THE REGION TODAY...CEILINGS
HAVE STILL DEVELOPED WHILE LAKE EFFECT CLOUD COVER CONTINUES TO
MOVE OVERHEAD. THESE BOTH WILL SCATTER/DIMINISH THROUGH THIS
EVENING AS THIS HIGH BUILDS ACROSS THE TERMINALS. BEFORE THIS
OCCURS...PERIODS OF HIGH END MVFR CEILINGS WILL STILL BE POSSIBLE.
THEN EXPECT DRY AND MOSTLY CLEAR SKIES THROUGH THE REST OF THE
FORECAST PERIOD. NORTHEAST WINDS/GUSTS WILL PREVAIL THIS AFTERNOON
BEFORE DIMINISHING LATER THIS EVENING...AND THEN REMAIN MORE
EASTERLY AND UNDER 10 KT EARLY WEDNESDAY MORNING THROUGH THE REST
OF THE FORECAST PERIOD.

RODRIGUEZ

//ORD AND MDW CONFIDENCE...UPDATED 22Z...

* MEDIUM-HIGH CONFIDENCE WITH WIND SPEED/DIRECTION.

* HIGH CONFIDENCE WITH MVFR CEILINGS THROUGH 01 TO 02 UTC.

RODRIGUEZ/KB

//OUTLOOK FOR ORD/MDW FOR 00Z THURSDAY-12Z TUESDAY...UPDATED 12Z...

* WEDNESDAY NIGHT...DRY/VFR.
* THURSDAY...CHANCE OF SHRA. SOUTH WINDS.
* FRIDAY AND SATURDAY...DRY/VFR. WEST/SOUTHWEST WINDS.
* SUNDAY...DRY/VFR. SOUTH WINDS.
* MONDAY...SLIGHT CHANCE OF SHRA. GUSTY SOUTHWEST WINDS.

&&

.MARINE...

215 PM...LOW PRESSURE OVER WESTERN NEW YORK WILL MERGE WITH ANOTHER
LOW OVER NEAR THE DELMARVA AREA TONIGHT...AND RAPIDLY DEEPEN
WEDNESDAY NIGHT AND THURSDAY JUST SOUTH OF CAPE COD. THIS LOW WILL
THEN TRACK NORTHEAST TO NOVA SCOTIA BY SATURDAY MORNING.
MEANWHILE...HIGH PRESSURE CENTERED OVER THE SOUTHERN TIP OF JAMES
BAY...WITH HIGH PRESSURE RIDGING EXTENDING THROUGH THE MIDDLE
MISSISSIPPI VALLEY...WILL SLOWLY BUILD EAST. THE BRISK
NORTHEASTERLY WINDS CURRENTLY OVER THE LAKE WILL DIMINISH AND
BECOME LIGHT AND VARIABLE LATE TONIGHT AND EARLY WEDNESDAY AS THE
RIDGE AXIS CROSSES THE LAKE. WHILE WINDS SHOULD DROP BELOW SMALL
CRAFT ADVISORY LEVELS DURG THE AFTERNOON AND EARLY THIS
EVENING...RESIDUAL WAVE ACTION WILL BE SLOWER TO DAMPEN AND STILL
EXPECT THAT WAVES WILL REMAIN...ABOVE SMALL CRAFT ADVISORY LEVELS
THROUGH MUCH OF THE NIGHT. AS THE RIDGE MOVES TO THE EAST OF THE
LAKE WEDNESDAY NIGHT...A TROUGH OF LOW PRESSURE WILL CROSS THE
CENTRAL PLAINS...REACHING THE UPPER MISSISSIPPI VALLEY BY THURSDAY
MORNING. THIS WILL SET UP A STRENGTHENING SOUTHERLY GRADIENT OVER
THE LAKE WITH WINDS INCREASING TO ARND 20-25KT THURSDAY AFTERNOON.
WINDS WILL REMAIN SOUTHERLY UNTIL AN ASSOCIATED WEAK COLD FRONT
PUSHES ACROSS THE LAKE THURSDAY NIGHT.

KREIN

&&

.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...SMALL CRAFT ADVISORY...NEARSHORE WATERS
     UNTIL 7 AM WEDNESDAY.

&&

$$

VISIT US AT HTTP://WEATHER.GOV/CHICAGO (ALL LOWERCASE)

FOLLOW US ON FACEBOOK...TWITTER...AND YOUTUBE AT:
WWW.FACEBOOK.COM/NWSCHICAGO
WWW.TWITTER.COM/NWSCHICAGO
WWW.YOUTUBE.COM/NWSCHICAGO







000
FXUS63 KLOT 212155
AFDLOT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
455 PM CDT TUE OCT 21 2014

.DISCUSSION...
309 PM CDT

MAIN FORECAST CONCERNS FOCUS ON PRECIPITATION CHANCES AND TIMING
WITH A COUPLE OF SYSTEMS WHICH WILL AFFECT THE REGION THURSDAY AND
NEXT MONDAY. ALSO...IT APPEARS THAT SOME 70 DEGREE TEMPERATURES ARE
POSSIBLE FOR PARTS OF THE FORECAST AREA OVER THE WEEKEND AS WELL AS
ON MONDAY.

TONIGHT THROUGH WEDNESDAY NIGHT...

GOES WATER VAPOR IMAGERY DEPICTS A STRONG MID-LEVEL SHORT WAVE
TROUGH WHICH HAD DUG SOUTH ACROSS THE REGION TODAY IS NOW EXITING
THE AREA ACROSS THE OHIO VALLEY TO THE SOUTHEAST. SUBSIDENCE IN THE
WAKE OF THIS FEATURE WAS EVIDENT BOTH IN RISING SURFACE PRESSURE
ACROSS THE CWA...AND IN VISIBLE SATELLITE IMAGERY AS EXTENSIVE AREA
OF STRATOCU ACROSS THE REGION ERODES FROM THE NORTH ACROSS WI/MI AND
LAKE MICHIGAN. EARLIER LAKE-INDUCED SHOWERS HAVE WEAKENED AND FADED
AS EXPECTED DUE TO LOWERING SUBSIDENCE INVERSION AND ASSOCIATED
WARMING ALOFT. CLOUD COVER IS EXPECTED TO CONTINUE TO DECREASE IN
COVERAGE INTO THE EVENING HOURS...WITH PERHAPS JUST SOME PATCHY THIN
SHALLOW STRATOCU LINGERING OFF THE LAKE BY LATE EVENING. LOOKING AT
THE BIGGER PICTURE...HIGH-AMPLITUDE UPPER RIDGE ANALYZED OVER THE
CENTRAL PORTION OF THE NATION WILL MOVE ACROSS THE MISSISSIPPI
VALLEY AND WESTERN/NORTHERN GREAT LAKES REGION THROUGH WEDNESDAY
MORNING...MAINTAINING SUBSIDENCE WHICH SHOULD FURTHER ERODE
LINGERING CLOUDS AND ALLOW SURFACE HIGH PRESSURE RIDGE TO MOVE
ACROSS THE AREA TONIGHT AND WEDNESDAY. WITH CLEARING SKIES AND
DECREASING WINDS ASSOCIATED WITH THE SURFACE RIDGE AXIS TONIGHT...
TEMPS ARE EXPECTED TO DROP OFF INTO THE 30S IN MANY AREAS AWAY FROM
THE IMMEDIATE LAKE MICHIGAN SHORE AND CORE OF CHICAGO. LATE NIGHT
MINS IN THE MID 30S AWAY FROM THE METRO AREA WILL LIKELY ALLOW AREAS
OF FROST TO DEVELOP WHERE WINDS DECOUPLE BECOME LIGHT/VARIABLE.
UPPER AND LOW LEVEL HIGH PRESSURE RIDGES REMAIN OVER THE AREA
WEDNESDAY ALLOWING PLENTIFUL SUNSHINE...THOUGH WITH ONLY MODEST
WARMING DUE TO EASTERLY WIND COMPONENT OFF LAKE AND COOLER UPSTREAM
AIR MASS. A BLEND OF MOS GUIDANCE APPEARS REASONABLE BASED ON RAW
MODEL LOW LEVEL THERMAL FIELDS...WITH WEDNESDAY AFTERNOON MAXES
EXPECTED TO RANGE FROM THE LOW 50S ALONG THE LAKE TO THE UPPER 50S
ACROSS THE FAR WESTERN/SOUTHERN COUNTIES OF THE CWA. ATTENTION THEN
TURNS BACK TOWARD THE NORTHWEST WEDNESDAY NIGHT...AS A WELL-DEFINED
SHORT WAVE TROUGH TRACKS ACROSS THE SOUTHERN CANADIAN PRAIRIES AND
DAKOTAS BEFORE APPROACHING THE UPPER MISSISSIPPI VALLEY WEDNESDAY
EVENING. HEIGHT/PRESSURE FALLS ACROSS THE UPPER MIDWEST NUDGES THE
SURFACE RIDGE AWAY TO OUR EAST AND INDUCES INCREASING
SOUTH-SOUTHEAST WINDS AHEAD OF THE APPROACHING SURFACE TROUGH
OVERNIGHT. CLEAR-PARTLY CLOUDY CONDITIONS AND LIGHT WINDS WILL
LIKELY ALLOW FOR QUICK DECOUPLING OF BOUNDARY LAYER WINDS EARLY
WEDNESDAY EVENING WITH TEMPS DROPPING INTO THE 30S AGAIN IN OUTLYING
AREAS...THOUGH SOME INCREASE IN HIGH CLOUDS AND THE INCREASE IN
WINDS OVERNIGHT WILL LIKELY LIMIT FROST SOMEWHAT.

THURSDAY THROUGH FRIDAY...

THE UPPER MIDWEST SHORT WAVE CONTINUES TO MOVE EAST-SOUTHEAST INTO
THE GREAT LAKES REGION THURSDAY...WITH THE BEST ORGANIZED DEEP LIFT
GENERALLY NORTH OF THE WFO CHICAGO CWA. THE MID-LEVEL TROUGH AXIS
DOES SHIFT ACROSS THE AREA LATER IN THE DAY AND OVERNIGHT HOWEVER...
THOUGH WITH MOISTURE RETURN FROM THE GULF INITIALLY BLOCKED BY THE
SURFACE HIGH PRESSURE RIDGE WHICH EXTENDS SOUTHWEST ACROSS THE
ARKLATEX REGION FOR MUCH OF THE PERIOD. THUS MOISTURE RETURN IS NOT
OVERLY IMPRESSIVE WITH THIS SYSTEM...THOUGH A PERIOD OF SHOWERS DOES
LOOK FAIRLY LIKELY THURSDAY INTO THURSDAY NIGHT. PRECIP POTENTIAL
LOOKS TO INCREASE AHEAD OF THE MID-LEVEL TROUGH AS IT MOVES INTO
NORTH CENTRAL IL DURING THE MID-LATE MORNING HOURS AND SPREADING
INTO NORTHEAST IL DURING THE AFTERNOON. FORCING WEAKENS THURSDAY
EVENING AS THE TROUGH RUNS INTO THE WEAKENING UPPER RIDGE...WITH
PRECIP EXPECTED TO BECOME MORE SPOTTY THURSDAY NIGHT AS IT MOVES
ACROSS THE EASTERN HALF OF THE FORECAST AREA. MID-LEVEL TROUGH AND
WEAKENING SURFACE TROUGH/COLD FRONT OF PACIFIC ORIGIN PASS EAST OF
THE AREA FRIDAY MORNING...WITH WEAK HIGH PRESSURE BUILDING IN DURING
THE DAY. TEMPERATURES ACTUALLY WARM IN THE WAKE OF THIS SYSTEM AS
THE SURFACE RIDGE DRIFTS EAST DURING THE DAY AND WESTERLY FLOW ALOFT
AROUND REBUILDING UPPER RIDGE OVER THE PLAINS ALLOWS WARM ADVECTION
BY AFTERNOON. MODEL THERMAL PROGS INDICATE SOME LOW-MID 60S ACROSS
NORTHERN IL FRIDAY AFTERNOON.

FRIDAY NIGHT THROUGH TUESDAY...

LONGER RANGE MODEL GUIDANCE IN GOOD AGREEMENT IN SPREADING BROAD
UPPER RIDGE EASTWARD FROM THE PLAINS AND ACROSS THE MIDWEST AND
GREAT LAKES REGION THROUGH THE WEEKEND...WHILE DEEP UPPER TROUGH
MOVES INTO THE WESTERN CONUS. MODELS DEPICT STRONG SOUTHERLY FLOW
AND WARM ADVECTION DEVELOPING AS SURFACE LOW PRESSURE DEVELOPS AND
LIFTS NORTHEAST ACROSS THE PLAINS AND THE UPPER MIDWEST SUNDAY...
THOUGH AGAIN WITH LIMITED MOISTURE RETURN FOR THE MAGNITUDE OF THE
FLOW. THIS ALLOWS US TO WARM UP SIGNIFICANTLY HOWEVER...WITH HIGHS
LIKELY GETTING ABOVE 70 DEGREES SATURDAY AND SUNDAY ACROSS PORTIONS
OF THE CWA...AND OVER MOST OF IT MONDAY. SURFACE TROUGH/COLD FRONT
APPROACHES MONDAY WITH AN ATTENDANT CHANCE OF RAIN AND INCREASED
CLOUD COVER. A SECOND LOW IS DEPICTED LIFTING ACROSS THE AREA MONDAY
NIGHT-TUESDAY MAINTAINING RAIN THREAT...AND ALSO LEADING TO MUCH
COOLER WEATHER AGAIN TUESDAY BEHIND THE SYSTEM COLD FRONT.

RATZER

&&

.AVIATION...

//ORD AND MDW CONCERNS...UPDATED 22Z...

* NORTH/NORTHEAST WINDS 10-14 KT THROUGH EARLY EVENING...THEN
  GRADUALLY ABATING.

* MVFR CEILINGS HOLDING ON THROUGH AROUND 01 TO 02 UTC.

RODRIGUEZ/KB

//DISCUSSION...UPDATED 18Z...

DESPITE HIGH PRESSURE BUILDING ACROSS THE REGION TODAY...CEILINGS
HAVE STILL DEVELOPED WHILE LAKE EFFECT CLOUD COVER CONTINUES TO
MOVE OVERHEAD. THESE BOTH WILL SCATTER/DIMINISH THROUGH THIS
EVENING AS THIS HIGH BUILDS ACROSS THE TERMINALS. BEFORE THIS
OCCURS...PERIODS OF HIGH END MVFR CEILINGS WILL STILL BE POSSIBLE.
THEN EXPECT DRY AND MOSTLY CLEAR SKIES THROUGH THE REST OF THE
FORECAST PERIOD. NORTHEAST WINDS/GUSTS WILL PREVAIL THIS AFTERNOON
BEFORE DIMINISHING LATER THIS EVENING...AND THEN REMAIN MORE
EASTERLY AND UNDER 10 KT EARLY WEDNESDAY MORNING THROUGH THE REST
OF THE FORECAST PERIOD.

RODRIGUEZ

//ORD AND MDW CONFIDENCE...UPDATED 22Z...

* MEDIUM-HIGH CONFIDENCE WITH WIND SPEED/DIRECTION.

* HIGH CONFIDENCE WITH MVFR CEILINGS THROUGH 01 TO 02 UTC.

RODRIGUEZ/KB

//OUTLOOK FOR ORD/MDW FOR 00Z THURSDAY-12Z TUESDAY...UPDATED 12Z...

* WEDNESDAY NIGHT...DRY/VFR.
* THURSDAY...CHANCE OF SHRA. SOUTH WINDS.
* FRIDAY AND SATURDAY...DRY/VFR. WEST/SOUTHWEST WINDS.
* SUNDAY...DRY/VFR. SOUTH WINDS.
* MONDAY...SLIGHT CHANCE OF SHRA. GUSTY SOUTHWEST WINDS.

&&

.MARINE...

215 PM...LOW PRESSURE OVER WESTERN NEW YORK WILL MERGE WITH ANOTHER
LOW OVER NEAR THE DELMARVA AREA TONIGHT...AND RAPIDLY DEEPEN
WEDNESDAY NIGHT AND THURSDAY JUST SOUTH OF CAPE COD. THIS LOW WILL
THEN TRACK NORTHEAST TO NOVA SCOTIA BY SATURDAY MORNING.
MEANWHILE...HIGH PRESSURE CENTERED OVER THE SOUTHERN TIP OF JAMES
BAY...WITH HIGH PRESSURE RIDGING EXTENDING THROUGH THE MIDDLE
MISSISSIPPI VALLEY...WILL SLOWLY BUILD EAST. THE BRISK
NORTHEASTERLY WINDS CURRENTLY OVER THE LAKE WILL DIMINISH AND
BECOME LIGHT AND VARIABLE LATE TONIGHT AND EARLY WEDNESDAY AS THE
RIDGE AXIS CROSSES THE LAKE. WHILE WINDS SHOULD DROP BELOW SMALL
CRAFT ADVISORY LEVELS DURG THE AFTERNOON AND EARLY THIS
EVENING...RESIDUAL WAVE ACTION WILL BE SLOWER TO DAMPEN AND STILL
EXPECT THAT WAVES WILL REMAIN...ABOVE SMALL CRAFT ADVISORY LEVELS
THROUGH MUCH OF THE NIGHT. AS THE RIDGE MOVES TO THE EAST OF THE
LAKE WEDNESDAY NIGHT...A TROUGH OF LOW PRESSURE WILL CROSS THE
CENTRAL PLAINS...REACHING THE UPPER MISSISSIPPI VALLEY BY THURSDAY
MORNING. THIS WILL SET UP A STRENGTHENING SOUTHERLY GRADIENT OVER
THE LAKE WITH WINDS INCREASING TO ARND 20-25KT THURSDAY AFTERNOON.
WINDS WILL REMAIN SOUTHERLY UNTIL AN ASSOCIATED WEAK COLD FRONT
PUSHES ACROSS THE LAKE THURSDAY NIGHT.

KREIN

&&

.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...SMALL CRAFT ADVISORY...NEARSHORE WATERS
     UNTIL 7 AM WEDNESDAY.

&&

$$

VISIT US AT HTTP://WEATHER.GOV/CHICAGO (ALL LOWERCASE)

FOLLOW US ON FACEBOOK...TWITTER...AND YOUTUBE AT:
WWW.FACEBOOK.COM/NWSCHICAGO
WWW.TWITTER.COM/NWSCHICAGO
WWW.YOUTUBE.COM/NWSCHICAGO







000
FXUS63 KLOT 212010
AFDLOT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
310 PM CDT TUE OCT 21 2014

.DISCUSSION...
309 PM CDT

MAIN FORECAST CONCERNS FOCUS ON PRECIPITATION CHANCES AND TIMING
WITH A COUPLE OF SYSTEMS WHICH WILL AFFECT THE REGION THURSDAY AND
NEXT MONDAY. ALSO...IT APPEARS THAT SOME 70 DEGREE TEMPERATURES ARE
POSSIBLE FOR PARTS OF THE FORECAST AREA OVER THE WEEKEND AS WELL AS
ON MONDAY.

TONIGHT THROUGH WEDNESDAY NIGHT...

GOES WATER VAPOR IMAGERY DEPICTS A STRONG MID-LEVEL SHORT WAVE
TROUGH WHICH HAD DUG SOUTH ACROSS THE REGION TODAY IS NOW EXITING
THE AREA ACROSS THE OHIO VALLEY TO THE SOUTHEAST. SUBSIDENCE IN THE
WAKE OF THIS FEATURE WAS EVIDENT BOTH IN RISING SURFACE PRESSURE
ACROSS THE CWA...AND IN VISIBLE SATELLITE IMAGERY AS EXTENSIVE AREA
OF STRATOCU ACROSS THE REGION ERODES FROM THE NORTH ACROSS WI/MI AND
LAKE MICHIGAN. EARLIER LAKE-INDUCED SHOWERS HAVE WEAKENED AND FADED
AS EXPECTED DUE TO LOWERING SUBSIDENCE INVERSION AND ASSOCIATED
WARMING ALOFT. CLOUD COVER IS EXPECTED TO CONTINUE TO DECREASE IN
COVERAGE INTO THE EVENING HOURS...WITH PERHAPS JUST SOME PATCHY THIN
SHALLOW STRATOCU LINGERING OFF THE LAKE BY LATE EVENING. LOOKING AT
THE BIGGER PICTURE...HIGH-AMPLITUDE UPPER RIDGE ANALYZED OVER THE
CENTRAL PORTION OF THE NATION WILL MOVE ACROSS THE MISSISSIPPI
VALLEY AND WESTERN/NORTHERN GREAT LAKES REGION THROUGH WEDNESDAY
MORNING...MAINTAINING SUBSIDENCE WHICH SHOULD FURTHER ERODE
LINGERING CLOUDS AND ALLOW SURFACE HIGH PRESSURE RIDGE TO MOVE
ACROSS THE AREA TONIGHT AND WEDNESDAY. WITH CLEARING SKIES AND
DECREASING WINDS ASSOCIATED WITH THE SURFACE RIDGE AXIS TONIGHT...
TEMPS ARE EXPECTED TO DROP OFF INTO THE 30S IN MANY AREAS AWAY FROM
THE IMMEDIATE LAKE MICHIGAN SHORE AND CORE OF CHICAGO. LATE NIGHT
MINS IN THE MID 30S AWAY FROM THE METRO AREA WILL LIKELY ALLOW AREAS
OF FROST TO DEVELOP WHERE WINDS DECOUPLE BECOME LIGHT/VARIABLE.
UPPER AND LOW LEVEL HIGH PRESSURE RIDGES REMAIN OVER THE AREA
WEDNESDAY ALLOWING PLENTIFUL SUNSHINE...THOUGH WITH ONLY MODEST
WARMING DUE TO EASTERLY WIND COMPONENT OFF LAKE AND COOLER UPSTREAM
AIR MASS. A BLEND OF MOS GUIDANCE APPEARS REASONABLE BASED ON RAW
MODEL LOW LEVEL THERMAL FIELDS...WITH WEDNESDAY AFTERNOON MAXES
EXPECTED TO RANGE FROM THE LOW 50S ALONG THE LAKE TO THE UPPER 50S
ACROSS THE FAR WESTERN/SOUTHERN COUNTIES OF THE CWA. ATTENTION THEN
TURNS BACK TOWARD THE NORTHWEST WEDNESDAY NIGHT...AS A WELL-DEFINED
SHORT WAVE TROUGH TRACKS ACROSS THE SOUTHERN CANADIAN PRAIRIES AND
DAKOTAS BEFORE APPROACHING THE UPPER MISSISSIPPI VALLEY WEDNESDAY
EVENING. HEIGHT/PRESSURE FALLS ACROSS THE UPPER MIDWEST NUDGES THE
SURFACE RIDGE AWAY TO OUR EAST AND INDUCES INCREASING
SOUTH-SOUTHEAST WINDS AHEAD OF THE APPROACHING SURFACE TROUGH
OVERNIGHT. CLEAR-PARTLY CLOUDY CONDITIONS AND LIGHT WINDS WILL
LIKELY ALLOW FOR QUICK DECOUPLING OF BOUNDARY LAYER WINDS EARLY
WEDNESDAY EVENING WITH TEMPS DROPPING INTO THE 30S AGAIN IN OUTLYING
AREAS...THOUGH SOME INCREASE IN HIGH CLOUDS AND THE INCREASE IN
WINDS OVERNIGHT WILL LIKELY LIMIT FROST SOMEWHAT.

THURSDAY THROUGH FRIDAY...

THE UPPER MIDWEST SHORT WAVE CONTINUES TO MOVE EAST-SOUTHEAST INTO
THE GREAT LAKES REGION THURSDAY...WITH THE BEST ORGANIZED DEEP LIFT
GENERALLY NORTH OF THE WFO CHICAGO CWA. THE MID-LEVEL TROUGH AXIS
DOES SHIFT ACROSS THE AREA LATER IN THE DAY AND OVERNIGHT HOWEVER...
THOUGH WITH MOISTURE RETURN FROM THE GULF INITIALLY BLOCKED BY THE
SURFACE HIGH PRESSURE RIDGE WHICH EXTENDS SOUTHWEST ACROSS THE
ARKLATEX REGION FOR MUCH OF THE PERIOD. THUS MOISTURE RETURN IS NOT
OVERLY IMPRESSIVE WITH THIS SYSTEM...THOUGH A PERIOD OF SHOWERS DOES
LOOK FAIRLY LIKELY THURSDAY INTO THURSDAY NIGHT. PRECIP POTENTIAL
LOOKS TO INCREASE AHEAD OF THE MID-LEVEL TROUGH AS IT MOVES INTO
NORTH CENTRAL IL DURING THE MID-LATE MORNING HOURS AND SPREADING
INTO NORTHEAST IL DURING THE AFTERNOON. FORCING WEAKENS THURSDAY
EVENING AS THE TROUGH RUNS INTO THE WEAKENING UPPER RIDGE...WITH
PRECIP EXPECTED TO BECOME MORE SPOTTY THURSDAY NIGHT AS IT MOVES
ACROSS THE EASTERN HALF OF THE FORECAST AREA. MID-LEVEL TROUGH AND
WEAKENING SURFACE TROUGH/COLD FRONT OF PACIFIC ORIGIN PASS EAST OF
THE AREA FRIDAY MORNING...WITH WEAK HIGH PRESSURE BUILDING IN DURING
THE DAY. TEMPERATURES ACTUALLY WARM IN THE WAKE OF THIS SYSTEM AS
THE SURFACE RIDGE DRIFTS EAST DURING THE DAY AND WESTERLY FLOW ALOFT
AROUND REBUILDING UPPER RIDGE OVER THE PLAINS ALLOWS WARM ADVECTION
BY AFTERNOON. MODEL THERMAL PROGS INDICATE SOME LOW-MID 60S ACROSS
NORTHERN IL FRIDAY AFTERNOON.


FRIDAY NIGHT THROUGH TUESDAY...

LONGER RANGE MODEL GUIDANCE IN GOOD AGREEMENT IN SPREADING BROAD
UPPER RIDGE EASTWARD FROM THE PLAINS AND ACROSS THE MIDWEST AND
GREAT LAKES REGION THROUGH THE WEEKEND...WHILE DEEP UPPER TROUGH
MOVES INTO THE WESTERN CONUS. MODELS DEPICT STRONG SOUTHERLY FLOW
AND WARM ADVECTION DEVELOPING AS SURFACE LOW PRESSURE DEVELOPS AND
LIFTS NORTHEAST ACROSS THE PLAINS AND THE UPPER MIDWEST SUNDAY...
THOUGH AGAIN WITH LIMITED MOISTURE RETURN FOR THE MAGNITUDE OF THE
FLOW. THIS ALLOWS US TO WARM UP SIGNIFICANTLY HOWEVER...WITH HIGHS
LIKELY GETTING ABOVE 70 DEGREES SATURDAY AND SUNDAY ACROSS PORTIONS
OF THE CWA...AND OVER MOST OF IT MONDAY. SURFACE TROUGH/COLD FRONT
APPROACHES MONDAY WITH AN ATTENDANT CHANCE OF RAIN AND INCREASED
CLOUD COVER. A SECOND LOW IS DEPICTED LIFTING ACROSS THE AREA MONDAY
NIGHT-TUESDAY MAINTAINING RAIN THREAT...AND ALSO LEADING TO MUCH
COOLER WEATHER AGAIN TUESDAY BEHIND THE SYSTEM COLD FRONT.

RATZER

&&

.AVIATION...

//ORD AND MDW CONCERNS...UPDATED 20Z...

* NORTH/NORTHEAST WINDS 10-14 KT AND GUSTY THROUGH EARLY EVENING.

* MVFR CEILINGS THROUGH AFTERNOON.

RODRIGUEZ

//DISCUSSION...UPDATED 18Z...

DESPITE HIGH PRESSURE BUILDING ACROSS THE REGION TODAY...CEILINGS
HAVE STILL DEVELOPED WHILE LAKE EFFECT CLOUD COVER CONTINUES TO
MOVE OVERHEAD. THESE BOTH WILL SCATTER/DIMINISH THROUGH THIS
EVENING AS THIS HIGH BUILDS ACROSS THE TERMINALS. BEFORE THIS
OCCURS...PERIODS OF HIGH END MVFR CEILINGS WILL STILL BE POSSIBLE.
THEN EXPECT DRY AND MOSTLY CLEAR SKIES THROUGH THE REST OF THE
FORECAST PERIOD. NORTHEAST WINDS/GUSTS WILL PREVAIL THIS AFTERNOON
BEFORE DIMINISHING LATER THIS EVENING...AND THEN REMAIN MORE
EASTERLY AND UNDER 10 KT EARLY WEDNESDAY MORNING THROUGH THE REST
OF THE FORECAST PERIOD.

RODRIGUEZ

//ORD AND MDW CONFIDENCE...UPDATED 20Z...

* HIGH CONFIDENCE WITH WIND SPEED/DIRECTION.

* HIGH CONFIDENCE WITH MVFR CEILINGS...MEDIUM CONFIDENCE OF
  DURATION.

RODRIGUEZ

//OUTLOOK FOR ORD/MDW FOR 00Z THURSDAY-12Z TUESDAY...UPDATED 12Z...

* WEDNESDAY NIGHT...DRY/VFR.
* THURSDAY...CHANCE OF SHRA. SOUTH WINDS.
* FRIDAY AND SATURDAY...DRY/VFR. WEST/SOUTHWEST WINDS.
* SUNDAY...DRY/VFR. SOUTH WINDS.
* MONDAY...SLIGHT CHANCE OF SHRA. GUSTY SOUTHWEST WINDS.

&&

.MARINE...

215 PM...LOW PRESSURE OVER WESTERN NEW YORK WILL MERGE WITH ANOTHER
LOW OVER NEAR THE DELMARVA AREA TONIGHT...AND RAPIDLY DEEPEN
WEDNESDAY NIGHT AND THURSDAY JUST SOUTH OF CAPE COD. THIS LOW WILL
THEN TRACK NORTHEAST TO NOVA SCOTIA BY SATURDAY MORNING.
MEANWHILE...HIGH PRESSURE CENTERED OVER THE SOUTHERN TIP OF JAMES
BAY...WITH HIGH PRESSURE RIDGING EXTENDING THROUGH THE MIDDLE
MISSISSIPPI VALLEY...WILL SLOWLY BUILD EAST. THE BRISK
NORTHEASTERLY WINDS CURRENTLY OVER THE LAKE WILL DIMINISH AND
BECOME LIGHT AND VARIABLE LATE TONIGHT AND EARLY WEDNESDAY AS THE
RIDGE AXIS CROSSES THE LAKE. WHILE WINDS SHOULD DROP BELOW SMALL
CRAFT ADVISORY LEVELS DURG THE AFTERNOON AND EARLY THIS
EVENING...RESIDUAL WAVE ACTION WILL BE SLOWER TO DAMPEN AND STILL
EXPECT THAT WAVES WILL REMAIN...ABOVE SMALL CRAFT ADVISORY LEVELS
THROUGH MUCH OF THE NIGHT. AS THE RIDGE MOVES TO THE EAST OF THE
LAKE WEDNESDAY NIGHT...A TROUGH OF LOW PRESSURE WILL CROSS THE
CENTRAL PLAINS...REACHING THE UPPER MISSISSIPPI VALLEY BY THURSDAY
MORNING. THIS WILL SET UP A STRENGTHENING SOUTHERLY GRADIENT OVER
THE LAKE WITH WINDS INCREASING TO ARND 20-25KT THURSDAY AFTERNOON.
WINDS WILL REMAIN SOUTHERLY UNTIL AN ASSOCIATED WEAK COLD FRONT
PUSHES ACROSS THE LAKE THURSDAY NIGHT.

KREIN

&&

.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...SMALL CRAFT ADVISORY...NEARSHORE WATERS
     UNTIL 7 AM WEDNESDAY.

&&

$$

VISIT US AT HTTP://WEATHER.GOV/CHICAGO (ALL LOWERCASE)

FOLLOW US ON FACEBOOK...TWITTER...AND YOUTUBE AT:
WWW.FACEBOOK.COM/NWSCHICAGO
WWW.TWITTER.COM/NWSCHICAGO
WWW.YOUTUBE.COM/NWSCHICAGO








000
FXUS63 KLOT 212005
AFDLOT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
305 PM CDT TUE OCT 21 2014

.DISCUSSION...
218 AM CDT

BELOW AVERAGE TEMPERATURES THE NEXT COUPLE OF DAYS WILL GRADUALLY
GIVE WAY TO A BOUT OF INDIAN SUMMER OVER THE WEEKEND.

WATER VAPOR IMAGERY SHOWS AN AMPLIFYING UPPER TROUGH OVER THE
EASTERN CONUS THIS MORNING WITH LAST EVENING`S UPPER AIR ANALYSIS
SHOWING A POCKET OF SUB-FREEZING 850MB TEMPS ADVECTING SOUTH INTO
THE WESTERN GREAT LAKES REGION. THE CHILLY AIR MOVING OVER THE
RELATIVELY MILDER LAKE WATER IS CURRENTLY RESULTING IN A MARGINAL
LAKE EFFECT SHOWER SET-UP WITH SCATTERED LIGHT SHOWERS OR SPRINKLES
SHOWING UP OVER SOUTHERN LM INTO NW IN. LOW LEVEL FLOW WILL VEER TO
MORE NORTHEASTERLY DIRECTION TODAY AND SEND SOME OF THE LAKE EFFECT
CLOUDINESS AND POTENTIALLY SPRINKLES/LIGHT SHOWERS INTO EXTREME NE
IL THIS MORNING. RELATIVELY LOW INVERSION HEIGHTS AND SOMEWHAT WEAK
INSTABILITY MAKE THE CHANCES OF MEASURABLE PRECIP LOW AND HAVE KEPT
POPS IN THE LOWER END OF THE CHANCE CATEGORY. CLOUDINESS SHOULD BE
MOST PREVALENT TODAY NEAR THE LAKE WITH BETTER INCREASINGLY SUNNY
SKIES WELL INLAND. CLOUD COVER SHOULD KEEP HIGHS STRUGGLING INTO THE
LOWER 50S IN NE IL WHILE MID OR EVEN UPPER 50S ARE POSSIBLE OUT
TOWARD MENDOTA AND FAR SOUTHWESTERN CWA WHERE MORE SUN CAN BE
EXPECTED.

LOW CONFIDENCE IN THE EXTENT OF LAKE CLOUDINESS TONIGHT...WHICH
WOULD PLAY A ROLE IN LOW TEMPS. MORE CLOUDS NEAR THE LAKE WOULD
RESULT IN LOWS A COUPLE DEGREES WARMER THAN CURRENTLY FORECAST AND
VICE VERSA IF MAINLY CLEAR. SUNNY SKIES ARE EXPECTED WEDNESDAY AS
TRANSIENT UPPER RIDGE BUILDS INTO THE AREA BETWEEN DEPARTING DEEP
UPPER TROUGH/LOW AND THE NEXT STRONG NORTHERN STREAM SHORTWAVE
SLATED TO ARRIVE IN OUR AREA LATER THURSDAY. NOT LOOKING FOR MUCH OF
A CHANCE OF SUBSTANTIAL WARMING WEDNESDAY WITH A STILL SOMEWHAT COOL
EASTERLY LOW LEVEL FLOW AND ONLY WEAK LOW LEVEL WARM AIR ADVECTION.

BY THURSDAY SHOWER CHANCES WILL BE ON THE INCREASE AS SHARP NORTHERN
STREAM TROUGH TRACKS SOUTHEAST INTO THE WESTERN LAKES. LACK OF
RETURN FLOW SHOULD RESULT IN LIMITED MOISTURE FOR THE SYSTEM...BUT
FAIRLY STRONG FORCING SHOULD ALLOW FOR A PERIOD OF SHOWERS ACROSS
THE CWA THURSDAY AFTERNOON OR EVENING. NOT MUCH COOLING BEHIND THIS
SYSTEM FRIDAY...THEN A FAST MOVING WEAK CANADIAN COLD FRONT SHOULD
BRING A BRIEF COOL DOWN SATURDAY BEFORE MORE SUBSTANTIAL WARM AIR
ADVECTION SUNDAY INTO MONDAY LIKELY SENDS TEMPERATURES NEAR IF NOT
INTO THE 70S ACROSS THE CWA. MEDIUM RANGE MODELS DO SHOW A
PROGRESSIVE LONG WAVE TROUGH MOVING ACROSS THE CONUS BY EARLY NEXT
WEEK WITH COLD FRONT LIKELY TO ARRIVE LATER MONDAY OR TUESDAY
BRINGING AN END TO OUR BRIEF BUT POTENTIALLY IMPRESSIVE WARM UP.

IZZI

&&

.AVIATION...

//ORD AND MDW CONCERNS...UPDATED 20Z...

* NORTH/NORTHEAST WINDS 10-14 KT AND GUSTY THROUGH EARLY EVENING.

* MVFR CEILINGS THROUGH AFTERNOON.

RODRIGUEZ

//DISCUSSION...UPDATED 18Z...

DESPITE HIGH PRESSURE BUILDING ACROSS THE REGION TODAY...CEILINGS
HAVE STILL DEVELOPED WHILE LAKE EFFECT CLOUD COVER CONTINUES TO
MOVE OVERHEAD. THESE BOTH WILL SCATTER/DIMINISH THROUGH THIS
EVENING AS THIS HIGH BUILDS ACROSS THE TERMINALS. BEFORE THIS
OCCURS...PERIODS OF HIGH END MVFR CEILINGS WILL STILL BE POSSIBLE.
THEN EXPECT DRY AND MOSTLY CLEAR SKIES THROUGH THE REST OF THE
FORECAST PERIOD. NORTHEAST WINDS/GUSTS WILL PREVAIL THIS AFTERNOON
BEFORE DIMINISHING LATER THIS EVENING...AND THEN REMAIN MORE
EASTERLY AND UNDER 10 KT EARLY WEDNESDAY MORNING THROUGH THE REST
OF THE FORECAST PERIOD.

RODRIGUEZ

//ORD AND MDW CONFIDENCE...UPDATED 20Z...

* HIGH CONFIDENCE WITH WIND SPEED/DIRECTION.

* HIGH CONFIDENCE WITH MVFR CEILINGS...MEDIUM CONFIDENCE OF
  DURATION.

RODRIGUEZ

//OUTLOOK FOR ORD/MDW FOR 00Z THURSDAY-12Z TUESDAY...UPDATED 12Z...

* WEDNESDAY NIGHT...DRY/VFR.
* THURSDAY...CHANCE OF SHRA. SOUTH WINDS.
* FRIDAY AND SATURDAY...DRY/VFR. WEST/SOUTHWEST WINDS.
* SUNDAY...DRY/VFR. SOUTH WINDS.
* MONDAY...SLIGHT CHANCE OF SHRA. GUSTY SOUTHWEST WINDS.

&&

.MARINE...

215 PM...LOW PRESSURE OVER WESTERN NEW YORK WILL MERGE WITH ANOTHER
LOW OVER NEAR THE DELMARVA AREA TONIGHT...AND RAPIDLY DEEPEN
WEDNESDAY NIGHT AND THURSDAY JUST SOUTH OF CAPE COD. THIS LOW WILL
THEN TRACK NORTHEAST TO NOVA SCOTIA BY SATURDAY MORNING.
MEANWHILE...HIGH PRESSURE CENTERED OVER THE SOUTHERN TIP OF JAMES
BAY...WITH HIGH PRESSURE RIDGING EXTENDING THROUGH THE MIDDLE
MISSISSIPPI VALLEY...WILL SLOWLY BUILD EAST. THE BRISK
NORTHEASTERLY WINDS CURRENTLY OVER THE LAKE WILL DIMINISH AND
BECOME LIGHT AND VARIABLE LATE TONIGHT AND EARLY WEDNESDAY AS THE
RIDGE AXIS CROSSES THE LAKE. WHILE WINDS SHOULD DROP BELOW SMALL
CRAFT ADVISORY LEVELS DURG THE AFTERNOON AND EARLY THIS
EVENING...RESIDUAL WAVE ACTION WILL BE SLOWER TO DAMPEN AND STILL
EXPECT THAT WAVES WILL REMAIN...ABOVE SMALL CRAFT ADVISORY LEVELS
THROUGH MUCH OF THE NIGHT. AS THE RIDGE MOVES TO THE EAST OF THE
LAKE WEDNESDAY NIGHT...A TROUGH OF LOW PRESSURE WILL CROSS THE
CENTRAL PLAINS...REACHING THE UPPER MISSISSIPPI VALLEY BY THURSDAY
MORNING. THIS WILL SET UP A STRENGTHENING SOUTHERLY GRADIENT OVER
THE LAKE WITH WINDS INCREASING TO ARND 20-25KT THURSDAY AFTERNOON.
WINDS WILL REMAIN SOUTHERLY UNTIL AN ASSOCIATED WEAK COLD FRONT
PUSHES ACROSS THE LAKE THURSDAY NIGHT.

KREIN

&&

.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...SMALL CRAFT ADVISORY...NEARSHORE WATERS
     UNTIL 7 AM WEDNESDAY.

&&

$$

VISIT US AT HTTP://WEATHER.GOV/CHICAGO (ALL LOWERCASE)

FOLLOW US ON FACEBOOK...TWITTER...AND YOUTUBE AT:
WWW.FACEBOOK.COM/NWSCHICAGO
WWW.TWITTER.COM/NWSCHICAGO
WWW.YOUTUBE.COM/NWSCHICAGO







000
FXUS63 KLOT 211914
AFDLOT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
214 PM CDT TUE OCT 21 2014

.DISCUSSION...
218 AM CDT

BELOW AVERAGE TEMPERATURES THE NEXT COUPLE OF DAYS WILL GRADUALLY
GIVE WAY TO A BOUT OF INDIAN SUMMER OVER THE WEEKEND.

WATER VAPOR IMAGERY SHOWS AN AMPLIFYING UPPER TROUGH OVER THE
EASTERN CONUS THIS MORNING WITH LAST EVENING`S UPPER AIR ANALYSIS
SHOWING A POCKET OF SUB-FREEZING 850MB TEMPS ADVECTING SOUTH INTO
THE WESTERN GREAT LAKES REGION. THE CHILLY AIR MOVING OVER THE
RELATIVELY MILDER LAKE WATER IS CURRENTLY RESULTING IN A MARGINAL
LAKE EFFECT SHOWER SET-UP WITH SCATTERED LIGHT SHOWERS OR SPRINKLES
SHOWING UP OVER SOUTHERN LM INTO NW IN. LOW LEVEL FLOW WILL VEER TO
MORE NORTHEASTERLY DIRECTION TODAY AND SEND SOME OF THE LAKE EFFECT
CLOUDINESS AND POTENTIALLY SPRINKLES/LIGHT SHOWERS INTO EXTREME NE
IL THIS MORNING. RELATIVELY LOW INVERSION HEIGHTS AND SOMEWHAT WEAK
INSTABILITY MAKE THE CHANCES OF MEASURABLE PRECIP LOW AND HAVE KEPT
POPS IN THE LOWER END OF THE CHANCE CATEGORY. CLOUDINESS SHOULD BE
MOST PREVALENT TODAY NEAR THE LAKE WITH BETTER INCREASINGLY SUNNY
SKIES WELL INLAND. CLOUD COVER SHOULD KEEP HIGHS STRUGGLING INTO THE
LOWER 50S IN NE IL WHILE MID OR EVEN UPPER 50S ARE POSSIBLE OUT
TOWARD MENDOTA AND FAR SOUTHWESTERN CWA WHERE MORE SUN CAN BE
EXPECTED.

LOW CONFIDENCE IN THE EXTENT OF LAKE CLOUDINESS TONIGHT...WHICH
WOULD PLAY A ROLE IN LOW TEMPS. MORE CLOUDS NEAR THE LAKE WOULD
RESULT IN LOWS A COUPLE DEGREES WARMER THAN CURRENTLY FORECAST AND
VICE VERSA IF MAINLY CLEAR. SUNNY SKIES ARE EXPECTED WEDNESDAY AS
TRANSIENT UPPER RIDGE BUILDS INTO THE AREA BETWEEN DEPARTING DEEP
UPPER TROUGH/LOW AND THE NEXT STRONG NORTHERN STREAM SHORTWAVE
SLATED TO ARRIVE IN OUR AREA LATER THURSDAY. NOT LOOKING FOR MUCH OF
A CHANCE OF SUBSTANTIAL WARMING WEDNESDAY WITH A STILL SOMEWHAT COOL
EASTERLY LOW LEVEL FLOW AND ONLY WEAK LOW LEVEL WARM AIR ADVECTION.

BY THURSDAY SHOWER CHANCES WILL BE ON THE INCREASE AS SHARP NORTHERN
STREAM TROUGH TRACKS SOUTHEAST INTO THE WESTERN LAKES. LACK OF
RETURN FLOW SHOULD RESULT IN LIMITED MOISTURE FOR THE SYSTEM...BUT
FAIRLY STRONG FORCING SHOULD ALLOW FOR A PERIOD OF SHOWERS ACROSS
THE CWA THURSDAY AFTERNOON OR EVENING. NOT MUCH COOLING BEHIND THIS
SYSTEM FRIDAY...THEN A FAST MOVING WEAK CANADIAN COLD FRONT SHOULD
BRING A BRIEF COOL DOWN SATURDAY BEFORE MORE SUBSTANTIAL WARM AIR
ADVECTION SUNDAY INTO MONDAY LIKELY SENDS TEMPERATURES NEAR IF NOT
INTO THE 70S ACROSS THE CWA. MEDIUM RANGE MODELS DO SHOW A
PROGRESSIVE LONG WAVE TROUGH MOVING ACROSS THE CONUS BY EARLY NEXT
WEEK WITH COLD FRONT LIKELY TO ARRIVE LATER MONDAY OR TUESDAY
BRINGING AN END TO OUR BRIEF BUT POTENTIALLY IMPRESSIVE WARM UP.

IZZI

&&

.AVIATION...

//ORD AND MDW CONCERNS...UPDATED 18Z...

* NORTH/NORTHEAST WINDS 10-14 KT AND GUSTY THROUGH EARLY EVENING.

* MVFR CEILINGS POSSIBLE THROUGH AFTERNOON.

RODRIGUEZ

//DISCUSSION...UPDATED 18Z...

DESPITE HIGH PRESSURE BUILDING ACROSS THE REGION TODAY...CEILINGS
HAVE STILL DEVELOPED WHILE LAKE EFFECT CLOUD COVER CONTINUES TO
MOVE OVERHEAD. THESE BOTH WILL SCATTER/DIMINISH THROUGH THIS
EVENING AS THIS HIGH BUILDS ACROSS THE TERMINALS. BEFORE THIS
OCCURS...PERIODS OF HIGH END MVFR CEILINGS WILL STILL BE POSSIBLE.
THEN EXPECT DRY AND MOSTLY CLEAR SKIES THROUGH THE REST OF THE
FORECAST PERIOD. NORTHEAST WINDS/GUSTS WILL PREVAIL THIS AFTERNOON
BEFORE DIMINISHING LATER THIS EVENING...AND THEN REMAIN MORE
EASTERLY AND UNDER 10 KT EARLY WEDNESDAY MORNING THROUGH THE REST
OF THE FORECAST PERIOD.

RODRIGUEZ

//ORD AND MDW CONFIDENCE...UPDATED 18Z...

* HIGH CONFIDENCE WITH WIND SPEED/DIRECTION.

* MEDIUM CONFIDENCE WITH MVFR CEILINGS...MEDIUM CONFIDENCE OF
  DURATION.

RODRIGUEZ

//OUTLOOK FOR ORD/MDW FOR 00Z THURSDAY-12Z TUESDAY...UPDATED 12Z...

* WEDNESDAY NIGHT...DRY/VFR.
* THURSDAY...CHANCE OF SHRA. SOUTH WINDS.
* FRIDAY AND SATURDAY...DRY/VFR. WEST/SOUTHWEST WINDS.
* SUNDAY...DRY/VFR. SOUTH WINDS.
* MONDAY...SLIGHT CHANCE OF SHRA. GUSTY SOUTHWEST WINDS.

&&

.MARINE...

215 PM...LOW PRESSURE OVER WESTERN NEW YORK WILL MERGE WITH ANOTHER
LOW OVER NEAR THE DELMARVA AREA TONIGHT...AND RAPIDLY DEEPEN
WEDNESDAY NIGHT AND THURSDAY JUST SOUTH OF CAPE COD. THIS LOW WILL
THEN TRACK NORTHEAST TO NOVA SCOTIA BY SATURDAY MORNING.
MEANWHILE...HIGH PRESSURE CENTERED OVER THE SOUTHERN TIP OF JAMES
BAY...WITH HIGH PRESSURE RIDGING EXTENDING THROUGH THE MIDDLE
MISSISSIPPI VALLEY...WILL SLOWLY BUILD EAST. THE BRISK
NORTHEASTERLY WINDS CURRENTLY OVER THE LAKE WILL DIMINISH AND
BECOME LIGHT AND VARIABLE LATE TONIGHT AND EARLY WEDNESDAY AS THE
RIDGE AXIS CROSSES THE LAKE. WHILE WINDS SHOULD DROP BELOW SMALL
CRAFT ADVISORY LEVELS DURG THE AFTERNOON AND EARLY THIS
EVENING...RESIDUAL WAVE ACTION WILL BE SLOWER TO DAMPEN AND STILL
EXPECT THAT WAVES WILL REMAIN...ABOVE SMALL CRAFT ADVISORY LEVELS
THROUGH MUCH OF THE NIGHT. AS THE RIDGE MOVES TO THE EAST OF THE
LAKE WEDNESDAY NIGHT...A TROUGH OF LOW PRESSURE WILL CROSS THE
CENTRAL PLAINS...REACHING THE UPPER MISSISSIPPI VALLEY BY THURSDAY
MORNING. THIS WILL SET UP A STRENGTHENING SOUTHERLY GRADIENT OVER
THE LAKE WITH WINDS INCREASING TO ARND 20-25KT THURSDAY AFTERNOON.
WINDS WILL REMAIN SOUTHERLY UNTIL AN ASSOCIATED WEAK COLD FRONT
PUSHES ACROSS THE LAKE THURSDAY NIGHT.

KREIN

&&

.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...SMALL CRAFT ADVISORY...NEARSHORE WATERS
     UNTIL 7 AM WEDNESDAY.

&&

$$

VISIT US AT HTTP://WEATHER.GOV/CHICAGO (ALL LOWERCASE)

FOLLOW US ON FACEBOOK...TWITTER...AND YOUTUBE AT:
WWW.FACEBOOK.COM/NWSCHICAGO
WWW.TWITTER.COM/NWSCHICAGO
WWW.YOUTUBE.COM/NWSCHICAGO







000
FXUS63 KLOT 211805
AFDLOT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
105 PM CDT TUE OCT 21 2014

.DISCUSSION...
218 AM CDT

BELOW AVERAGE TEMPERATURES THE NEXT COUPLE OF DAYS WILL GRADUALLY
GIVE WAY TO A BOUT OF INDIAN SUMMER OVER THE WEEKEND.

WATER VAPOR IMAGERY SHOWS AN AMPLIFYING UPPER TROUGH OVER THE
EASTERN CONUS THIS MORNING WITH LAST EVENING`S UPPER AIR ANALYSIS
SHOWING A POCKET OF SUB-FREEZING 850MB TEMPS ADVECTING SOUTH INTO
THE WESTERN GREAT LAKES REGION. THE CHILLY AIR MOVING OVER THE
RELATIVELY MILDER LAKE WATER IS CURRENTLY RESULTING IN A MARGINAL
LAKE EFFECT SHOWER SET-UP WITH SCATTERED LIGHT SHOWERS OR SPRINKLES
SHOWING UP OVER SOUTHERN LM INTO NW IN. LOW LEVEL FLOW WILL VEER TO
MORE NORTHEASTERLY DIRECTION TODAY AND SEND SOME OF THE LAKE EFFECT
CLOUDINESS AND POTENTIALLY SPRINKLES/LIGHT SHOWERS INTO EXTREME NE
IL THIS MORNING. RELATIVELY LOW INVERSION HEIGHTS AND SOMEWHAT WEAK
INSTABILITY MAKE THE CHANCES OF MEASURABLE PRECIP LOW AND HAVE KEPT
POPS IN THE LOWER END OF THE CHANCE CATEGORY. CLOUDINESS SHOULD BE
MOST PREVALENT TODAY NEAR THE LAKE WITH BETTER INCREASINGLY SUNNY
SKIES WELL INLAND. CLOUD COVER SHOULD KEEP HIGHS STRUGGLING INTO THE
LOWER 50S IN NE IL WHILE MID OR EVEN UPPER 50S ARE POSSIBLE OUT
TOWARD MENDOTA AND FAR SOUTHWESTERN CWA WHERE MORE SUN CAN BE
EXPECTED.

LOW CONFIDENCE IN THE EXTENT OF LAKE CLOUDINESS TONIGHT...WHICH
WOULD PLAY A ROLE IN LOW TEMPS. MORE CLOUDS NEAR THE LAKE WOULD
RESULT IN LOWS A COUPLE DEGREES WARMER THAN CURRENTLY FORECAST AND
VICE VERSA IF MAINLY CLEAR. SUNNY SKIES ARE EXPECTED WEDNESDAY AS
TRANSIENT UPPER RIDGE BUILDS INTO THE AREA BETWEEN DEPARTING DEEP
UPPER TROUGH/LOW AND THE NEXT STRONG NORTHERN STREAM SHORTWAVE
SLATED TO ARRIVE IN OUR AREA LATER THURSDAY. NOT LOOKING FOR MUCH OF
A CHANCE OF SUBSTANTIAL WARMING WEDNESDAY WITH A STILL SOMEWHAT COOL
EASTERLY LOW LEVEL FLOW AND ONLY WEAK LOW LEVEL WARM AIR ADVECTION.

BY THURSDAY SHOWER CHANCES WILL BE ON THE INCREASE AS SHARP NORTHERN
STREAM TROUGH TRACKS SOUTHEAST INTO THE WESTERN LAKES. LACK OF
RETURN FLOW SHOULD RESULT IN LIMITED MOISTURE FOR THE SYSTEM...BUT
FAIRLY STRONG FORCING SHOULD ALLOW FOR A PERIOD OF SHOWERS ACROSS
THE CWA THURSDAY AFTERNOON OR EVENING. NOT MUCH COOLING BEHIND THIS
SYSTEM FRIDAY...THEN A FAST MOVING WEAK CANADIAN COLD FRONT SHOULD
BRING A BRIEF COOL DOWN SATURDAY BEFORE MORE SUBSTANTIAL WARM AIR
ADVECTION SUNDAY INTO MONDAY LIKELY SENDS TEMPERATURES NEAR IF NOT
INTO THE 70S ACROSS THE CWA. MEDIUM RANGE MODELS DO SHOW A
PROGRESSIVE LONG WAVE TROUGH MOVING ACROSS THE CONUS BY EARLY NEXT
WEEK WITH COLD FRONT LIKELY TO ARRIVE LATER MONDAY OR TUESDAY
BRINGING AN END TO OUR BRIEF BUT POTENTIALLY IMPRESSIVE WARM UP.

IZZI

&&

.AVIATION...

//ORD AND MDW CONCERNS...UPDATED 18Z...

* NORTH/NORTHEAST WINDS 10-14 KT AND GUSTY THROUGH EARLY EVENING.

* MVFR CEILINGS POSSIBLE THROUGH AFTERNOON.

RODRIGUEZ

//DISCUSSION...UPDATED 18Z...

DESPITE HIGH PRESSURE BUILDING ACROSS THE REGION TODAY...CEILINGS
HAVE STILL DEVELOPED WHILE LAKE EFFECT CLOUD COVER CONTINUES TO
MOVE OVERHEAD. THESE BOTH WILL SCATTER/DIMINISH THROUGH THIS
EVENING AS THIS HIGH BUILDS ACROSS THE TERMINALS. BEFORE THIS
OCCURS...PERIODS OF HIGH END MVFR CEILINGS WILL STILL BE POSSIBLE.
THEN EXPECT DRY AND MOSTLY CLEAR SKIES THROUGH THE REST OF THE
FORECAST PERIOD. NORTHEAST WINDS/GUSTS WILL PREVAIL THIS AFTERNOON
BEFORE DIMINISHING LATER THIS EVENING...AND THEN REMAIN MORE
EASTERLY AND UNDER 10 KT EARLY WEDNESDAY MORNING THROUGH THE REST
OF THE FORECAST PERIOD.

RODRIGUEZ


//ORD AND MDW CONFIDENCE...UPDATED 18Z...

* HIGH CONFIDENCE WITH WIND SPEED/DIRECTION.

* MEDIUM CONFIDENCE WITH MVFR CEILINGS...MEDIUM CONFIDENCE OF
  DURATION.

RODRIGUEZ

//OUTLOOK FOR ORD/MDW FOR 00Z THURSDAY-12Z TUESDAY...UPDATED 12Z...

* WEDNESDAY NIGHT...DRY/VFR.
* THURSDAY...CHANCE OF SHRA. SOUTH WINDS.
* FRIDAY AND SATURDAY...DRY/VFR. WEST/SOUTHWEST WINDS.
* SUNDAY...DRY/VFR. SOUTH WINDS.
* MONDAY...SLIGHT CHANCE OF SHRA. GUSTY SOUTHWEST WINDS.

&&

.MARINE...

258 AM...LOW PRESSURE NEAR LAKE ONTARIO WILL MOVE OFF THE MID
ATLANTIC COAST WEDNESDAY MORNING THEN DEEPEN AGAIN AS IT MOVES
NORTHEAST ALONG THE NEW ENGLAND COAST WEDNESDAY NIGHT THROUGH
THURSDAY NIGHT. HIGH PRESSURE OVER ONTARIO WILL STRENGTHEN AS IT
MOVES INTO QUEBEC TONIGHT AND WEDNESDAY...WITH A TRAILING WEAKER
RIDGE BUILDING ACROSS THE WESTERN LAKES TODAY AND CROSSING LAKE
MICHIGAN TONIGHT. NORTH WINDS ARE STILL EXPECTED TO INCREASE TO
30 KT WITH A TIGHT GRADIENT BETWEEN THE APPROACHING RIDGE AND THE
DEPARTING LOW BUT SPEEDS WILL PROBABLY DIMINISH A LITTLE FASTER
THAN PREVIOUSLY INDICATED LATE THIS AFTERNOON INTO THIS EVENING.
THE RIDGE WILL BECOME STATIONARY OVER THE EASTERN LAKES WEDNESDAY
NIGHT AND THURSDAY AS IT WEAKENS. CMS

&&

.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...SMALL CRAFT ADVISORY...NEARSHORE WATERS
     UNTIL 7 AM WEDNESDAY.

&&

$$

VISIT US AT HTTP://WEATHER.GOV/CHICAGO (ALL LOWERCASE)

FOLLOW US ON FACEBOOK...TWITTER...AND YOUTUBE AT:
WWW.FACEBOOK.COM/NWSCHICAGO
WWW.TWITTER.COM/NWSCHICAGO
WWW.YOUTUBE.COM/NWSCHICAGO







000
FXUS63 KLOT 211622
AFDLOT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
1122 AM CDT TUE OCT 21 2014

.DISCUSSION...
218 AM CDT

BELOW AVERAGE TEMPERATURES THE NEXT COUPLE OF DAYS WILL GRADUALLY
GIVE WAY TO A BOUT OF INDIAN SUMMER OVER THE WEEKEND.

WATER VAPOR IMAGERY SHOWS AN AMPLIFYING UPPER TROUGH OVER THE
EASTERN CONUS THIS MORNING WITH LAST EVENING`S UPPER AIR ANALYSIS
SHOWING A POCKET OF SUB-FREEZING 850MB TEMPS ADVECTING SOUTH INTO
THE WESTERN GREAT LAKES REGION. THE CHILLY AIR MOVING OVER THE
RELATIVELY MILDER LAKE WATER IS CURRENTLY RESULTING IN A MARGINAL
LAKE EFFECT SHOWER SET-UP WITH SCATTERED LIGHT SHOWERS OR SPRINKLES
SHOWING UP OVER SOUTHERN LM INTO NW IN. LOW LEVEL FLOW WILL VEER TO
MORE NORTHEASTERLY DIRECTION TODAY AND SEND SOME OF THE LAKE EFFECT
CLOUDINESS AND POTENTIALLY SPRINKLES/LIGHT SHOWERS INTO EXTREME NE
IL THIS MORNING. RELATIVELY LOW INVERSION HEIGHTS AND SOMEWHAT WEAK
INSTABILITY MAKE THE CHANCES OF MEASURABLE PRECIP LOW AND HAVE KEPT
POPS IN THE LOWER END OF THE CHANCE CATEGORY. CLOUDINESS SHOULD BE
MOST PREVALENT TODAY NEAR THE LAKE WITH BETTER INCREASINGLY SUNNY
SKIES WELL INLAND. CLOUD COVER SHOULD KEEP HIGHS STRUGGLING INTO THE
LOWER 50S IN NE IL WHILE MID OR EVEN UPPER 50S ARE POSSIBLE OUT
TOWARD MENDOTA AND FAR SOUTHWESTERN CWA WHERE MORE SUN CAN BE
EXPECTED.

LOW CONFIDENCE IN THE EXTENT OF LAKE CLOUDINESS TONIGHT...WHICH
WOULD PLAY A ROLE IN LOW TEMPS. MORE CLOUDS NEAR THE LAKE WOULD
RESULT IN LOWS A COUPLE DEGREES WARMER THAN CURRENTLY FORECAST AND
VICE VERSA IF MAINLY CLEAR. SUNNY SKIES ARE EXPECTED WEDNESDAY AS
TRANSIENT UPPER RIDGE BUILDS INTO THE AREA BETWEEN DEPARTING DEEP
UPPER TROUGH/LOW AND THE NEXT STRONG NORTHERN STREAM SHORTWAVE
SLATED TO ARRIVE IN OUR AREA LATER THURSDAY. NOT LOOKING FOR MUCH OF
A CHANCE OF SUBSTANTIAL WARMING WEDNESDAY WITH A STILL SOMEWHAT COOL
EASTERLY LOW LEVEL FLOW AND ONLY WEAK LOW LEVEL WARM AIR ADVECTION.

BY THURSDAY SHOWER CHANCES WILL BE ON THE INCREASE AS SHARP NORTHERN
STREAM TROUGH TRACKS SOUTHEAST INTO THE WESTERN LAKES. LACK OF
RETURN FLOW SHOULD RESULT IN LIMITED MOISTURE FOR THE SYSTEM...BUT
FAIRLY STRONG FORCING SHOULD ALLOW FOR A PERIOD OF SHOWERS ACROSS
THE CWA THURSDAY AFTERNOON OR EVENING. NOT MUCH COOLING BEHIND THIS
SYSTEM FRIDAY...THEN A FAST MOVING WEAK CANADIAN COLD FRONT SHOULD
BRING A BRIEF COOL DOWN SATURDAY BEFORE MORE SUBSTANTIAL WARM AIR
ADVECTION SUNDAY INTO MONDAY LIKELY SENDS TEMPERATURES NEAR IF NOT
INTO THE 70S ACROSS THE CWA. MEDIUM RANGE MODELS DO SHOW A
PROGRESSIVE LONG WAVE TROUGH MOVING ACROSS THE CONUS BY EARLY NEXT
WEEK WITH COLD FRONT LIKELY TO ARRIVE LATER MONDAY OR TUESDAY
BRINGING AN END TO OUR BRIEF BUT POTENTIALLY IMPRESSIVE WARM UP.

IZZI

&&

.AVIATION...

//ORD AND MDW CONCERNS...UPDATED 16Z...

* NORTH/NORTHEAST WINDS 10-14 KTS AND GUSTY THRU LATE AFTERNOON.

* SLIGHT CHANCE FOR -SHRA THRU MID AFTERNOON.

* MVFR CEILINGS THRU AFTERNOON.

RODRIGUEZ

//DISCUSSION...UPDATED 12Z...

NO SIGNIFICANT CHANGES TO PREVIOUS FORECAST. NORTHERLY WINDS WILL
INCREASE TO 10-14KTS IN THE NEXT FEW HOURS AND TURN MORE TO THE
NORTHEAST THIS MORNING AND THIS AFTERNOON. GUSTS INTO THE 16-20KT
RANGE WILL ALSO DEVELOP MID MORNING AND CONTINUE INTO THE
AFTERNOON. WINDS WILL QUICKLY DIMINISH BY EARLY EVENING AND TURN
MORE EAST/NORTHEAST TONIGHT.

LAKE EFFECT RAIN SHOWERS CONTINUE TO MOVE SOUTH INTO NORTHWEST
INDIANA AND WILL AFFECT GYY AT TIMES THIS MORNING. AS THE WINDS
TURN MORE NORTHEAST...THESE SHOWERS MAY MOVE FAR ENOUGH INLAND TO
REACH ORD/MDW. HOWEVER...HAVE MAINTAINED A DRY FORECAST GIVEN THE
EXPECTED SHORT DURATION AND ISOLATED COVERAGE.

4-5KFT VFR CIGS WILL LOWER TO MVFR MID/LATE MORNING...WITH MVFR
CIGS ACROSS EASTERN WI AND SPREADING SOUTH. TIMING AND DURATION
WILL LIKELY NEED TO BE ADJUSTED WITH MORNING UPDATES. CMS

//ORD AND MDW CONFIDENCE...UPDATED 16Z...

* HIGH CONFIDENCE FOR WIND SPEEDS/GUSTS/DIRECTIONS THRU THE
  PERIOD.

* MEDIUM CONFIDENCE FOR SHRA THRU MID AFTERNOON.

* HIGH CONFIDENCE FOR MVFR CEILINGS...MEDIUM CONFIDENCE OF
  DURATION.

RODRIGUEZ

//OUTLOOK FOR ORD/MDW FOR 00Z THURSDAY-12Z TUESDAY...UPDATED 12Z...

* WEDNESDAY NIGHT...DRY/VFR.
* THURSDAY...CHANCE OF SHRA. SOUTH WINDS.
* FRIDAY AND SATURDAY...DRY/VFR. WEST/SOUTHWEST WINDS.
* SUNDAY...DRY/VFR. SOUTH WINDS.
* MONDAY...SLIGHT CHANCE OF SHRA. GUSTY SOUTHWEST WINDS.

&&

.MARINE...

258 AM...LOW PRESSURE NEAR LAKE ONTARIO WILL MOVE OFF THE MID
ATLANTIC COAST WEDNESDAY MORNING THEN DEEPEN AGAIN AS IT MOVES
NORTHEAST ALONG THE NEW ENGLAND COAST WEDNESDAY NIGHT THROUGH
THURSDAY NIGHT. HIGH PRESSURE OVER ONTARIO WILL STRENGTHEN AS IT
MOVES INTO QUEBEC TONIGHT AND WEDNESDAY...WITH A TRAILING WEAKER
RIDGE BUILDING ACROSS THE WESTERN LAKES TODAY AND CROSSING LAKE
MICHIGAN TONIGHT. NORTH WINDS ARE STILL EXPECTED TO INCREASE TO
30 KT WITH A TIGHT GRADIENT BETWEEN THE APPROACHING RIDGE AND THE
DEPARTING LOW BUT SPEEDS WILL PROBABLY DIMINISH A LITTLE FASTER
THAN PREVIOUSLY INDICATED LATE THIS AFTERNOON INTO THIS EVENING.
THE RIDGE WILL BECOME STATIONARY OVER THE EASTERN LAKES WEDNESDAY
NIGHT AND THURSDAY AS IT WEAKENS. CMS

&&

.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...SMALL CRAFT ADVISORY...NEARSHORE WATERS
     UNTIL 7 AM WEDNESDAY.

&&

$$

VISIT US AT HTTP://WEATHER.GOV/CHICAGO (ALL LOWERCASE)

FOLLOW US ON FACEBOOK...TWITTER...AND YOUTUBE AT:
WWW.FACEBOOK.COM/NWSCHICAGO
WWW.TWITTER.COM/NWSCHICAGO
WWW.YOUTUBE.COM/NWSCHICAGO







000
FXUS63 KLOT 211622
AFDLOT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
1122 AM CDT TUE OCT 21 2014

.DISCUSSION...
218 AM CDT

BELOW AVERAGE TEMPERATURES THE NEXT COUPLE OF DAYS WILL GRADUALLY
GIVE WAY TO A BOUT OF INDIAN SUMMER OVER THE WEEKEND.

WATER VAPOR IMAGERY SHOWS AN AMPLIFYING UPPER TROUGH OVER THE
EASTERN CONUS THIS MORNING WITH LAST EVENING`S UPPER AIR ANALYSIS
SHOWING A POCKET OF SUB-FREEZING 850MB TEMPS ADVECTING SOUTH INTO
THE WESTERN GREAT LAKES REGION. THE CHILLY AIR MOVING OVER THE
RELATIVELY MILDER LAKE WATER IS CURRENTLY RESULTING IN A MARGINAL
LAKE EFFECT SHOWER SET-UP WITH SCATTERED LIGHT SHOWERS OR SPRINKLES
SHOWING UP OVER SOUTHERN LM INTO NW IN. LOW LEVEL FLOW WILL VEER TO
MORE NORTHEASTERLY DIRECTION TODAY AND SEND SOME OF THE LAKE EFFECT
CLOUDINESS AND POTENTIALLY SPRINKLES/LIGHT SHOWERS INTO EXTREME NE
IL THIS MORNING. RELATIVELY LOW INVERSION HEIGHTS AND SOMEWHAT WEAK
INSTABILITY MAKE THE CHANCES OF MEASURABLE PRECIP LOW AND HAVE KEPT
POPS IN THE LOWER END OF THE CHANCE CATEGORY. CLOUDINESS SHOULD BE
MOST PREVALENT TODAY NEAR THE LAKE WITH BETTER INCREASINGLY SUNNY
SKIES WELL INLAND. CLOUD COVER SHOULD KEEP HIGHS STRUGGLING INTO THE
LOWER 50S IN NE IL WHILE MID OR EVEN UPPER 50S ARE POSSIBLE OUT
TOWARD MENDOTA AND FAR SOUTHWESTERN CWA WHERE MORE SUN CAN BE
EXPECTED.

LOW CONFIDENCE IN THE EXTENT OF LAKE CLOUDINESS TONIGHT...WHICH
WOULD PLAY A ROLE IN LOW TEMPS. MORE CLOUDS NEAR THE LAKE WOULD
RESULT IN LOWS A COUPLE DEGREES WARMER THAN CURRENTLY FORECAST AND
VICE VERSA IF MAINLY CLEAR. SUNNY SKIES ARE EXPECTED WEDNESDAY AS
TRANSIENT UPPER RIDGE BUILDS INTO THE AREA BETWEEN DEPARTING DEEP
UPPER TROUGH/LOW AND THE NEXT STRONG NORTHERN STREAM SHORTWAVE
SLATED TO ARRIVE IN OUR AREA LATER THURSDAY. NOT LOOKING FOR MUCH OF
A CHANCE OF SUBSTANTIAL WARMING WEDNESDAY WITH A STILL SOMEWHAT COOL
EASTERLY LOW LEVEL FLOW AND ONLY WEAK LOW LEVEL WARM AIR ADVECTION.

BY THURSDAY SHOWER CHANCES WILL BE ON THE INCREASE AS SHARP NORTHERN
STREAM TROUGH TRACKS SOUTHEAST INTO THE WESTERN LAKES. LACK OF
RETURN FLOW SHOULD RESULT IN LIMITED MOISTURE FOR THE SYSTEM...BUT
FAIRLY STRONG FORCING SHOULD ALLOW FOR A PERIOD OF SHOWERS ACROSS
THE CWA THURSDAY AFTERNOON OR EVENING. NOT MUCH COOLING BEHIND THIS
SYSTEM FRIDAY...THEN A FAST MOVING WEAK CANADIAN COLD FRONT SHOULD
BRING A BRIEF COOL DOWN SATURDAY BEFORE MORE SUBSTANTIAL WARM AIR
ADVECTION SUNDAY INTO MONDAY LIKELY SENDS TEMPERATURES NEAR IF NOT
INTO THE 70S ACROSS THE CWA. MEDIUM RANGE MODELS DO SHOW A
PROGRESSIVE LONG WAVE TROUGH MOVING ACROSS THE CONUS BY EARLY NEXT
WEEK WITH COLD FRONT LIKELY TO ARRIVE LATER MONDAY OR TUESDAY
BRINGING AN END TO OUR BRIEF BUT POTENTIALLY IMPRESSIVE WARM UP.

IZZI

&&

.AVIATION...

//ORD AND MDW CONCERNS...UPDATED 16Z...

* NORTH/NORTHEAST WINDS 10-14 KTS AND GUSTY THRU LATE AFTERNOON.

* SLIGHT CHANCE FOR -SHRA THRU MID AFTERNOON.

* MVFR CEILINGS THRU AFTERNOON.

RODRIGUEZ

//DISCUSSION...UPDATED 12Z...

NO SIGNIFICANT CHANGES TO PREVIOUS FORECAST. NORTHERLY WINDS WILL
INCREASE TO 10-14KTS IN THE NEXT FEW HOURS AND TURN MORE TO THE
NORTHEAST THIS MORNING AND THIS AFTERNOON. GUSTS INTO THE 16-20KT
RANGE WILL ALSO DEVELOP MID MORNING AND CONTINUE INTO THE
AFTERNOON. WINDS WILL QUICKLY DIMINISH BY EARLY EVENING AND TURN
MORE EAST/NORTHEAST TONIGHT.

LAKE EFFECT RAIN SHOWERS CONTINUE TO MOVE SOUTH INTO NORTHWEST
INDIANA AND WILL AFFECT GYY AT TIMES THIS MORNING. AS THE WINDS
TURN MORE NORTHEAST...THESE SHOWERS MAY MOVE FAR ENOUGH INLAND TO
REACH ORD/MDW. HOWEVER...HAVE MAINTAINED A DRY FORECAST GIVEN THE
EXPECTED SHORT DURATION AND ISOLATED COVERAGE.

4-5KFT VFR CIGS WILL LOWER TO MVFR MID/LATE MORNING...WITH MVFR
CIGS ACROSS EASTERN WI AND SPREADING SOUTH. TIMING AND DURATION
WILL LIKELY NEED TO BE ADJUSTED WITH MORNING UPDATES. CMS

//ORD AND MDW CONFIDENCE...UPDATED 16Z...

* HIGH CONFIDENCE FOR WIND SPEEDS/GUSTS/DIRECTIONS THRU THE
  PERIOD.

* MEDIUM CONFIDENCE FOR SHRA THRU MID AFTERNOON.

* HIGH CONFIDENCE FOR MVFR CEILINGS...MEDIUM CONFIDENCE OF
  DURATION.

RODRIGUEZ

//OUTLOOK FOR ORD/MDW FOR 00Z THURSDAY-12Z TUESDAY...UPDATED 12Z...

* WEDNESDAY NIGHT...DRY/VFR.
* THURSDAY...CHANCE OF SHRA. SOUTH WINDS.
* FRIDAY AND SATURDAY...DRY/VFR. WEST/SOUTHWEST WINDS.
* SUNDAY...DRY/VFR. SOUTH WINDS.
* MONDAY...SLIGHT CHANCE OF SHRA. GUSTY SOUTHWEST WINDS.

&&

.MARINE...

258 AM...LOW PRESSURE NEAR LAKE ONTARIO WILL MOVE OFF THE MID
ATLANTIC COAST WEDNESDAY MORNING THEN DEEPEN AGAIN AS IT MOVES
NORTHEAST ALONG THE NEW ENGLAND COAST WEDNESDAY NIGHT THROUGH
THURSDAY NIGHT. HIGH PRESSURE OVER ONTARIO WILL STRENGTHEN AS IT
MOVES INTO QUEBEC TONIGHT AND WEDNESDAY...WITH A TRAILING WEAKER
RIDGE BUILDING ACROSS THE WESTERN LAKES TODAY AND CROSSING LAKE
MICHIGAN TONIGHT. NORTH WINDS ARE STILL EXPECTED TO INCREASE TO
30 KT WITH A TIGHT GRADIENT BETWEEN THE APPROACHING RIDGE AND THE
DEPARTING LOW BUT SPEEDS WILL PROBABLY DIMINISH A LITTLE FASTER
THAN PREVIOUSLY INDICATED LATE THIS AFTERNOON INTO THIS EVENING.
THE RIDGE WILL BECOME STATIONARY OVER THE EASTERN LAKES WEDNESDAY
NIGHT AND THURSDAY AS IT WEAKENS. CMS

&&

.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...SMALL CRAFT ADVISORY...NEARSHORE WATERS
     UNTIL 7 AM WEDNESDAY.

&&

$$

VISIT US AT HTTP://WEATHER.GOV/CHICAGO (ALL LOWERCASE)

FOLLOW US ON FACEBOOK...TWITTER...AND YOUTUBE AT:
WWW.FACEBOOK.COM/NWSCHICAGO
WWW.TWITTER.COM/NWSCHICAGO
WWW.YOUTUBE.COM/NWSCHICAGO






000
FXUS63 KLOT 211428
AFDLOT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
928 AM CDT TUE OCT 21 2014

.DISCUSSION...
218 AM CDT

BELOW AVERAGE TEMPERATURES THE NEXT COUPLE OF DAYS WILL GRADUALLY
GIVE WAY TO A BOUT OF INDIAN SUMMER OVER THE WEEKEND.

WATER VAPOR IMAGERY SHOWS AN AMPLIFYING UPPER TROUGH OVER THE
EASTERN CONUS THIS MORNING WITH LAST EVENING`S UPPER AIR ANALYSIS
SHOWING A POCKET OF SUB-FREEZING 850MB TEMPS ADVECTING SOUTH INTO
THE WESTERN GREAT LAKES REGION. THE CHILLY AIR MOVING OVER THE
RELATIVELY MILDER LAKE WATER IS CURRENTLY RESULTING IN A MARGINAL
LAKE EFFECT SHOWER SET-UP WITH SCATTERED LIGHT SHOWERS OR SPRINKLES
SHOWING UP OVER SOUTHERN LM INTO NW IN. LOW LEVEL FLOW WILL VEER TO
MORE NORTHEASTERLY DIRECTION TODAY AND SEND SOME OF THE LAKE EFFECT
CLOUDINESS AND POTENTIALLY SPRINKLES/LIGHT SHOWERS INTO EXTREME NE
IL THIS MORNING. RELATIVELY LOW INVERSION HEIGHTS AND SOMEWHAT WEAK
INSTABILITY MAKE THE CHANCES OF MEASURABLE PRECIP LOW AND HAVE KEPT
POPS IN THE LOWER END OF THE CHANCE CATEGORY. CLOUDINESS SHOULD BE
MOST PREVALENT TODAY NEAR THE LAKE WITH BETTER INCREASINGLY SUNNY
SKIES WELL INLAND. CLOUD COVER SHOULD KEEP HIGHS STRUGGLING INTO THE
LOWER 50S IN NE IL WHILE MID OR EVEN UPPER 50S ARE POSSIBLE OUT
TOWARD MENDOTA AND FAR SOUTHWESTERN CWA WHERE MORE SUN CAN BE
EXPECTED.

LOW CONFIDENCE IN THE EXTENT OF LAKE CLOUDINESS TONIGHT...WHICH
WOULD PLAY A ROLE IN LOW TEMPS. MORE CLOUDS NEAR THE LAKE WOULD
RESULT IN LOWS A COUPLE DEGREES WARMER THAN CURRENTLY FORECAST AND
VICE VERSA IF MAINLY CLEAR. SUNNY SKIES ARE EXPECTED WEDNESDAY AS
TRANSIENT UPPER RIDGE BUILDS INTO THE AREA BETWEEN DEPARTING DEEP
UPPER TROUGH/LOW AND THE NEXT STRONG NORTHERN STREAM SHORTWAVE
SLATED TO ARRIVE IN OUR AREA LATER THURSDAY. NOT LOOKING FOR MUCH OF
A CHANCE OF SUBSTANTIAL WARMING WEDNESDAY WITH A STILL SOMEWHAT COOL
EASTERLY LOW LEVEL FLOW AND ONLY WEAK LOW LEVEL WARM AIR ADVECTION.

BY THURSDAY SHOWER CHANCES WILL BE ON THE INCREASE AS SHARP NORTHERN
STREAM TROUGH TRACKS SOUTHEAST INTO THE WESTERN LAKES. LACK OF
RETURN FLOW SHOULD RESULT IN LIMITED MOISTURE FOR THE SYSTEM...BUT
FAIRLY STRONG FORCING SHOULD ALLOW FOR A PERIOD OF SHOWERS ACROSS
THE CWA THURSDAY AFTERNOON OR EVENING. NOT MUCH COOLING BEHIND THIS
SYSTEM FRIDAY...THEN A FAST MOVING WEAK CANADIAN COLD FRONT SHOULD
BRING A BRIEF COOL DOWN SATURDAY BEFORE MORE SUBSTANTIAL WARM AIR
ADVECTION SUNDAY INTO MONDAY LIKELY SENDS TEMPERATURES NEAR IF NOT
INTO THE 70S ACROSS THE CWA. MEDIUM RANGE MODELS DO SHOW A
PROGRESSIVE LONG WAVE TROUGH MOVING ACROSS THE CONUS BY EARLY NEXT
WEEK WITH COLD FRONT LIKELY TO ARRIVE LATER MONDAY OR TUESDAY
BRINGING AN END TO OUR BRIEF BUT POTENTIALLY IMPRESSIVE WARM UP.

IZZI

&&

.AVIATION...

//ORD AND MDW CONCERNS...UPDATED 14Z...

* NORTH/NORTHEAST WINDS 10-14 KTS AND GUSTY MID MORNING THRU LATE
  AFTERNOON.

* SLIGHT CHANCE FOR -SHRA MID MORNING THRU MID AFTERNOON.

* PERIODIC MVFR CEILINGS LATE MORNING THROUGH EARLY AFTERNOON.

RODRIGUEZ

//DISCUSSION...UPDATED 12Z...

NO SIGNIFICANT CHANGES TO PREVIOUS FORECAST. NORTHERLY WINDS WILL
INCREASE TO 10-14KTS IN THE NEXT FEW HOURS AND TURN MORE TO THE
NORTHEAST THIS MORNING AND THIS AFTERNOON. GUSTS INTO THE 16-20KT
RANGE WILL ALSO DEVELOP MID MORNING AND CONTINUE INTO THE
AFTERNOON. WINDS WILL QUICKLY DIMINISH BY EARLY EVENING AND TURN
MORE EAST/NORTHEAST TONIGHT.

LAKE EFFECT RAIN SHOWERS CONTINUE TO MOVE SOUTH INTO NORTHWEST
INDIANA AND WILL AFFECT GYY AT TIMES THIS MORNING. AS THE WINDS
TURN MORE NORTHEAST...THESE SHOWERS MAY MOVE FAR ENOUGH INLAND TO
REACH ORD/MDW. HOWEVER...HAVE MAINTAINED A DRY FORECAST GIVEN THE
EXPECTED SHORT DURATION AND ISOLATED COVERAGE.

4-5KFT VFR CIGS WILL LOWER TO MVFR MID/LATE MORNING...WITH MVFR
CIGS ACROSS EASTERN WI AND SPREADING SOUTH. TIMING AND DURATION
WILL LIKELY NEED TO BE ADJUSTED WITH MORNING UPDATES. CMS

//ORD AND MDW CONFIDENCE...UPDATED 14Z...

* HIGH CONFIDENCE FOR WIND SPEEDS/GUSTS/DIRECTIONS THRU THE
  PERIOD.

* MEDIUM CONFIDENCE FOR SHRA MID MORNING THRU MID AFTERNOON.

* MEDIUM CONFIDENCE FOR MVFR CEILINGS.

RODRIGUEZ

//OUTLOOK FOR ORD/MDW FOR 00Z THURSDAY-12Z TUESDAY...UPDATED 12Z...

* WEDNESDAY NIGHT...DRY/VFR.
* THURSDAY...CHANCE OF SHRA. SOUTH WINDS.
* FRIDAY AND SATURDAY...DRY/VFR. WEST/SOUTHWEST WINDS.
* SUNDAY...DRY/VFR. SOUTH WINDS.
* MONDAY...SLIGHT CHANCE OF SHRA. GUSTY SOUTHWEST WINDS.

&&

.MARINE...

258 AM...LOW PRESSURE NEAR LAKE ONTARIO WILL MOVE OFF THE MID
ATLANTIC COAST WEDNESDAY MORNING THEN DEEPEN AGAIN AS IT MOVES
NORTHEAST ALONG THE NEW ENGLAND COAST WEDNESDAY NIGHT THROUGH
THURSDAY NIGHT. HIGH PRESSURE OVER ONTARIO WILL STRENGTHEN AS IT
MOVES INTO QUEBEC TONIGHT AND WEDNESDAY...WITH A TRAILING WEAKER
RIDGE BUILDING ACROSS THE WESTERN LAKES TODAY AND CROSSING LAKE
MICHIGAN TONIGHT. NORTH WINDS ARE STILL EXPECTED TO INCREASE TO
30 KT WITH A TIGHT GRADIENT BETWEEN THE APPROACHING RIDGE AND THE
DEPARTING LOW BUT SPEEDS WILL PROBABLY DIMINISH A LITTLE FASTER
THAN PREVIOUSLY INDICATED LATE THIS AFTERNOON INTO THIS EVENING.
THE RIDGE WILL BECOME STATIONARY OVER THE EASTERN LAKES WEDNESDAY
NIGHT AND THURSDAY AS IT WEAKENS. CMS

&&

.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...SMALL CRAFT ADVISORY...NEARSHORE WATERS
     UNTIL 7 AM WEDNESDAY.

&&

$$

VISIT US AT HTTP://WEATHER.GOV/CHICAGO (ALL LOWERCASE)

FOLLOW US ON FACEBOOK...TWITTER...AND YOUTUBE AT:
WWW.FACEBOOK.COM/NWSCHICAGO
WWW.TWITTER.COM/NWSCHICAGO
WWW.YOUTUBE.COM/NWSCHICAGO






000
FXUS63 KLOT 211428
AFDLOT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
928 AM CDT TUE OCT 21 2014

.DISCUSSION...
218 AM CDT

BELOW AVERAGE TEMPERATURES THE NEXT COUPLE OF DAYS WILL GRADUALLY
GIVE WAY TO A BOUT OF INDIAN SUMMER OVER THE WEEKEND.

WATER VAPOR IMAGERY SHOWS AN AMPLIFYING UPPER TROUGH OVER THE
EASTERN CONUS THIS MORNING WITH LAST EVENING`S UPPER AIR ANALYSIS
SHOWING A POCKET OF SUB-FREEZING 850MB TEMPS ADVECTING SOUTH INTO
THE WESTERN GREAT LAKES REGION. THE CHILLY AIR MOVING OVER THE
RELATIVELY MILDER LAKE WATER IS CURRENTLY RESULTING IN A MARGINAL
LAKE EFFECT SHOWER SET-UP WITH SCATTERED LIGHT SHOWERS OR SPRINKLES
SHOWING UP OVER SOUTHERN LM INTO NW IN. LOW LEVEL FLOW WILL VEER TO
MORE NORTHEASTERLY DIRECTION TODAY AND SEND SOME OF THE LAKE EFFECT
CLOUDINESS AND POTENTIALLY SPRINKLES/LIGHT SHOWERS INTO EXTREME NE
IL THIS MORNING. RELATIVELY LOW INVERSION HEIGHTS AND SOMEWHAT WEAK
INSTABILITY MAKE THE CHANCES OF MEASURABLE PRECIP LOW AND HAVE KEPT
POPS IN THE LOWER END OF THE CHANCE CATEGORY. CLOUDINESS SHOULD BE
MOST PREVALENT TODAY NEAR THE LAKE WITH BETTER INCREASINGLY SUNNY
SKIES WELL INLAND. CLOUD COVER SHOULD KEEP HIGHS STRUGGLING INTO THE
LOWER 50S IN NE IL WHILE MID OR EVEN UPPER 50S ARE POSSIBLE OUT
TOWARD MENDOTA AND FAR SOUTHWESTERN CWA WHERE MORE SUN CAN BE
EXPECTED.

LOW CONFIDENCE IN THE EXTENT OF LAKE CLOUDINESS TONIGHT...WHICH
WOULD PLAY A ROLE IN LOW TEMPS. MORE CLOUDS NEAR THE LAKE WOULD
RESULT IN LOWS A COUPLE DEGREES WARMER THAN CURRENTLY FORECAST AND
VICE VERSA IF MAINLY CLEAR. SUNNY SKIES ARE EXPECTED WEDNESDAY AS
TRANSIENT UPPER RIDGE BUILDS INTO THE AREA BETWEEN DEPARTING DEEP
UPPER TROUGH/LOW AND THE NEXT STRONG NORTHERN STREAM SHORTWAVE
SLATED TO ARRIVE IN OUR AREA LATER THURSDAY. NOT LOOKING FOR MUCH OF
A CHANCE OF SUBSTANTIAL WARMING WEDNESDAY WITH A STILL SOMEWHAT COOL
EASTERLY LOW LEVEL FLOW AND ONLY WEAK LOW LEVEL WARM AIR ADVECTION.

BY THURSDAY SHOWER CHANCES WILL BE ON THE INCREASE AS SHARP NORTHERN
STREAM TROUGH TRACKS SOUTHEAST INTO THE WESTERN LAKES. LACK OF
RETURN FLOW SHOULD RESULT IN LIMITED MOISTURE FOR THE SYSTEM...BUT
FAIRLY STRONG FORCING SHOULD ALLOW FOR A PERIOD OF SHOWERS ACROSS
THE CWA THURSDAY AFTERNOON OR EVENING. NOT MUCH COOLING BEHIND THIS
SYSTEM FRIDAY...THEN A FAST MOVING WEAK CANADIAN COLD FRONT SHOULD
BRING A BRIEF COOL DOWN SATURDAY BEFORE MORE SUBSTANTIAL WARM AIR
ADVECTION SUNDAY INTO MONDAY LIKELY SENDS TEMPERATURES NEAR IF NOT
INTO THE 70S ACROSS THE CWA. MEDIUM RANGE MODELS DO SHOW A
PROGRESSIVE LONG WAVE TROUGH MOVING ACROSS THE CONUS BY EARLY NEXT
WEEK WITH COLD FRONT LIKELY TO ARRIVE LATER MONDAY OR TUESDAY
BRINGING AN END TO OUR BRIEF BUT POTENTIALLY IMPRESSIVE WARM UP.

IZZI

&&

.AVIATION...

//ORD AND MDW CONCERNS...UPDATED 14Z...

* NORTH/NORTHEAST WINDS 10-14 KTS AND GUSTY MID MORNING THRU LATE
  AFTERNOON.

* SLIGHT CHANCE FOR -SHRA MID MORNING THRU MID AFTERNOON.

* PERIODIC MVFR CEILINGS LATE MORNING THROUGH EARLY AFTERNOON.

RODRIGUEZ

//DISCUSSION...UPDATED 12Z...

NO SIGNIFICANT CHANGES TO PREVIOUS FORECAST. NORTHERLY WINDS WILL
INCREASE TO 10-14KTS IN THE NEXT FEW HOURS AND TURN MORE TO THE
NORTHEAST THIS MORNING AND THIS AFTERNOON. GUSTS INTO THE 16-20KT
RANGE WILL ALSO DEVELOP MID MORNING AND CONTINUE INTO THE
AFTERNOON. WINDS WILL QUICKLY DIMINISH BY EARLY EVENING AND TURN
MORE EAST/NORTHEAST TONIGHT.

LAKE EFFECT RAIN SHOWERS CONTINUE TO MOVE SOUTH INTO NORTHWEST
INDIANA AND WILL AFFECT GYY AT TIMES THIS MORNING. AS THE WINDS
TURN MORE NORTHEAST...THESE SHOWERS MAY MOVE FAR ENOUGH INLAND TO
REACH ORD/MDW. HOWEVER...HAVE MAINTAINED A DRY FORECAST GIVEN THE
EXPECTED SHORT DURATION AND ISOLATED COVERAGE.

4-5KFT VFR CIGS WILL LOWER TO MVFR MID/LATE MORNING...WITH MVFR
CIGS ACROSS EASTERN WI AND SPREADING SOUTH. TIMING AND DURATION
WILL LIKELY NEED TO BE ADJUSTED WITH MORNING UPDATES. CMS

//ORD AND MDW CONFIDENCE...UPDATED 14Z...

* HIGH CONFIDENCE FOR WIND SPEEDS/GUSTS/DIRECTIONS THRU THE
  PERIOD.

* MEDIUM CONFIDENCE FOR SHRA MID MORNING THRU MID AFTERNOON.

* MEDIUM CONFIDENCE FOR MVFR CEILINGS.

RODRIGUEZ

//OUTLOOK FOR ORD/MDW FOR 00Z THURSDAY-12Z TUESDAY...UPDATED 12Z...

* WEDNESDAY NIGHT...DRY/VFR.
* THURSDAY...CHANCE OF SHRA. SOUTH WINDS.
* FRIDAY AND SATURDAY...DRY/VFR. WEST/SOUTHWEST WINDS.
* SUNDAY...DRY/VFR. SOUTH WINDS.
* MONDAY...SLIGHT CHANCE OF SHRA. GUSTY SOUTHWEST WINDS.

&&

.MARINE...

258 AM...LOW PRESSURE NEAR LAKE ONTARIO WILL MOVE OFF THE MID
ATLANTIC COAST WEDNESDAY MORNING THEN DEEPEN AGAIN AS IT MOVES
NORTHEAST ALONG THE NEW ENGLAND COAST WEDNESDAY NIGHT THROUGH
THURSDAY NIGHT. HIGH PRESSURE OVER ONTARIO WILL STRENGTHEN AS IT
MOVES INTO QUEBEC TONIGHT AND WEDNESDAY...WITH A TRAILING WEAKER
RIDGE BUILDING ACROSS THE WESTERN LAKES TODAY AND CROSSING LAKE
MICHIGAN TONIGHT. NORTH WINDS ARE STILL EXPECTED TO INCREASE TO
30 KT WITH A TIGHT GRADIENT BETWEEN THE APPROACHING RIDGE AND THE
DEPARTING LOW BUT SPEEDS WILL PROBABLY DIMINISH A LITTLE FASTER
THAN PREVIOUSLY INDICATED LATE THIS AFTERNOON INTO THIS EVENING.
THE RIDGE WILL BECOME STATIONARY OVER THE EASTERN LAKES WEDNESDAY
NIGHT AND THURSDAY AS IT WEAKENS. CMS

&&

.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...SMALL CRAFT ADVISORY...NEARSHORE WATERS
     UNTIL 7 AM WEDNESDAY.

&&

$$

VISIT US AT HTTP://WEATHER.GOV/CHICAGO (ALL LOWERCASE)

FOLLOW US ON FACEBOOK...TWITTER...AND YOUTUBE AT:
WWW.FACEBOOK.COM/NWSCHICAGO
WWW.TWITTER.COM/NWSCHICAGO
WWW.YOUTUBE.COM/NWSCHICAGO







000
FXUS63 KLOT 211144
AFDLOT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
644 AM CDT TUE OCT 21 2014

.DISCUSSION...
218 AM CDT

BELOW AVERAGE TEMPERATURES THE NEXT COUPLE OF DAYS WILL GRADUALLY
GIVE WAY TO A BOUT OF INDIAN SUMMER OVER THE WEEKEND.

WATER VAPOR IMAGERY SHOWS AN AMPLIFYING UPPER TROUGH OVER THE
EASTERN CONUS THIS MORNING WITH LAST EVENING`S UPPER AIR ANALYSIS
SHOWING A POCKET OF SUB-FREEZING 850MB TEMPS ADVECTING SOUTH INTO
THE WESTERN GREAT LAKES REGION. THE CHILLY AIR MOVING OVER THE
RELATIVELY MILDER LAKE WATER IS CURRENTLY RESULTING IN A MARGINAL
LAKE EFFECT SHOWER SET-UP WITH SCATTERED LIGHT SHOWERS OR SPRINKLES
SHOWING UP OVER SOUTHERN LM INTO NW IN. LOW LEVEL FLOW WILL VEER TO
MORE NORTHEASTERLY DIRECTION TODAY AND SEND SOME OF THE LAKE EFFECT
CLOUDINESS AND POTENTIALLY SPRINKLES/LIGHT SHOWERS INTO EXTREME NE
IL THIS MORNING. RELATIVELY LOW INVERSION HEIGHTS AND SOMEWHAT WEAK
INSTABILITY MAKE THE CHANCES OF MEASURABLE PRECIP LOW AND HAVE KEPT
POPS IN THE LOWER END OF THE CHANCE CATEGORY. CLOUDINESS SHOULD BE
MOST PREVALENT TODAY NEAR THE LAKE WITH BETTER INCREASINGLY SUNNY
SKIES WELL INLAND. CLOUD COVER SHOULD KEEP HIGHS STRUGGLING INTO THE
LOWER 50S IN NE IL WHILE MID OR EVEN UPPER 50S ARE POSSIBLE OUT
TOWARD MENDOTA AND FAR SOUTHWESTERN CWA WHERE MORE SUN CAN BE
EXPECTED.

LOW CONFIDENCE IN THE EXTENT OF LAKE CLOUDINESS TONIGHT...WHICH
WOULD PLAY A ROLE IN LOW TEMPS. MORE CLOUDS NEAR THE LAKE WOULD
RESULT IN LOWS A COUPLE DEGREES WARMER THAN CURRENTLY FORECAST AND
VICE VERSA IF MAINLY CLEAR. SUNNY SKIES ARE EXPECTED WEDNESDAY AS
TRANSIENT UPPER RIDGE BUILDS INTO THE AREA BETWEEN DEPARTING DEEP
UPPER TROUGH/LOW AND THE NEXT STRONG NORTHERN STREAM SHORTWAVE
SLATED TO ARRIVE IN OUR AREA LATER THURSDAY. NOT LOOKING FOR MUCH OF
A CHANCE OF SUBSTANTIAL WARMING WEDNESDAY WITH A STILL SOMEWHAT COOL
EASTERLY LOW LEVEL FLOW AND ONLY WEAK LOW LEVEL WARM AIR ADVECTION.

BY THURSDAY SHOWER CHANCES WILL BE ON THE INCREASE AS SHARP NORTHERN
STREAM TROUGH TRACKS SOUTHEAST INTO THE WESTERN LAKES. LACK OF
RETURN FLOW SHOULD RESULT IN LIMITED MOISTURE FOR THE SYSTEM...BUT
FAIRLY STRONG FORCING SHOULD ALLOW FOR A PERIOD OF SHOWERS ACROSS
THE CWA THURSDAY AFTERNOON OR EVENING. NOT MUCH COOLING BEHIND THIS
SYSTEM FRIDAY...THEN A FAST MOVING WEAK CANADIAN COLD FRONT SHOULD
BRING A BRIEF COOL DOWN SATURDAY BEFORE MORE SUBSTANTIAL WARM AIR
ADVECTION SUNDAY INTO MONDAY LIKELY SENDS TEMPERATURES NEAR IF NOT
INTO THE 70S ACROSS THE CWA. MEDIUM RANGE MODELS DO SHOW A
PROGRESSIVE LONG WAVE TROUGH MOVING ACROSS THE CONUS BY EARLY NEXT
WEEK WITH COLD FRONT LIKELY TO ARRIVE LATER MONDAY OR TUESDAY
BRINGING AN END TO OUR BRIEF BUT POTENTIALLY IMPRESSIVE WARM UP.

IZZI

&&

.AVIATION...

//ORD AND MDW CONCERNS...UPDATED 12Z...

* NORTH/NORTHEAST WINDS 10-14 KTS AND GUSTY MID MORNING THRU LATE
  AFTERNOON.
* SLIGHT CHANCE FOR SHRA MID MORNING THRU MID AFTERNOON.
* MVFR CIGS MID MORNING THRU MID AFTERNOON. CMS

//DISCUSSION...UPDATED 12Z...

NO SIGNIFICANT CHANGES TO PREVIOUS FORECAST. NORTHERLY WINDS WILL
INCREASE TO 10-14KTS IN THE NEXT FEW HOURS AND TURN MORE TO THE
NORTHEAST THIS MORNING AND THIS AFTERNOON. GUSTS INTO THE 16-20KT
RANGE WILL ALSO DEVELOP MID MORNING AND CONTINUE INTO THE
AFTERNOON. WINDS WILL QUICKLY DIMINISH BY EARLY EVENING AND TURN
MORE EAST/NORTHEAST TONIGHT.

LAKE EFFECT RAIN SHOWERS CONTINUE TO MOVE SOUTH INTO NORTHWEST
INDIANA AND WILL AFFECT GYY AT TIMES THIS MORNING. AS THE WINDS
TURN MORE NORTHEAST...THESE SHOWERS MAY MOVE FAR ENOUGH INLAND TO
REACH ORD/MDW. HOWEVER...HAVE MAINTAINED A DRY FORECAST GIVEN THE
EXPECTED SHORT DURATION AND ISOLATED COVERAGE.

4-5KFT VFR CIGS WILL LOWER TO MVFR MID/LATE MORNING...WITH MVFR
CIGS ACROSS EASTERN WI AND SPREADING SOUTH. TIMING AND DURATION
WILL LIKELY NEED TO BE ADJUSTED WITH MORNING UPDATES. CMS

//ORD AND MDW CONFIDENCE...UPDATED 12Z...

* HIGH FOR WIND SPEEDS/GUSTS/DIRECTIONS THRU THE PERIOD.
* LOW FOR SHRA MID MORNING THRU MID AFTERNOON.
* MEDIUM FOR MVFR CIGS. CMS

//OUTLOOK FOR ORD/MDW FOR 00Z THURSDAY-12Z TUESDAY...UPDATED 12Z...

* WEDNESDAY NIGHT...DRY/VFR.
* THURSDAY...CHANCE OF SHRA. SOUTH WINDS.
* FRIDAY AND SATURDAY...DRY/VFR. WEST/SOUTHWEST WINDS.
* SUNDAY...DRY/VFR. SOUTH WINDS.
* MONDAY...SLIGHT CHANCE OF SHRA. GUSTY SOUTHWEST WINDS.

&&

.MARINE...

258 AM...LOW PRESSURE NEAR LAKE ONTARIO WILL MOVE OFF THE MID
ATLANTIC COAST WEDNESDAY MORNING THEN DEEPEN AGAIN AS IT MOVES
NORTHEAST ALONG THE NEW ENGLAND COAST WEDNESDAY NIGHT THROUGH
THURSDAY NIGHT. HIGH PRESSURE OVER ONTARIO WILL STRENGTHEN AS IT
MOVES INTO QUEBEC TONIGHT AND WEDNESDAY...WITH A TRAILING WEAKER
RIDGE BUILDING ACROSS THE WESTERN LAKES TODAY AND CROSSING LAKE
MICHIGAN TONIGHT. NORTH WINDS ARE STILL EXPECTED TO INCREASE TO
30 KT WITH A TIGHT GRADIENT BETWEEN THE APPROACHING RIDGE AND THE
DEPARTING LOW BUT SPEEDS WILL PROBABLY DIMINISH A LITTLE FASTER
THAN PREVIOUSLY INDICATED LATE THIS AFTERNOON INTO THIS EVENING.
THE RIDGE WILL BECOME STATIONARY OVER THE EASTERN LAKES WEDNESDAY
NIGHT AND THURSDAY AS IT WEAKENS. CMS

&&

.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...SMALL CRAFT ADVISORY...NEARSHORE WATERS UNTIL 7 AM WEDNESDAY.

&&

$$

VISIT US AT HTTP://WEATHER.GOV/CHICAGO (ALL LOWERCASE)

FOLLOW US ON FACEBOOK...TWITTER...AND YOUTUBE AT:
WWW.FACEBOOK.COM/NWSCHICAGO
WWW.TWITTER.COM/NWSCHICAGO
WWW.YOUTUBE.COM/NWSCHICAGO







000
FXUS63 KLOT 211144
AFDLOT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
644 AM CDT TUE OCT 21 2014

.DISCUSSION...
218 AM CDT

BELOW AVERAGE TEMPERATURES THE NEXT COUPLE OF DAYS WILL GRADUALLY
GIVE WAY TO A BOUT OF INDIAN SUMMER OVER THE WEEKEND.

WATER VAPOR IMAGERY SHOWS AN AMPLIFYING UPPER TROUGH OVER THE
EASTERN CONUS THIS MORNING WITH LAST EVENING`S UPPER AIR ANALYSIS
SHOWING A POCKET OF SUB-FREEZING 850MB TEMPS ADVECTING SOUTH INTO
THE WESTERN GREAT LAKES REGION. THE CHILLY AIR MOVING OVER THE
RELATIVELY MILDER LAKE WATER IS CURRENTLY RESULTING IN A MARGINAL
LAKE EFFECT SHOWER SET-UP WITH SCATTERED LIGHT SHOWERS OR SPRINKLES
SHOWING UP OVER SOUTHERN LM INTO NW IN. LOW LEVEL FLOW WILL VEER TO
MORE NORTHEASTERLY DIRECTION TODAY AND SEND SOME OF THE LAKE EFFECT
CLOUDINESS AND POTENTIALLY SPRINKLES/LIGHT SHOWERS INTO EXTREME NE
IL THIS MORNING. RELATIVELY LOW INVERSION HEIGHTS AND SOMEWHAT WEAK
INSTABILITY MAKE THE CHANCES OF MEASURABLE PRECIP LOW AND HAVE KEPT
POPS IN THE LOWER END OF THE CHANCE CATEGORY. CLOUDINESS SHOULD BE
MOST PREVALENT TODAY NEAR THE LAKE WITH BETTER INCREASINGLY SUNNY
SKIES WELL INLAND. CLOUD COVER SHOULD KEEP HIGHS STRUGGLING INTO THE
LOWER 50S IN NE IL WHILE MID OR EVEN UPPER 50S ARE POSSIBLE OUT
TOWARD MENDOTA AND FAR SOUTHWESTERN CWA WHERE MORE SUN CAN BE
EXPECTED.

LOW CONFIDENCE IN THE EXTENT OF LAKE CLOUDINESS TONIGHT...WHICH
WOULD PLAY A ROLE IN LOW TEMPS. MORE CLOUDS NEAR THE LAKE WOULD
RESULT IN LOWS A COUPLE DEGREES WARMER THAN CURRENTLY FORECAST AND
VICE VERSA IF MAINLY CLEAR. SUNNY SKIES ARE EXPECTED WEDNESDAY AS
TRANSIENT UPPER RIDGE BUILDS INTO THE AREA BETWEEN DEPARTING DEEP
UPPER TROUGH/LOW AND THE NEXT STRONG NORTHERN STREAM SHORTWAVE
SLATED TO ARRIVE IN OUR AREA LATER THURSDAY. NOT LOOKING FOR MUCH OF
A CHANCE OF SUBSTANTIAL WARMING WEDNESDAY WITH A STILL SOMEWHAT COOL
EASTERLY LOW LEVEL FLOW AND ONLY WEAK LOW LEVEL WARM AIR ADVECTION.

BY THURSDAY SHOWER CHANCES WILL BE ON THE INCREASE AS SHARP NORTHERN
STREAM TROUGH TRACKS SOUTHEAST INTO THE WESTERN LAKES. LACK OF
RETURN FLOW SHOULD RESULT IN LIMITED MOISTURE FOR THE SYSTEM...BUT
FAIRLY STRONG FORCING SHOULD ALLOW FOR A PERIOD OF SHOWERS ACROSS
THE CWA THURSDAY AFTERNOON OR EVENING. NOT MUCH COOLING BEHIND THIS
SYSTEM FRIDAY...THEN A FAST MOVING WEAK CANADIAN COLD FRONT SHOULD
BRING A BRIEF COOL DOWN SATURDAY BEFORE MORE SUBSTANTIAL WARM AIR
ADVECTION SUNDAY INTO MONDAY LIKELY SENDS TEMPERATURES NEAR IF NOT
INTO THE 70S ACROSS THE CWA. MEDIUM RANGE MODELS DO SHOW A
PROGRESSIVE LONG WAVE TROUGH MOVING ACROSS THE CONUS BY EARLY NEXT
WEEK WITH COLD FRONT LIKELY TO ARRIVE LATER MONDAY OR TUESDAY
BRINGING AN END TO OUR BRIEF BUT POTENTIALLY IMPRESSIVE WARM UP.

IZZI

&&

.AVIATION...

//ORD AND MDW CONCERNS...UPDATED 12Z...

* NORTH/NORTHEAST WINDS 10-14 KTS AND GUSTY MID MORNING THRU LATE
  AFTERNOON.
* SLIGHT CHANCE FOR SHRA MID MORNING THRU MID AFTERNOON.
* MVFR CIGS MID MORNING THRU MID AFTERNOON. CMS

//DISCUSSION...UPDATED 12Z...

NO SIGNIFICANT CHANGES TO PREVIOUS FORECAST. NORTHERLY WINDS WILL
INCREASE TO 10-14KTS IN THE NEXT FEW HOURS AND TURN MORE TO THE
NORTHEAST THIS MORNING AND THIS AFTERNOON. GUSTS INTO THE 16-20KT
RANGE WILL ALSO DEVELOP MID MORNING AND CONTINUE INTO THE
AFTERNOON. WINDS WILL QUICKLY DIMINISH BY EARLY EVENING AND TURN
MORE EAST/NORTHEAST TONIGHT.

LAKE EFFECT RAIN SHOWERS CONTINUE TO MOVE SOUTH INTO NORTHWEST
INDIANA AND WILL AFFECT GYY AT TIMES THIS MORNING. AS THE WINDS
TURN MORE NORTHEAST...THESE SHOWERS MAY MOVE FAR ENOUGH INLAND TO
REACH ORD/MDW. HOWEVER...HAVE MAINTAINED A DRY FORECAST GIVEN THE
EXPECTED SHORT DURATION AND ISOLATED COVERAGE.

4-5KFT VFR CIGS WILL LOWER TO MVFR MID/LATE MORNING...WITH MVFR
CIGS ACROSS EASTERN WI AND SPREADING SOUTH. TIMING AND DURATION
WILL LIKELY NEED TO BE ADJUSTED WITH MORNING UPDATES. CMS

//ORD AND MDW CONFIDENCE...UPDATED 12Z...

* HIGH FOR WIND SPEEDS/GUSTS/DIRECTIONS THRU THE PERIOD.
* LOW FOR SHRA MID MORNING THRU MID AFTERNOON.
* MEDIUM FOR MVFR CIGS. CMS

//OUTLOOK FOR ORD/MDW FOR 00Z THURSDAY-12Z TUESDAY...UPDATED 12Z...

* WEDNESDAY NIGHT...DRY/VFR.
* THURSDAY...CHANCE OF SHRA. SOUTH WINDS.
* FRIDAY AND SATURDAY...DRY/VFR. WEST/SOUTHWEST WINDS.
* SUNDAY...DRY/VFR. SOUTH WINDS.
* MONDAY...SLIGHT CHANCE OF SHRA. GUSTY SOUTHWEST WINDS.

&&

.MARINE...

258 AM...LOW PRESSURE NEAR LAKE ONTARIO WILL MOVE OFF THE MID
ATLANTIC COAST WEDNESDAY MORNING THEN DEEPEN AGAIN AS IT MOVES
NORTHEAST ALONG THE NEW ENGLAND COAST WEDNESDAY NIGHT THROUGH
THURSDAY NIGHT. HIGH PRESSURE OVER ONTARIO WILL STRENGTHEN AS IT
MOVES INTO QUEBEC TONIGHT AND WEDNESDAY...WITH A TRAILING WEAKER
RIDGE BUILDING ACROSS THE WESTERN LAKES TODAY AND CROSSING LAKE
MICHIGAN TONIGHT. NORTH WINDS ARE STILL EXPECTED TO INCREASE TO
30 KT WITH A TIGHT GRADIENT BETWEEN THE APPROACHING RIDGE AND THE
DEPARTING LOW BUT SPEEDS WILL PROBABLY DIMINISH A LITTLE FASTER
THAN PREVIOUSLY INDICATED LATE THIS AFTERNOON INTO THIS EVENING.
THE RIDGE WILL BECOME STATIONARY OVER THE EASTERN LAKES WEDNESDAY
NIGHT AND THURSDAY AS IT WEAKENS. CMS

&&

.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...SMALL CRAFT ADVISORY...NEARSHORE WATERS UNTIL 7 AM WEDNESDAY.

&&

$$

VISIT US AT HTTP://WEATHER.GOV/CHICAGO (ALL LOWERCASE)

FOLLOW US ON FACEBOOK...TWITTER...AND YOUTUBE AT:
WWW.FACEBOOK.COM/NWSCHICAGO
WWW.TWITTER.COM/NWSCHICAGO
WWW.YOUTUBE.COM/NWSCHICAGO







000
FXUS63 KLOT 211144
AFDLOT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
644 AM CDT TUE OCT 21 2014

.DISCUSSION...
218 AM CDT

BELOW AVERAGE TEMPERATURES THE NEXT COUPLE OF DAYS WILL GRADUALLY
GIVE WAY TO A BOUT OF INDIAN SUMMER OVER THE WEEKEND.

WATER VAPOR IMAGERY SHOWS AN AMPLIFYING UPPER TROUGH OVER THE
EASTERN CONUS THIS MORNING WITH LAST EVENING`S UPPER AIR ANALYSIS
SHOWING A POCKET OF SUB-FREEZING 850MB TEMPS ADVECTING SOUTH INTO
THE WESTERN GREAT LAKES REGION. THE CHILLY AIR MOVING OVER THE
RELATIVELY MILDER LAKE WATER IS CURRENTLY RESULTING IN A MARGINAL
LAKE EFFECT SHOWER SET-UP WITH SCATTERED LIGHT SHOWERS OR SPRINKLES
SHOWING UP OVER SOUTHERN LM INTO NW IN. LOW LEVEL FLOW WILL VEER TO
MORE NORTHEASTERLY DIRECTION TODAY AND SEND SOME OF THE LAKE EFFECT
CLOUDINESS AND POTENTIALLY SPRINKLES/LIGHT SHOWERS INTO EXTREME NE
IL THIS MORNING. RELATIVELY LOW INVERSION HEIGHTS AND SOMEWHAT WEAK
INSTABILITY MAKE THE CHANCES OF MEASURABLE PRECIP LOW AND HAVE KEPT
POPS IN THE LOWER END OF THE CHANCE CATEGORY. CLOUDINESS SHOULD BE
MOST PREVALENT TODAY NEAR THE LAKE WITH BETTER INCREASINGLY SUNNY
SKIES WELL INLAND. CLOUD COVER SHOULD KEEP HIGHS STRUGGLING INTO THE
LOWER 50S IN NE IL WHILE MID OR EVEN UPPER 50S ARE POSSIBLE OUT
TOWARD MENDOTA AND FAR SOUTHWESTERN CWA WHERE MORE SUN CAN BE
EXPECTED.

LOW CONFIDENCE IN THE EXTENT OF LAKE CLOUDINESS TONIGHT...WHICH
WOULD PLAY A ROLE IN LOW TEMPS. MORE CLOUDS NEAR THE LAKE WOULD
RESULT IN LOWS A COUPLE DEGREES WARMER THAN CURRENTLY FORECAST AND
VICE VERSA IF MAINLY CLEAR. SUNNY SKIES ARE EXPECTED WEDNESDAY AS
TRANSIENT UPPER RIDGE BUILDS INTO THE AREA BETWEEN DEPARTING DEEP
UPPER TROUGH/LOW AND THE NEXT STRONG NORTHERN STREAM SHORTWAVE
SLATED TO ARRIVE IN OUR AREA LATER THURSDAY. NOT LOOKING FOR MUCH OF
A CHANCE OF SUBSTANTIAL WARMING WEDNESDAY WITH A STILL SOMEWHAT COOL
EASTERLY LOW LEVEL FLOW AND ONLY WEAK LOW LEVEL WARM AIR ADVECTION.

BY THURSDAY SHOWER CHANCES WILL BE ON THE INCREASE AS SHARP NORTHERN
STREAM TROUGH TRACKS SOUTHEAST INTO THE WESTERN LAKES. LACK OF
RETURN FLOW SHOULD RESULT IN LIMITED MOISTURE FOR THE SYSTEM...BUT
FAIRLY STRONG FORCING SHOULD ALLOW FOR A PERIOD OF SHOWERS ACROSS
THE CWA THURSDAY AFTERNOON OR EVENING. NOT MUCH COOLING BEHIND THIS
SYSTEM FRIDAY...THEN A FAST MOVING WEAK CANADIAN COLD FRONT SHOULD
BRING A BRIEF COOL DOWN SATURDAY BEFORE MORE SUBSTANTIAL WARM AIR
ADVECTION SUNDAY INTO MONDAY LIKELY SENDS TEMPERATURES NEAR IF NOT
INTO THE 70S ACROSS THE CWA. MEDIUM RANGE MODELS DO SHOW A
PROGRESSIVE LONG WAVE TROUGH MOVING ACROSS THE CONUS BY EARLY NEXT
WEEK WITH COLD FRONT LIKELY TO ARRIVE LATER MONDAY OR TUESDAY
BRINGING AN END TO OUR BRIEF BUT POTENTIALLY IMPRESSIVE WARM UP.

IZZI

&&

.AVIATION...

//ORD AND MDW CONCERNS...UPDATED 12Z...

* NORTH/NORTHEAST WINDS 10-14 KTS AND GUSTY MID MORNING THRU LATE
  AFTERNOON.
* SLIGHT CHANCE FOR SHRA MID MORNING THRU MID AFTERNOON.
* MVFR CIGS MID MORNING THRU MID AFTERNOON. CMS

//DISCUSSION...UPDATED 12Z...

NO SIGNIFICANT CHANGES TO PREVIOUS FORECAST. NORTHERLY WINDS WILL
INCREASE TO 10-14KTS IN THE NEXT FEW HOURS AND TURN MORE TO THE
NORTHEAST THIS MORNING AND THIS AFTERNOON. GUSTS INTO THE 16-20KT
RANGE WILL ALSO DEVELOP MID MORNING AND CONTINUE INTO THE
AFTERNOON. WINDS WILL QUICKLY DIMINISH BY EARLY EVENING AND TURN
MORE EAST/NORTHEAST TONIGHT.

LAKE EFFECT RAIN SHOWERS CONTINUE TO MOVE SOUTH INTO NORTHWEST
INDIANA AND WILL AFFECT GYY AT TIMES THIS MORNING. AS THE WINDS
TURN MORE NORTHEAST...THESE SHOWERS MAY MOVE FAR ENOUGH INLAND TO
REACH ORD/MDW. HOWEVER...HAVE MAINTAINED A DRY FORECAST GIVEN THE
EXPECTED SHORT DURATION AND ISOLATED COVERAGE.

4-5KFT VFR CIGS WILL LOWER TO MVFR MID/LATE MORNING...WITH MVFR
CIGS ACROSS EASTERN WI AND SPREADING SOUTH. TIMING AND DURATION
WILL LIKELY NEED TO BE ADJUSTED WITH MORNING UPDATES. CMS

//ORD AND MDW CONFIDENCE...UPDATED 12Z...

* HIGH FOR WIND SPEEDS/GUSTS/DIRECTIONS THRU THE PERIOD.
* LOW FOR SHRA MID MORNING THRU MID AFTERNOON.
* MEDIUM FOR MVFR CIGS. CMS

//OUTLOOK FOR ORD/MDW FOR 00Z THURSDAY-12Z TUESDAY...UPDATED 12Z...

* WEDNESDAY NIGHT...DRY/VFR.
* THURSDAY...CHANCE OF SHRA. SOUTH WINDS.
* FRIDAY AND SATURDAY...DRY/VFR. WEST/SOUTHWEST WINDS.
* SUNDAY...DRY/VFR. SOUTH WINDS.
* MONDAY...SLIGHT CHANCE OF SHRA. GUSTY SOUTHWEST WINDS.

&&

.MARINE...

258 AM...LOW PRESSURE NEAR LAKE ONTARIO WILL MOVE OFF THE MID
ATLANTIC COAST WEDNESDAY MORNING THEN DEEPEN AGAIN AS IT MOVES
NORTHEAST ALONG THE NEW ENGLAND COAST WEDNESDAY NIGHT THROUGH
THURSDAY NIGHT. HIGH PRESSURE OVER ONTARIO WILL STRENGTHEN AS IT
MOVES INTO QUEBEC TONIGHT AND WEDNESDAY...WITH A TRAILING WEAKER
RIDGE BUILDING ACROSS THE WESTERN LAKES TODAY AND CROSSING LAKE
MICHIGAN TONIGHT. NORTH WINDS ARE STILL EXPECTED TO INCREASE TO
30 KT WITH A TIGHT GRADIENT BETWEEN THE APPROACHING RIDGE AND THE
DEPARTING LOW BUT SPEEDS WILL PROBABLY DIMINISH A LITTLE FASTER
THAN PREVIOUSLY INDICATED LATE THIS AFTERNOON INTO THIS EVENING.
THE RIDGE WILL BECOME STATIONARY OVER THE EASTERN LAKES WEDNESDAY
NIGHT AND THURSDAY AS IT WEAKENS. CMS

&&

.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...SMALL CRAFT ADVISORY...NEARSHORE WATERS UNTIL 7 AM WEDNESDAY.

&&

$$

VISIT US AT HTTP://WEATHER.GOV/CHICAGO (ALL LOWERCASE)

FOLLOW US ON FACEBOOK...TWITTER...AND YOUTUBE AT:
WWW.FACEBOOK.COM/NWSCHICAGO
WWW.TWITTER.COM/NWSCHICAGO
WWW.YOUTUBE.COM/NWSCHICAGO






000
FXUS63 KLOT 210903
AFDLOT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
403 AM CDT TUE OCT 21 2014

.DISCUSSION...
218 AM CDT

BELOW AVERAGE TEMPERATURES THE NEXT COUPLE OF DAYS WILL GRADUALLY
GIVE WAY TO A BOUT OF INDIAN SUMMER OVER THE WEEKEND.

WATER VAPOR IMAGERY SHOWS AN AMPLIFYING UPPER TROUGH OVER THE
EASTERN CONUS THIS MORNING WITH LAST EVENING`S UPPER AIR ANALYSIS
SHOWING A POCKET OF SUB-FREEZING 850MB TEMPS ADVECTING SOUTH INTO
THE WESTERN GREAT LAKES REGION. THE CHILLY AIR MOVING OVER THE
RELATIVELY MILDER LAKE WATER IS CURRENTLY RESULTING IN A MARGINAL
LAKE EFFECT SHOWER SET-UP WITH SCATTERED LIGHT SHOWERS OR SPRINKLES
SHOWING UP OVER SOUTHERN LM INTO NW IN. LOW LEVEL FLOW WILL VEER TO
MORE NORTHEASTERLY DIRECTION TODAY AND SEND SOME OF THE LAKE EFFECT
CLOUDINESS AND POTENTIALLY SPRINKLES/LIGHT SHOWERS INTO EXTREME NE
IL THIS MORNING. RELATIVELY LOW INVERSION HEIGHTS AND SOMEWHAT WEAK
INSTABILITY MAKE THE CHANCES OF MEASURABLE PRECIP LOW AND HAVE KEPT
POPS IN THE LOWER END OF THE CHANCE CATEGORY. CLOUDINESS SHOULD BE
MOST PREVALENT TODAY NEAR THE LAKE WITH BETTER INCREASINGLY SUNNY
SKIES WELL INLAND. CLOUD COVER SHOULD KEEP HIGHS STRUGGLING INTO THE
LOWER 50S IN NE IL WHILE MID OR EVEN UPPER 50S ARE POSSIBLE OUT
TOWARD MENDOTA AND FAR SOUTHWESTERN CWA WHERE MORE SUN CAN BE
EXPECTED.

LOW CONFIDENCE IN THE EXTENT OF LAKE CLOUDINESS TONIGHT...WHICH
WOULD PLAY A ROLE IN LOW TEMPS. MORE CLOUDS NEAR THE LAKE WOULD
RESULT IN LOWS A COUPLE DEGREES WARMER THAN CURRENTLY FORECAST AND
VICE VERSA IF MAINLY CLEAR. SUNNY SKIES ARE EXPECTED WEDNESDAY AS
TRANSIENT UPPER RIDGE BUILDS INTO THE AREA BETWEEN DEPARTING DEEP
UPPER TROUGH/LOW AND THE NEXT STRONG NORTHERN STREAM SHORTWAVE
SLATED TO ARRIVE IN OUR AREA LATER THURSDAY. NOT LOOKING FOR MUCH OF
A CHANCE OF SUBSTANTIAL WARMING WEDNESDAY WITH A STILL SOMEWHAT COOL
EASTERLY LOW LEVEL FLOW AND ONLY WEAK LOW LEVEL WARM AIR ADVECTION.

BY THURSDAY SHOWER CHANCES WILL BE ON THE INCREASE AS SHARP NORTHERN
STREAM TROUGH TRACKS SOUTHEAST INTO THE WESTERN LAKES. LACK OF
RETURN FLOW SHOULD RESULT IN LIMITED MOISTURE FOR THE SYSTEM...BUT
FAIRLY STRONG FORCING SHOULD ALLOW FOR A PERIOD OF SHOWERS ACROSS
THE CWA THURSDAY AFTERNOON OR EVENING. NOT MUCH COOLING BEHIND THIS
SYSTEM FRIDAY...THEN A FAST MOVING WEAK CANADIAN COLD FRONT SHOULD
BRING A BRIEF COOL DOWN SATURDAY BEFORE MORE SUBSTANTIAL WARM AIR
ADVECTION SUNDAY INTO MONDAY LIKELY SENDS TEMPERATURES NEAR IF NOT
INTO THE 70S ACROSS THE CWA. MEDIUM RANGE MODELS DO SHOW A
PROGRESSIVE LONG WAVE TROUGH MOVING ACROSS THE CONUS BY EARLY NEXT
WEEK WITH COLD FRONT LIKELY TO ARRIVE LATER MONDAY OR TUESDAY
BRINGING AN END TO OUR BRIEF BUT POTENTIALLY IMPRESSIVE WARM UP.

IZZI

&&

.AVIATION...

//ORD AND MDW CONCERNS...UPDATED 09Z...

* NORTH/NORTHEAST WINDS 10-14 KTS AND GUSTY MID MORNING THRU LATE
  AFTERNOON.
* SLIGHT CHANCE FOR SHRA MID MORNING THRU MID AFTERNOON.
* POSSIBLE MVFR CIGS MID MORNING THRU MID AFTERNOON. CMS

//DISCUSSION...UPDATED 06Z...

A RIDGE OF HIGH PRESSURE WILL BUILD ACROSS THE WESTERN LAKES AND
NORTHERN IL LATE THIS AFTERNOON INTO TONIGHT. NORTHERLY WINDS
AROUND/JUST UNDER 10KTS BEFORE SUNRISE WILL TURN MORE TO THE
NORTHEAST MID/LATE MORNING AND INCREASE IN SPEED TO 10-14KTS WITH
HIGHER GUSTS IN THE UPPER TEEN RANGE LIKELY. SPEEDS/GUSTS SHOULD
QUICKLY DIMINISH BY EARLY EVENING AS THE HIGH CONTINUES BUILDING
SOUTHEAST.

COLDER AIR SPREADING SOUTH WILL AID LAKE EFFECT RAIN SHOWER
DEVELOPMENT EARLY THIS MORNING WHICH WILL AFFECT NORTHWEST INDIANA
AND GYY...BUT AS WINDS TURN NORTHEAST...MAY MOVE WEST TOWARD ORD
AND MDW. CONFIDENCE REGARDING HOW WIDESPREAD THE SHOWERS BECOME IS
FAIRLY LOW...AND THUS JUST NOT CONFIDENT ENOUGH ON COVERAGE TO
INCLUDE AT ORD OR MDW. TRENDS WILL NEED TO BE MONITORED THRU THE
MORNING.

VFR CIGS 4-5KFT EXTEND WELL NORTH INTO WI WITH MVFR OVER THE UPPER
PENINSULA AND FAR NORTHEAST WI. AS THE COLDER AIR ARRIVES...IT
WILL LIKELY PUSH CIGS INTO HIGH MVFR...BUT CONFIDENCE ALSO REMAINS
LOW FOR DURATION OF MVFR CIGS. CMS

//ORD AND MDW CONFIDENCE...UPDATED 09Z...

* HIGH FOR WIND SPEEDS/GUSTS/DIRECTIONS THRU THE PERIOD.
* LOW FOR SHRA MID MORNING THRU MID AFTERNOON.
* MEDIUM FOR MVFR CIGS...LOW FOR TIMING/DURATION. CMS

//OUTLOOK FOR ORD/MDW FOR 12Z WEDNESDAY-12Z MONDAY...UPDATED 00Z...

* WEDNESDAY...DRY/VFR. EAST/NORTHEAST WINDS.
* THURSDAY...DRY/VFR. SOUTH WINDS.
* FRIDAY...DRY/VFR. SOUTHWEST WINDS.
* SATURDAY...DRY/VFR. WEST WINDS.
* SUNDAY...DRY/VFR. SOUTH WINDS.

MDB

&&

.MARINE...

258 AM...LOW PRESSURE NEAR LAKE ONTARIO WILL MOVE OFF THE MID
ATLANTIC COAST WEDNESDAY MORNING THEN DEEPEN AGAIN AS IT MOVES
NORTHEAST ALONG THE NEW ENGLAND COAST WEDNESDAY NIGHT THROUGH
THURSDAY NIGHT. HIGH PRESSURE OVER ONTARIO WILL STRENGTHEN AS IT
MOVES INTO QUEBEC TONIGHT AND WEDNESDAY...WITH A TRAILING WEAKER
RIDGE BUILDING ACROSS THE WESTERN LAKES TODAY AND CROSSING LAKE
MICHIGAN TONIGHT. NORTH WINDS ARE STILL EXPECTED TO INCREASE TO
30 KT WITH A TIGHT GRADIENT BETWEEN THE APPROACHING RIDGE AND THE
DEPARTING LOW BUT SPEEDS WILL PROBABLY DIMINISH A LITTLE FASTER
THAN PREVIOUSLY INDICATED LATE THIS AFTERNOON INTO THIS EVENING.
THE RIDGE WILL BECOME STATIONARY OVER THE EASTERN LAKES WEDNESDAY
NIGHT AND THURSDAY AS IT WEAKENS. CMS

&&

.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...SMALL CRAFT ADVISORY...NEARSHORE WATERS UNTIL 7 AM WEDNESDAY.

&&

$$

VISIT US AT HTTP://WEATHER.GOV/CHICAGO (ALL LOWERCASE)

FOLLOW US ON FACEBOOK...TWITTER...AND YOUTUBE AT:
WWW.FACEBOOK.COM/NWSCHICAGO
WWW.TWITTER.COM/NWSCHICAGO
WWW.YOUTUBE.COM/NWSCHICAGO






000
FXUS63 KLOT 210758
AFDLOT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
258 AM CDT TUE OCT 21 2014

.DISCUSSION...
218 AM CDT

BELOW AVERAGE TEMPERATURES THE NEXT COUPLE OF DAYS WILL GRADUALLY
GIVE WAY TO A BOUT OF INDIAN SUMMER OVER THE WEEKEND.

WATER VAPOR IMAGERY SHOWS AN AMPLIFYING UPPER TROUGH OVER THE
EASTERN CONUS THIS MORNING WITH LAST EVENING`S UPPER AIR ANALYSIS
SHOWING A POCKET OF SUB-FREEZING 850MB TEMPS ADVECTING SOUTH INTO
THE WESTERN GREAT LAKES REGION. THE CHILLY AIR MOVING OVER THE
RELATIVELY MILDER LAKE WATER IS CURRENTLY RESULTING IN A MARGINAL
LAKE EFFECT SHOWER SET-UP WITH SCATTERED LIGHT SHOWERS OR SPRINKLES
SHOWING UP OVER SOUTHERN LM INTO NW IN. LOW LEVEL FLOW WILL VEER TO
MORE NORTHEASTERLY DIRECTION TODAY AND SEND SOME OF THE LAKE EFFECT
CLOUDINESS AND POTENTIALLY SPRINKLES/LIGHT SHOWERS INTO EXTREME NE
IL THIS MORNING. RELATIVELY LOW INVERSION HEIGHTS AND SOMEWHAT WEAK
INSTABILITY MAKE THE CHANCES OF MEASURABLE PRECIP LOW AND HAVE KEPT
POPS IN THE LOWER END OF THE CHANCE CATEGORY. CLOUDINESS SHOULD BE
MOST PREVALENT TODAY NEAR THE LAKE WITH BETTER INCREASINGLY SUNNY
SKIES WELL INLAND. CLOUD COVER SHOULD KEEP HIGHS STRUGGLING INTO THE
LOWER 50S IN NE IL WHILE MID OR EVEN UPPER 50S ARE POSSIBLE OUT
TOWARD MENDOTA AND FAR SOUTHWESTERN CWA WHERE MORE SUN CAN BE
EXPECTED.

LOW CONFIDENCE IN THE EXTENT OF LAKE CLOUDINESS TONIGHT...WHICH
WOULD PLAY A ROLE IN LOW TEMPS. MORE CLOUDS NEAR THE LAKE WOULD
RESULT IN LOWS A COUPLE DEGREES WARMER THAN CURRENTLY FORECAST AND
VICE VERSA IF MAINLY CLEAR. SUNNY SKIES ARE EXPECTED WEDNESDAY AS
TRANSIENT UPPER RIDGE BUILDS INTO THE AREA BETWEEN DEPARTING DEEP
UPPER TROUGH/LOW AND THE NEXT STRONG NORTHERN STREAM SHORTWAVE
SLATED TO ARRIVE IN OUR AREA LATER THURSDAY. NOT LOOKING FOR MUCH OF
A CHANCE OF SUBSTANTIAL WARMING WEDNESDAY WITH A STILL SOMEWHAT COOL
EASTERLY LOW LEVEL FLOW AND ONLY WEAK LOW LEVEL WARM AIR ADVECTION.

BY THURSDAY SHOWER CHANCES WILL BE ON THE INCREASE AS SHARP NORTHERN
STREAM TROUGH TRACKS SOUTHEAST INTO THE WESTERN LAKES. LACK OF
RETURN FLOW SHOULD RESULT IN LIMITED MOISTURE FOR THE SYSTEM...BUT
FAIRLY STRONG FORCING SHOULD ALLOW FOR A PERIOD OF SHOWERS ACROSS
THE CWA THURSDAY AFTERNOON OR EVENING. NOT MUCH COOLING BEHIND THIS
SYSTEM FRIDAY...THEN A FAST MOVING WEAK CANADIAN COLD FRONT SHOULD
BRING A BRIEF COOL DOWN SATURDAY BEFORE MORE SUBSTANTIAL WARM AIR
ADVECTION SUNDAY INTO MONDAY LIKELY SENDS TEMPERATURES NEAR IF NOT
INTO THE 70S ACROSS THE CWA. MEDIUM RANGE MODELS DO SHOW A
PROGRESSIVE LONG WAVE TROUGH MOVING ACROSS THE CONUS BY EARLY NEXT
WEEK WITH COLD FRONT LIKELY TO ARRIVE LATER MONDAY OR TUESDAY
BRINGING AN END TO OUR BRIEF BUT POTENTIALLY IMPRESSIVE WARM UP.

IZZI

&&

.AVIATION...

//ORD AND MDW CONCERNS...UPDATED 06Z...

* NORTH/NORTHEAST WINDS 10-14 KTS AND GUSTY MID MORNING THRU LATE
  AFTERNOON.
* SLIGHT CHANCE FOR SHRA MID MORNING THRU MID AFTERNOON.
* POSSIBLE MVFR CIGS MID MORNING THRU MID AFTERNOON. CMS

//DISCUSSION...UPDATED 06Z...

A RIDGE OF HIGH PRESSURE WILL BUILD ACROSS THE WESTERN LAKES AND
NORTHERN IL LATE THIS AFTERNOON INTO TONIGHT. NORTHERLY WINDS
AROUND/JUST UNDER 10KTS BEFORE SUNRISE WILL TURN MORE TO THE
NORTHEAST MID/LATE MORNING AND INCREASE IN SPEED TO 10-14KTS WITH
HIGHER GUSTS IN THE UPPER TEEN RANGE LIKELY. SPEEDS/GUSTS SHOULD
QUICKLY DIMINISH BY EARLY EVENING AS THE HIGH CONTINUES BUILDING
SOUTHEAST.

COLDER AIR SPREADING SOUTH WILL AID LAKE EFFECT RAIN SHOWER
DEVELOPMENT EARLY THIS MORNING WHICH WILL AFFECT NORTHWEST INDIANA
AND GYY...BUT AS WINDS TURN NORTHEAST...MAY MOVE WEST TOWARD ORD
AND MDW. CONFIDENCE REGARDING HOW WIDESPREAD THE SHOWERS BECOME IS
FAIRLY LOW...AND THUS JUST NOT CONFIDENT ENOUGH ON COVERAGE TO
INCLUDE AT ORD OR MDW. TRENDS WILL NEED TO BE MONITORED THRU THE
MORNING.

VFR CIGS 4-5KFT EXTEND WELL NORTH INTO WI WITH MVFR OVER THE UPPER
PENINSULA AND FAR NORTHEAST WI. AS THE COLDER AIR ARRIVES...IT
WILL LIKELY PUSH CIGS INTO HIGH MVFR...BUT CONFIDENCE ALSO REMAINS
LOW FOR DURATION OF MVFR CIGS. CMS

//ORD AND MDW CONFIDENCE...UPDATED 06Z...

* HIGH FOR WIND SPEEDS/GUSTS/DIRECTIONS THRU THE PERIOD.
* LOW FOR SHRA MID MORNING THRU MID AFTERNOON.
* MEDIUM FOR MVFR CIGS...LOW FOR TIMING/DURATION. CMS

//OUTLOOK FOR ORD/MDW FOR 12Z WEDNESDAY-12Z MONDAY...UPDATED 00Z...

* WEDNESDAY...DRY/VFR. EAST/NORTHEAST WINDS.
* THURSDAY...DRY/VFR. SOUTH WINDS.
* FRIDAY...DRY/VFR. SOUTHWEST WINDS.
* SATURDAY...DRY/VFR. WEST WINDS.
* SUNDAY...DRY/VFR. SOUTH WINDS.

MDB

&&

.MARINE...

258 AM...LOW PRESSURE NEAR LAKE ONTARIO WILL MOVE OFF THE MID
ATLANTIC COAST WEDNESDAY MORNING THEN DEEPEN AGAIN AS IT MOVES
NORTHEAST ALONG THE NEW ENGLAND COAST WEDNESDAY NIGHT THROUGH
THURSDAY NIGHT. HIGH PRESSURE OVER ONTARIO WILL STRENGTHEN AS IT
MOVES INTO QUEBEC TONIGHT AND WEDNESDAY...WITH A TRAILING WEAKER
RIDGE BUILDING ACROSS THE WESTERN LAKES TODAY AND CROSSING LAKE
MICHIGAN TONIGHT. NORTH WINDS ARE STILL EXPECTED TO INCREASE TO
30 KT WITH A TIGHT GRADIENT BETWEEN THE APPROACHING RIDGE AND THE
DEPARTING LOW BUT SPEEDS WILL PROBABLY DIMINISH A LITTLE FASTER
THAN PREVIOUSLY INDICATED LATE THIS AFTERNOON INTO THIS EVENING.
THE RIDGE WILL BECOME STATIONARY OVER THE EASTERN LAKES WEDNESDAY
NIGHT AND THURSDAY AS IT WEAKENS. CMS

&&

.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...SMALL CRAFT ADVISORY...NEARSHORE WATERS UNTIL 7 AM WEDNESDAY.

&&

$$

VISIT US AT HTTP://WEATHER.GOV/CHICAGO (ALL LOWERCASE)

FOLLOW US ON FACEBOOK...TWITTER...AND YOUTUBE AT:
WWW.FACEBOOK.COM/NWSCHICAGO
WWW.TWITTER.COM/NWSCHICAGO
WWW.YOUTUBE.COM/NWSCHICAGO







000
FXUS63 KLOT 210758
AFDLOT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
258 AM CDT TUE OCT 21 2014

.DISCUSSION...
218 AM CDT

BELOW AVERAGE TEMPERATURES THE NEXT COUPLE OF DAYS WILL GRADUALLY
GIVE WAY TO A BOUT OF INDIAN SUMMER OVER THE WEEKEND.

WATER VAPOR IMAGERY SHOWS AN AMPLIFYING UPPER TROUGH OVER THE
EASTERN CONUS THIS MORNING WITH LAST EVENING`S UPPER AIR ANALYSIS
SHOWING A POCKET OF SUB-FREEZING 850MB TEMPS ADVECTING SOUTH INTO
THE WESTERN GREAT LAKES REGION. THE CHILLY AIR MOVING OVER THE
RELATIVELY MILDER LAKE WATER IS CURRENTLY RESULTING IN A MARGINAL
LAKE EFFECT SHOWER SET-UP WITH SCATTERED LIGHT SHOWERS OR SPRINKLES
SHOWING UP OVER SOUTHERN LM INTO NW IN. LOW LEVEL FLOW WILL VEER TO
MORE NORTHEASTERLY DIRECTION TODAY AND SEND SOME OF THE LAKE EFFECT
CLOUDINESS AND POTENTIALLY SPRINKLES/LIGHT SHOWERS INTO EXTREME NE
IL THIS MORNING. RELATIVELY LOW INVERSION HEIGHTS AND SOMEWHAT WEAK
INSTABILITY MAKE THE CHANCES OF MEASURABLE PRECIP LOW AND HAVE KEPT
POPS IN THE LOWER END OF THE CHANCE CATEGORY. CLOUDINESS SHOULD BE
MOST PREVALENT TODAY NEAR THE LAKE WITH BETTER INCREASINGLY SUNNY
SKIES WELL INLAND. CLOUD COVER SHOULD KEEP HIGHS STRUGGLING INTO THE
LOWER 50S IN NE IL WHILE MID OR EVEN UPPER 50S ARE POSSIBLE OUT
TOWARD MENDOTA AND FAR SOUTHWESTERN CWA WHERE MORE SUN CAN BE
EXPECTED.

LOW CONFIDENCE IN THE EXTENT OF LAKE CLOUDINESS TONIGHT...WHICH
WOULD PLAY A ROLE IN LOW TEMPS. MORE CLOUDS NEAR THE LAKE WOULD
RESULT IN LOWS A COUPLE DEGREES WARMER THAN CURRENTLY FORECAST AND
VICE VERSA IF MAINLY CLEAR. SUNNY SKIES ARE EXPECTED WEDNESDAY AS
TRANSIENT UPPER RIDGE BUILDS INTO THE AREA BETWEEN DEPARTING DEEP
UPPER TROUGH/LOW AND THE NEXT STRONG NORTHERN STREAM SHORTWAVE
SLATED TO ARRIVE IN OUR AREA LATER THURSDAY. NOT LOOKING FOR MUCH OF
A CHANCE OF SUBSTANTIAL WARMING WEDNESDAY WITH A STILL SOMEWHAT COOL
EASTERLY LOW LEVEL FLOW AND ONLY WEAK LOW LEVEL WARM AIR ADVECTION.

BY THURSDAY SHOWER CHANCES WILL BE ON THE INCREASE AS SHARP NORTHERN
STREAM TROUGH TRACKS SOUTHEAST INTO THE WESTERN LAKES. LACK OF
RETURN FLOW SHOULD RESULT IN LIMITED MOISTURE FOR THE SYSTEM...BUT
FAIRLY STRONG FORCING SHOULD ALLOW FOR A PERIOD OF SHOWERS ACROSS
THE CWA THURSDAY AFTERNOON OR EVENING. NOT MUCH COOLING BEHIND THIS
SYSTEM FRIDAY...THEN A FAST MOVING WEAK CANADIAN COLD FRONT SHOULD
BRING A BRIEF COOL DOWN SATURDAY BEFORE MORE SUBSTANTIAL WARM AIR
ADVECTION SUNDAY INTO MONDAY LIKELY SENDS TEMPERATURES NEAR IF NOT
INTO THE 70S ACROSS THE CWA. MEDIUM RANGE MODELS DO SHOW A
PROGRESSIVE LONG WAVE TROUGH MOVING ACROSS THE CONUS BY EARLY NEXT
WEEK WITH COLD FRONT LIKELY TO ARRIVE LATER MONDAY OR TUESDAY
BRINGING AN END TO OUR BRIEF BUT POTENTIALLY IMPRESSIVE WARM UP.

IZZI

&&

.AVIATION...

//ORD AND MDW CONCERNS...UPDATED 06Z...

* NORTH/NORTHEAST WINDS 10-14 KTS AND GUSTY MID MORNING THRU LATE
  AFTERNOON.
* SLIGHT CHANCE FOR SHRA MID MORNING THRU MID AFTERNOON.
* POSSIBLE MVFR CIGS MID MORNING THRU MID AFTERNOON. CMS

//DISCUSSION...UPDATED 06Z...

A RIDGE OF HIGH PRESSURE WILL BUILD ACROSS THE WESTERN LAKES AND
NORTHERN IL LATE THIS AFTERNOON INTO TONIGHT. NORTHERLY WINDS
AROUND/JUST UNDER 10KTS BEFORE SUNRISE WILL TURN MORE TO THE
NORTHEAST MID/LATE MORNING AND INCREASE IN SPEED TO 10-14KTS WITH
HIGHER GUSTS IN THE UPPER TEEN RANGE LIKELY. SPEEDS/GUSTS SHOULD
QUICKLY DIMINISH BY EARLY EVENING AS THE HIGH CONTINUES BUILDING
SOUTHEAST.

COLDER AIR SPREADING SOUTH WILL AID LAKE EFFECT RAIN SHOWER
DEVELOPMENT EARLY THIS MORNING WHICH WILL AFFECT NORTHWEST INDIANA
AND GYY...BUT AS WINDS TURN NORTHEAST...MAY MOVE WEST TOWARD ORD
AND MDW. CONFIDENCE REGARDING HOW WIDESPREAD THE SHOWERS BECOME IS
FAIRLY LOW...AND THUS JUST NOT CONFIDENT ENOUGH ON COVERAGE TO
INCLUDE AT ORD OR MDW. TRENDS WILL NEED TO BE MONITORED THRU THE
MORNING.

VFR CIGS 4-5KFT EXTEND WELL NORTH INTO WI WITH MVFR OVER THE UPPER
PENINSULA AND FAR NORTHEAST WI. AS THE COLDER AIR ARRIVES...IT
WILL LIKELY PUSH CIGS INTO HIGH MVFR...BUT CONFIDENCE ALSO REMAINS
LOW FOR DURATION OF MVFR CIGS. CMS

//ORD AND MDW CONFIDENCE...UPDATED 06Z...

* HIGH FOR WIND SPEEDS/GUSTS/DIRECTIONS THRU THE PERIOD.
* LOW FOR SHRA MID MORNING THRU MID AFTERNOON.
* MEDIUM FOR MVFR CIGS...LOW FOR TIMING/DURATION. CMS

//OUTLOOK FOR ORD/MDW FOR 12Z WEDNESDAY-12Z MONDAY...UPDATED 00Z...

* WEDNESDAY...DRY/VFR. EAST/NORTHEAST WINDS.
* THURSDAY...DRY/VFR. SOUTH WINDS.
* FRIDAY...DRY/VFR. SOUTHWEST WINDS.
* SATURDAY...DRY/VFR. WEST WINDS.
* SUNDAY...DRY/VFR. SOUTH WINDS.

MDB

&&

.MARINE...

258 AM...LOW PRESSURE NEAR LAKE ONTARIO WILL MOVE OFF THE MID
ATLANTIC COAST WEDNESDAY MORNING THEN DEEPEN AGAIN AS IT MOVES
NORTHEAST ALONG THE NEW ENGLAND COAST WEDNESDAY NIGHT THROUGH
THURSDAY NIGHT. HIGH PRESSURE OVER ONTARIO WILL STRENGTHEN AS IT
MOVES INTO QUEBEC TONIGHT AND WEDNESDAY...WITH A TRAILING WEAKER
RIDGE BUILDING ACROSS THE WESTERN LAKES TODAY AND CROSSING LAKE
MICHIGAN TONIGHT. NORTH WINDS ARE STILL EXPECTED TO INCREASE TO
30 KT WITH A TIGHT GRADIENT BETWEEN THE APPROACHING RIDGE AND THE
DEPARTING LOW BUT SPEEDS WILL PROBABLY DIMINISH A LITTLE FASTER
THAN PREVIOUSLY INDICATED LATE THIS AFTERNOON INTO THIS EVENING.
THE RIDGE WILL BECOME STATIONARY OVER THE EASTERN LAKES WEDNESDAY
NIGHT AND THURSDAY AS IT WEAKENS. CMS

&&

.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...SMALL CRAFT ADVISORY...NEARSHORE WATERS UNTIL 7 AM WEDNESDAY.

&&

$$

VISIT US AT HTTP://WEATHER.GOV/CHICAGO (ALL LOWERCASE)

FOLLOW US ON FACEBOOK...TWITTER...AND YOUTUBE AT:
WWW.FACEBOOK.COM/NWSCHICAGO
WWW.TWITTER.COM/NWSCHICAGO
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000
FXUS63 KLOT 210718
AFDLOT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
218 AM CDT TUE OCT 21 2014

.DISCUSSION...
218 AM CDT

BELOW AVERAGE TEMPERATURES THE NEXT COUPLE OF DAYS WILL GRADUALLY
GIVE WAY TO A BOUT OF INDIAN SUMMER OVER THE WEEKEND.

WATER VAPOR IMAGERY SHOWS AN AMPLIFYING UPPER TROUGH OVER THE
EASTERN CONUS THIS MORNING WITH LAST EVENING`S UPPER AIR ANALYSIS
SHOWING A POCKET OF SUB-FREEZING 850MB TEMPS ADVECTING SOUTH INTO
THE WESTERN GREAT LAKES REGION. THE CHILLY AIR MOVING OVER THE
RELATIVELY MILDER LAKE WATER IS CURRENTLY RESULTING IN A MARGINAL
LAKE EFFECT SHOWER SET-UP WITH SCATTERED LIGHT SHOWERS OR SPRINKLES
SHOWING UP OVER SOUTHERN LM INTO NW IN. LOW LEVEL FLOW WILL VEER TO
MORE NORTHEASTERLY DIRECTION TODAY AND SEND SOME OF THE LAKE EFFECT
CLOUDINESS AND POTENTIALLY SPRINKLES/LIGHT SHOWERS INTO EXTREME NE
IL THIS MORNING. RELATIVELY LOW INVERSION HEIGHTS AND SOMEWHAT WEAK
INSTABILITY MAKE THE CHANCES OF MEASURABLE PRECIP LOW AND HAVE KEPT
POPS IN THE LOWER END OF THE CHANCE CATEGORY. CLOUDINESS SHOULD BE
MOST PREVALENT TODAY NEAR THE LAKE WITH BETTER INCREASINGLY SUNNY
SKIES WELL INLAND. CLOUD COVER SHOULD KEEP HIGHS STRUGGLING INTO THE
LOWER 50S IN NE IL WHILE MID OR EVEN UPPER 50S ARE POSSIBLE OUT
TOWARD MENDOTA AND FAR SOUTHWESTERN CWA WHERE MORE SUN CAN BE
EXPECTED.

LOW CONFIDENCE IN THE EXTENT OF LAKE CLOUDINESS TONIGHT...WHICH
WOULD PLAY A ROLE IN LOW TEMPS. MORE CLOUDS NEAR THE LAKE WOULD
RESULT IN LOWS A COUPLE DEGREES WARMER THAN CURRENTLY FORECAST AND
VICE VERSA IF MAINLY CLEAR. SUNNY SKIES ARE EXPECTED WEDNESDAY AS
TRANSIENT UPPER RIDGE BUILDS INTO THE AREA BETWEEN DEPARTING DEEP
UPPER TROUGH/LOW AND THE NEXT STRONG NORTHERN STREAM SHORTWAVE
SLATED TO ARRIVE IN OUR AREA LATER THURSDAY. NOT LOOKING FOR MUCH OF
A CHANCE OF SUBSTANTIAL WARMING WEDNESDAY WITH A STILL SOMEWHAT COOL
EASTERLY LOW LEVEL FLOW AND ONLY WEAK LOW LEVEL WARM AIR ADVECTION.

BY THURSDAY SHOWER CHANCES WILL BE ON THE INCREASE AS SHARP NORTHERN
STREAM TROUGH TRACKS SOUTHEAST INTO THE WESTERN LAKES. LACK OF
RETURN FLOW SHOULD RESULT IN LIMITED MOISTURE FOR THE SYSTEM...BUT
FAIRLY STRONG FORCING SHOULD ALLOW FOR A PERIOD OF SHOWERS ACROSS
THE CWA THURSDAY AFTERNOON OR EVENING. NOT MUCH COOLING BEHIND THIS
SYSTEM FRIDAY...THEN A FAST MOVING WEAK CANADIAN COLD FRONT SHOULD
BRING A BRIEF COOL DOWN SATURDAY BEFORE MORE SUBSTANTIAL WARM AIR
ADVECTION SUNDAY INTO MONDAY LIKELY SENDS TEMPERATURES NEAR IF NOT
INTO THE 70S ACROSS THE CWA. MEDIUM RANGE MODELS DO SHOW A
PROGRESSIVE LONG WAVE TROUGH MOVING ACROSS THE CONUS BY EARLY NEXT
WEEK WITH COLD FRONT LIKELY TO ARRIVE LATER MONDAY OR TUESDAY
BRINGING AN END TO OUR BRIEF BUT POTENTIALLY IMPRESSIVE WARM UP.

IZZI

&&

.AVIATION...

//ORD AND MDW CONCERNS...UPDATED 06Z...

* NORTH/NORTHEAST WINDS 10-14 KTS AND GUSTY MID MORNING THRU LATE
  AFTERNOON.
* SLIGHT CHANCE FOR SHRA MID MORNING THRU MID AFTERNOON.
* POSSIBLE MVFR CIGS MID MORNING THRU MID AFTERNOON. CMS

//DISCUSSION...UPDATED 06Z...

A RIDGE OF HIGH PRESSURE WILL BUILD ACROSS THE WESTERN LAKES AND
NORTHERN IL LATE THIS AFTERNOON INTO TONIGHT. NORTHERLY WINDS
AROUND/JUST UNDER 10KTS BEFORE SUNRISE WILL TURN MORE TO THE
NORTHEAST MID/LATE MORNING AND INCREASE IN SPEED TO 10-14KTS WITH
HIGHER GUSTS IN THE UPPER TEEN RANGE LIKELY. SPEEDS/GUSTS SHOULD
QUICKLY DIMINISH BY EARLY EVENING AS THE HIGH CONTINUES BUILDING
SOUTHEAST.

COLDER AIR SPREADING SOUTH WILL AID LAKE EFFECT RAIN SHOWER
DEVELOPMENT EARLY THIS MORNING WHICH WILL AFFECT NORTHWEST INDIANA
AND GYY...BUT AS WINDS TURN NORTHEAST...MAY MOVE WEST TOWARD ORD
AND MDW. CONFIDENCE REGARDING HOW WIDESPREAD THE SHOWERS BECOME IS
FAIRLY LOW...AND THUS JUST NOT CONFIDENT ENOUGH ON COVERAGE TO
INCLUDE AT ORD OR MDW. TRENDS WILL NEED TO BE MONITORED THRU THE
MORNING.

VFR CIGS 4-5KFT EXTEND WELL NORTH INTO WI WITH MVFR OVER THE UPPER
PENINSULA AND FAR NORTHEAST WI. AS THE COLDER AIR ARRIVES...IT
WILL LIKELY PUSH CIGS INTO HIGH MVFR...BUT CONFIDENCE ALSO REMAINS
LOW FOR DURATION OF MVFR CIGS. CMS

//ORD AND MDW CONFIDENCE...UPDATED 06Z...

* HIGH FOR WIND SPEEDS/GUSTS/DIRECTIONS THRU THE PERIOD.
* LOW FOR SHRA MID MORNING THRU MID AFTERNOON.
* MEDIUM FOR MVFR CIGS...LOW FOR TIMING/DURATION. CMS

//OUTLOOK FOR ORD/MDW FOR 12Z WEDNESDAY-12Z MONDAY...UPDATED 00Z...

* WEDNESDAY...DRY/VFR. EAST/NORTHEAST WINDS.
* THURSDAY...DRY/VFR. SOUTH WINDS.
* FRIDAY...DRY/VFR. SOUTHWEST WINDS.
* SATURDAY...DRY/VFR. WEST WINDS.
* SUNDAY...DRY/VFR. SOUTH WINDS.

MDB

&&

.MARINE...

250 PM...LOW PRESSURE CONTINUES TO INFLUENCE THE REGION CENTERED
OVER NORTHERN LAKE HURON LATE THIS AFTERNOON AND IS EXPECTED TO
SLOWLY DRIFT EAST OVERNIGHT. THIS LOW WILL THEN REACH LAKE ONTARIO
AROUND DAYBREAK TUE. THE BACK EDGE OF THIS LOW CONTINUES TO
FEATURE A TIGHTENING PRESSURE GRADIENT...WHICH HAS PRODUCED GUSTY
WINDS JUST BEGINNING TO SLIDE OVER THE NORTHERN PORTIONS OF THE
LAKE. THESE GUSTY WINDS WILL EVENTUALLY SLIDE SOUTH THIS
EVENING...AND EXPECT NORTH GUSTS UP TO 30 KTS. HIGH PRESSURE OVER
ONTARIO WILL BEGIN TO BUILD SOUTH OVERNIGHT...THEN STRETCH FROM
ONTARIO SOUTH TO THE WESTERN GULF OF MEXICO BY TUE NGT. THIS WILL
BRING MUCH LIGHTER WINDS TO THE LAKE BY WED.

BEACHLER

&&

.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...SMALL CRAFT ADVISORY...NEARSHORE WATERS
     UNTIL 7 AM WEDNESDAY.

&&

$$

VISIT US AT HTTP://WEATHER.GOV/CHICAGO (ALL LOWERCASE)

FOLLOW US ON FACEBOOK...TWITTER...AND YOUTUBE AT:
WWW.FACEBOOK.COM/NWSCHICAGO
WWW.TWITTER.COM/NWSCHICAGO
WWW.YOUTUBE.COM/NWSCHICAGO






000
FXUS63 KLOT 210718
AFDLOT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
218 AM CDT TUE OCT 21 2014

.DISCUSSION...
218 AM CDT

BELOW AVERAGE TEMPERATURES THE NEXT COUPLE OF DAYS WILL GRADUALLY
GIVE WAY TO A BOUT OF INDIAN SUMMER OVER THE WEEKEND.

WATER VAPOR IMAGERY SHOWS AN AMPLIFYING UPPER TROUGH OVER THE
EASTERN CONUS THIS MORNING WITH LAST EVENING`S UPPER AIR ANALYSIS
SHOWING A POCKET OF SUB-FREEZING 850MB TEMPS ADVECTING SOUTH INTO
THE WESTERN GREAT LAKES REGION. THE CHILLY AIR MOVING OVER THE
RELATIVELY MILDER LAKE WATER IS CURRENTLY RESULTING IN A MARGINAL
LAKE EFFECT SHOWER SET-UP WITH SCATTERED LIGHT SHOWERS OR SPRINKLES
SHOWING UP OVER SOUTHERN LM INTO NW IN. LOW LEVEL FLOW WILL VEER TO
MORE NORTHEASTERLY DIRECTION TODAY AND SEND SOME OF THE LAKE EFFECT
CLOUDINESS AND POTENTIALLY SPRINKLES/LIGHT SHOWERS INTO EXTREME NE
IL THIS MORNING. RELATIVELY LOW INVERSION HEIGHTS AND SOMEWHAT WEAK
INSTABILITY MAKE THE CHANCES OF MEASURABLE PRECIP LOW AND HAVE KEPT
POPS IN THE LOWER END OF THE CHANCE CATEGORY. CLOUDINESS SHOULD BE
MOST PREVALENT TODAY NEAR THE LAKE WITH BETTER INCREASINGLY SUNNY
SKIES WELL INLAND. CLOUD COVER SHOULD KEEP HIGHS STRUGGLING INTO THE
LOWER 50S IN NE IL WHILE MID OR EVEN UPPER 50S ARE POSSIBLE OUT
TOWARD MENDOTA AND FAR SOUTHWESTERN CWA WHERE MORE SUN CAN BE
EXPECTED.

LOW CONFIDENCE IN THE EXTENT OF LAKE CLOUDINESS TONIGHT...WHICH
WOULD PLAY A ROLE IN LOW TEMPS. MORE CLOUDS NEAR THE LAKE WOULD
RESULT IN LOWS A COUPLE DEGREES WARMER THAN CURRENTLY FORECAST AND
VICE VERSA IF MAINLY CLEAR. SUNNY SKIES ARE EXPECTED WEDNESDAY AS
TRANSIENT UPPER RIDGE BUILDS INTO THE AREA BETWEEN DEPARTING DEEP
UPPER TROUGH/LOW AND THE NEXT STRONG NORTHERN STREAM SHORTWAVE
SLATED TO ARRIVE IN OUR AREA LATER THURSDAY. NOT LOOKING FOR MUCH OF
A CHANCE OF SUBSTANTIAL WARMING WEDNESDAY WITH A STILL SOMEWHAT COOL
EASTERLY LOW LEVEL FLOW AND ONLY WEAK LOW LEVEL WARM AIR ADVECTION.

BY THURSDAY SHOWER CHANCES WILL BE ON THE INCREASE AS SHARP NORTHERN
STREAM TROUGH TRACKS SOUTHEAST INTO THE WESTERN LAKES. LACK OF
RETURN FLOW SHOULD RESULT IN LIMITED MOISTURE FOR THE SYSTEM...BUT
FAIRLY STRONG FORCING SHOULD ALLOW FOR A PERIOD OF SHOWERS ACROSS
THE CWA THURSDAY AFTERNOON OR EVENING. NOT MUCH COOLING BEHIND THIS
SYSTEM FRIDAY...THEN A FAST MOVING WEAK CANADIAN COLD FRONT SHOULD
BRING A BRIEF COOL DOWN SATURDAY BEFORE MORE SUBSTANTIAL WARM AIR
ADVECTION SUNDAY INTO MONDAY LIKELY SENDS TEMPERATURES NEAR IF NOT
INTO THE 70S ACROSS THE CWA. MEDIUM RANGE MODELS DO SHOW A
PROGRESSIVE LONG WAVE TROUGH MOVING ACROSS THE CONUS BY EARLY NEXT
WEEK WITH COLD FRONT LIKELY TO ARRIVE LATER MONDAY OR TUESDAY
BRINGING AN END TO OUR BRIEF BUT POTENTIALLY IMPRESSIVE WARM UP.

IZZI

&&

.AVIATION...

//ORD AND MDW CONCERNS...UPDATED 06Z...

* NORTH/NORTHEAST WINDS 10-14 KTS AND GUSTY MID MORNING THRU LATE
  AFTERNOON.
* SLIGHT CHANCE FOR SHRA MID MORNING THRU MID AFTERNOON.
* POSSIBLE MVFR CIGS MID MORNING THRU MID AFTERNOON. CMS

//DISCUSSION...UPDATED 06Z...

A RIDGE OF HIGH PRESSURE WILL BUILD ACROSS THE WESTERN LAKES AND
NORTHERN IL LATE THIS AFTERNOON INTO TONIGHT. NORTHERLY WINDS
AROUND/JUST UNDER 10KTS BEFORE SUNRISE WILL TURN MORE TO THE
NORTHEAST MID/LATE MORNING AND INCREASE IN SPEED TO 10-14KTS WITH
HIGHER GUSTS IN THE UPPER TEEN RANGE LIKELY. SPEEDS/GUSTS SHOULD
QUICKLY DIMINISH BY EARLY EVENING AS THE HIGH CONTINUES BUILDING
SOUTHEAST.

COLDER AIR SPREADING SOUTH WILL AID LAKE EFFECT RAIN SHOWER
DEVELOPMENT EARLY THIS MORNING WHICH WILL AFFECT NORTHWEST INDIANA
AND GYY...BUT AS WINDS TURN NORTHEAST...MAY MOVE WEST TOWARD ORD
AND MDW. CONFIDENCE REGARDING HOW WIDESPREAD THE SHOWERS BECOME IS
FAIRLY LOW...AND THUS JUST NOT CONFIDENT ENOUGH ON COVERAGE TO
INCLUDE AT ORD OR MDW. TRENDS WILL NEED TO BE MONITORED THRU THE
MORNING.

VFR CIGS 4-5KFT EXTEND WELL NORTH INTO WI WITH MVFR OVER THE UPPER
PENINSULA AND FAR NORTHEAST WI. AS THE COLDER AIR ARRIVES...IT
WILL LIKELY PUSH CIGS INTO HIGH MVFR...BUT CONFIDENCE ALSO REMAINS
LOW FOR DURATION OF MVFR CIGS. CMS

//ORD AND MDW CONFIDENCE...UPDATED 06Z...

* HIGH FOR WIND SPEEDS/GUSTS/DIRECTIONS THRU THE PERIOD.
* LOW FOR SHRA MID MORNING THRU MID AFTERNOON.
* MEDIUM FOR MVFR CIGS...LOW FOR TIMING/DURATION. CMS

//OUTLOOK FOR ORD/MDW FOR 12Z WEDNESDAY-12Z MONDAY...UPDATED 00Z...

* WEDNESDAY...DRY/VFR. EAST/NORTHEAST WINDS.
* THURSDAY...DRY/VFR. SOUTH WINDS.
* FRIDAY...DRY/VFR. SOUTHWEST WINDS.
* SATURDAY...DRY/VFR. WEST WINDS.
* SUNDAY...DRY/VFR. SOUTH WINDS.

MDB

&&

.MARINE...

250 PM...LOW PRESSURE CONTINUES TO INFLUENCE THE REGION CENTERED
OVER NORTHERN LAKE HURON LATE THIS AFTERNOON AND IS EXPECTED TO
SLOWLY DRIFT EAST OVERNIGHT. THIS LOW WILL THEN REACH LAKE ONTARIO
AROUND DAYBREAK TUE. THE BACK EDGE OF THIS LOW CONTINUES TO
FEATURE A TIGHTENING PRESSURE GRADIENT...WHICH HAS PRODUCED GUSTY
WINDS JUST BEGINNING TO SLIDE OVER THE NORTHERN PORTIONS OF THE
LAKE. THESE GUSTY WINDS WILL EVENTUALLY SLIDE SOUTH THIS
EVENING...AND EXPECT NORTH GUSTS UP TO 30 KTS. HIGH PRESSURE OVER
ONTARIO WILL BEGIN TO BUILD SOUTH OVERNIGHT...THEN STRETCH FROM
ONTARIO SOUTH TO THE WESTERN GULF OF MEXICO BY TUE NGT. THIS WILL
BRING MUCH LIGHTER WINDS TO THE LAKE BY WED.

BEACHLER

&&

.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...SMALL CRAFT ADVISORY...NEARSHORE WATERS
     UNTIL 7 AM WEDNESDAY.

&&

$$

VISIT US AT HTTP://WEATHER.GOV/CHICAGO (ALL LOWERCASE)

FOLLOW US ON FACEBOOK...TWITTER...AND YOUTUBE AT:
WWW.FACEBOOK.COM/NWSCHICAGO
WWW.TWITTER.COM/NWSCHICAGO
WWW.YOUTUBE.COM/NWSCHICAGO







000
FXUS63 KLOT 210529
AFDLOT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
1229 AM CDT TUE OCT 21 2014

.DISCUSSION...
249 PM CDT

TONIGHT...
UPPER LEVEL WAVE CONTINUES TO ROTATE OVER NORTHEAST ONTARIO...WITH A
A COUPLE WEAK LOBES OF VORTICITY ROTATING AROUND THE BACK EDGE OF
THIS SYSTEM...PUSHING SOUTH INTO THE NORTHERN GREAT LAKES. VISIBLE
IMAGERY SHOWS CONSIDERABLE CLOUD COVER ACROSS MICHIGAN...STRETCHING
WEST ACROSS THE LAKE AND BEGINNING TO SLIDE INTO FAR NORTHEAST IL.
GUIDANCE SUGGESTS A FEW LIGHT SHOWERS WILL ACCOMPANY THIS WAVE AS IT
PUSHES SOUTHEAST ACROSS WISCONSIN AND PERHAPS INTO FAR NORTHEAST IL
LATE THIS EVE...BEFORE SHIFTING EAST INTO FAR NORTHWEST IN BY
DAYBREAK TUE. OTHERWISE EXPECT CLOUDS TO THICKEN THIS EVE ACROSS THE
CWFA...PERHAPS LESS CLOUD COVER ACROSS THE FAR WEST/SOUTHWEST
PORTIONS OF THE FORECAST AREA. WITH THE CLOUD COVER TONIGHT...THIS
SHOULD KEEP TEMPS GENERALLY AROUND 40 TO THE LOW 40S TONIGHT.

TUESDAY THROUGH THURSDAY...
500MB TROUGH AXIS WILL BEGIN TO PUSH EAST...WITH A HIGH AMPLITUDE
RIDGE BEGINNING TO BUILD INTO THE REGION FROM THE CENTRAL PLAINS.
THIS WILL BRING A BROAD SFC RIDGE TO THE AREA STRETCHING FROM
CENTRAL CANADA SOUTH TO THE WESTERN GULF. GUIDANCE THEN CONTINUES TO
MAINTAIN THIS FEATURE THROUGH THUR MORNING...HOWEVER THERE IS A WEAK
WAVE SLIDING EAST ACROSS THE CENTRAL CONUS WED NGT THAT IS PROGGED
TO LIFT NORTHEAST OF THE CWFA THUR AFTN/EVE. THIS SYSTEM COULD BRING
SOME LIGHT PRECIP TO THE AREA...BUT AT THIS TIME HAVE ONLY GONE WITH
SLIGHT CHANCE OF POPS GIVEN THE MOISTURE AVAILABILITY APPEARS TO BE
MINIMAL. TEMPS WILL GENERALLY BE IN THE UPR 50S TO LOW 60S...WITH
OVERNIGHT LOWS IN THE MID 30S TO MID 40S.

FRIDAY THROUGH MONDAY...
ENSEMBLES CONTINUE TO FEATURE A TROUGH PERSISTING ALONG THE FAR
SOUTHWEST CONUS...ALLOWING RIDGING TO DOMINATE THE CENTRAL CONUS
LATE IN THE WEEK INTO THE WEEKEND. THIS WILL LIKELY CONTINUE THE DRY
PATTERN FOR THE REGION. IN ADDITION IT APPEARS TEMPS WILL BE ABLE TO
STEADILY MODERATE...PERHAPS REACHING THE UPR 60S TO ARND 70.

ENSEMBLES DO SUGGEST THAT TOWARDS THE SECOND HALF OF THE WEEKEND THE
RIDGE WILL BEGIN TO DRIFT EAST...WITH A TROUGH DIGGING INTO THE
CENTRAL CONUS AND PERHAPS BRINGING UNSETTLED WEATHER BACK INTO THE
REGION EARLY NEXT WEEK.

BEACHLER

&&

.AVIATION...

//ORD AND MDW CONCERNS...UPDATED 06Z...

* NORTH/NORTHEAST WINDS 10-14 KTS AND GUSTY MID MORNING THRU LATE
  AFTERNOON.
* SLIGHT CHANCE FOR SHRA MID MORNING THRU MID AFTERNOON.
* POSSIBLE MVFR CIGS MID MORNING THRU MID AFTERNOON. CMS

//DISCUSSION...UPDATED 06Z...

A RIDGE OF HIGH PRESSURE WILL BUILD ACROSS THE WESTERN LAKES AND
NORTHERN IL LATE THIS AFTERNOON INTO TONIGHT. NORTHERLY WINDS
AROUND/JUST UNDER 10KTS BEFORE SUNRISE WILL TURN MORE TO THE
NORTHEAST MID/LATE MORNING AND INCREASE IN SPEED TO 10-14KTS WITH
HIGHER GUSTS IN THE UPPER TEEN RANGE LIKELY. SPEEDS/GUSTS SHOULD
QUICKLY DIMINISH BY EARLY EVENING AS THE HIGH CONTINUES BUILDING
SOUTHEAST.

COLDER AIR SPREADING SOUTH WILL AID LAKE EFFECT RAIN SHOWER
DEVELOPMENT EARLY THIS MORNING WHICH WILL AFFECT NORTHWEST INDIANA
AND GYY...BUT AS WINDS TURN NORTHEAST...MAY MOVE WEST TOWARD ORD
AND MDW. CONFIDENCE REGARDING HOW WIDESPREAD THE SHOWERS BECOME IS
FAIRLY LOW...AND THUS JUST NOT CONFIDENT ENOUGH ON COVERAGE TO
INCLUDE AT ORD OR MDW. TRENDS WILL NEED TO BE MONITORED THRU THE
MORNING.

VFR CIGS 4-5KFT EXTEND WELL NORTH INTO WI WITH MVFR OVER THE UPPER
PENINSULA AND FAR NORTHEAST WI. AS THE COLDER AIR ARRIVES...IT
WILL LIKELY PUSH CIGS INTO HIGH MVFR...BUT CONFIDENCE ALSO REMAINS
LOW FOR DURATION OF MVFR CIGS. CMS

//ORD AND MDW CONFIDENCE...UPDATED 06Z...

* HIGH FOR WIND SPEEDS/GUSTS/DIRECTIONS THRU THE PERIOD.
* LOW FOR SHRA MID MORNING THRU MID AFTERNOON.
* MEDIUM FOR MVFR CIGS...LOW FOR TIMING/DURATION. CMS

//OUTLOOK FOR ORD/MDW FOR 12Z WEDNESDAY-12Z MONDAY...UPDATED 00Z...

* WEDNESDAY...DRY/VFR. EAST/NORTHEAST WINDS.
* THURSDAY...DRY/VFR. SOUTH WINDS.
* FRIDAY...DRY/VFR. SOUTHWEST WINDS.
* SATURDAY...DRY/VFR. WEST WINDS.
* SUNDAY...DRY/VFR. SOUTH WINDS.

MDB

&&

.MARINE...

250 PM...LOW PRESSURE CONTINUES TO INFLUENCE THE REGION CENTERED
OVER NORTHERN LAKE HURON LATE THIS AFTERNOON AND IS EXPECTED TO
SLOWLY DRIFT EAST OVERNIGHT. THIS LOW WILL THEN REACH LAKE ONTARIO
AROUND DAYBREAK TUE. THE BACK EDGE OF THIS LOW CONTINUES TO
FEATURE A TIGHTENING PRESSURE GRADIENT...WHICH HAS PRODUCED GUSTY
WINDS JUST BEGINNING TO SLIDE OVER THE NORTHERN PORTIONS OF THE
LAKE. THESE GUSTY WINDS WILL EVENTUALLY SLIDE SOUTH THIS
EVENING...AND EXPECT NORTH GUSTS UP TO 30 KTS. HIGH PRESSURE OVER
ONTARIO WILL BEGIN TO BUILD SOUTH OVERNIGHT...THEN STRETCH FROM
ONTARIO SOUTH TO THE WESTERN GULF OF MEXICO BY TUE NGT. THIS WILL
BRING MUCH LIGHTER WINDS TO THE LAKE BY WED.

BEACHLER

&&

.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...SMALL CRAFT ADVISORY...NEARSHORE WATERS UNTIL 7 AM WEDNESDAY.

&&

$$

VISIT US AT HTTP://WEATHER.GOV/CHICAGO (ALL LOWERCASE)

FOLLOW US ON FACEBOOK...TWITTER...AND YOUTUBE AT:
WWW.FACEBOOK.COM/NWSCHICAGO
WWW.TWITTER.COM/NWSCHICAGO
WWW.YOUTUBE.COM/NWSCHICAGO






000
FXUS63 KLOT 210529
AFDLOT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
1229 AM CDT TUE OCT 21 2014

.DISCUSSION...
249 PM CDT

TONIGHT...
UPPER LEVEL WAVE CONTINUES TO ROTATE OVER NORTHEAST ONTARIO...WITH A
A COUPLE WEAK LOBES OF VORTICITY ROTATING AROUND THE BACK EDGE OF
THIS SYSTEM...PUSHING SOUTH INTO THE NORTHERN GREAT LAKES. VISIBLE
IMAGERY SHOWS CONSIDERABLE CLOUD COVER ACROSS MICHIGAN...STRETCHING
WEST ACROSS THE LAKE AND BEGINNING TO SLIDE INTO FAR NORTHEAST IL.
GUIDANCE SUGGESTS A FEW LIGHT SHOWERS WILL ACCOMPANY THIS WAVE AS IT
PUSHES SOUTHEAST ACROSS WISCONSIN AND PERHAPS INTO FAR NORTHEAST IL
LATE THIS EVE...BEFORE SHIFTING EAST INTO FAR NORTHWEST IN BY
DAYBREAK TUE. OTHERWISE EXPECT CLOUDS TO THICKEN THIS EVE ACROSS THE
CWFA...PERHAPS LESS CLOUD COVER ACROSS THE FAR WEST/SOUTHWEST
PORTIONS OF THE FORECAST AREA. WITH THE CLOUD COVER TONIGHT...THIS
SHOULD KEEP TEMPS GENERALLY AROUND 40 TO THE LOW 40S TONIGHT.

TUESDAY THROUGH THURSDAY...
500MB TROUGH AXIS WILL BEGIN TO PUSH EAST...WITH A HIGH AMPLITUDE
RIDGE BEGINNING TO BUILD INTO THE REGION FROM THE CENTRAL PLAINS.
THIS WILL BRING A BROAD SFC RIDGE TO THE AREA STRETCHING FROM
CENTRAL CANADA SOUTH TO THE WESTERN GULF. GUIDANCE THEN CONTINUES TO
MAINTAIN THIS FEATURE THROUGH THUR MORNING...HOWEVER THERE IS A WEAK
WAVE SLIDING EAST ACROSS THE CENTRAL CONUS WED NGT THAT IS PROGGED
TO LIFT NORTHEAST OF THE CWFA THUR AFTN/EVE. THIS SYSTEM COULD BRING
SOME LIGHT PRECIP TO THE AREA...BUT AT THIS TIME HAVE ONLY GONE WITH
SLIGHT CHANCE OF POPS GIVEN THE MOISTURE AVAILABILITY APPEARS TO BE
MINIMAL. TEMPS WILL GENERALLY BE IN THE UPR 50S TO LOW 60S...WITH
OVERNIGHT LOWS IN THE MID 30S TO MID 40S.

FRIDAY THROUGH MONDAY...
ENSEMBLES CONTINUE TO FEATURE A TROUGH PERSISTING ALONG THE FAR
SOUTHWEST CONUS...ALLOWING RIDGING TO DOMINATE THE CENTRAL CONUS
LATE IN THE WEEK INTO THE WEEKEND. THIS WILL LIKELY CONTINUE THE DRY
PATTERN FOR THE REGION. IN ADDITION IT APPEARS TEMPS WILL BE ABLE TO
STEADILY MODERATE...PERHAPS REACHING THE UPR 60S TO ARND 70.

ENSEMBLES DO SUGGEST THAT TOWARDS THE SECOND HALF OF THE WEEKEND THE
RIDGE WILL BEGIN TO DRIFT EAST...WITH A TROUGH DIGGING INTO THE
CENTRAL CONUS AND PERHAPS BRINGING UNSETTLED WEATHER BACK INTO THE
REGION EARLY NEXT WEEK.

BEACHLER

&&

.AVIATION...

//ORD AND MDW CONCERNS...UPDATED 06Z...

* NORTH/NORTHEAST WINDS 10-14 KTS AND GUSTY MID MORNING THRU LATE
  AFTERNOON.
* SLIGHT CHANCE FOR SHRA MID MORNING THRU MID AFTERNOON.
* POSSIBLE MVFR CIGS MID MORNING THRU MID AFTERNOON. CMS

//DISCUSSION...UPDATED 06Z...

A RIDGE OF HIGH PRESSURE WILL BUILD ACROSS THE WESTERN LAKES AND
NORTHERN IL LATE THIS AFTERNOON INTO TONIGHT. NORTHERLY WINDS
AROUND/JUST UNDER 10KTS BEFORE SUNRISE WILL TURN MORE TO THE
NORTHEAST MID/LATE MORNING AND INCREASE IN SPEED TO 10-14KTS WITH
HIGHER GUSTS IN THE UPPER TEEN RANGE LIKELY. SPEEDS/GUSTS SHOULD
QUICKLY DIMINISH BY EARLY EVENING AS THE HIGH CONTINUES BUILDING
SOUTHEAST.

COLDER AIR SPREADING SOUTH WILL AID LAKE EFFECT RAIN SHOWER
DEVELOPMENT EARLY THIS MORNING WHICH WILL AFFECT NORTHWEST INDIANA
AND GYY...BUT AS WINDS TURN NORTHEAST...MAY MOVE WEST TOWARD ORD
AND MDW. CONFIDENCE REGARDING HOW WIDESPREAD THE SHOWERS BECOME IS
FAIRLY LOW...AND THUS JUST NOT CONFIDENT ENOUGH ON COVERAGE TO
INCLUDE AT ORD OR MDW. TRENDS WILL NEED TO BE MONITORED THRU THE
MORNING.

VFR CIGS 4-5KFT EXTEND WELL NORTH INTO WI WITH MVFR OVER THE UPPER
PENINSULA AND FAR NORTHEAST WI. AS THE COLDER AIR ARRIVES...IT
WILL LIKELY PUSH CIGS INTO HIGH MVFR...BUT CONFIDENCE ALSO REMAINS
LOW FOR DURATION OF MVFR CIGS. CMS

//ORD AND MDW CONFIDENCE...UPDATED 06Z...

* HIGH FOR WIND SPEEDS/GUSTS/DIRECTIONS THRU THE PERIOD.
* LOW FOR SHRA MID MORNING THRU MID AFTERNOON.
* MEDIUM FOR MVFR CIGS...LOW FOR TIMING/DURATION. CMS

//OUTLOOK FOR ORD/MDW FOR 12Z WEDNESDAY-12Z MONDAY...UPDATED 00Z...

* WEDNESDAY...DRY/VFR. EAST/NORTHEAST WINDS.
* THURSDAY...DRY/VFR. SOUTH WINDS.
* FRIDAY...DRY/VFR. SOUTHWEST WINDS.
* SATURDAY...DRY/VFR. WEST WINDS.
* SUNDAY...DRY/VFR. SOUTH WINDS.

MDB

&&

.MARINE...

250 PM...LOW PRESSURE CONTINUES TO INFLUENCE THE REGION CENTERED
OVER NORTHERN LAKE HURON LATE THIS AFTERNOON AND IS EXPECTED TO
SLOWLY DRIFT EAST OVERNIGHT. THIS LOW WILL THEN REACH LAKE ONTARIO
AROUND DAYBREAK TUE. THE BACK EDGE OF THIS LOW CONTINUES TO
FEATURE A TIGHTENING PRESSURE GRADIENT...WHICH HAS PRODUCED GUSTY
WINDS JUST BEGINNING TO SLIDE OVER THE NORTHERN PORTIONS OF THE
LAKE. THESE GUSTY WINDS WILL EVENTUALLY SLIDE SOUTH THIS
EVENING...AND EXPECT NORTH GUSTS UP TO 30 KTS. HIGH PRESSURE OVER
ONTARIO WILL BEGIN TO BUILD SOUTH OVERNIGHT...THEN STRETCH FROM
ONTARIO SOUTH TO THE WESTERN GULF OF MEXICO BY TUE NGT. THIS WILL
BRING MUCH LIGHTER WINDS TO THE LAKE BY WED.

BEACHLER

&&

.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...SMALL CRAFT ADVISORY...NEARSHORE WATERS UNTIL 7 AM WEDNESDAY.

&&

$$

VISIT US AT HTTP://WEATHER.GOV/CHICAGO (ALL LOWERCASE)

FOLLOW US ON FACEBOOK...TWITTER...AND YOUTUBE AT:
WWW.FACEBOOK.COM/NWSCHICAGO
WWW.TWITTER.COM/NWSCHICAGO
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000
FXUS63 KLOT 210310
AFDLOT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
1010 PM CDT MON OCT 20 2014

.DISCUSSION...
249 PM CDT

TONIGHT...
UPPER LEVEL WAVE CONTINUES TO ROTATE OVER NORTHEAST ONTARIO...WITH A
A COUPLE WEAK LOBES OF VORTICITY ROTATING AROUND THE BACK EDGE OF
THIS SYSTEM...PUSHING SOUTH INTO THE NORTHERN GREAT LAKES. VISIBLE
IMAGERY SHOWS CONSIDERABLE CLOUD COVER ACROSS MICHIGAN...STRETCHING
WEST ACROSS THE LAKE AND BEGINNING TO SLIDE INTO FAR NORTHEAST IL.
GUIDANCE SUGGESTS A FEW LIGHT SHOWERS WILL ACCOMPANY THIS WAVE AS IT
PUSHES SOUTHEAST ACROSS WISCONSIN AND PERHAPS INTO FAR NORTHEAST IL
LATE THIS EVE...BEFORE SHIFTING EAST INTO FAR NORTHWEST IN BY
DAYBREAK TUE. OTHERWISE EXPECT CLOUDS TO THICKEN THIS EVE ACROSS THE
CWFA...PERHAPS LESS CLOUD COVER ACROSS THE FAR WEST/SOUTHWEST
PORTIONS OF THE FORECAST AREA. WITH THE CLOUD COVER TONIGHT...THIS
SHOULD KEEP TEMPS GENERALLY AROUND 40 TO THE LOW 40S TONIGHT.

TUESDAY THROUGH THURSDAY...
500MB TROUGH AXIS WILL BEGIN TO PUSH EAST...WITH A HIGH AMPLITUDE
RIDGE BEGINNING TO BUILD INTO THE REGION FROM THE CENTRAL PLAINS.
THIS WILL BRING A BROAD SFC RIDGE TO THE AREA STRETCHING FROM
CENTRAL CANADA SOUTH TO THE WESTERN GULF. GUIDANCE THEN CONTINUES TO
MAINTAIN THIS FEATURE THROUGH THUR MORNING...HOWEVER THERE IS A WEAK
WAVE SLIDING EAST ACROSS THE CENTRAL CONUS WED NGT THAT IS PROGGED
TO LIFT NORTHEAST OF THE CWFA THUR AFTN/EVE. THIS SYSTEM COULD BRING
SOME LIGHT PRECIP TO THE AREA...BUT AT THIS TIME HAVE ONLY GONE WITH
SLIGHT CHANCE OF POPS GIVEN THE MOISTURE AVAILABILITY APPEARS TO BE
MINIMAL. TEMPS WILL GENERALLY BE IN THE UPR 50S TO LOW 60S...WITH
OVERNIGHT LOWS IN THE MID 30S TO MID 40S.

FRIDAY THROUGH MONDAY...
ENSEMBLES CONTINUE TO FEATURE A TROUGH PERSISTING ALONG THE FAR
SOUTHWEST CONUS...ALLOWING RIDGING TO DOMINATE THE CENTRAL CONUS
LATE IN THE WEEK INTO THE WEEKEND. THIS WILL LIKELY CONTINUE THE DRY
PATTERN FOR THE REGION. IN ADDITION IT APPEARS TEMPS WILL BE ABLE TO
STEADILY MODERATE...PERHAPS REACHING THE UPR 60S TO ARND 70.

ENSEMBLES DO SUGGEST THAT TOWARDS THE SECOND HALF OF THE WEEKEND THE
RIDGE WILL BEGIN TO DRIFT EAST...WITH A TROUGH DIGGING INTO THE
CENTRAL CONUS AND PERHAPS BRINGING UNSETTLED WEATHER BACK INTO THE
REGION EARLY NEXT WEEK.

BEACHLER

&&

.AVIATION...

//ORD AND MDW CONCERNS...UPDATED 03Z...

* NORTH-NORTHEAST WINDS GREATER THAN 10 KT WITH GUSTS OF 17-20 KT
  TUESDAY.

* CIGS LOWER TO MVFR TUESDAY MORNING WITH ISOLATED SHOWERS
  POSSIBLE...ESPECIALLY AT MDW.

* MVFR CIGS PERSIST THROUGH MUCH OF THE DAY THEN SCATTER LATE
  AFTERNOON OR EARLY TUESDAY EVENING.

MDB

//DISCUSSION...UPDATED 03Z...

RESIDUAL LAKE INFLUENCE CONTINUES TO PRODUCE NORTHEAST WINDS AT
ORD/MDW/GYY. EXPECT THE LAKE IMPACT TO FADE IN THE NEXT HOUR OR
TWO ALLOWING WINDS TO TURN MORE STEADILY TO THE NORTH/NORTH-
NORTHWEST. CIGS WILL LOWER THROUGH THE NIGHT AND SHOULD BECOME
MVFR TUESDAY MORNING. ISOLATED TO SCATTERED SHOWERS ARE EXPECTED
TO DEVELOP OVER LAKE MICHIGAN LATE TONIGHT AND TUESDAY MORNING
WHICH WILL LIKELY IMPACT GYY AT TIMES. THE ILLINOIS SHORELINE WILL
PROBABLY ALSO SEE SOME SPOTTY SHOWERS WHICH MAY REACH ORD/MDW WITH
MDW HAVING THE GREATER POTENTIAL.

STEADY NORTH-NORTHEAST WINDS WILL SET UP TUESDAY MORNING WITH
GUSTS INTO THE 15-20 KT RANGE WHICH WILL EASE OUT TOWARDS RFD IN
THE AFTERNOON...THEN ELSEWHERE WITH SUNSET. MVFR CIGS LOOK TO
PERSIST THROUGH MUCH OF THE DAY WITH THE EXCEPTION BEING RFD WHICH
SHOULD SEE LESS COVERAGE BUT MAY VARY BETWEEN SCT AND BKN. DO NOT
HAVE A GREAT DEAL OF CONFIDENCE IN HOW LONG MVFR PERSISTS INTO THE
AFTERNOON OR EVENING BUT SUSPECT THERE WILL BE AT LEAST SOME
SCATTERING LATER IN THE DAY.

MDB

//ORD AND MDW CONFIDENCE...UPDATED 03Z...

* HIGH CONFIDENCE IN WIND FORECAST THROUGH TUESDAY.

* HIGH CONFIDENCE IN CIGS LOWERING TO MVFR TUESDAY MORNING
  PERSISTING THROUGH TUESDAY AFTERNOON BUT LOW CONFIDENCE IN
  TIMING OF LIFTING/SCATTERING TO VFR TUESDAY AFTERNOON/EVENING.

* MEDIUM CONFIDENCE IN SHRA OCCURRING AT MDW AND LOW CONFIDENCE IN
  OCCURRENCE AT ORD.

MDB

//OUTLOOK FOR ORD/MDW FOR 12Z WEDNESDAY-12Z MONDAY...UPDATED 00Z...

* WEDNESDAY...DRY/VFR. EAST/NORTHEAST WINDS.
* THURSDAY...DRY/VFR. SOUTH WINDS.
* FRIDAY...DRY/VFR. SOUTHWEST WINDS.
* SATURDAY...DRY/VFR. WEST WINDS.
* SUNDAY...DRY/VFR. SOUTH WINDS.

MDB

&&

.MARINE...

250 PM...LOW PRESSURE CONTINUES TO INFLUENCE THE REGION CENTERED
OVER NORTHERN LAKE HURON LATE THIS AFTERNOON AND IS EXPECTED TO
SLOWLY DRIFT EAST OVERNIGHT. THIS LOW WILL THEN REACH LAKE ONTARIO
AROUND DAYBREAK TUE. THE BACK EDGE OF THIS LOW CONTINUES TO
FEATURE A TIGHTENING PRESSURE GRADIENT...WHICH HAS PRODUCED GUSTY
WINDS JUST BEGINNING TO SLIDE OVER THE NORTHERN PORTIONS OF THE
LAKE. THESE GUSTY WINDS WILL EVENTUALLY SLIDE SOUTH THIS
EVENING...AND EXPECT NORTH GUSTS UP TO 30 KTS. HIGH PRESSURE OVER
ONTARIO WILL BEGIN TO BUILD SOUTH OVERNIGHT...THEN STRETCH FROM
ONTARIO SOUTH TO THE WESTERN GULF OF MEXICO BY TUE NGT. THIS WILL
BRING MUCH LIGHTER WINDS TO THE LAKE BY WED.

BEACHLER

&&

.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...SMALL CRAFT ADVISORY...NEARSHORE WATERS
     UNTIL 7 AM WEDNESDAY.

&&

$$

VISIT US AT HTTP://WEATHER.GOV/CHICAGO (ALL LOWERCASE)

FOLLOW US ON FACEBOOK...TWITTER...AND YOUTUBE AT:
WWW.FACEBOOK.COM/NWSCHICAGO
WWW.TWITTER.COM/NWSCHICAGO
WWW.YOUTUBE.COM/NWSCHICAGO






000
FXUS63 KLOT 210310
AFDLOT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
1010 PM CDT MON OCT 20 2014

.DISCUSSION...
249 PM CDT

TONIGHT...
UPPER LEVEL WAVE CONTINUES TO ROTATE OVER NORTHEAST ONTARIO...WITH A
A COUPLE WEAK LOBES OF VORTICITY ROTATING AROUND THE BACK EDGE OF
THIS SYSTEM...PUSHING SOUTH INTO THE NORTHERN GREAT LAKES. VISIBLE
IMAGERY SHOWS CONSIDERABLE CLOUD COVER ACROSS MICHIGAN...STRETCHING
WEST ACROSS THE LAKE AND BEGINNING TO SLIDE INTO FAR NORTHEAST IL.
GUIDANCE SUGGESTS A FEW LIGHT SHOWERS WILL ACCOMPANY THIS WAVE AS IT
PUSHES SOUTHEAST ACROSS WISCONSIN AND PERHAPS INTO FAR NORTHEAST IL
LATE THIS EVE...BEFORE SHIFTING EAST INTO FAR NORTHWEST IN BY
DAYBREAK TUE. OTHERWISE EXPECT CLOUDS TO THICKEN THIS EVE ACROSS THE
CWFA...PERHAPS LESS CLOUD COVER ACROSS THE FAR WEST/SOUTHWEST
PORTIONS OF THE FORECAST AREA. WITH THE CLOUD COVER TONIGHT...THIS
SHOULD KEEP TEMPS GENERALLY AROUND 40 TO THE LOW 40S TONIGHT.

TUESDAY THROUGH THURSDAY...
500MB TROUGH AXIS WILL BEGIN TO PUSH EAST...WITH A HIGH AMPLITUDE
RIDGE BEGINNING TO BUILD INTO THE REGION FROM THE CENTRAL PLAINS.
THIS WILL BRING A BROAD SFC RIDGE TO THE AREA STRETCHING FROM
CENTRAL CANADA SOUTH TO THE WESTERN GULF. GUIDANCE THEN CONTINUES TO
MAINTAIN THIS FEATURE THROUGH THUR MORNING...HOWEVER THERE IS A WEAK
WAVE SLIDING EAST ACROSS THE CENTRAL CONUS WED NGT THAT IS PROGGED
TO LIFT NORTHEAST OF THE CWFA THUR AFTN/EVE. THIS SYSTEM COULD BRING
SOME LIGHT PRECIP TO THE AREA...BUT AT THIS TIME HAVE ONLY GONE WITH
SLIGHT CHANCE OF POPS GIVEN THE MOISTURE AVAILABILITY APPEARS TO BE
MINIMAL. TEMPS WILL GENERALLY BE IN THE UPR 50S TO LOW 60S...WITH
OVERNIGHT LOWS IN THE MID 30S TO MID 40S.

FRIDAY THROUGH MONDAY...
ENSEMBLES CONTINUE TO FEATURE A TROUGH PERSISTING ALONG THE FAR
SOUTHWEST CONUS...ALLOWING RIDGING TO DOMINATE THE CENTRAL CONUS
LATE IN THE WEEK INTO THE WEEKEND. THIS WILL LIKELY CONTINUE THE DRY
PATTERN FOR THE REGION. IN ADDITION IT APPEARS TEMPS WILL BE ABLE TO
STEADILY MODERATE...PERHAPS REACHING THE UPR 60S TO ARND 70.

ENSEMBLES DO SUGGEST THAT TOWARDS THE SECOND HALF OF THE WEEKEND THE
RIDGE WILL BEGIN TO DRIFT EAST...WITH A TROUGH DIGGING INTO THE
CENTRAL CONUS AND PERHAPS BRINGING UNSETTLED WEATHER BACK INTO THE
REGION EARLY NEXT WEEK.

BEACHLER

&&

.AVIATION...

//ORD AND MDW CONCERNS...UPDATED 03Z...

* NORTH-NORTHEAST WINDS GREATER THAN 10 KT WITH GUSTS OF 17-20 KT
  TUESDAY.

* CIGS LOWER TO MVFR TUESDAY MORNING WITH ISOLATED SHOWERS
  POSSIBLE...ESPECIALLY AT MDW.

* MVFR CIGS PERSIST THROUGH MUCH OF THE DAY THEN SCATTER LATE
  AFTERNOON OR EARLY TUESDAY EVENING.

MDB

//DISCUSSION...UPDATED 03Z...

RESIDUAL LAKE INFLUENCE CONTINUES TO PRODUCE NORTHEAST WINDS AT
ORD/MDW/GYY. EXPECT THE LAKE IMPACT TO FADE IN THE NEXT HOUR OR
TWO ALLOWING WINDS TO TURN MORE STEADILY TO THE NORTH/NORTH-
NORTHWEST. CIGS WILL LOWER THROUGH THE NIGHT AND SHOULD BECOME
MVFR TUESDAY MORNING. ISOLATED TO SCATTERED SHOWERS ARE EXPECTED
TO DEVELOP OVER LAKE MICHIGAN LATE TONIGHT AND TUESDAY MORNING
WHICH WILL LIKELY IMPACT GYY AT TIMES. THE ILLINOIS SHORELINE WILL
PROBABLY ALSO SEE SOME SPOTTY SHOWERS WHICH MAY REACH ORD/MDW WITH
MDW HAVING THE GREATER POTENTIAL.

STEADY NORTH-NORTHEAST WINDS WILL SET UP TUESDAY MORNING WITH
GUSTS INTO THE 15-20 KT RANGE WHICH WILL EASE OUT TOWARDS RFD IN
THE AFTERNOON...THEN ELSEWHERE WITH SUNSET. MVFR CIGS LOOK TO
PERSIST THROUGH MUCH OF THE DAY WITH THE EXCEPTION BEING RFD WHICH
SHOULD SEE LESS COVERAGE BUT MAY VARY BETWEEN SCT AND BKN. DO NOT
HAVE A GREAT DEAL OF CONFIDENCE IN HOW LONG MVFR PERSISTS INTO THE
AFTERNOON OR EVENING BUT SUSPECT THERE WILL BE AT LEAST SOME
SCATTERING LATER IN THE DAY.

MDB

//ORD AND MDW CONFIDENCE...UPDATED 03Z...

* HIGH CONFIDENCE IN WIND FORECAST THROUGH TUESDAY.

* HIGH CONFIDENCE IN CIGS LOWERING TO MVFR TUESDAY MORNING
  PERSISTING THROUGH TUESDAY AFTERNOON BUT LOW CONFIDENCE IN
  TIMING OF LIFTING/SCATTERING TO VFR TUESDAY AFTERNOON/EVENING.

* MEDIUM CONFIDENCE IN SHRA OCCURRING AT MDW AND LOW CONFIDENCE IN
  OCCURRENCE AT ORD.

MDB

//OUTLOOK FOR ORD/MDW FOR 12Z WEDNESDAY-12Z MONDAY...UPDATED 00Z...

* WEDNESDAY...DRY/VFR. EAST/NORTHEAST WINDS.
* THURSDAY...DRY/VFR. SOUTH WINDS.
* FRIDAY...DRY/VFR. SOUTHWEST WINDS.
* SATURDAY...DRY/VFR. WEST WINDS.
* SUNDAY...DRY/VFR. SOUTH WINDS.

MDB

&&

.MARINE...

250 PM...LOW PRESSURE CONTINUES TO INFLUENCE THE REGION CENTERED
OVER NORTHERN LAKE HURON LATE THIS AFTERNOON AND IS EXPECTED TO
SLOWLY DRIFT EAST OVERNIGHT. THIS LOW WILL THEN REACH LAKE ONTARIO
AROUND DAYBREAK TUE. THE BACK EDGE OF THIS LOW CONTINUES TO
FEATURE A TIGHTENING PRESSURE GRADIENT...WHICH HAS PRODUCED GUSTY
WINDS JUST BEGINNING TO SLIDE OVER THE NORTHERN PORTIONS OF THE
LAKE. THESE GUSTY WINDS WILL EVENTUALLY SLIDE SOUTH THIS
EVENING...AND EXPECT NORTH GUSTS UP TO 30 KTS. HIGH PRESSURE OVER
ONTARIO WILL BEGIN TO BUILD SOUTH OVERNIGHT...THEN STRETCH FROM
ONTARIO SOUTH TO THE WESTERN GULF OF MEXICO BY TUE NGT. THIS WILL
BRING MUCH LIGHTER WINDS TO THE LAKE BY WED.

BEACHLER

&&

.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...SMALL CRAFT ADVISORY...NEARSHORE WATERS
     UNTIL 7 AM WEDNESDAY.

&&

$$

VISIT US AT HTTP://WEATHER.GOV/CHICAGO (ALL LOWERCASE)

FOLLOW US ON FACEBOOK...TWITTER...AND YOUTUBE AT:
WWW.FACEBOOK.COM/NWSCHICAGO
WWW.TWITTER.COM/NWSCHICAGO
WWW.YOUTUBE.COM/NWSCHICAGO






000
FXUS63 KLOT 210310
AFDLOT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
1010 PM CDT MON OCT 20 2014

.DISCUSSION...
249 PM CDT

TONIGHT...
UPPER LEVEL WAVE CONTINUES TO ROTATE OVER NORTHEAST ONTARIO...WITH A
A COUPLE WEAK LOBES OF VORTICITY ROTATING AROUND THE BACK EDGE OF
THIS SYSTEM...PUSHING SOUTH INTO THE NORTHERN GREAT LAKES. VISIBLE
IMAGERY SHOWS CONSIDERABLE CLOUD COVER ACROSS MICHIGAN...STRETCHING
WEST ACROSS THE LAKE AND BEGINNING TO SLIDE INTO FAR NORTHEAST IL.
GUIDANCE SUGGESTS A FEW LIGHT SHOWERS WILL ACCOMPANY THIS WAVE AS IT
PUSHES SOUTHEAST ACROSS WISCONSIN AND PERHAPS INTO FAR NORTHEAST IL
LATE THIS EVE...BEFORE SHIFTING EAST INTO FAR NORTHWEST IN BY
DAYBREAK TUE. OTHERWISE EXPECT CLOUDS TO THICKEN THIS EVE ACROSS THE
CWFA...PERHAPS LESS CLOUD COVER ACROSS THE FAR WEST/SOUTHWEST
PORTIONS OF THE FORECAST AREA. WITH THE CLOUD COVER TONIGHT...THIS
SHOULD KEEP TEMPS GENERALLY AROUND 40 TO THE LOW 40S TONIGHT.

TUESDAY THROUGH THURSDAY...
500MB TROUGH AXIS WILL BEGIN TO PUSH EAST...WITH A HIGH AMPLITUDE
RIDGE BEGINNING TO BUILD INTO THE REGION FROM THE CENTRAL PLAINS.
THIS WILL BRING A BROAD SFC RIDGE TO THE AREA STRETCHING FROM
CENTRAL CANADA SOUTH TO THE WESTERN GULF. GUIDANCE THEN CONTINUES TO
MAINTAIN THIS FEATURE THROUGH THUR MORNING...HOWEVER THERE IS A WEAK
WAVE SLIDING EAST ACROSS THE CENTRAL CONUS WED NGT THAT IS PROGGED
TO LIFT NORTHEAST OF THE CWFA THUR AFTN/EVE. THIS SYSTEM COULD BRING
SOME LIGHT PRECIP TO THE AREA...BUT AT THIS TIME HAVE ONLY GONE WITH
SLIGHT CHANCE OF POPS GIVEN THE MOISTURE AVAILABILITY APPEARS TO BE
MINIMAL. TEMPS WILL GENERALLY BE IN THE UPR 50S TO LOW 60S...WITH
OVERNIGHT LOWS IN THE MID 30S TO MID 40S.

FRIDAY THROUGH MONDAY...
ENSEMBLES CONTINUE TO FEATURE A TROUGH PERSISTING ALONG THE FAR
SOUTHWEST CONUS...ALLOWING RIDGING TO DOMINATE THE CENTRAL CONUS
LATE IN THE WEEK INTO THE WEEKEND. THIS WILL LIKELY CONTINUE THE DRY
PATTERN FOR THE REGION. IN ADDITION IT APPEARS TEMPS WILL BE ABLE TO
STEADILY MODERATE...PERHAPS REACHING THE UPR 60S TO ARND 70.

ENSEMBLES DO SUGGEST THAT TOWARDS THE SECOND HALF OF THE WEEKEND THE
RIDGE WILL BEGIN TO DRIFT EAST...WITH A TROUGH DIGGING INTO THE
CENTRAL CONUS AND PERHAPS BRINGING UNSETTLED WEATHER BACK INTO THE
REGION EARLY NEXT WEEK.

BEACHLER

&&

.AVIATION...

//ORD AND MDW CONCERNS...UPDATED 03Z...

* NORTH-NORTHEAST WINDS GREATER THAN 10 KT WITH GUSTS OF 17-20 KT
  TUESDAY.

* CIGS LOWER TO MVFR TUESDAY MORNING WITH ISOLATED SHOWERS
  POSSIBLE...ESPECIALLY AT MDW.

* MVFR CIGS PERSIST THROUGH MUCH OF THE DAY THEN SCATTER LATE
  AFTERNOON OR EARLY TUESDAY EVENING.

MDB

//DISCUSSION...UPDATED 03Z...

RESIDUAL LAKE INFLUENCE CONTINUES TO PRODUCE NORTHEAST WINDS AT
ORD/MDW/GYY. EXPECT THE LAKE IMPACT TO FADE IN THE NEXT HOUR OR
TWO ALLOWING WINDS TO TURN MORE STEADILY TO THE NORTH/NORTH-
NORTHWEST. CIGS WILL LOWER THROUGH THE NIGHT AND SHOULD BECOME
MVFR TUESDAY MORNING. ISOLATED TO SCATTERED SHOWERS ARE EXPECTED
TO DEVELOP OVER LAKE MICHIGAN LATE TONIGHT AND TUESDAY MORNING
WHICH WILL LIKELY IMPACT GYY AT TIMES. THE ILLINOIS SHORELINE WILL
PROBABLY ALSO SEE SOME SPOTTY SHOWERS WHICH MAY REACH ORD/MDW WITH
MDW HAVING THE GREATER POTENTIAL.

STEADY NORTH-NORTHEAST WINDS WILL SET UP TUESDAY MORNING WITH
GUSTS INTO THE 15-20 KT RANGE WHICH WILL EASE OUT TOWARDS RFD IN
THE AFTERNOON...THEN ELSEWHERE WITH SUNSET. MVFR CIGS LOOK TO
PERSIST THROUGH MUCH OF THE DAY WITH THE EXCEPTION BEING RFD WHICH
SHOULD SEE LESS COVERAGE BUT MAY VARY BETWEEN SCT AND BKN. DO NOT
HAVE A GREAT DEAL OF CONFIDENCE IN HOW LONG MVFR PERSISTS INTO THE
AFTERNOON OR EVENING BUT SUSPECT THERE WILL BE AT LEAST SOME
SCATTERING LATER IN THE DAY.

MDB

//ORD AND MDW CONFIDENCE...UPDATED 03Z...

* HIGH CONFIDENCE IN WIND FORECAST THROUGH TUESDAY.

* HIGH CONFIDENCE IN CIGS LOWERING TO MVFR TUESDAY MORNING
  PERSISTING THROUGH TUESDAY AFTERNOON BUT LOW CONFIDENCE IN
  TIMING OF LIFTING/SCATTERING TO VFR TUESDAY AFTERNOON/EVENING.

* MEDIUM CONFIDENCE IN SHRA OCCURRING AT MDW AND LOW CONFIDENCE IN
  OCCURRENCE AT ORD.

MDB

//OUTLOOK FOR ORD/MDW FOR 12Z WEDNESDAY-12Z MONDAY...UPDATED 00Z...

* WEDNESDAY...DRY/VFR. EAST/NORTHEAST WINDS.
* THURSDAY...DRY/VFR. SOUTH WINDS.
* FRIDAY...DRY/VFR. SOUTHWEST WINDS.
* SATURDAY...DRY/VFR. WEST WINDS.
* SUNDAY...DRY/VFR. SOUTH WINDS.

MDB

&&

.MARINE...

250 PM...LOW PRESSURE CONTINUES TO INFLUENCE THE REGION CENTERED
OVER NORTHERN LAKE HURON LATE THIS AFTERNOON AND IS EXPECTED TO
SLOWLY DRIFT EAST OVERNIGHT. THIS LOW WILL THEN REACH LAKE ONTARIO
AROUND DAYBREAK TUE. THE BACK EDGE OF THIS LOW CONTINUES TO
FEATURE A TIGHTENING PRESSURE GRADIENT...WHICH HAS PRODUCED GUSTY
WINDS JUST BEGINNING TO SLIDE OVER THE NORTHERN PORTIONS OF THE
LAKE. THESE GUSTY WINDS WILL EVENTUALLY SLIDE SOUTH THIS
EVENING...AND EXPECT NORTH GUSTS UP TO 30 KTS. HIGH PRESSURE OVER
ONTARIO WILL BEGIN TO BUILD SOUTH OVERNIGHT...THEN STRETCH FROM
ONTARIO SOUTH TO THE WESTERN GULF OF MEXICO BY TUE NGT. THIS WILL
BRING MUCH LIGHTER WINDS TO THE LAKE BY WED.

BEACHLER

&&

.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...SMALL CRAFT ADVISORY...NEARSHORE WATERS
     UNTIL 7 AM WEDNESDAY.

&&

$$

VISIT US AT HTTP://WEATHER.GOV/CHICAGO (ALL LOWERCASE)

FOLLOW US ON FACEBOOK...TWITTER...AND YOUTUBE AT:
WWW.FACEBOOK.COM/NWSCHICAGO
WWW.TWITTER.COM/NWSCHICAGO
WWW.YOUTUBE.COM/NWSCHICAGO







000
FXUS63 KLOT 202352
AFDLOT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
652 PM CDT MON OCT 20 2014

.DISCUSSION...
249 PM CDT

TONIGHT...
UPPER LEVEL WAVE CONTINUES TO ROTATE OVER NORTHEAST ONTARIO...WITH A
A COUPLE WEAK LOBES OF VORTICITY ROTATING AROUND THE BACK EDGE OF
THIS SYSTEM...PUSHING SOUTH INTO THE NORTHERN GREAT LAKES. VISIBLE
IMAGERY SHOWS CONSIDERABLE CLOUD COVER ACROSS MICHIGAN...STRETCHING
WEST ACROSS THE LAKE AND BEGINNING TO SLIDE INTO FAR NORTHEAST IL.
GUIDANCE SUGGESTS A FEW LIGHT SHOWERS WILL ACCOMPANY THIS WAVE AS IT
PUSHES SOUTHEAST ACROSS WISCONSIN AND PERHAPS INTO FAR NORTHEAST IL
LATE THIS EVE...BEFORE SHIFTING EAST INTO FAR NORTHWEST IN BY
DAYBREAK TUE. OTHERWISE EXPECT CLOUDS TO THICKEN THIS EVE ACROSS THE
CWFA...PERHAPS LESS CLOUD COVER ACROSS THE FAR WEST/SOUTHWEST
PORTIONS OF THE FORECAST AREA. WITH THE CLOUD COVER TONIGHT...THIS
SHOULD KEEP TEMPS GENERALLY AROUND 40 TO THE LOW 40S TONIGHT.

TUESDAY THROUGH THURSDAY...
500MB TROUGH AXIS WILL BEGIN TO PUSH EAST...WITH A HIGH AMPLITUDE
RIDGE BEGINNING TO BUILD INTO THE REGION FROM THE CENTRAL PLAINS.
THIS WILL BRING A BROAD SFC RIDGE TO THE AREA STRETCHING FROM
CENTRAL CANADA SOUTH TO THE WESTERN GULF. GUIDANCE THEN CONTINUES TO
MAINTAIN THIS FEATURE THROUGH THUR MORNING...HOWEVER THERE IS A WEAK
WAVE SLIDING EAST ACROSS THE CENTRAL CONUS WED NGT THAT IS PROGGED
TO LIFT NORTHEAST OF THE CWFA THUR AFTN/EVE. THIS SYSTEM COULD BRING
SOME LIGHT PRECIP TO THE AREA...BUT AT THIS TIME HAVE ONLY GONE WITH
SLIGHT CHANCE OF POPS GIVEN THE MOISTURE AVAILABILITY APPEARS TO BE
MINIMAL. TEMPS WILL GENERALLY BE IN THE UPR 50S TO LOW 60S...WITH
OVERNIGHT LOWS IN THE MID 30S TO MID 40S.

FRIDAY THROUGH MONDAY...
ENSEMBLES CONTINUE TO FEATURE A TROUGH PERSISTING ALONG THE FAR
SOUTHWEST CONUS...ALLOWING RIDGING TO DOMINATE THE CENTRAL CONUS
LATE IN THE WEEK INTO THE WEEKEND. THIS WILL LIKELY CONTINUE THE DRY
PATTERN FOR THE REGION. IN ADDITION IT APPEARS TEMPS WILL BE ABLE TO
STEADILY MODERATE...PERHAPS REACHING THE UPR 60S TO ARND 70.

ENSEMBLES DO SUGGEST THAT TOWARDS THE SECOND HALF OF THE WEEKEND THE
RIDGE WILL BEGIN TO DRIFT EAST...WITH A TROUGH DIGGING INTO THE
CENTRAL CONUS AND PERHAPS BRINGING UNSETTLED WEATHER BACK INTO THE
REGION EARLY NEXT WEEK.

BEACHLER

&&

.AVIATION...

//ORD AND MDW CONCERNS...UPDATED 00Z...

* VARIABLE NORTH TO NORTHEAST WINDS UNDER 10 KT BECOMING STEADIER
  FROM THE NORTH-NORTHWEST EARLY THIS EVENING.

* NORTH-NORTHEAST WINDS GREATER THAN 10 KT WITH GUSTS OF 17-20 KT
  TUESDAY.

* CIGS LOWER TO MVFR OVERNIGHT WITH ISOLATED SHOWERS POSSIBLE BY
  MORNING...ESPECIALLY AT MDW.

* MVFR CIGS PERSIST THROUGH MUCH OF THE DAY THEN SCATTER LATE
  AFTERNOON OR EARLY TUESDAY EVENING.

MDB

//DISCUSSION...UPDATED 00Z...

RESIDUAL LAKE INFLUENCE CONTINUES TO PRODUCE NORTHEAST WINDS AT
ORD/MDW/GYY. EXPECT THE LAKE IMPACT TO FADE IN THE NEXT HOUR OR
TWO ALLOWING WINDS TO TURN MORE STEADILY TO THE NORTH/NORTH-
NORTHWEST. CIGS WILL LOWER THROUGH THE EVENING AND SHOULD BECOME
MVFR TONIGHT. ISOLATED TO SCATTERED SHOWERS ARE EXPECTED TO
DEVELOP OVER LAKE MICHIGAN LATE TONIGHT AND TUESDAY MORNING WHICH
WILL LIKELY IMPACT GYY AT TIMES. THE ILLINOIS SHORELINE WILL
PROBABLY ALSO SEE SOME SPOTTY SHOWERS WHICH MAY REACH ORD/MDW WITH
MDW HAVING THE GREATER POTENTIAL.

STEADY NORTH-NORTHEAST WINDS WILL SET UP TUESDAY MORNING WITH
GUSTS INTO THE 15-20 KT RANGE WHICH WILL EASE OUT TOWARDS RFD IN
THE AFTERNOON...THEN ELSEWHERE WITH SUNSET. MVFR CIGS LOOK TO
PERSIST THROUGH MUCH OF THE DAY WITH THE EXCEPTION BEING RFD WHICH
SHOULD SEE LESS COVERAGE BUT MAY VARY BETWEEN SCT AND BKN. DO NOT
HAVE A GREAT DEAL OF CONFIDENCE IN HOW LONG MVFR PERSISTS INTO THE
AFTERNOON OR EVENING BUT SUSPECT THERE WILL BE AT LEAST SOME
SCATTERING LATER IN THE DAY.

MDB

//ORD AND MDW CONFIDENCE...UPDATED 00Z...

* HIGH CONFIDENCE IN WIND FORECAST THROUGH TUESDAY.

* HIGH CONFIDENCE IN CIGS LOWERING TO MVFR TONIGHT PERSISTING
  THROUGH TUESDAY AFTERNOON BUT LOW CONFIDENCE IN TIMING OF
  LIFTING/SCATTERING TO VFR TUESDAY AFTERNOON/EVENING.

* MEDIUM CONFIDENCE IN SHRA OCCURRING AT MDW AND LOW CONFIDENCE IN
  OCCURRENCE AT ORD.

MDB

//OUTLOOK FOR ORD/MDW FOR 12Z WEDNESDAY-12Z MONDAY...UPDATED 00Z...

* WEDNESDAY...DRY/VFR. EAST/NORTHEAST WINDS.
* THURSDAY...DRY/VFR. SOUTH WINDS.
* FRIDAY...DRY/VFR. SOUTHWEST WINDS.
* SATURDAY...DRY/VFR. WEST WINDS.
* SUNDAY...DRY/VFR. SOUTH WINDS.

MDB

&&

.MARINE...

250 PM...LOW PRESSURE CONTINUES TO INFLUENCE THE REGION CENTERED
OVER NORTHERN LAKE HURON LATE THIS AFTERNOON AND IS EXPECTED TO
SLOWLY DRIFT EAST OVERNIGHT. THIS LOW WILL THEN REACH LAKE ONTARIO
AROUND DAYBREAK TUE. THE BACK EDGE OF THIS LOW CONTINUES TO
FEATURE A TIGHTENING PRESSURE GRADIENT...WHICH HAS PRODUCED GUSTY
WINDS JUST BEGINNING TO SLIDE OVER THE NORTHERN PORTIONS OF THE
LAKE. THESE GUSTY WINDS WILL EVENTUALLY SLIDE SOUTH THIS
EVENING...AND EXPECT NORTH GUSTS UP TO 30 KTS. HIGH PRESSURE OVER
ONTARIO WILL BEGIN TO BUILD SOUTH OVERNIGHT...THEN STRETCH FROM
ONTARIO SOUTH TO THE WESTERN GULF OF MEXICO BY TUE NGT. THIS WILL
BRING MUCH LIGHTER WINDS TO THE LAKE BY WED.

BEACHLER

&&

.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...SMALL CRAFT ADVISORY...LMZ740-LMZ741-LMZ742-LMZ743-LMZ744-
     LMZ745...10 PM MONDAY TO 7 AM WEDNESDAY.

&&

$$

VISIT US AT HTTP://WEATHER.GOV/CHICAGO (ALL LOWERCASE)

FOLLOW US ON FACEBOOK...TWITTER...AND YOUTUBE AT:
WWW.FACEBOOK.COM/NWSCHICAGO
WWW.TWITTER.COM/NWSCHICAGO
WWW.YOUTUBE.COM/NWSCHICAGO






000
FXUS63 KLOT 202352
AFDLOT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
652 PM CDT MON OCT 20 2014

.DISCUSSION...
249 PM CDT

TONIGHT...
UPPER LEVEL WAVE CONTINUES TO ROTATE OVER NORTHEAST ONTARIO...WITH A
A COUPLE WEAK LOBES OF VORTICITY ROTATING AROUND THE BACK EDGE OF
THIS SYSTEM...PUSHING SOUTH INTO THE NORTHERN GREAT LAKES. VISIBLE
IMAGERY SHOWS CONSIDERABLE CLOUD COVER ACROSS MICHIGAN...STRETCHING
WEST ACROSS THE LAKE AND BEGINNING TO SLIDE INTO FAR NORTHEAST IL.
GUIDANCE SUGGESTS A FEW LIGHT SHOWERS WILL ACCOMPANY THIS WAVE AS IT
PUSHES SOUTHEAST ACROSS WISCONSIN AND PERHAPS INTO FAR NORTHEAST IL
LATE THIS EVE...BEFORE SHIFTING EAST INTO FAR NORTHWEST IN BY
DAYBREAK TUE. OTHERWISE EXPECT CLOUDS TO THICKEN THIS EVE ACROSS THE
CWFA...PERHAPS LESS CLOUD COVER ACROSS THE FAR WEST/SOUTHWEST
PORTIONS OF THE FORECAST AREA. WITH THE CLOUD COVER TONIGHT...THIS
SHOULD KEEP TEMPS GENERALLY AROUND 40 TO THE LOW 40S TONIGHT.

TUESDAY THROUGH THURSDAY...
500MB TROUGH AXIS WILL BEGIN TO PUSH EAST...WITH A HIGH AMPLITUDE
RIDGE BEGINNING TO BUILD INTO THE REGION FROM THE CENTRAL PLAINS.
THIS WILL BRING A BROAD SFC RIDGE TO THE AREA STRETCHING FROM
CENTRAL CANADA SOUTH TO THE WESTERN GULF. GUIDANCE THEN CONTINUES TO
MAINTAIN THIS FEATURE THROUGH THUR MORNING...HOWEVER THERE IS A WEAK
WAVE SLIDING EAST ACROSS THE CENTRAL CONUS WED NGT THAT IS PROGGED
TO LIFT NORTHEAST OF THE CWFA THUR AFTN/EVE. THIS SYSTEM COULD BRING
SOME LIGHT PRECIP TO THE AREA...BUT AT THIS TIME HAVE ONLY GONE WITH
SLIGHT CHANCE OF POPS GIVEN THE MOISTURE AVAILABILITY APPEARS TO BE
MINIMAL. TEMPS WILL GENERALLY BE IN THE UPR 50S TO LOW 60S...WITH
OVERNIGHT LOWS IN THE MID 30S TO MID 40S.

FRIDAY THROUGH MONDAY...
ENSEMBLES CONTINUE TO FEATURE A TROUGH PERSISTING ALONG THE FAR
SOUTHWEST CONUS...ALLOWING RIDGING TO DOMINATE THE CENTRAL CONUS
LATE IN THE WEEK INTO THE WEEKEND. THIS WILL LIKELY CONTINUE THE DRY
PATTERN FOR THE REGION. IN ADDITION IT APPEARS TEMPS WILL BE ABLE TO
STEADILY MODERATE...PERHAPS REACHING THE UPR 60S TO ARND 70.

ENSEMBLES DO SUGGEST THAT TOWARDS THE SECOND HALF OF THE WEEKEND THE
RIDGE WILL BEGIN TO DRIFT EAST...WITH A TROUGH DIGGING INTO THE
CENTRAL CONUS AND PERHAPS BRINGING UNSETTLED WEATHER BACK INTO THE
REGION EARLY NEXT WEEK.

BEACHLER

&&

.AVIATION...

//ORD AND MDW CONCERNS...UPDATED 00Z...

* VARIABLE NORTH TO NORTHEAST WINDS UNDER 10 KT BECOMING STEADIER
  FROM THE NORTH-NORTHWEST EARLY THIS EVENING.

* NORTH-NORTHEAST WINDS GREATER THAN 10 KT WITH GUSTS OF 17-20 KT
  TUESDAY.

* CIGS LOWER TO MVFR OVERNIGHT WITH ISOLATED SHOWERS POSSIBLE BY
  MORNING...ESPECIALLY AT MDW.

* MVFR CIGS PERSIST THROUGH MUCH OF THE DAY THEN SCATTER LATE
  AFTERNOON OR EARLY TUESDAY EVENING.

MDB

//DISCUSSION...UPDATED 00Z...

RESIDUAL LAKE INFLUENCE CONTINUES TO PRODUCE NORTHEAST WINDS AT
ORD/MDW/GYY. EXPECT THE LAKE IMPACT TO FADE IN THE NEXT HOUR OR
TWO ALLOWING WINDS TO TURN MORE STEADILY TO THE NORTH/NORTH-
NORTHWEST. CIGS WILL LOWER THROUGH THE EVENING AND SHOULD BECOME
MVFR TONIGHT. ISOLATED TO SCATTERED SHOWERS ARE EXPECTED TO
DEVELOP OVER LAKE MICHIGAN LATE TONIGHT AND TUESDAY MORNING WHICH
WILL LIKELY IMPACT GYY AT TIMES. THE ILLINOIS SHORELINE WILL
PROBABLY ALSO SEE SOME SPOTTY SHOWERS WHICH MAY REACH ORD/MDW WITH
MDW HAVING THE GREATER POTENTIAL.

STEADY NORTH-NORTHEAST WINDS WILL SET UP TUESDAY MORNING WITH
GUSTS INTO THE 15-20 KT RANGE WHICH WILL EASE OUT TOWARDS RFD IN
THE AFTERNOON...THEN ELSEWHERE WITH SUNSET. MVFR CIGS LOOK TO
PERSIST THROUGH MUCH OF THE DAY WITH THE EXCEPTION BEING RFD WHICH
SHOULD SEE LESS COVERAGE BUT MAY VARY BETWEEN SCT AND BKN. DO NOT
HAVE A GREAT DEAL OF CONFIDENCE IN HOW LONG MVFR PERSISTS INTO THE
AFTERNOON OR EVENING BUT SUSPECT THERE WILL BE AT LEAST SOME
SCATTERING LATER IN THE DAY.

MDB

//ORD AND MDW CONFIDENCE...UPDATED 00Z...

* HIGH CONFIDENCE IN WIND FORECAST THROUGH TUESDAY.

* HIGH CONFIDENCE IN CIGS LOWERING TO MVFR TONIGHT PERSISTING
  THROUGH TUESDAY AFTERNOON BUT LOW CONFIDENCE IN TIMING OF
  LIFTING/SCATTERING TO VFR TUESDAY AFTERNOON/EVENING.

* MEDIUM CONFIDENCE IN SHRA OCCURRING AT MDW AND LOW CONFIDENCE IN
  OCCURRENCE AT ORD.

MDB

//OUTLOOK FOR ORD/MDW FOR 12Z WEDNESDAY-12Z MONDAY...UPDATED 00Z...

* WEDNESDAY...DRY/VFR. EAST/NORTHEAST WINDS.
* THURSDAY...DRY/VFR. SOUTH WINDS.
* FRIDAY...DRY/VFR. SOUTHWEST WINDS.
* SATURDAY...DRY/VFR. WEST WINDS.
* SUNDAY...DRY/VFR. SOUTH WINDS.

MDB

&&

.MARINE...

250 PM...LOW PRESSURE CONTINUES TO INFLUENCE THE REGION CENTERED
OVER NORTHERN LAKE HURON LATE THIS AFTERNOON AND IS EXPECTED TO
SLOWLY DRIFT EAST OVERNIGHT. THIS LOW WILL THEN REACH LAKE ONTARIO
AROUND DAYBREAK TUE. THE BACK EDGE OF THIS LOW CONTINUES TO
FEATURE A TIGHTENING PRESSURE GRADIENT...WHICH HAS PRODUCED GUSTY
WINDS JUST BEGINNING TO SLIDE OVER THE NORTHERN PORTIONS OF THE
LAKE. THESE GUSTY WINDS WILL EVENTUALLY SLIDE SOUTH THIS
EVENING...AND EXPECT NORTH GUSTS UP TO 30 KTS. HIGH PRESSURE OVER
ONTARIO WILL BEGIN TO BUILD SOUTH OVERNIGHT...THEN STRETCH FROM
ONTARIO SOUTH TO THE WESTERN GULF OF MEXICO BY TUE NGT. THIS WILL
BRING MUCH LIGHTER WINDS TO THE LAKE BY WED.

BEACHLER

&&

.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...SMALL CRAFT ADVISORY...LMZ740-LMZ741-LMZ742-LMZ743-LMZ744-
     LMZ745...10 PM MONDAY TO 7 AM WEDNESDAY.

&&

$$

VISIT US AT HTTP://WEATHER.GOV/CHICAGO (ALL LOWERCASE)

FOLLOW US ON FACEBOOK...TWITTER...AND YOUTUBE AT:
WWW.FACEBOOK.COM/NWSCHICAGO
WWW.TWITTER.COM/NWSCHICAGO
WWW.YOUTUBE.COM/NWSCHICAGO







000
FXUS63 KLOT 202206
AFDLOT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
505 PM CDT MON OCT 20 2014

.DISCUSSION...
249 PM CDT

TONIGHT...
UPPER LEVEL WAVE CONTINUES TO ROTATE OVER NORTHEAST ONTARIO...WITH A
A COUPLE WEAK LOBES OF VORTICITY ROTATING AROUND THE BACK EDGE OF
THIS SYSTEM...PUSHING SOUTH INTO THE NORTHERN GREAT LAKES. VISIBLE
IMAGERY SHOWS CONSIDERABLE CLOUD COVER ACROSS MICHIGAN...STRETCHING
WEST ACROSS THE LAKE AND BEGINNING TO SLIDE INTO FAR NORTHEAST IL.
GUIDANCE SUGGESTS A FEW LIGHT SHOWERS WILL ACCOMPANY THIS WAVE AS IT
PUSHES SOUTHEAST ACROSS WISCONSIN AND PERHAPS INTO FAR NORTHEAST IL
LATE THIS EVE...BEFORE SHIFTING EAST INTO FAR NORTHWEST IN BY
DAYBREAK TUE. OTHERWISE EXPECT CLOUDS TO THICKEN THIS EVE ACROSS THE
CWFA...PERHAPS LESS CLOUD COVER ACROSS THE FAR WEST/SOUTHWEST
PORTIONS OF THE FORECAST AREA. WITH THE CLOUD COVER TONIGHT...THIS
SHOULD KEEP TEMPS GENERALLY AROUND 40 TO THE LOW 40S TONIGHT.

TUESDAY THROUGH THURSDAY...
500MB TROUGH AXIS WILL BEGIN TO PUSH EAST...WITH A HIGH AMPLITUDE
RIDGE BEGINNING TO BUILD INTO THE REGION FROM THE CENTRAL PLAINS.
THIS WILL BRING A BROAD SFC RIDGE TO THE AREA STRETCHING FROM
CENTRAL CANADA SOUTH TO THE WESTERN GULF. GUIDANCE THEN CONTINUES TO
MAINTAIN THIS FEATURE THROUGH THUR MORNING...HOWEVER THERE IS A WEAK
WAVE SLIDING EAST ACROSS THE CENTRAL CONUS WED NGT THAT IS PROGGED
TO LIFT NORTHEAST OF THE CWFA THUR AFTN/EVE. THIS SYSTEM COULD BRING
SOME LIGHT PRECIP TO THE AREA...BUT AT THIS TIME HAVE ONLY GONE WITH
SLIGHT CHANCE OF POPS GIVEN THE MOISTURE AVAILABILITY APPEARS TO BE
MINIMAL. TEMPS WILL GENERALLY BE IN THE UPR 50S TO LOW 60S...WITH
OVERNIGHT LOWS IN THE MID 30S TO MID 40S.

FRIDAY THROUGH MONDAY...
ENSEMBLES CONTINUE TO FEATURE A TROUGH PERSISTING ALONG THE FAR
SOUTHWEST CONUS...ALLOWING RIDGING TO DOMINATE THE CENTRAL CONUS
LATE IN THE WEEK INTO THE WEEKEND. THIS WILL LIKELY CONTINUE THE DRY
PATTERN FOR THE REGION. IN ADDITION IT APPEARS TEMPS WILL BE ABLE TO
STEADILY MODERATE...PERHAPS REACHING THE UPR 60S TO ARND 70.

ENSEMBLES DO SUGGEST THAT TOWARDS THE SECOND HALF OF THE WEEKEND THE
RIDGE WILL BEGIN TO DRIFT EAST...WITH A TROUGH DIGGING INTO THE
CENTRAL CONUS AND PERHAPS BRINGING UNSETTLED WEATHER BACK INTO THE
REGION EARLY NEXT WEEK.

BEACHLER

&&

.AVIATION...

//ORD AND MDW CONCERNS...UPDATED 22Z...

* NORTHEAST WINDS AROUND 10 KT BECOMING NORTH LESS THAN 10 KT
  EARLY THIS EVENING. NORTHEAST WINDS 10+KT TUESDAY.

* VFR CEILINGS BECOMING MVFR EARLY TUESDAY MORNING.

* PERIODIC/ISOLATED LIGHT SHOWERS POSSIBLE LATE TONIGHT/TUESDAY
  MORNING.

MDB

//DISCUSSION...UPDATED 22Z...

LAKE BREEZE BOUNDARY IS WEST OF ORD/MDW AND SOUTH OF GYY. WINDS
AT THESE TERMINALS WILL CONTINUE TO BE NORTHEASTERLY RIGHT AROUND
10 KT WITH GUSTS LIKELY TO HAVE ENDED. EXPECT A GRADUAL TREND BACK
TO A 360-010 WIND OVER THE NEXT 1-2 HRS WITH SPEEDS CONSISTENTLY
UNDER 10 KT BY 01Z IF NOT 00Z.

MDB

FROM 18Z...

MOSTLY CLEAR SKIES STILL PRESENT ACROSS THE TERMINALS EARLY THIS
AFTERNOON...WHILE NORTHWEST WINDS CONTINUE TO SLOWLY INCREASE.
DEVELOPING DIURNAL STRATOCU WILL SPREAD OVER THE AREA OVER THE
NEXT 1-2 HOURS AND ALTHOUGH THERE MAY BE A BRIEF PERIOD OF HIGH
END MVFR CEILINGS...DO THINK THAT VFR CEILINGS WILL PREVAIL THIS
AFTERNOON. NORTHWEST WINDS/GUSTS WILL STEADILY INCREASE OVER THE
NEXT COUPLE OF HOURS WITH A POSSIBILITY REMAINING FOR WINDS TO
BRIEFLY GO MORE NORTHERLY. THIS SHOULD ALSO BE BRIEF WITH A
NORTHWEST WIND LIKELY FAVORED. WITH VFR CEILINGS REMAINING
OVERHEAD TONIGHT...THE NORTHWEST WINDS WILL DIMINISH BEFORE
QUICKLY INCREASING ABOVE 10 KT OUT OF THE NORTHEAST EARLY TUESDAY
MORNING. AS THIS OCCURS...ANTICIPATE ALREADY PRESENT MVFR CEILINGS
OVER THE LAKE TO MOVE WEST ACROSS THE TERMINALS...EXCEPT RFD.
THERE WILL ALSO BE A PERIOD OF SCATTERED LIGHT SHOWERS TO SPILL
OFF THE LAKE DURING THIS TIME...BUT WITH MDW/GYY THE LIKELY
LOCATIONS TO OBSERVE THIS PRECIP.

RODRIGUEZ

//ORD AND MDW CONFIDENCE...UPDATED 22Z...

* HIGH CONFIDENCE IN WIND TRENDS.

* HIGH CONFIDENCE WITH VFR CEILINGS...MEDIUM CONFIDENCE WITH MVFR
  CEILINGS.

* MEDIUM CONFIDENCE IN SHOWERS IMPACTING THE TERMINALS.

MDB

//OUTLOOK FOR ORD/MDW FOR 00Z WEDNESDAY-12Z MONDAY...UPDATED 12Z...

* TUESDAY NIGHT...DRY/VFR.
* WEDNESDAY...DRY/VFR. EAST/NORTHEAST WINDS.
* THURSDAY...DRY/VFR. SOUTH WINDS.
* FRIDAY...DRY/VFR. SOUTHWEST WINDS.
* SATURDAY...DRY/VFR. WEST WINDS.
* SUNDAY...DRY/VFR. SOUTH WINDS.

&&

.MARINE...

250 PM...LOW PRESSURE CONTINUES TO INFLUENCE THE REGION CENTERED
OVER NORTHERN LAKE HURON LATE THIS AFTERNOON AND IS EXPECTED TO
SLOWLY DRIFT EAST OVERNIGHT. THIS LOW WILL THEN REACH LAKE ONTARIO
AROUND DAYBREAK TUE. THE BACK EDGE OF THIS LOW CONTINUES TO
FEATURE A TIGHTENING PRESSURE GRADIENT...WHICH HAS PRODUCED GUSTY
WINDS JUST BEGINNING TO SLIDE OVER THE NORTHERN PORTIONS OF THE
LAKE. THESE GUSTY WINDS WILL EVENTUALLY SLIDE SOUTH THIS
EVENING...AND EXPECT NORTH GUSTS UP TO 30 KTS. HIGH PRESSURE OVER
ONTARIO WILL BEGIN TO BUILD SOUTH OVERNIGHT...THEN STRETCH FROM
ONTARIO SOUTH TO THE WESTERN GULF OF MEXICO BY TUE NGT. THIS WILL
BRING MUCH LIGHTER WINDS TO THE LAKE BY WED.

BEACHLER

&&

.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...SMALL CRAFT ADVISORY...LMZ740-LMZ741-LMZ742-LMZ743-LMZ744-
     LMZ745...10 PM MONDAY TO 7 AM WEDNESDAY.

&&

$$

VISIT US AT HTTP://WEATHER.GOV/CHICAGO (ALL LOWERCASE)

FOLLOW US ON FACEBOOK...TWITTER...AND YOUTUBE AT:
WWW.FACEBOOK.COM/NWSCHICAGO
WWW.TWITTER.COM/NWSCHICAGO
WWW.YOUTUBE.COM/NWSCHICAGO






000
FXUS63 KLOT 202206
AFDLOT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
505 PM CDT MON OCT 20 2014

.DISCUSSION...
249 PM CDT

TONIGHT...
UPPER LEVEL WAVE CONTINUES TO ROTATE OVER NORTHEAST ONTARIO...WITH A
A COUPLE WEAK LOBES OF VORTICITY ROTATING AROUND THE BACK EDGE OF
THIS SYSTEM...PUSHING SOUTH INTO THE NORTHERN GREAT LAKES. VISIBLE
IMAGERY SHOWS CONSIDERABLE CLOUD COVER ACROSS MICHIGAN...STRETCHING
WEST ACROSS THE LAKE AND BEGINNING TO SLIDE INTO FAR NORTHEAST IL.
GUIDANCE SUGGESTS A FEW LIGHT SHOWERS WILL ACCOMPANY THIS WAVE AS IT
PUSHES SOUTHEAST ACROSS WISCONSIN AND PERHAPS INTO FAR NORTHEAST IL
LATE THIS EVE...BEFORE SHIFTING EAST INTO FAR NORTHWEST IN BY
DAYBREAK TUE. OTHERWISE EXPECT CLOUDS TO THICKEN THIS EVE ACROSS THE
CWFA...PERHAPS LESS CLOUD COVER ACROSS THE FAR WEST/SOUTHWEST
PORTIONS OF THE FORECAST AREA. WITH THE CLOUD COVER TONIGHT...THIS
SHOULD KEEP TEMPS GENERALLY AROUND 40 TO THE LOW 40S TONIGHT.

TUESDAY THROUGH THURSDAY...
500MB TROUGH AXIS WILL BEGIN TO PUSH EAST...WITH A HIGH AMPLITUDE
RIDGE BEGINNING TO BUILD INTO THE REGION FROM THE CENTRAL PLAINS.
THIS WILL BRING A BROAD SFC RIDGE TO THE AREA STRETCHING FROM
CENTRAL CANADA SOUTH TO THE WESTERN GULF. GUIDANCE THEN CONTINUES TO
MAINTAIN THIS FEATURE THROUGH THUR MORNING...HOWEVER THERE IS A WEAK
WAVE SLIDING EAST ACROSS THE CENTRAL CONUS WED NGT THAT IS PROGGED
TO LIFT NORTHEAST OF THE CWFA THUR AFTN/EVE. THIS SYSTEM COULD BRING
SOME LIGHT PRECIP TO THE AREA...BUT AT THIS TIME HAVE ONLY GONE WITH
SLIGHT CHANCE OF POPS GIVEN THE MOISTURE AVAILABILITY APPEARS TO BE
MINIMAL. TEMPS WILL GENERALLY BE IN THE UPR 50S TO LOW 60S...WITH
OVERNIGHT LOWS IN THE MID 30S TO MID 40S.

FRIDAY THROUGH MONDAY...
ENSEMBLES CONTINUE TO FEATURE A TROUGH PERSISTING ALONG THE FAR
SOUTHWEST CONUS...ALLOWING RIDGING TO DOMINATE THE CENTRAL CONUS
LATE IN THE WEEK INTO THE WEEKEND. THIS WILL LIKELY CONTINUE THE DRY
PATTERN FOR THE REGION. IN ADDITION IT APPEARS TEMPS WILL BE ABLE TO
STEADILY MODERATE...PERHAPS REACHING THE UPR 60S TO ARND 70.

ENSEMBLES DO SUGGEST THAT TOWARDS THE SECOND HALF OF THE WEEKEND THE
RIDGE WILL BEGIN TO DRIFT EAST...WITH A TROUGH DIGGING INTO THE
CENTRAL CONUS AND PERHAPS BRINGING UNSETTLED WEATHER BACK INTO THE
REGION EARLY NEXT WEEK.

BEACHLER

&&

.AVIATION...

//ORD AND MDW CONCERNS...UPDATED 22Z...

* NORTHEAST WINDS AROUND 10 KT BECOMING NORTH LESS THAN 10 KT
  EARLY THIS EVENING. NORTHEAST WINDS 10+KT TUESDAY.

* VFR CEILINGS BECOMING MVFR EARLY TUESDAY MORNING.

* PERIODIC/ISOLATED LIGHT SHOWERS POSSIBLE LATE TONIGHT/TUESDAY
  MORNING.

MDB

//DISCUSSION...UPDATED 22Z...

LAKE BREEZE BOUNDARY IS WEST OF ORD/MDW AND SOUTH OF GYY. WINDS
AT THESE TERMINALS WILL CONTINUE TO BE NORTHEASTERLY RIGHT AROUND
10 KT WITH GUSTS LIKELY TO HAVE ENDED. EXPECT A GRADUAL TREND BACK
TO A 360-010 WIND OVER THE NEXT 1-2 HRS WITH SPEEDS CONSISTENTLY
UNDER 10 KT BY 01Z IF NOT 00Z.

MDB

FROM 18Z...

MOSTLY CLEAR SKIES STILL PRESENT ACROSS THE TERMINALS EARLY THIS
AFTERNOON...WHILE NORTHWEST WINDS CONTINUE TO SLOWLY INCREASE.
DEVELOPING DIURNAL STRATOCU WILL SPREAD OVER THE AREA OVER THE
NEXT 1-2 HOURS AND ALTHOUGH THERE MAY BE A BRIEF PERIOD OF HIGH
END MVFR CEILINGS...DO THINK THAT VFR CEILINGS WILL PREVAIL THIS
AFTERNOON. NORTHWEST WINDS/GUSTS WILL STEADILY INCREASE OVER THE
NEXT COUPLE OF HOURS WITH A POSSIBILITY REMAINING FOR WINDS TO
BRIEFLY GO MORE NORTHERLY. THIS SHOULD ALSO BE BRIEF WITH A
NORTHWEST WIND LIKELY FAVORED. WITH VFR CEILINGS REMAINING
OVERHEAD TONIGHT...THE NORTHWEST WINDS WILL DIMINISH BEFORE
QUICKLY INCREASING ABOVE 10 KT OUT OF THE NORTHEAST EARLY TUESDAY
MORNING. AS THIS OCCURS...ANTICIPATE ALREADY PRESENT MVFR CEILINGS
OVER THE LAKE TO MOVE WEST ACROSS THE TERMINALS...EXCEPT RFD.
THERE WILL ALSO BE A PERIOD OF SCATTERED LIGHT SHOWERS TO SPILL
OFF THE LAKE DURING THIS TIME...BUT WITH MDW/GYY THE LIKELY
LOCATIONS TO OBSERVE THIS PRECIP.

RODRIGUEZ

//ORD AND MDW CONFIDENCE...UPDATED 22Z...

* HIGH CONFIDENCE IN WIND TRENDS.

* HIGH CONFIDENCE WITH VFR CEILINGS...MEDIUM CONFIDENCE WITH MVFR
  CEILINGS.

* MEDIUM CONFIDENCE IN SHOWERS IMPACTING THE TERMINALS.

MDB

//OUTLOOK FOR ORD/MDW FOR 00Z WEDNESDAY-12Z MONDAY...UPDATED 12Z...

* TUESDAY NIGHT...DRY/VFR.
* WEDNESDAY...DRY/VFR. EAST/NORTHEAST WINDS.
* THURSDAY...DRY/VFR. SOUTH WINDS.
* FRIDAY...DRY/VFR. SOUTHWEST WINDS.
* SATURDAY...DRY/VFR. WEST WINDS.
* SUNDAY...DRY/VFR. SOUTH WINDS.

&&

.MARINE...

250 PM...LOW PRESSURE CONTINUES TO INFLUENCE THE REGION CENTERED
OVER NORTHERN LAKE HURON LATE THIS AFTERNOON AND IS EXPECTED TO
SLOWLY DRIFT EAST OVERNIGHT. THIS LOW WILL THEN REACH LAKE ONTARIO
AROUND DAYBREAK TUE. THE BACK EDGE OF THIS LOW CONTINUES TO
FEATURE A TIGHTENING PRESSURE GRADIENT...WHICH HAS PRODUCED GUSTY
WINDS JUST BEGINNING TO SLIDE OVER THE NORTHERN PORTIONS OF THE
LAKE. THESE GUSTY WINDS WILL EVENTUALLY SLIDE SOUTH THIS
EVENING...AND EXPECT NORTH GUSTS UP TO 30 KTS. HIGH PRESSURE OVER
ONTARIO WILL BEGIN TO BUILD SOUTH OVERNIGHT...THEN STRETCH FROM
ONTARIO SOUTH TO THE WESTERN GULF OF MEXICO BY TUE NGT. THIS WILL
BRING MUCH LIGHTER WINDS TO THE LAKE BY WED.

BEACHLER

&&

.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...SMALL CRAFT ADVISORY...LMZ740-LMZ741-LMZ742-LMZ743-LMZ744-
     LMZ745...10 PM MONDAY TO 7 AM WEDNESDAY.

&&

$$

VISIT US AT HTTP://WEATHER.GOV/CHICAGO (ALL LOWERCASE)

FOLLOW US ON FACEBOOK...TWITTER...AND YOUTUBE AT:
WWW.FACEBOOK.COM/NWSCHICAGO
WWW.TWITTER.COM/NWSCHICAGO
WWW.YOUTUBE.COM/NWSCHICAGO







000
FXUS63 KLOT 202206
AFDLOT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
505 PM CDT MON OCT 20 2014

.DISCUSSION...
249 PM CDT

TONIGHT...
UPPER LEVEL WAVE CONTINUES TO ROTATE OVER NORTHEAST ONTARIO...WITH A
A COUPLE WEAK LOBES OF VORTICITY ROTATING AROUND THE BACK EDGE OF
THIS SYSTEM...PUSHING SOUTH INTO THE NORTHERN GREAT LAKES. VISIBLE
IMAGERY SHOWS CONSIDERABLE CLOUD COVER ACROSS MICHIGAN...STRETCHING
WEST ACROSS THE LAKE AND BEGINNING TO SLIDE INTO FAR NORTHEAST IL.
GUIDANCE SUGGESTS A FEW LIGHT SHOWERS WILL ACCOMPANY THIS WAVE AS IT
PUSHES SOUTHEAST ACROSS WISCONSIN AND PERHAPS INTO FAR NORTHEAST IL
LATE THIS EVE...BEFORE SHIFTING EAST INTO FAR NORTHWEST IN BY
DAYBREAK TUE. OTHERWISE EXPECT CLOUDS TO THICKEN THIS EVE ACROSS THE
CWFA...PERHAPS LESS CLOUD COVER ACROSS THE FAR WEST/SOUTHWEST
PORTIONS OF THE FORECAST AREA. WITH THE CLOUD COVER TONIGHT...THIS
SHOULD KEEP TEMPS GENERALLY AROUND 40 TO THE LOW 40S TONIGHT.

TUESDAY THROUGH THURSDAY...
500MB TROUGH AXIS WILL BEGIN TO PUSH EAST...WITH A HIGH AMPLITUDE
RIDGE BEGINNING TO BUILD INTO THE REGION FROM THE CENTRAL PLAINS.
THIS WILL BRING A BROAD SFC RIDGE TO THE AREA STRETCHING FROM
CENTRAL CANADA SOUTH TO THE WESTERN GULF. GUIDANCE THEN CONTINUES TO
MAINTAIN THIS FEATURE THROUGH THUR MORNING...HOWEVER THERE IS A WEAK
WAVE SLIDING EAST ACROSS THE CENTRAL CONUS WED NGT THAT IS PROGGED
TO LIFT NORTHEAST OF THE CWFA THUR AFTN/EVE. THIS SYSTEM COULD BRING
SOME LIGHT PRECIP TO THE AREA...BUT AT THIS TIME HAVE ONLY GONE WITH
SLIGHT CHANCE OF POPS GIVEN THE MOISTURE AVAILABILITY APPEARS TO BE
MINIMAL. TEMPS WILL GENERALLY BE IN THE UPR 50S TO LOW 60S...WITH
OVERNIGHT LOWS IN THE MID 30S TO MID 40S.

FRIDAY THROUGH MONDAY...
ENSEMBLES CONTINUE TO FEATURE A TROUGH PERSISTING ALONG THE FAR
SOUTHWEST CONUS...ALLOWING RIDGING TO DOMINATE THE CENTRAL CONUS
LATE IN THE WEEK INTO THE WEEKEND. THIS WILL LIKELY CONTINUE THE DRY
PATTERN FOR THE REGION. IN ADDITION IT APPEARS TEMPS WILL BE ABLE TO
STEADILY MODERATE...PERHAPS REACHING THE UPR 60S TO ARND 70.

ENSEMBLES DO SUGGEST THAT TOWARDS THE SECOND HALF OF THE WEEKEND THE
RIDGE WILL BEGIN TO DRIFT EAST...WITH A TROUGH DIGGING INTO THE
CENTRAL CONUS AND PERHAPS BRINGING UNSETTLED WEATHER BACK INTO THE
REGION EARLY NEXT WEEK.

BEACHLER

&&

.AVIATION...

//ORD AND MDW CONCERNS...UPDATED 22Z...

* NORTHEAST WINDS AROUND 10 KT BECOMING NORTH LESS THAN 10 KT
  EARLY THIS EVENING. NORTHEAST WINDS 10+KT TUESDAY.

* VFR CEILINGS BECOMING MVFR EARLY TUESDAY MORNING.

* PERIODIC/ISOLATED LIGHT SHOWERS POSSIBLE LATE TONIGHT/TUESDAY
  MORNING.

MDB

//DISCUSSION...UPDATED 22Z...

LAKE BREEZE BOUNDARY IS WEST OF ORD/MDW AND SOUTH OF GYY. WINDS
AT THESE TERMINALS WILL CONTINUE TO BE NORTHEASTERLY RIGHT AROUND
10 KT WITH GUSTS LIKELY TO HAVE ENDED. EXPECT A GRADUAL TREND BACK
TO A 360-010 WIND OVER THE NEXT 1-2 HRS WITH SPEEDS CONSISTENTLY
UNDER 10 KT BY 01Z IF NOT 00Z.

MDB

FROM 18Z...

MOSTLY CLEAR SKIES STILL PRESENT ACROSS THE TERMINALS EARLY THIS
AFTERNOON...WHILE NORTHWEST WINDS CONTINUE TO SLOWLY INCREASE.
DEVELOPING DIURNAL STRATOCU WILL SPREAD OVER THE AREA OVER THE
NEXT 1-2 HOURS AND ALTHOUGH THERE MAY BE A BRIEF PERIOD OF HIGH
END MVFR CEILINGS...DO THINK THAT VFR CEILINGS WILL PREVAIL THIS
AFTERNOON. NORTHWEST WINDS/GUSTS WILL STEADILY INCREASE OVER THE
NEXT COUPLE OF HOURS WITH A POSSIBILITY REMAINING FOR WINDS TO
BRIEFLY GO MORE NORTHERLY. THIS SHOULD ALSO BE BRIEF WITH A
NORTHWEST WIND LIKELY FAVORED. WITH VFR CEILINGS REMAINING
OVERHEAD TONIGHT...THE NORTHWEST WINDS WILL DIMINISH BEFORE
QUICKLY INCREASING ABOVE 10 KT OUT OF THE NORTHEAST EARLY TUESDAY
MORNING. AS THIS OCCURS...ANTICIPATE ALREADY PRESENT MVFR CEILINGS
OVER THE LAKE TO MOVE WEST ACROSS THE TERMINALS...EXCEPT RFD.
THERE WILL ALSO BE A PERIOD OF SCATTERED LIGHT SHOWERS TO SPILL
OFF THE LAKE DURING THIS TIME...BUT WITH MDW/GYY THE LIKELY
LOCATIONS TO OBSERVE THIS PRECIP.

RODRIGUEZ

//ORD AND MDW CONFIDENCE...UPDATED 22Z...

* HIGH CONFIDENCE IN WIND TRENDS.

* HIGH CONFIDENCE WITH VFR CEILINGS...MEDIUM CONFIDENCE WITH MVFR
  CEILINGS.

* MEDIUM CONFIDENCE IN SHOWERS IMPACTING THE TERMINALS.

MDB

//OUTLOOK FOR ORD/MDW FOR 00Z WEDNESDAY-12Z MONDAY...UPDATED 12Z...

* TUESDAY NIGHT...DRY/VFR.
* WEDNESDAY...DRY/VFR. EAST/NORTHEAST WINDS.
* THURSDAY...DRY/VFR. SOUTH WINDS.
* FRIDAY...DRY/VFR. SOUTHWEST WINDS.
* SATURDAY...DRY/VFR. WEST WINDS.
* SUNDAY...DRY/VFR. SOUTH WINDS.

&&

.MARINE...

250 PM...LOW PRESSURE CONTINUES TO INFLUENCE THE REGION CENTERED
OVER NORTHERN LAKE HURON LATE THIS AFTERNOON AND IS EXPECTED TO
SLOWLY DRIFT EAST OVERNIGHT. THIS LOW WILL THEN REACH LAKE ONTARIO
AROUND DAYBREAK TUE. THE BACK EDGE OF THIS LOW CONTINUES TO
FEATURE A TIGHTENING PRESSURE GRADIENT...WHICH HAS PRODUCED GUSTY
WINDS JUST BEGINNING TO SLIDE OVER THE NORTHERN PORTIONS OF THE
LAKE. THESE GUSTY WINDS WILL EVENTUALLY SLIDE SOUTH THIS
EVENING...AND EXPECT NORTH GUSTS UP TO 30 KTS. HIGH PRESSURE OVER
ONTARIO WILL BEGIN TO BUILD SOUTH OVERNIGHT...THEN STRETCH FROM
ONTARIO SOUTH TO THE WESTERN GULF OF MEXICO BY TUE NGT. THIS WILL
BRING MUCH LIGHTER WINDS TO THE LAKE BY WED.

BEACHLER

&&

.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...SMALL CRAFT ADVISORY...LMZ740-LMZ741-LMZ742-LMZ743-LMZ744-
     LMZ745...10 PM MONDAY TO 7 AM WEDNESDAY.

&&

$$

VISIT US AT HTTP://WEATHER.GOV/CHICAGO (ALL LOWERCASE)

FOLLOW US ON FACEBOOK...TWITTER...AND YOUTUBE AT:
WWW.FACEBOOK.COM/NWSCHICAGO
WWW.TWITTER.COM/NWSCHICAGO
WWW.YOUTUBE.COM/NWSCHICAGO






000
FXUS63 KLOT 202001
AFDLOT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
301 PM CDT MON OCT 20 2014

.DISCUSSION...
249 PM CDT

TONIGHT...
UPPER LEVEL WAVE CONTINUES TO ROTATE OVER NORTHEAST ONTARIO...WITH A
A COUPLE WEAK LOBES OF VORTICITY ROTATING AROUND THE BACKEDGE OF
THIS SYSTEM...PUSHING SOUTH INTO THE NORTHERN GREAT LAKES. VISIBLE
IMAGERY SHOWS CONSIDERABLE CLOUD COVER ACROSS MICHIGAN...STRETCHING
WEST ACROSS THE LAKE AND BEGINNING TO SLIDE INTO FAR NORTHEAST IL.
GUIDANCE SUGGESTS A FEW LIGHT SHOWERS WILL ACCOMPANY THIS WAVE AS IT
PUSHES SOUTHEAST ACROSS WISCONSIN AND PERHAPS INTO FAR NORTHEAST IL
LATE THIS EVE...BEFORE SHIFTING EAST INTO FAR NORTHWEST IN BY
DAYBREAK TUE. OTHERWISE EXPECT CLOUDS TO THICKEN THIS EVE ACROSS THE
CWFA...PERHAPS LESS CLOUD COVER ACROSS THE FAR WEST/SOUTHWEST
PORTIONS OF THE FORECAST AREA. WITH THE CLOUD COVER TONIGHT...THIS
SHOULD KEEP TEMPS GENERALLY AROUND 40 TO THE LOW 40S TONIGHT.

TUESDAY THROUGH THURSDAY...
500MB TROUGH AXIS WILL BEGIN TO PUSH EAST...WITH A HIGH AMPLITUDE
RIDGE BEGINNING TO BUILD INTO THE REGION FROM THE CENTRAL PLAINS.
THIS WILL BRING A BROAD SFC RIDGE TO THE AREA STRETCHING FROM
CENTRAL CANADA SOUTH TO THE WESTERN GULF. GUIDANCE THEN CONTINUES TO
MAINTAIN THIS FEATURE THROUGH THUR MORNING...HOWEVER THERE IS A WEAK
WAVE SLIDING EAST ACROSS THE CENTRAL CONUS WED NGT THAT IS PROGGED
TO LIFT NORTHEAST OF THE CWFA THUR AFTN/EVE. THIS SYSTEM COULD BRING
SOME LIGHT PRECIP TO THE AREA...BUT AT THIS TIME HAVE ONLY GONE WITH
SLIGHT CHANCE OF POPS GIVEN THE MOISTURE AVAILABILITY APPEARS TO BE
MINIMAL. TEMPS WILL GENERALLY BE IN THE UPR 50S TO LOW 60S...WITH
OVERNIGHT LOWS IN THE MID 30S TO MID 40S.

FRIDAY THROUGH MONDAY...
ENSEMBLES CONTINUE TO FEATURE A TROUGH PERSISTING ALONG THE FAR
SOUTHWEST CONUS...ALLOWING RIDGING TO DOMINATE THE CENTRAL CONUS
LATE IN THE WEEK INTO THE WEEKEND. THIS WILL LIKELY CONTINUE THE DRY
PATTERN FOR THE REGION. IN ADDITION IT APPEARS TEMPS WILL BE ABLE TO
STEADILY MODERATE...PERHAPS REACHING THE UPR 60S TO ARND 70.

ENSEMBLES DO SUGGEST THAT TOWARDS THE SECOND HALF OF THE WEEKEND THE
RIDGE WILL BEGIN TO DRIFT EAST...WITH A TROUGH DIGGING INTO THE
CENTRAL CONUS AND PERHAPS BRINGING UNSETTLED WEATHER BACK INTO THE
REGION EARLY NEXT WEEK.

BEACHLER

&&

.AVIATION...

//ORD AND MDW CONCERNS...UPDATED 20Z...

* NORTHWEST WINDS/GUSTS BRIEFLY BECOMING MORE NORTHERLY THIS
  AFTERNOON WITH VARYING LAKE BREEZE...THEN BECOMING NORTHEAST
  WITH SPEEDS AT OR ABOVE 10 KT TUESDAY MORNING.

* DEVELOPING VFR CEILINGS BECOMING MVFR EARLY TUESDAY MORNING.

* PERIODIC/ISOLATED LIGHT SHOWERS.

RODRIGUEZ

//DISCUSSION...UPDATED 18Z...

MOSTLY CLEAR SKIES STILL PRESENT ACROSS THE TERMINALS EARLY THIS
AFTERNOON...WHILE NORTHWEST WINDS CONTINUE TO SLOWLY INCREASE.
DEVELOPING DIURNAL STRATOCU WILL SPREAD OVER THE AREA OVER THE
NEXT 1-2 HOURS AND ALTHOUGH THERE MAY BE A BRIEF PERIOD OF HIGH
END MVFR CEILINGS...DO THINK THAT VFR CEILINGS WILL PREVAIL THIS
AFTERNOON. NORTHWEST WINDS/GUSTS WILL STEADILY INCREASE OVER THE
NEXT COUPLE OF HOURS WITH A POSSIBILITY REMAINING FOR WINDS TO
BRIEFLY GO MORE NORTHERLY. THIS SHOULD ALSO BE BRIEF WITH A
NORTHWEST WIND LIKELY FAVORED. WITH VFR CEILINGS REMAINING
OVERHEAD TONIGHT...THE NORTHWEST WINDS WILL DIMINISH BEFORE
QUICKLY INCREASING ABOVE 10 KT OUT OF THE NORTHEAST EARLY TUESDAY
MORNING. AS THIS OCCURS...ANTICIPATE ALREADY PRESENT MVFR CEILINGS
OVER THE LAKE TO MOVE WEST ACROSS THE TERMINALS...EXCEPT RFD.
THERE WILL ALSO BE A PERIOD OF SCATTERED LIGHT SHOWERS TO SPILL
OFF THE LAKE DURING THIS TIME...BUT WITH MDW/GYY THE LIKELY
LOCATIONS TO OBSERVE THIS PRECIP.

RODRIGUEZ

//ORD AND MDW CONFIDENCE...UPDATED 20Z...

* MEDIUM CONFIDENCE WITH WIND SPEED/DIRECTION.

* HIGH CONFIDENCE WITH VFR CEILINGS...MEDIUM CONFIDENCE WITH MVFR
  CEILINGS.

* MEDIUM CONFIDENCE WITH LIGHT SHOWERS.

RODRIGUEZ

//OUTLOOK FOR ORD/MDW FOR 00Z WEDNESDAY-12Z MONDAY...UPDATED 12Z...

* TUESDAY NIGHT...DRY/VFR.
* WEDNESDAY...DRY/VFR. EAST/NORTHEAST WINDS.
* THURSDAY...DRY/VFR. SOUTH WINDS.
* FRIDAY...DRY/VFR. SOUTHWEST WINDS.
* SATURDAY...DRY/VFR. WEST WINDS.
* SUNDAY...DRY/VFR. SOUTH WINDS.

&&

.MARINE...

250 PM...LOW PRESSURE CONTINUES TO INFLUENCE THE REGION CENTERED
OVER NORTHERN LAKE HURON LATE THIS AFTERNOON AND IS EXPECTED TO
SLOWLY DRIFT EAST OVERNIGHT. THIS LOW WILL THEN REACH LAKE ONTARIO
AROUND DAYBREAK TUE. THE BACK EDGE OF THIS LOW CONTINUES TO
FEATURE A TIGHTENING PRESSURE GRADIENT...WHICH HAS PRODUCED GUSTY
WINDS JUST BEGINNING TO SLIDE OVER THE NORTHERN PORTIONS OF THE
LAKE. THESE GUSTY WINDS WILL EVENTUALLY SLIDE SOUTH THIS
EVENING...AND EXPECT NORTH GUSTS UP TO 30 KTS. HIGH PRESSURE OVER
ONTARIO WILL BEGIN TO BUILD SOUTH OVERNIGHT...THEN STRETCH FROM
ONTARIO SOUTH TO THE WESTERN GULF OF MEXICO BY TUE NGT. THIS WILL
BRING MUCH LIGHTER WINDS TO THE LAKE BY WED.

BEACHLER

&&

.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...SMALL CRAFT ADVISORY...LMZ740-LMZ741-LMZ742-LMZ743-LMZ744-
     LMZ745...10 PM MONDAY TO 7 AM WEDNESDAY.

&&

$$

VISIT US AT HTTP://WEATHER.GOV/CHICAGO (ALL LOWERCASE)

FOLLOW US ON FACEBOOK...TWITTER...AND YOUTUBE AT:
WWW.FACEBOOK.COM/NWSCHICAGO
WWW.TWITTER.COM/NWSCHICAGO
WWW.YOUTUBE.COM/NWSCHICAGO







000
FXUS63 KLOT 202001
AFDLOT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
301 PM CDT MON OCT 20 2014

.DISCUSSION...
249 PM CDT

TONIGHT...
UPPER LEVEL WAVE CONTINUES TO ROTATE OVER NORTHEAST ONTARIO...WITH A
A COUPLE WEAK LOBES OF VORTICITY ROTATING AROUND THE BACKEDGE OF
THIS SYSTEM...PUSHING SOUTH INTO THE NORTHERN GREAT LAKES. VISIBLE
IMAGERY SHOWS CONSIDERABLE CLOUD COVER ACROSS MICHIGAN...STRETCHING
WEST ACROSS THE LAKE AND BEGINNING TO SLIDE INTO FAR NORTHEAST IL.
GUIDANCE SUGGESTS A FEW LIGHT SHOWERS WILL ACCOMPANY THIS WAVE AS IT
PUSHES SOUTHEAST ACROSS WISCONSIN AND PERHAPS INTO FAR NORTHEAST IL
LATE THIS EVE...BEFORE SHIFTING EAST INTO FAR NORTHWEST IN BY
DAYBREAK TUE. OTHERWISE EXPECT CLOUDS TO THICKEN THIS EVE ACROSS THE
CWFA...PERHAPS LESS CLOUD COVER ACROSS THE FAR WEST/SOUTHWEST
PORTIONS OF THE FORECAST AREA. WITH THE CLOUD COVER TONIGHT...THIS
SHOULD KEEP TEMPS GENERALLY AROUND 40 TO THE LOW 40S TONIGHT.

TUESDAY THROUGH THURSDAY...
500MB TROUGH AXIS WILL BEGIN TO PUSH EAST...WITH A HIGH AMPLITUDE
RIDGE BEGINNING TO BUILD INTO THE REGION FROM THE CENTRAL PLAINS.
THIS WILL BRING A BROAD SFC RIDGE TO THE AREA STRETCHING FROM
CENTRAL CANADA SOUTH TO THE WESTERN GULF. GUIDANCE THEN CONTINUES TO
MAINTAIN THIS FEATURE THROUGH THUR MORNING...HOWEVER THERE IS A WEAK
WAVE SLIDING EAST ACROSS THE CENTRAL CONUS WED NGT THAT IS PROGGED
TO LIFT NORTHEAST OF THE CWFA THUR AFTN/EVE. THIS SYSTEM COULD BRING
SOME LIGHT PRECIP TO THE AREA...BUT AT THIS TIME HAVE ONLY GONE WITH
SLIGHT CHANCE OF POPS GIVEN THE MOISTURE AVAILABILITY APPEARS TO BE
MINIMAL. TEMPS WILL GENERALLY BE IN THE UPR 50S TO LOW 60S...WITH
OVERNIGHT LOWS IN THE MID 30S TO MID 40S.

FRIDAY THROUGH MONDAY...
ENSEMBLES CONTINUE TO FEATURE A TROUGH PERSISTING ALONG THE FAR
SOUTHWEST CONUS...ALLOWING RIDGING TO DOMINATE THE CENTRAL CONUS
LATE IN THE WEEK INTO THE WEEKEND. THIS WILL LIKELY CONTINUE THE DRY
PATTERN FOR THE REGION. IN ADDITION IT APPEARS TEMPS WILL BE ABLE TO
STEADILY MODERATE...PERHAPS REACHING THE UPR 60S TO ARND 70.

ENSEMBLES DO SUGGEST THAT TOWARDS THE SECOND HALF OF THE WEEKEND THE
RIDGE WILL BEGIN TO DRIFT EAST...WITH A TROUGH DIGGING INTO THE
CENTRAL CONUS AND PERHAPS BRINGING UNSETTLED WEATHER BACK INTO THE
REGION EARLY NEXT WEEK.

BEACHLER

&&

.AVIATION...

//ORD AND MDW CONCERNS...UPDATED 20Z...

* NORTHWEST WINDS/GUSTS BRIEFLY BECOMING MORE NORTHERLY THIS
  AFTERNOON WITH VARYING LAKE BREEZE...THEN BECOMING NORTHEAST
  WITH SPEEDS AT OR ABOVE 10 KT TUESDAY MORNING.

* DEVELOPING VFR CEILINGS BECOMING MVFR EARLY TUESDAY MORNING.

* PERIODIC/ISOLATED LIGHT SHOWERS.

RODRIGUEZ

//DISCUSSION...UPDATED 18Z...

MOSTLY CLEAR SKIES STILL PRESENT ACROSS THE TERMINALS EARLY THIS
AFTERNOON...WHILE NORTHWEST WINDS CONTINUE TO SLOWLY INCREASE.
DEVELOPING DIURNAL STRATOCU WILL SPREAD OVER THE AREA OVER THE
NEXT 1-2 HOURS AND ALTHOUGH THERE MAY BE A BRIEF PERIOD OF HIGH
END MVFR CEILINGS...DO THINK THAT VFR CEILINGS WILL PREVAIL THIS
AFTERNOON. NORTHWEST WINDS/GUSTS WILL STEADILY INCREASE OVER THE
NEXT COUPLE OF HOURS WITH A POSSIBILITY REMAINING FOR WINDS TO
BRIEFLY GO MORE NORTHERLY. THIS SHOULD ALSO BE BRIEF WITH A
NORTHWEST WIND LIKELY FAVORED. WITH VFR CEILINGS REMAINING
OVERHEAD TONIGHT...THE NORTHWEST WINDS WILL DIMINISH BEFORE
QUICKLY INCREASING ABOVE 10 KT OUT OF THE NORTHEAST EARLY TUESDAY
MORNING. AS THIS OCCURS...ANTICIPATE ALREADY PRESENT MVFR CEILINGS
OVER THE LAKE TO MOVE WEST ACROSS THE TERMINALS...EXCEPT RFD.
THERE WILL ALSO BE A PERIOD OF SCATTERED LIGHT SHOWERS TO SPILL
OFF THE LAKE DURING THIS TIME...BUT WITH MDW/GYY THE LIKELY
LOCATIONS TO OBSERVE THIS PRECIP.

RODRIGUEZ

//ORD AND MDW CONFIDENCE...UPDATED 20Z...

* MEDIUM CONFIDENCE WITH WIND SPEED/DIRECTION.

* HIGH CONFIDENCE WITH VFR CEILINGS...MEDIUM CONFIDENCE WITH MVFR
  CEILINGS.

* MEDIUM CONFIDENCE WITH LIGHT SHOWERS.

RODRIGUEZ

//OUTLOOK FOR ORD/MDW FOR 00Z WEDNESDAY-12Z MONDAY...UPDATED 12Z...

* TUESDAY NIGHT...DRY/VFR.
* WEDNESDAY...DRY/VFR. EAST/NORTHEAST WINDS.
* THURSDAY...DRY/VFR. SOUTH WINDS.
* FRIDAY...DRY/VFR. SOUTHWEST WINDS.
* SATURDAY...DRY/VFR. WEST WINDS.
* SUNDAY...DRY/VFR. SOUTH WINDS.

&&

.MARINE...

250 PM...LOW PRESSURE CONTINUES TO INFLUENCE THE REGION CENTERED
OVER NORTHERN LAKE HURON LATE THIS AFTERNOON AND IS EXPECTED TO
SLOWLY DRIFT EAST OVERNIGHT. THIS LOW WILL THEN REACH LAKE ONTARIO
AROUND DAYBREAK TUE. THE BACK EDGE OF THIS LOW CONTINUES TO
FEATURE A TIGHTENING PRESSURE GRADIENT...WHICH HAS PRODUCED GUSTY
WINDS JUST BEGINNING TO SLIDE OVER THE NORTHERN PORTIONS OF THE
LAKE. THESE GUSTY WINDS WILL EVENTUALLY SLIDE SOUTH THIS
EVENING...AND EXPECT NORTH GUSTS UP TO 30 KTS. HIGH PRESSURE OVER
ONTARIO WILL BEGIN TO BUILD SOUTH OVERNIGHT...THEN STRETCH FROM
ONTARIO SOUTH TO THE WESTERN GULF OF MEXICO BY TUE NGT. THIS WILL
BRING MUCH LIGHTER WINDS TO THE LAKE BY WED.

BEACHLER

&&

.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...SMALL CRAFT ADVISORY...LMZ740-LMZ741-LMZ742-LMZ743-LMZ744-
     LMZ745...10 PM MONDAY TO 7 AM WEDNESDAY.

&&

$$

VISIT US AT HTTP://WEATHER.GOV/CHICAGO (ALL LOWERCASE)

FOLLOW US ON FACEBOOK...TWITTER...AND YOUTUBE AT:
WWW.FACEBOOK.COM/NWSCHICAGO
WWW.TWITTER.COM/NWSCHICAGO
WWW.YOUTUBE.COM/NWSCHICAGO






000
FXUS63 KLOT 201955
AFDLOT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
255 PM CDT MON OCT 20 2014

.DISCUSSION...
249 PM CDT

TONIGHT...
UPPER LEVEL WAVE CONTINUES TO ROTATE OVER NORTHEAST ONTARIO...WITH A
A COUPLE WEAK LOBES OF VORTICITY ROTATING AROUND THE BACKEDGE OF
THIS SYSTEM...PUSHING SOUTH INTO THE NORTHERN GREAT LAKES. VISIBLE
IMAGERY SHOWS CONSIDERABLE CLOUD COVER ACROSS MICHIGAN...STRETCHING
WEST ACROSS THE LAKE AND BEGINNING TO SLIDE INTO FAR NORTHEAST IL.
GUIDANCE SUGGESTS A FEW LIGHT SHOWERS WILL ACCOMPANY THIS WAVE AS IT
PUSHES SOUTHEAST ACROSS WISCONSIN AND PERHAPS INTO FAR NORTHEAST IL
LATE THIS EVE...BEFORE SHIFTING EAST INTO FAR NORTHWEST IN BY
DAYBREAK TUE. OTHERWISE EXPECT CLOUDS TO THICKEN THIS EVE ACROSS THE
CWFA...PERHAPS LESS CLOUD COVER ACROSS THE FAR WEST/SOUTHWEST
PORTIONS OF THE FORECAST AREA. WITH THE CLOUD COVER TONIGHT...THIS
SHOULD KEEP TEMPS GENERALLY AROUND 40 TO THE LOW 40S TONIGHT.

TUESDAY THROUGH THURSDAY...
500MB TROUGH AXIS WILL BEGIN TO PUSH EAST...WITH A HIGH AMPLITUDE
RIDGE BEGINNING TO BUILD INTO THE REGION FROM THE CENTRAL PLAINS.
THIS WILL BRING A BROAD SFC RIDGE TO THE AREA STRETCHING FROM
CENTRAL CANADA SOUTH TO THE WESTERN GULF. GUIDANCE THEN CONTINUES TO
MAINTAIN THIS FEATURE THROUGH THUR MORNING...HOWEVER THERE IS A WEAK
WAVE SLIDING EAST ACROSS THE CENTRAL CONUS WED NGT THAT IS PROGGED
TO LIFT NORTHEAST OF THE CWFA THUR AFTN/EVE. THIS SYSTEM COULD BRING
SOME LIGHT PRECIP TO THE AREA...BUT AT THIS TIME HAVE ONLY GONE WITH
SLIGHT CHANCE OF POPS GIVEN THE MOISTURE AVAILABILITY APPEARS TO BE
MINIMAL. TEMPS WILL GENERALLY BE IN THE UPR 50S TO LOW 60S...WITH
OVERNIGHT LOWS IN THE MID 30S TO MID 40S.

FRIDAY THROUGH MONDAY...
ENSEMBLES CONTINUE TO FEATURE A TROUGH PERSISTING ALONG THE FAR
SOUTHWEST CONUS...ALLOWING RIDGING TO DOMINATE THE CENTRAL CONUS
LATE IN THE WEEK INTO THE WEEKEND. THIS WILL LIKELY CONTINUE THE DRY
PATTERN FOR THE REGION. IN ADDITION IT APPEARS TEMPS WILL BE ABLE TO
STEADILY MODERATE...PERHAPS REACHING THE UPR 60S TO ARND 70.

ENSEMBLES DO SUGGEST THAT TOWARDS THE SECOND HALF OF THE WEEKEND THE
RIDGE WILL BEGIN TO DRIFT EAST...WITH A TROUGH DIGGING INTO THE
CENTRAL CONUS AND PERHAPS BRINGING UNSETTLED WEATHER BACK INTO THE
REGION EARLY NEXT WEEK.


BEACHLER

&&

.AVIATION...

//ORD AND MDW CONCERNS...UPDATED 18Z...

* NORTHWEST WINDS/GUSTS BRIEFLY BECOMING MORE NORTHERLY THIS
  AFTERNOON...THEN BECOMING NORTHEAST WITH SPEEDS AT OR ABOVE 10
  KT TUESDAY MORNING.

* DEVELOPING VFR CEILINGS BECOMING MVFR EARLY TUESDAY MORNING.

* PERIODIC/ISOLATED LIGHT SHOWERS.

RODRIGUEZ

//DISCUSSION...UPDATED 18Z...

MOSTLY CLEAR SKIES STILL PRESENT ACROSS THE TERMINALS EARLY THIS
AFTERNOON...WHILE NORTHWEST WINDS CONTINUE TO SLOWLY INCREASE.
DEVELOPING DIURNAL STRATOCU WILL SPREAD OVER THE AREA OVER THE
NEXT 1-2 HOURS AND ALTHOUGH THERE MAY BE A BRIEF PERIOD OF HIGH
END MVFR CEILINGS...DO THINK THAT VFR CEILINGS WILL PREVAIL THIS
AFTERNOON. NORTHWEST WINDS/GUSTS WILL STEADILY INCREASE OVER THE
NEXT COUPLE OF HOURS WITH A POSSIBILITY REMAINING FOR WINDS TO
BRIEFLY GO MORE NORTHERLY. THIS SHOULD ALSO BE BRIEF WITH A
NORTHWEST WIND LIKELY FAVORED. WITH VFR CEILINGS REMAINING
OVERHEAD TONIGHT...THE NORTHWEST WINDS WILL DIMINISH BEFORE
QUICKLY INCREASING ABOVE 10 KT OUT OF THE NORTHEAST EARLY TUESDAY
MORNING. AS THIS OCCURS...ANTICIPATE ALREADY PRESENT MVFR CEILINGS
OVER THE LAKE TO MOVE WEST ACROSS THE TERMINALS...EXCEPT RFD.
THERE WILL ALSO BE A PERIOD OF SCATTERED LIGHT SHOWERS TO SPILL
OFF THE LAKE DURING THIS TIME...BUT WITH MDW/GYY THE LIKELY
LOCATIONS TO OBSERVE THIS PRECIP.

RODRIGUEZ

//ORD AND MDW CONFIDENCE...UPDATED 18Z...

* MEDIUM HIGH CONFIDENCE WITH WIND SPEED/DIRECTION.

* HIGH CONFIDENCE WITH VFR CEILINGS...MEDIUM CONFIDENCE WITH MVFR
  CEILINGS.

* MEDIUM CONFIDENCE WITH LIGHT SHOWERS.

RODRIGUEZ

//OUTLOOK FOR ORD/MDW FOR 00Z WEDNESDAY-12Z MONDAY...UPDATED 12Z...

* TUESDAY NIGHT...DRY/VFR.
* WEDNESDAY...DRY/VFR. EAST/NORTHEAST WINDS.
* THURSDAY...DRY/VFR. SOUTH WINDS.
* FRIDAY...DRY/VFR. SOUTHWEST WINDS.
* SATURDAY...DRY/VFR. WEST WINDS.
* SUNDAY...DRY/VFR. SOUTH WINDS.

&&

.MARINE...

250 PM...LOW PRESSURE CONTINUES TO INFLUENCE THE REGION CENTERED
OVER NORTHERN LAKE HURON LATE THIS AFTERNOON AND IS EXPECTED TO
SLOWLY DRIFT EAST OVERNIGHT. THIS LOW WILL THEN REACH LAKE ONTARIO
AROUND DAYBREAK TUE. THE BACK EDGE OF THIS LOW CONTINUES TO
FEATURE A TIGHTENING PRESSURE GRADIENT...WHICH HAS PRODUCED GUSTY
WINDS JUST BEGINNING TO SLIDE OVER THE NORTHERN PORTIONS OF THE
LAKE. THESE GUSTY WINDS WILL EVENTUALLY SLIDE SOUTH THIS
EVENING...AND EXPECT NORTH GUSTS UP TO 30 KTS. HIGH PRESSURE OVER
ONTARIO WILL BEGIN TO BUILD SOUTH OVERNIGHT...THEN STRETCH FROM
ONTARIO SOUTH TO THE WESTERN GULF OF MEXICO BY TUE NGT. THIS WILL
BRING MUCH LIGHTER WINDS TO THE LAKE BY WED.

BEACHLER

&&

.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...SMALL CRAFT ADVISORY...LMZ740-LMZ741-LMZ742-LMZ743-LMZ744-
     LMZ745...10 PM MONDAY TO 7 AM WEDNESDAY.

&&

$$

VISIT US AT HTTP://WEATHER.GOV/CHICAGO (ALL LOWERCASE)

FOLLOW US ON FACEBOOK...TWITTER...AND YOUTUBE AT:
WWW.FACEBOOK.COM/NWSCHICAGO
WWW.TWITTER.COM/NWSCHICAGO
WWW.YOUTUBE.COM/NWSCHICAGO






000
FXUS63 KLOT 201955
AFDLOT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
255 PM CDT MON OCT 20 2014

.DISCUSSION...
249 PM CDT

TONIGHT...
UPPER LEVEL WAVE CONTINUES TO ROTATE OVER NORTHEAST ONTARIO...WITH A
A COUPLE WEAK LOBES OF VORTICITY ROTATING AROUND THE BACKEDGE OF
THIS SYSTEM...PUSHING SOUTH INTO THE NORTHERN GREAT LAKES. VISIBLE
IMAGERY SHOWS CONSIDERABLE CLOUD COVER ACROSS MICHIGAN...STRETCHING
WEST ACROSS THE LAKE AND BEGINNING TO SLIDE INTO FAR NORTHEAST IL.
GUIDANCE SUGGESTS A FEW LIGHT SHOWERS WILL ACCOMPANY THIS WAVE AS IT
PUSHES SOUTHEAST ACROSS WISCONSIN AND PERHAPS INTO FAR NORTHEAST IL
LATE THIS EVE...BEFORE SHIFTING EAST INTO FAR NORTHWEST IN BY
DAYBREAK TUE. OTHERWISE EXPECT CLOUDS TO THICKEN THIS EVE ACROSS THE
CWFA...PERHAPS LESS CLOUD COVER ACROSS THE FAR WEST/SOUTHWEST
PORTIONS OF THE FORECAST AREA. WITH THE CLOUD COVER TONIGHT...THIS
SHOULD KEEP TEMPS GENERALLY AROUND 40 TO THE LOW 40S TONIGHT.

TUESDAY THROUGH THURSDAY...
500MB TROUGH AXIS WILL BEGIN TO PUSH EAST...WITH A HIGH AMPLITUDE
RIDGE BEGINNING TO BUILD INTO THE REGION FROM THE CENTRAL PLAINS.
THIS WILL BRING A BROAD SFC RIDGE TO THE AREA STRETCHING FROM
CENTRAL CANADA SOUTH TO THE WESTERN GULF. GUIDANCE THEN CONTINUES TO
MAINTAIN THIS FEATURE THROUGH THUR MORNING...HOWEVER THERE IS A WEAK
WAVE SLIDING EAST ACROSS THE CENTRAL CONUS WED NGT THAT IS PROGGED
TO LIFT NORTHEAST OF THE CWFA THUR AFTN/EVE. THIS SYSTEM COULD BRING
SOME LIGHT PRECIP TO THE AREA...BUT AT THIS TIME HAVE ONLY GONE WITH
SLIGHT CHANCE OF POPS GIVEN THE MOISTURE AVAILABILITY APPEARS TO BE
MINIMAL. TEMPS WILL GENERALLY BE IN THE UPR 50S TO LOW 60S...WITH
OVERNIGHT LOWS IN THE MID 30S TO MID 40S.

FRIDAY THROUGH MONDAY...
ENSEMBLES CONTINUE TO FEATURE A TROUGH PERSISTING ALONG THE FAR
SOUTHWEST CONUS...ALLOWING RIDGING TO DOMINATE THE CENTRAL CONUS
LATE IN THE WEEK INTO THE WEEKEND. THIS WILL LIKELY CONTINUE THE DRY
PATTERN FOR THE REGION. IN ADDITION IT APPEARS TEMPS WILL BE ABLE TO
STEADILY MODERATE...PERHAPS REACHING THE UPR 60S TO ARND 70.

ENSEMBLES DO SUGGEST THAT TOWARDS THE SECOND HALF OF THE WEEKEND THE
RIDGE WILL BEGIN TO DRIFT EAST...WITH A TROUGH DIGGING INTO THE
CENTRAL CONUS AND PERHAPS BRINGING UNSETTLED WEATHER BACK INTO THE
REGION EARLY NEXT WEEK.


BEACHLER

&&

.AVIATION...

//ORD AND MDW CONCERNS...UPDATED 18Z...

* NORTHWEST WINDS/GUSTS BRIEFLY BECOMING MORE NORTHERLY THIS
  AFTERNOON...THEN BECOMING NORTHEAST WITH SPEEDS AT OR ABOVE 10
  KT TUESDAY MORNING.

* DEVELOPING VFR CEILINGS BECOMING MVFR EARLY TUESDAY MORNING.

* PERIODIC/ISOLATED LIGHT SHOWERS.

RODRIGUEZ

//DISCUSSION...UPDATED 18Z...

MOSTLY CLEAR SKIES STILL PRESENT ACROSS THE TERMINALS EARLY THIS
AFTERNOON...WHILE NORTHWEST WINDS CONTINUE TO SLOWLY INCREASE.
DEVELOPING DIURNAL STRATOCU WILL SPREAD OVER THE AREA OVER THE
NEXT 1-2 HOURS AND ALTHOUGH THERE MAY BE A BRIEF PERIOD OF HIGH
END MVFR CEILINGS...DO THINK THAT VFR CEILINGS WILL PREVAIL THIS
AFTERNOON. NORTHWEST WINDS/GUSTS WILL STEADILY INCREASE OVER THE
NEXT COUPLE OF HOURS WITH A POSSIBILITY REMAINING FOR WINDS TO
BRIEFLY GO MORE NORTHERLY. THIS SHOULD ALSO BE BRIEF WITH A
NORTHWEST WIND LIKELY FAVORED. WITH VFR CEILINGS REMAINING
OVERHEAD TONIGHT...THE NORTHWEST WINDS WILL DIMINISH BEFORE
QUICKLY INCREASING ABOVE 10 KT OUT OF THE NORTHEAST EARLY TUESDAY
MORNING. AS THIS OCCURS...ANTICIPATE ALREADY PRESENT MVFR CEILINGS
OVER THE LAKE TO MOVE WEST ACROSS THE TERMINALS...EXCEPT RFD.
THERE WILL ALSO BE A PERIOD OF SCATTERED LIGHT SHOWERS TO SPILL
OFF THE LAKE DURING THIS TIME...BUT WITH MDW/GYY THE LIKELY
LOCATIONS TO OBSERVE THIS PRECIP.

RODRIGUEZ

//ORD AND MDW CONFIDENCE...UPDATED 18Z...

* MEDIUM HIGH CONFIDENCE WITH WIND SPEED/DIRECTION.

* HIGH CONFIDENCE WITH VFR CEILINGS...MEDIUM CONFIDENCE WITH MVFR
  CEILINGS.

* MEDIUM CONFIDENCE WITH LIGHT SHOWERS.

RODRIGUEZ

//OUTLOOK FOR ORD/MDW FOR 00Z WEDNESDAY-12Z MONDAY...UPDATED 12Z...

* TUESDAY NIGHT...DRY/VFR.
* WEDNESDAY...DRY/VFR. EAST/NORTHEAST WINDS.
* THURSDAY...DRY/VFR. SOUTH WINDS.
* FRIDAY...DRY/VFR. SOUTHWEST WINDS.
* SATURDAY...DRY/VFR. WEST WINDS.
* SUNDAY...DRY/VFR. SOUTH WINDS.

&&

.MARINE...

250 PM...LOW PRESSURE CONTINUES TO INFLUENCE THE REGION CENTERED
OVER NORTHERN LAKE HURON LATE THIS AFTERNOON AND IS EXPECTED TO
SLOWLY DRIFT EAST OVERNIGHT. THIS LOW WILL THEN REACH LAKE ONTARIO
AROUND DAYBREAK TUE. THE BACK EDGE OF THIS LOW CONTINUES TO
FEATURE A TIGHTENING PRESSURE GRADIENT...WHICH HAS PRODUCED GUSTY
WINDS JUST BEGINNING TO SLIDE OVER THE NORTHERN PORTIONS OF THE
LAKE. THESE GUSTY WINDS WILL EVENTUALLY SLIDE SOUTH THIS
EVENING...AND EXPECT NORTH GUSTS UP TO 30 KTS. HIGH PRESSURE OVER
ONTARIO WILL BEGIN TO BUILD SOUTH OVERNIGHT...THEN STRETCH FROM
ONTARIO SOUTH TO THE WESTERN GULF OF MEXICO BY TUE NGT. THIS WILL
BRING MUCH LIGHTER WINDS TO THE LAKE BY WED.

BEACHLER

&&

.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...SMALL CRAFT ADVISORY...LMZ740-LMZ741-LMZ742-LMZ743-LMZ744-
     LMZ745...10 PM MONDAY TO 7 AM WEDNESDAY.

&&

$$

VISIT US AT HTTP://WEATHER.GOV/CHICAGO (ALL LOWERCASE)

FOLLOW US ON FACEBOOK...TWITTER...AND YOUTUBE AT:
WWW.FACEBOOK.COM/NWSCHICAGO
WWW.TWITTER.COM/NWSCHICAGO
WWW.YOUTUBE.COM/NWSCHICAGO







000
FXUS63 KLOT 201813
AFDLOT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
113 PM CDT MON OCT 20 2014

.DISCUSSION...
557 AM CDT

WE ARE SEEING SCATTERED SHOWERS SPARK NEAR CHICAGO AS OF 555 AM
AHEAD OF THE UPPER DISTURBANCE MENTIONED IN THE PREVIOUS
DISCUSSION. THIS DISTURBANCE HAS A POCKET OF STEEP LAPSE RATES
ALOFT /500MB-750MB/ OF 8C/KM AND GREATER AND THAT IS AIDING SOME
OF THESE SHOWER UPDRAFTS. THIS IS INDICATED BY A COUPLE LIGHTNING
STRIKES OVER LAKE MI AND THE OBSERVERS AT ORD AND MDW REPORTING
INTRA-CLOUD AND CLOUD-TO-AIR LIGHTNING. THE GOOD NEWS IS THIS
UPPER WAVE AND ITS FORCING IS MOVING ABOUT 35-40 MPH SO NOT
EXPECTING THESE TO STICK AROUND THE CHICAGO AREA AFTER 7 AM.
CONTINUE THE SHOWER CHANCES THIS MORNING AS IS IN NORTHWEST
INDIANA AND HAVE ADDED A SLIGHT CHANCE OF THUNDER FOR AREAS NEAR
THE I-80/I-90 CORRIDOR.

MTF

//PREV DISCUSSION...
319 AM CDT

A QUIET WEATHER PATTERN WILL REMAIN IN PLACE IN TERMS OF LACK OF
PRECIPITATION CHANCES AND ANY HIGH IMPACT WEATHER THROUGH NEXT
WEEKEND...THOUGH STILL SEVERAL LITTLE INTERESTS TO TACKLE. THESE
INCLUDED HOW WIDESPREAD CLOUDS WILL REACH LATER TODAY THROUGH
TUESDAY AS WELL AS LAKE EFFECT SHOWER POTENTIAL DURING THAT TIME.
THEN LOOKING AT WHEN AND HOW QUICKLY OF A WARM-UP OCCURS LATE IN
THE WEEK INTO THE WEEKEND.

TODAY THROUGH TUESDAY...
THE CONTINUED AMPLIFIED BUT PROGRESSIVE FLOW OVER CANADA AND THE
NORTHERN CONUS CONTINUES FOR A LITTLE LONGER WITH A PACIFIC/CLIPPER
HYBRID SYSTEM MOVING SOUTHEASTWARD FROM THE CENTRAL GREAT LAKES.
AROUND THIS A WELL-DEFINED SHORT WAVE ON GOES WATER VAPOR IMAGERY IS
MOVING INTO NORTHERN IL EARLY THIS MORNING. THIS IS FAIRLY MOISTURE
STARVED BUT CANNOT RULE OUT A FEW SHOWERS THIS MORNING MAINLY IN
NORTHWEST INDIANA. THIS SHORT WAVE ALSO BEGINS TO BREAK DOWN THE
LOW-LEVEL THERMAL RIDGE OVER THE AREA...WITH CLOUDS LIKELY TO
ADVECT/DEVELOP SOUTHWARD INTO THE FORECAST AREA THIS AFTERNOON. IN
ADDITION...TEMPERATURES MAY ALSO PEAK EARLY IN THE AFTERNOON AND
THEN EXPERIENCE A SLOW DROP. TEMPERATURES SHOULD STILL PEAK AROUND
CLIMATOLOGICAL NORMAL /60 TO 65/ WITH THE MORNING SUN. THE CYCLONIC
FLOW OVER THE REGION AND RAPIDLY COOLING 850-925MB TEMPERATURES LOOK
TO SUPPORT CLOUDS OVER MUCH OF THE AREA BY EARLY THIS EVENING AND
UPSTREAM OBSERVATIONAL TRENDS SUPPORT THIS. HAVE GONE WELL ABOVE
MOST GUIDANCE IN SKY COVER FROM LATE TODAY ALL THE WAY THROUGH
TUESDAY MORNING AS HIGH-RESOLUTION MODEL CONDENSATE /SUCH AS THE
4KM SPC WRF/ SEEMS TO WORK BETTER IN SUCH A PATTERN WITH THIN BUT
PROBABLY BROKEN-OVERCAST CLOUD COVER. THE CLOUDS AND NORTH-
NORTHEAST WINDS ON TUESDAY MORNING SHOULD LIMIT WARMING BY QUITE A
BIT WITH SOME LOCATIONS POSSIBLY NOT REACHING 50.

AS THE COOLER AIR AT OR AROUND 0C AT 850MB EXPANDS SOUTHWARD DOWN
THE LAKE LATER TODAY FORESEE DEEPENING LAKE EFFECT CLOUDS AND
SOME SHOWERS DEVELOPING. THESE SHOWERS LOOK TO BE NOT PARTICULARLY
CONCENTRATED WITH LIMITED CONVERGENCE AND MAINLY LIGHT IN
INTENSITY WITH LAKE-INDUCED EQUILIBRIUM LEVELS FORECAST BY THE
NAM OF AROUND 5000 FT. THE BOUNDARY LAYER FLOW FETCH SHOULD FAVOR
NORTHWEST INDIANA FOR THESE SHOWERS TONIGHT INTO EARLY
TUESDAY...THOUGH SOME VEERING TOWARD THE IL/IN STATE LINE AND EVEN
POTENTIALLY CHICAGO TUESDAY MORNING COULD SUPPORT SOME LIGHT
SHOWER ACTIVITY TUESDAY MORNING IN THOSE PLACES. THE HOPWRF-TS
SUPPORTS SUCH A GENERAL EVOLUTION WITH ITS RECENTLY ADDED EXTENDED
HIGH-RES OUTPUT.

TUESDAY NIGHT THROUGH THURSDAY...
SURFACE HIGH PRESSURE WILL BUILD OVER THE AREA FROM THE NORTH DURING
THIS TIME AS THE OVERALL UPPER PATTERN SLOWS THANKS TO AMPLIFICATION
OF A TROUGH ALONG THE WEST COAST OF NORTH AMERICA. OVERALL BENIGN
WEATHER LOOKS TO BE THE RULE WITH TEMPS SLIGHTLY BELOW NORMAL THOUGH
GRADUALLY MODIFYING. MODEL GUIDANCE DOES INDICATE AN ELONGATED SHORT
WAVE TO MOVE INTO THE UPPER MISSISSIPPI VALLEY DURING OR AROUND
THURSDAY NIGHT THOUGH THIS WILL BE MOVING INTO AN UNFAVORABLE
UPPER LEVEL AND MOISTURE SUPPORTIVE PATTERN. SO CONTINUE THE DRY
FORECAST.

FRIDAY INTO NEXT WEEKEND...
THE ONLY CHANGE WITH THIS PORTION OF THE FORECAST WAS TO INCREASE
TEMPERATURES...MAINLY ON SATURDAY. IF CLOUD COVER CAN REMAIN LIMITED
WITH THE PATTERN FORECAST...THE 850MB-925MB TEMPERATURES WOULD
SUPPORT TEMPERATURES POTENTIALLY IN THE 70S WITH A THERMAL RIDGE
STEERED IN FROM THE WEST-SOUTHWEST.

MTF

&&

.AVIATION...

//ORD AND MDW CONCERNS...UPDATED 18Z...

* NORTHWEST WINDS/GUSTS BRIEFLY BECOMING MORE NORTHERLY THIS
  AFTERNOON...THEN BECOMING NORTHEAST WITH SPEEDS AT OR ABOVE 10
  KT TUESDAY MORNING.

* DEVELOPING VFR CEILINGS BECOMING MVFR EARLY TUESDAY MORNING.

* PERIODIC/ISOLATED LIGHT SHOWERS.

RODRIGUEZ

//DISCUSSION...UPDATED 18Z...

MOSTLY CLEAR SKIES STILL PRESENT ACROSS THE TERMINALS EARLY THIS
AFTERNOON...WHILE NORTHWEST WINDS CONTINUE TO SLOWLY INCREASE.
DEVELOPING DIURNAL STRATOCU WILL SPREAD OVER THE AREA OVER THE
NEXT 1-2 HOURS AND ALTHOUGH THERE MAY BE A BRIEF PERIOD OF HIGH
END MVFR CEILINGS...DO THINK THAT VFR CEILINGS WILL PREVAIL THIS
AFTERNOON. NORTHWEST WINDS/GUSTS WILL STEADILY INCREASE OVER THE
NEXT COUPLE OF HOURS WITH A POSSIBILITY REMAINING FOR WINDS TO
BRIEFLY GO MORE NORTHERLY. THIS SHOULD ALSO BE BRIEF WITH A
NORTHWEST WIND LIKELY FAVORED. WITH VFR CEILINGS REMAINING
OVERHEAD TONIGHT...THE NORTHWEST WINDS WILL DIMINISH BEFORE
QUICKLY INCREASING ABOVE 10 KT OUT OF THE NORTHEAST EARLY TUESDAY
MORNING. AS THIS OCCURS...ANTICIPATE ALREADY PRESENT MVFR CEILINGS
OVER THE LAKE TO MOVE WEST ACROSS THE TERMINALS...EXCEPT RFD.
THERE WILL ALSO BE A PERIOD OF SCATTERED LIGHT SHOWERS TO SPILL
OFF THE LAKE DURING THIS TIME...BUT WITH MDW/GYY THE LIKELY
LOCATIONS TO OBSERVE THIS PRECIP.

RODRIGUEZ


//ORD AND MDW CONFIDENCE...UPDATED 18Z...

* MEDIUM HIGH CONFIDENCE WITH WIND SPEED/DIRECTION.

* HIGH CONFIDENCE WITH VFR CEILINGS...MEDIUM CONFIDENCE WITH MVFR
  CEILINGS.

* MEDIUM CONFIDENCE WITH LIGHT SHOWERS.

RODRIGUEZ

//OUTLOOK FOR ORD/MDW FOR 00Z WEDNESDAY-12Z MONDAY...UPDATED 12Z...

* TUESDAY NIGHT...DRY/VFR.
* WEDNESDAY...DRY/VFR. EAST/NORTHEAST WINDS.
* THURSDAY...DRY/VFR. SOUTH WINDS.
* FRIDAY...DRY/VFR. SOUTHWEST WINDS.
* SATURDAY...DRY/VFR. WEST WINDS.
* SUNDAY...DRY/VFR. SOUTH WINDS.

&&

.MARINE...

309 AM...LOW PRESSURE OVER THE UPPER PENINSULA OF MICHIGAN WILL
MOVE SOUTHEAST TODAY AND TONIGHT REACHING THE MID ATLANTIC ON
TUESDAY. A TRAILING COLD FRONT WILL MOVE ACROSS LAKE MICHIGAN THIS
MORNING. SOUTHWEST WINDS WILL TURN NORTHWEST THIS MORNING THEN
NORTH THIS EVENING. THE GRADIENT REMAINS FAIRLY TIGHT ACROSS THE
SOUTHERN THIRD OR SO OF THE LAKE...WITH GUSTS TO 30KT POSSIBLE FOR
A FEW MORE HOURS. HIGH PRESSURE WILL BUILD ACROSS ONTARIO TODAY
AND TONIGHT AS IT STRENGTHENS. WHILE THE CENTER OF THIS HIGH WILL
MOVE EAST INTO QUEBEC TUESDAY NIGHT...A RIDGE WILL EXTEND SOUTH
ACROSS THE WESTERN LAKES TONIGHT AND TUESDAY...THEN MOVE ACROSS
THE LAKE WEDNESDAY. THE GRADIENT WILL TIGHTEN BETWEEN THIS
APPROACHING RIDGE AND THE DEPARTING LOW WITH NORTHERLY WINDS
INCREASING TO 30 KT THIS EVENING AND REMAINING THERE UNTIL TUESDAY
AFTERNOON...AS THE RIDGE SLOWLY WORKS EAST. CMS

&&

.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...SMALL CRAFT ADVISORY...LMZ740-LMZ741-LMZ742-LMZ743-LMZ744-
     LMZ745...10 PM MONDAY TO 7 AM WEDNESDAY.

&&

$$

VISIT US AT HTTP://WEATHER.GOV/CHICAGO (ALL LOWERCASE)

FOLLOW US ON FACEBOOK...TWITTER...AND YOUTUBE AT:
WWW.FACEBOOK.COM/NWSCHICAGO
WWW.TWITTER.COM/NWSCHICAGO
WWW.YOUTUBE.COM/NWSCHICAGO







000
FXUS63 KLOT 201813
AFDLOT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
113 PM CDT MON OCT 20 2014

.DISCUSSION...
557 AM CDT

WE ARE SEEING SCATTERED SHOWERS SPARK NEAR CHICAGO AS OF 555 AM
AHEAD OF THE UPPER DISTURBANCE MENTIONED IN THE PREVIOUS
DISCUSSION. THIS DISTURBANCE HAS A POCKET OF STEEP LAPSE RATES
ALOFT /500MB-750MB/ OF 8C/KM AND GREATER AND THAT IS AIDING SOME
OF THESE SHOWER UPDRAFTS. THIS IS INDICATED BY A COUPLE LIGHTNING
STRIKES OVER LAKE MI AND THE OBSERVERS AT ORD AND MDW REPORTING
INTRA-CLOUD AND CLOUD-TO-AIR LIGHTNING. THE GOOD NEWS IS THIS
UPPER WAVE AND ITS FORCING IS MOVING ABOUT 35-40 MPH SO NOT
EXPECTING THESE TO STICK AROUND THE CHICAGO AREA AFTER 7 AM.
CONTINUE THE SHOWER CHANCES THIS MORNING AS IS IN NORTHWEST
INDIANA AND HAVE ADDED A SLIGHT CHANCE OF THUNDER FOR AREAS NEAR
THE I-80/I-90 CORRIDOR.

MTF

//PREV DISCUSSION...
319 AM CDT

A QUIET WEATHER PATTERN WILL REMAIN IN PLACE IN TERMS OF LACK OF
PRECIPITATION CHANCES AND ANY HIGH IMPACT WEATHER THROUGH NEXT
WEEKEND...THOUGH STILL SEVERAL LITTLE INTERESTS TO TACKLE. THESE
INCLUDED HOW WIDESPREAD CLOUDS WILL REACH LATER TODAY THROUGH
TUESDAY AS WELL AS LAKE EFFECT SHOWER POTENTIAL DURING THAT TIME.
THEN LOOKING AT WHEN AND HOW QUICKLY OF A WARM-UP OCCURS LATE IN
THE WEEK INTO THE WEEKEND.

TODAY THROUGH TUESDAY...
THE CONTINUED AMPLIFIED BUT PROGRESSIVE FLOW OVER CANADA AND THE
NORTHERN CONUS CONTINUES FOR A LITTLE LONGER WITH A PACIFIC/CLIPPER
HYBRID SYSTEM MOVING SOUTHEASTWARD FROM THE CENTRAL GREAT LAKES.
AROUND THIS A WELL-DEFINED SHORT WAVE ON GOES WATER VAPOR IMAGERY IS
MOVING INTO NORTHERN IL EARLY THIS MORNING. THIS IS FAIRLY MOISTURE
STARVED BUT CANNOT RULE OUT A FEW SHOWERS THIS MORNING MAINLY IN
NORTHWEST INDIANA. THIS SHORT WAVE ALSO BEGINS TO BREAK DOWN THE
LOW-LEVEL THERMAL RIDGE OVER THE AREA...WITH CLOUDS LIKELY TO
ADVECT/DEVELOP SOUTHWARD INTO THE FORECAST AREA THIS AFTERNOON. IN
ADDITION...TEMPERATURES MAY ALSO PEAK EARLY IN THE AFTERNOON AND
THEN EXPERIENCE A SLOW DROP. TEMPERATURES SHOULD STILL PEAK AROUND
CLIMATOLOGICAL NORMAL /60 TO 65/ WITH THE MORNING SUN. THE CYCLONIC
FLOW OVER THE REGION AND RAPIDLY COOLING 850-925MB TEMPERATURES LOOK
TO SUPPORT CLOUDS OVER MUCH OF THE AREA BY EARLY THIS EVENING AND
UPSTREAM OBSERVATIONAL TRENDS SUPPORT THIS. HAVE GONE WELL ABOVE
MOST GUIDANCE IN SKY COVER FROM LATE TODAY ALL THE WAY THROUGH
TUESDAY MORNING AS HIGH-RESOLUTION MODEL CONDENSATE /SUCH AS THE
4KM SPC WRF/ SEEMS TO WORK BETTER IN SUCH A PATTERN WITH THIN BUT
PROBABLY BROKEN-OVERCAST CLOUD COVER. THE CLOUDS AND NORTH-
NORTHEAST WINDS ON TUESDAY MORNING SHOULD LIMIT WARMING BY QUITE A
BIT WITH SOME LOCATIONS POSSIBLY NOT REACHING 50.

AS THE COOLER AIR AT OR AROUND 0C AT 850MB EXPANDS SOUTHWARD DOWN
THE LAKE LATER TODAY FORESEE DEEPENING LAKE EFFECT CLOUDS AND
SOME SHOWERS DEVELOPING. THESE SHOWERS LOOK TO BE NOT PARTICULARLY
CONCENTRATED WITH LIMITED CONVERGENCE AND MAINLY LIGHT IN
INTENSITY WITH LAKE-INDUCED EQUILIBRIUM LEVELS FORECAST BY THE
NAM OF AROUND 5000 FT. THE BOUNDARY LAYER FLOW FETCH SHOULD FAVOR
NORTHWEST INDIANA FOR THESE SHOWERS TONIGHT INTO EARLY
TUESDAY...THOUGH SOME VEERING TOWARD THE IL/IN STATE LINE AND EVEN
POTENTIALLY CHICAGO TUESDAY MORNING COULD SUPPORT SOME LIGHT
SHOWER ACTIVITY TUESDAY MORNING IN THOSE PLACES. THE HOPWRF-TS
SUPPORTS SUCH A GENERAL EVOLUTION WITH ITS RECENTLY ADDED EXTENDED
HIGH-RES OUTPUT.

TUESDAY NIGHT THROUGH THURSDAY...
SURFACE HIGH PRESSURE WILL BUILD OVER THE AREA FROM THE NORTH DURING
THIS TIME AS THE OVERALL UPPER PATTERN SLOWS THANKS TO AMPLIFICATION
OF A TROUGH ALONG THE WEST COAST OF NORTH AMERICA. OVERALL BENIGN
WEATHER LOOKS TO BE THE RULE WITH TEMPS SLIGHTLY BELOW NORMAL THOUGH
GRADUALLY MODIFYING. MODEL GUIDANCE DOES INDICATE AN ELONGATED SHORT
WAVE TO MOVE INTO THE UPPER MISSISSIPPI VALLEY DURING OR AROUND
THURSDAY NIGHT THOUGH THIS WILL BE MOVING INTO AN UNFAVORABLE
UPPER LEVEL AND MOISTURE SUPPORTIVE PATTERN. SO CONTINUE THE DRY
FORECAST.

FRIDAY INTO NEXT WEEKEND...
THE ONLY CHANGE WITH THIS PORTION OF THE FORECAST WAS TO INCREASE
TEMPERATURES...MAINLY ON SATURDAY. IF CLOUD COVER CAN REMAIN LIMITED
WITH THE PATTERN FORECAST...THE 850MB-925MB TEMPERATURES WOULD
SUPPORT TEMPERATURES POTENTIALLY IN THE 70S WITH A THERMAL RIDGE
STEERED IN FROM THE WEST-SOUTHWEST.

MTF

&&

.AVIATION...

//ORD AND MDW CONCERNS...UPDATED 18Z...

* NORTHWEST WINDS/GUSTS BRIEFLY BECOMING MORE NORTHERLY THIS
  AFTERNOON...THEN BECOMING NORTHEAST WITH SPEEDS AT OR ABOVE 10
  KT TUESDAY MORNING.

* DEVELOPING VFR CEILINGS BECOMING MVFR EARLY TUESDAY MORNING.

* PERIODIC/ISOLATED LIGHT SHOWERS.

RODRIGUEZ

//DISCUSSION...UPDATED 18Z...

MOSTLY CLEAR SKIES STILL PRESENT ACROSS THE TERMINALS EARLY THIS
AFTERNOON...WHILE NORTHWEST WINDS CONTINUE TO SLOWLY INCREASE.
DEVELOPING DIURNAL STRATOCU WILL SPREAD OVER THE AREA OVER THE
NEXT 1-2 HOURS AND ALTHOUGH THERE MAY BE A BRIEF PERIOD OF HIGH
END MVFR CEILINGS...DO THINK THAT VFR CEILINGS WILL PREVAIL THIS
AFTERNOON. NORTHWEST WINDS/GUSTS WILL STEADILY INCREASE OVER THE
NEXT COUPLE OF HOURS WITH A POSSIBILITY REMAINING FOR WINDS TO
BRIEFLY GO MORE NORTHERLY. THIS SHOULD ALSO BE BRIEF WITH A
NORTHWEST WIND LIKELY FAVORED. WITH VFR CEILINGS REMAINING
OVERHEAD TONIGHT...THE NORTHWEST WINDS WILL DIMINISH BEFORE
QUICKLY INCREASING ABOVE 10 KT OUT OF THE NORTHEAST EARLY TUESDAY
MORNING. AS THIS OCCURS...ANTICIPATE ALREADY PRESENT MVFR CEILINGS
OVER THE LAKE TO MOVE WEST ACROSS THE TERMINALS...EXCEPT RFD.
THERE WILL ALSO BE A PERIOD OF SCATTERED LIGHT SHOWERS TO SPILL
OFF THE LAKE DURING THIS TIME...BUT WITH MDW/GYY THE LIKELY
LOCATIONS TO OBSERVE THIS PRECIP.

RODRIGUEZ


//ORD AND MDW CONFIDENCE...UPDATED 18Z...

* MEDIUM HIGH CONFIDENCE WITH WIND SPEED/DIRECTION.

* HIGH CONFIDENCE WITH VFR CEILINGS...MEDIUM CONFIDENCE WITH MVFR
  CEILINGS.

* MEDIUM CONFIDENCE WITH LIGHT SHOWERS.

RODRIGUEZ

//OUTLOOK FOR ORD/MDW FOR 00Z WEDNESDAY-12Z MONDAY...UPDATED 12Z...

* TUESDAY NIGHT...DRY/VFR.
* WEDNESDAY...DRY/VFR. EAST/NORTHEAST WINDS.
* THURSDAY...DRY/VFR. SOUTH WINDS.
* FRIDAY...DRY/VFR. SOUTHWEST WINDS.
* SATURDAY...DRY/VFR. WEST WINDS.
* SUNDAY...DRY/VFR. SOUTH WINDS.

&&

.MARINE...

309 AM...LOW PRESSURE OVER THE UPPER PENINSULA OF MICHIGAN WILL
MOVE SOUTHEAST TODAY AND TONIGHT REACHING THE MID ATLANTIC ON
TUESDAY. A TRAILING COLD FRONT WILL MOVE ACROSS LAKE MICHIGAN THIS
MORNING. SOUTHWEST WINDS WILL TURN NORTHWEST THIS MORNING THEN
NORTH THIS EVENING. THE GRADIENT REMAINS FAIRLY TIGHT ACROSS THE
SOUTHERN THIRD OR SO OF THE LAKE...WITH GUSTS TO 30KT POSSIBLE FOR
A FEW MORE HOURS. HIGH PRESSURE WILL BUILD ACROSS ONTARIO TODAY
AND TONIGHT AS IT STRENGTHENS. WHILE THE CENTER OF THIS HIGH WILL
MOVE EAST INTO QUEBEC TUESDAY NIGHT...A RIDGE WILL EXTEND SOUTH
ACROSS THE WESTERN LAKES TONIGHT AND TUESDAY...THEN MOVE ACROSS
THE LAKE WEDNESDAY. THE GRADIENT WILL TIGHTEN BETWEEN THIS
APPROACHING RIDGE AND THE DEPARTING LOW WITH NORTHERLY WINDS
INCREASING TO 30 KT THIS EVENING AND REMAINING THERE UNTIL TUESDAY
AFTERNOON...AS THE RIDGE SLOWLY WORKS EAST. CMS

&&

.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...SMALL CRAFT ADVISORY...LMZ740-LMZ741-LMZ742-LMZ743-LMZ744-
     LMZ745...10 PM MONDAY TO 7 AM WEDNESDAY.

&&

$$

VISIT US AT HTTP://WEATHER.GOV/CHICAGO (ALL LOWERCASE)

FOLLOW US ON FACEBOOK...TWITTER...AND YOUTUBE AT:
WWW.FACEBOOK.COM/NWSCHICAGO
WWW.TWITTER.COM/NWSCHICAGO
WWW.YOUTUBE.COM/NWSCHICAGO






000
FXUS63 KLOT 201622
AFDLOT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
1122 AM CDT MON OCT 20 2014

.DISCUSSION...
557 AM CDT

WE ARE SEEING SCATTERED SHOWERS SPARK NEAR CHICAGO AS OF 555 AM
AHEAD OF THE UPPER DISTURBANCE MENTIONED IN THE PREVIOUS
DISCUSSION. THIS DISTURBANCE HAS A POCKET OF STEEP LAPSE RATES
ALOFT /500MB-750MB/ OF 8C/KM AND GREATER AND THAT IS AIDING SOME
OF THESE SHOWER UPDRAFTS. THIS IS INDICATED BY A COUPLE LIGHTNING
STRIKES OVER LAKE MI AND THE OBSERVERS AT ORD AND MDW REPORTING
INTRA-CLOUD AND CLOUD-TO-AIR LIGHTNING. THE GOOD NEWS IS THIS
UPPER WAVE AND ITS FORCING IS MOVING ABOUT 35-40 MPH SO NOT
EXPECTING THESE TO STICK AROUND THE CHICAGO AREA AFTER 7 AM.
CONTINUE THE SHOWER CHANCES THIS MORNING AS IS IN NORTHWEST
INDIANA AND HAVE ADDED A SLIGHT CHANCE OF THUNDER FOR AREAS NEAR
THE I-80/I-90 CORRIDOR.

MTF

//PREV DISCUSSION...
319 AM CDT

A QUIET WEATHER PATTERN WILL REMAIN IN PLACE IN TERMS OF LACK OF
PRECIPITATION CHANCES AND ANY HIGH IMPACT WEATHER THROUGH NEXT
WEEKEND...THOUGH STILL SEVERAL LITTLE INTERESTS TO TACKLE. THESE
INCLUDED HOW WIDESPREAD CLOUDS WILL REACH LATER TODAY THROUGH
TUESDAY AS WELL AS LAKE EFFECT SHOWER POTENTIAL DURING THAT TIME.
THEN LOOKING AT WHEN AND HOW QUICKLY OF A WARM-UP OCCURS LATE IN
THE WEEK INTO THE WEEKEND.

TODAY THROUGH TUESDAY...
THE CONTINUED AMPLIFIED BUT PROGRESSIVE FLOW OVER CANADA AND THE
NORTHERN CONUS CONTINUES FOR A LITTLE LONGER WITH A PACIFIC/CLIPPER
HYBRID SYSTEM MOVING SOUTHEASTWARD FROM THE CENTRAL GREAT LAKES.
AROUND THIS A WELL-DEFINED SHORT WAVE ON GOES WATER VAPOR IMAGERY IS
MOVING INTO NORTHERN IL EARLY THIS MORNING. THIS IS FAIRLY MOISTURE
STARVED BUT CANNOT RULE OUT A FEW SHOWERS THIS MORNING MAINLY IN
NORTHWEST INDIANA. THIS SHORT WAVE ALSO BEGINS TO BREAK DOWN THE
LOW-LEVEL THERMAL RIDGE OVER THE AREA...WITH CLOUDS LIKELY TO
ADVECT/DEVELOP SOUTHWARD INTO THE FORECAST AREA THIS AFTERNOON. IN
ADDITION...TEMPERATURES MAY ALSO PEAK EARLY IN THE AFTERNOON AND
THEN EXPERIENCE A SLOW DROP. TEMPERATURES SHOULD STILL PEAK AROUND
CLIMATOLOGICAL NORMAL /60 TO 65/ WITH THE MORNING SUN. THE CYCLONIC
FLOW OVER THE REGION AND RAPIDLY COOLING 850-925MB TEMPERATURES LOOK
TO SUPPORT CLOUDS OVER MUCH OF THE AREA BY EARLY THIS EVENING AND
UPSTREAM OBSERVATIONAL TRENDS SUPPORT THIS. HAVE GONE WELL ABOVE
MOST GUIDANCE IN SKY COVER FROM LATE TODAY ALL THE WAY THROUGH
TUESDAY MORNING AS HIGH-RESOLUTION MODEL CONDENSATE /SUCH AS THE
4KM SPC WRF/ SEEMS TO WORK BETTER IN SUCH A PATTERN WITH THIN BUT
PROBABLY BROKEN-OVERCAST CLOUD COVER. THE CLOUDS AND NORTH-
NORTHEAST WINDS ON TUESDAY MORNING SHOULD LIMIT WARMING BY QUITE A
BIT WITH SOME LOCATIONS POSSIBLY NOT REACHING 50.

AS THE COOLER AIR AT OR AROUND 0C AT 850MB EXPANDS SOUTHWARD DOWN
THE LAKE LATER TODAY FORESEE DEEPENING LAKE EFFECT CLOUDS AND
SOME SHOWERS DEVELOPING. THESE SHOWERS LOOK TO BE NOT PARTICULARLY
CONCENTRATED WITH LIMITED CONVERGENCE AND MAINLY LIGHT IN
INTENSITY WITH LAKE-INDUCED EQUILIBRIUM LEVELS FORECAST BY THE
NAM OF AROUND 5000 FT. THE BOUNDARY LAYER FLOW FETCH SHOULD FAVOR
NORTHWEST INDIANA FOR THESE SHOWERS TONIGHT INTO EARLY
TUESDAY...THOUGH SOME VEERING TOWARD THE IL/IN STATE LINE AND EVEN
POTENTIALLY CHICAGO TUESDAY MORNING COULD SUPPORT SOME LIGHT
SHOWER ACTIVITY TUESDAY MORNING IN THOSE PLACES. THE HOPWRF-TS
SUPPORTS SUCH A GENERAL EVOLUTION WITH ITS RECENTLY ADDED EXTENDED
HIGH-RES OUTPUT.

TUESDAY NIGHT THROUGH THURSDAY...
SURFACE HIGH PRESSURE WILL BUILD OVER THE AREA FROM THE NORTH DURING
THIS TIME AS THE OVERALL UPPER PATTERN SLOWS THANKS TO AMPLIFICATION
OF A TROUGH ALONG THE WEST COAST OF NORTH AMERICA. OVERALL BENIGN
WEATHER LOOKS TO BE THE RULE WITH TEMPS SLIGHTLY BELOW NORMAL THOUGH
GRADUALLY MODIFYING. MODEL GUIDANCE DOES INDICATE AN ELONGATED SHORT
WAVE TO MOVE INTO THE UPPER MISSISSIPPI VALLEY DURING OR AROUND
THURSDAY NIGHT THOUGH THIS WILL BE MOVING INTO AN UNFAVORABLE
UPPER LEVEL AND MOISTURE SUPPORTIVE PATTERN. SO CONTINUE THE DRY
FORECAST.

FRIDAY INTO NEXT WEEKEND...
THE ONLY CHANGE WITH THIS PORTION OF THE FORECAST WAS TO INCREASE
TEMPERATURES...MAINLY ON SATURDAY. IF CLOUD COVER CAN REMAIN LIMITED
WITH THE PATTERN FORECAST...THE 850MB-925MB TEMPERATURES WOULD
SUPPORT TEMPERATURES POTENTIALLY IN THE 70S WITH A THERMAL RIDGE
STEERED IN FROM THE WEST-SOUTHWEST.

MTF

&&

.AVIATION...

//ORD AND MDW CONCERNS...UPDATED 16Z...

* NORTHWEST WINDS BRIEFLY BECOMING MORE NORTHERLY THIS
  AFTERNOON...WITH GUSTS DEVELOPING BY MIDDAY.

* POSSIBLE MVFR CIGS TODAY AND EVENING.

RODRIGUEZ

//DISCUSSION...UPDATED 12Z...

LINE OF SHRA/TSRA DEVELOPED OVER FAR NORTHEAST IL IN THE PAST HOUR
OR SO AHEAD OF AN UPPER LEVEL WAVE. THIS ACTIVITY WILL CONTINUE TO
MOVE EAST...AFFECTING GYY SHORTLY. THE SURFACE COLD FRONT WILL
MOVE ACROSS THE TERMINALS THIS MORNING SHIFTING WEST/SOUTHWEST
WINDS TO THE NORTHWEST. WINDS WILL CONTINUE TO SLOWLY TURN MORE
NORTH/NORTHWEST BY MID/LATE AFTERNOON. THE GRADIENT IS THEN
EXPECTED TO WEAKEN ENOUGH FOR WIND DIRECTIONS TO SHIFT TO THE
NORTH/NORTHEAST EITHER LATE THIS AFTERNOON OR EARLY THIS EVENING
WITH PREVAILING SPEEDS AT THAT TIME LIKELY UNDER 10KTS. WINDS WILL
TURN BACK TO THE NORTH/NORTHWEST OVERNIGHT.

LOW VFR/HIGH MVFR CIGS ACROSS NORTHERN WI WILL MOVE SOUTH THIS
MORNING REACHING THE TERMINALS LATE THIS MORNING OR EARLY THIS
AFTERNOON. CONFIDENCE REGARDING SPECIFIC CIG HEIGHTS IS FAIRLY LOW
WITH CIGS POSSIBLE DIPPING INTO HIGH MVFR FROM MID AFTERNOON INTO
THE EVENING HOURS.

//ORD AND MDW CONFIDENCE...UPDATED 16Z...

* HIGH CONFIDENCE WITH WIND SPEED/DIRECTION THROUGH EARLY
  AFTERNOON...THEN MEDIUM CONFIDENCE WITH DIRECTION LATER THIS
  AFTERNOON.

* MEDIUM CONFIDENCE WITH MVFR CIGS TODAY AND EVENING.

RODRIGUEZ

//OUTLOOK FOR ORD/MDW FOR 00Z WEDNESDAY-12Z MONDAY...UPDATED 12Z...

* TUESDAY NIGHT...DRY/VFR.
* WEDNESDAY...DRY/VFR. EAST/NORTHEAST WINDS.
* THURSDAY...DRY/VFR. SOUTH WINDS.
* FRIDAY...DRY/VFR. SOUTHWEST WINDS.
* SATURDAY...DRY/VFR. WEST WINDS.
* SUNDAY...DRY/VFR. SOUTH WINDS.

&&

.MARINE...

309 AM...LOW PRESSURE OVER THE UPPER PENINSULA OF MICHIGAN WILL
MOVE SOUTHEAST TODAY AND TONIGHT REACHING THE MID ATLANTIC ON
TUESDAY. A TRAILING COLD FRONT WILL MOVE ACROSS LAKE MICHIGAN THIS
MORNING. SOUTHWEST WINDS WILL TURN NORTHWEST THIS MORNING THEN
NORTH THIS EVENING. THE GRADIENT REMAINS FAIRLY TIGHT ACROSS THE
SOUTHERN THIRD OR SO OF THE LAKE...WITH GUSTS TO 30KT POSSIBLE FOR
A FEW MORE HOURS. HIGH PRESSURE WILL BUILD ACROSS ONTARIO TODAY
AND TONIGHT AS IT STRENGTHENS. WHILE THE CENTER OF THIS HIGH WILL
MOVE EAST INTO QUEBEC TUESDAY NIGHT...A RIDGE WILL EXTEND SOUTH
ACROSS THE WESTERN LAKES TONIGHT AND TUESDAY...THEN MOVE ACROSS
THE LAKE WEDNESDAY. THE GRADIENT WILL TIGHTEN BETWEEN THIS
APPROACHING RIDGE AND THE DEPARTING LOW WITH NORTHERLY WINDS
INCREASING TO 30 KT THIS EVENING AND REMAINING THERE UNTIL TUESDAY
AFTERNOON...AS THE RIDGE SLOWLY WORKS EAST. CMS

&&

.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...SMALL CRAFT ADVISORY...LMZ740-LMZ741-LMZ742-LMZ743-LMZ744-
     LMZ745...10 PM MONDAY TO 7 AM WEDNESDAY.

&&

$$

VISIT US AT HTTP://WEATHER.GOV/CHICAGO (ALL LOWERCASE)

FOLLOW US ON FACEBOOK...TWITTER...AND YOUTUBE AT:
WWW.FACEBOOK.COM/NWSCHICAGO
WWW.TWITTER.COM/NWSCHICAGO
WWW.YOUTUBE.COM/NWSCHICAGO







000
FXUS63 KLOT 201622
AFDLOT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
1122 AM CDT MON OCT 20 2014

.DISCUSSION...
557 AM CDT

WE ARE SEEING SCATTERED SHOWERS SPARK NEAR CHICAGO AS OF 555 AM
AHEAD OF THE UPPER DISTURBANCE MENTIONED IN THE PREVIOUS
DISCUSSION. THIS DISTURBANCE HAS A POCKET OF STEEP LAPSE RATES
ALOFT /500MB-750MB/ OF 8C/KM AND GREATER AND THAT IS AIDING SOME
OF THESE SHOWER UPDRAFTS. THIS IS INDICATED BY A COUPLE LIGHTNING
STRIKES OVER LAKE MI AND THE OBSERVERS AT ORD AND MDW REPORTING
INTRA-CLOUD AND CLOUD-TO-AIR LIGHTNING. THE GOOD NEWS IS THIS
UPPER WAVE AND ITS FORCING IS MOVING ABOUT 35-40 MPH SO NOT
EXPECTING THESE TO STICK AROUND THE CHICAGO AREA AFTER 7 AM.
CONTINUE THE SHOWER CHANCES THIS MORNING AS IS IN NORTHWEST
INDIANA AND HAVE ADDED A SLIGHT CHANCE OF THUNDER FOR AREAS NEAR
THE I-80/I-90 CORRIDOR.

MTF

//PREV DISCUSSION...
319 AM CDT

A QUIET WEATHER PATTERN WILL REMAIN IN PLACE IN TERMS OF LACK OF
PRECIPITATION CHANCES AND ANY HIGH IMPACT WEATHER THROUGH NEXT
WEEKEND...THOUGH STILL SEVERAL LITTLE INTERESTS TO TACKLE. THESE
INCLUDED HOW WIDESPREAD CLOUDS WILL REACH LATER TODAY THROUGH
TUESDAY AS WELL AS LAKE EFFECT SHOWER POTENTIAL DURING THAT TIME.
THEN LOOKING AT WHEN AND HOW QUICKLY OF A WARM-UP OCCURS LATE IN
THE WEEK INTO THE WEEKEND.

TODAY THROUGH TUESDAY...
THE CONTINUED AMPLIFIED BUT PROGRESSIVE FLOW OVER CANADA AND THE
NORTHERN CONUS CONTINUES FOR A LITTLE LONGER WITH A PACIFIC/CLIPPER
HYBRID SYSTEM MOVING SOUTHEASTWARD FROM THE CENTRAL GREAT LAKES.
AROUND THIS A WELL-DEFINED SHORT WAVE ON GOES WATER VAPOR IMAGERY IS
MOVING INTO NORTHERN IL EARLY THIS MORNING. THIS IS FAIRLY MOISTURE
STARVED BUT CANNOT RULE OUT A FEW SHOWERS THIS MORNING MAINLY IN
NORTHWEST INDIANA. THIS SHORT WAVE ALSO BEGINS TO BREAK DOWN THE
LOW-LEVEL THERMAL RIDGE OVER THE AREA...WITH CLOUDS LIKELY TO
ADVECT/DEVELOP SOUTHWARD INTO THE FORECAST AREA THIS AFTERNOON. IN
ADDITION...TEMPERATURES MAY ALSO PEAK EARLY IN THE AFTERNOON AND
THEN EXPERIENCE A SLOW DROP. TEMPERATURES SHOULD STILL PEAK AROUND
CLIMATOLOGICAL NORMAL /60 TO 65/ WITH THE MORNING SUN. THE CYCLONIC
FLOW OVER THE REGION AND RAPIDLY COOLING 850-925MB TEMPERATURES LOOK
TO SUPPORT CLOUDS OVER MUCH OF THE AREA BY EARLY THIS EVENING AND
UPSTREAM OBSERVATIONAL TRENDS SUPPORT THIS. HAVE GONE WELL ABOVE
MOST GUIDANCE IN SKY COVER FROM LATE TODAY ALL THE WAY THROUGH
TUESDAY MORNING AS HIGH-RESOLUTION MODEL CONDENSATE /SUCH AS THE
4KM SPC WRF/ SEEMS TO WORK BETTER IN SUCH A PATTERN WITH THIN BUT
PROBABLY BROKEN-OVERCAST CLOUD COVER. THE CLOUDS AND NORTH-
NORTHEAST WINDS ON TUESDAY MORNING SHOULD LIMIT WARMING BY QUITE A
BIT WITH SOME LOCATIONS POSSIBLY NOT REACHING 50.

AS THE COOLER AIR AT OR AROUND 0C AT 850MB EXPANDS SOUTHWARD DOWN
THE LAKE LATER TODAY FORESEE DEEPENING LAKE EFFECT CLOUDS AND
SOME SHOWERS DEVELOPING. THESE SHOWERS LOOK TO BE NOT PARTICULARLY
CONCENTRATED WITH LIMITED CONVERGENCE AND MAINLY LIGHT IN
INTENSITY WITH LAKE-INDUCED EQUILIBRIUM LEVELS FORECAST BY THE
NAM OF AROUND 5000 FT. THE BOUNDARY LAYER FLOW FETCH SHOULD FAVOR
NORTHWEST INDIANA FOR THESE SHOWERS TONIGHT INTO EARLY
TUESDAY...THOUGH SOME VEERING TOWARD THE IL/IN STATE LINE AND EVEN
POTENTIALLY CHICAGO TUESDAY MORNING COULD SUPPORT SOME LIGHT
SHOWER ACTIVITY TUESDAY MORNING IN THOSE PLACES. THE HOPWRF-TS
SUPPORTS SUCH A GENERAL EVOLUTION WITH ITS RECENTLY ADDED EXTENDED
HIGH-RES OUTPUT.

TUESDAY NIGHT THROUGH THURSDAY...
SURFACE HIGH PRESSURE WILL BUILD OVER THE AREA FROM THE NORTH DURING
THIS TIME AS THE OVERALL UPPER PATTERN SLOWS THANKS TO AMPLIFICATION
OF A TROUGH ALONG THE WEST COAST OF NORTH AMERICA. OVERALL BENIGN
WEATHER LOOKS TO BE THE RULE WITH TEMPS SLIGHTLY BELOW NORMAL THOUGH
GRADUALLY MODIFYING. MODEL GUIDANCE DOES INDICATE AN ELONGATED SHORT
WAVE TO MOVE INTO THE UPPER MISSISSIPPI VALLEY DURING OR AROUND
THURSDAY NIGHT THOUGH THIS WILL BE MOVING INTO AN UNFAVORABLE
UPPER LEVEL AND MOISTURE SUPPORTIVE PATTERN. SO CONTINUE THE DRY
FORECAST.

FRIDAY INTO NEXT WEEKEND...
THE ONLY CHANGE WITH THIS PORTION OF THE FORECAST WAS TO INCREASE
TEMPERATURES...MAINLY ON SATURDAY. IF CLOUD COVER CAN REMAIN LIMITED
WITH THE PATTERN FORECAST...THE 850MB-925MB TEMPERATURES WOULD
SUPPORT TEMPERATURES POTENTIALLY IN THE 70S WITH A THERMAL RIDGE
STEERED IN FROM THE WEST-SOUTHWEST.

MTF

&&

.AVIATION...

//ORD AND MDW CONCERNS...UPDATED 16Z...

* NORTHWEST WINDS BRIEFLY BECOMING MORE NORTHERLY THIS
  AFTERNOON...WITH GUSTS DEVELOPING BY MIDDAY.

* POSSIBLE MVFR CIGS TODAY AND EVENING.

RODRIGUEZ

//DISCUSSION...UPDATED 12Z...

LINE OF SHRA/TSRA DEVELOPED OVER FAR NORTHEAST IL IN THE PAST HOUR
OR SO AHEAD OF AN UPPER LEVEL WAVE. THIS ACTIVITY WILL CONTINUE TO
MOVE EAST...AFFECTING GYY SHORTLY. THE SURFACE COLD FRONT WILL
MOVE ACROSS THE TERMINALS THIS MORNING SHIFTING WEST/SOUTHWEST
WINDS TO THE NORTHWEST. WINDS WILL CONTINUE TO SLOWLY TURN MORE
NORTH/NORTHWEST BY MID/LATE AFTERNOON. THE GRADIENT IS THEN
EXPECTED TO WEAKEN ENOUGH FOR WIND DIRECTIONS TO SHIFT TO THE
NORTH/NORTHEAST EITHER LATE THIS AFTERNOON OR EARLY THIS EVENING
WITH PREVAILING SPEEDS AT THAT TIME LIKELY UNDER 10KTS. WINDS WILL
TURN BACK TO THE NORTH/NORTHWEST OVERNIGHT.

LOW VFR/HIGH MVFR CIGS ACROSS NORTHERN WI WILL MOVE SOUTH THIS
MORNING REACHING THE TERMINALS LATE THIS MORNING OR EARLY THIS
AFTERNOON. CONFIDENCE REGARDING SPECIFIC CIG HEIGHTS IS FAIRLY LOW
WITH CIGS POSSIBLE DIPPING INTO HIGH MVFR FROM MID AFTERNOON INTO
THE EVENING HOURS.

//ORD AND MDW CONFIDENCE...UPDATED 16Z...

* HIGH CONFIDENCE WITH WIND SPEED/DIRECTION THROUGH EARLY
  AFTERNOON...THEN MEDIUM CONFIDENCE WITH DIRECTION LATER THIS
  AFTERNOON.

* MEDIUM CONFIDENCE WITH MVFR CIGS TODAY AND EVENING.

RODRIGUEZ

//OUTLOOK FOR ORD/MDW FOR 00Z WEDNESDAY-12Z MONDAY...UPDATED 12Z...

* TUESDAY NIGHT...DRY/VFR.
* WEDNESDAY...DRY/VFR. EAST/NORTHEAST WINDS.
* THURSDAY...DRY/VFR. SOUTH WINDS.
* FRIDAY...DRY/VFR. SOUTHWEST WINDS.
* SATURDAY...DRY/VFR. WEST WINDS.
* SUNDAY...DRY/VFR. SOUTH WINDS.

&&

.MARINE...

309 AM...LOW PRESSURE OVER THE UPPER PENINSULA OF MICHIGAN WILL
MOVE SOUTHEAST TODAY AND TONIGHT REACHING THE MID ATLANTIC ON
TUESDAY. A TRAILING COLD FRONT WILL MOVE ACROSS LAKE MICHIGAN THIS
MORNING. SOUTHWEST WINDS WILL TURN NORTHWEST THIS MORNING THEN
NORTH THIS EVENING. THE GRADIENT REMAINS FAIRLY TIGHT ACROSS THE
SOUTHERN THIRD OR SO OF THE LAKE...WITH GUSTS TO 30KT POSSIBLE FOR
A FEW MORE HOURS. HIGH PRESSURE WILL BUILD ACROSS ONTARIO TODAY
AND TONIGHT AS IT STRENGTHENS. WHILE THE CENTER OF THIS HIGH WILL
MOVE EAST INTO QUEBEC TUESDAY NIGHT...A RIDGE WILL EXTEND SOUTH
ACROSS THE WESTERN LAKES TONIGHT AND TUESDAY...THEN MOVE ACROSS
THE LAKE WEDNESDAY. THE GRADIENT WILL TIGHTEN BETWEEN THIS
APPROACHING RIDGE AND THE DEPARTING LOW WITH NORTHERLY WINDS
INCREASING TO 30 KT THIS EVENING AND REMAINING THERE UNTIL TUESDAY
AFTERNOON...AS THE RIDGE SLOWLY WORKS EAST. CMS

&&

.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...SMALL CRAFT ADVISORY...LMZ740-LMZ741-LMZ742-LMZ743-LMZ744-
     LMZ745...10 PM MONDAY TO 7 AM WEDNESDAY.

&&

$$

VISIT US AT HTTP://WEATHER.GOV/CHICAGO (ALL LOWERCASE)

FOLLOW US ON FACEBOOK...TWITTER...AND YOUTUBE AT:
WWW.FACEBOOK.COM/NWSCHICAGO
WWW.TWITTER.COM/NWSCHICAGO
WWW.YOUTUBE.COM/NWSCHICAGO






000
FXUS63 KLOT 201415
AFDLOT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
915 AM CDT MON OCT 20 2014

.DISCUSSION...
557 AM CDT

WE ARE SEEING SCATTERED SHOWERS SPARK NEAR CHICAGO AS OF 555 AM
AHEAD OF THE UPPER DISTURBANCE MENTIONED IN THE PREVIOUS
DISCUSSION. THIS DISTURBANCE HAS A POCKET OF STEEP LAPSE RATES
ALOFT /500MB-750MB/ OF 8C/KM AND GREATER AND THAT IS AIDING SOME
OF THESE SHOWER UPDRAFTS. THIS IS INDICATED BY A COUPLE LIGHTNING
STRIKES OVER LAKE MI AND THE OBSERVERS AT ORD AND MDW REPORTING
INTRA-CLOUD AND CLOUD-TO-AIR LIGHTNING. THE GOOD NEWS IS THIS
UPPER WAVE AND ITS FORCING IS MOVING ABOUT 35-40 MPH SO NOT
EXPECTING THESE TO STICK AROUND THE CHICAGO AREA AFTER 7 AM.
CONTINUE THE SHOWER CHANCES THIS MORNING AS IS IN NORTHWEST
INDIANA AND HAVE ADDED A SLIGHT CHANCE OF THUNDER FOR AREAS NEAR
THE I-80/I-90 CORRIDOR.

MTF

//PREV DISCUSSION...
319 AM CDT

A QUIET WEATHER PATTERN WILL REMAIN IN PLACE IN TERMS OF LACK OF
PRECIPITATION CHANCES AND ANY HIGH IMPACT WEATHER THROUGH NEXT
WEEKEND...THOUGH STILL SEVERAL LITTLE INTERESTS TO TACKLE. THESE
INCLUDED HOW WIDESPREAD CLOUDS WILL REACH LATER TODAY THROUGH
TUESDAY AS WELL AS LAKE EFFECT SHOWER POTENTIAL DURING THAT TIME.
THEN LOOKING AT WHEN AND HOW QUICKLY OF A WARM-UP OCCURS LATE IN
THE WEEK INTO THE WEEKEND.

TODAY THROUGH TUESDAY...
THE CONTINUED AMPLIFIED BUT PROGRESSIVE FLOW OVER CANADA AND THE
NORTHERN CONUS CONTINUES FOR A LITTLE LONGER WITH A PACIFIC/CLIPPER
HYBRID SYSTEM MOVING SOUTHEASTWARD FROM THE CENTRAL GREAT LAKES.
AROUND THIS A WELL-DEFINED SHORT WAVE ON GOES WATER VAPOR IMAGERY IS
MOVING INTO NORTHERN IL EARLY THIS MORNING. THIS IS FAIRLY MOISTURE
STARVED BUT CANNOT RULE OUT A FEW SHOWERS THIS MORNING MAINLY IN
NORTHWEST INDIANA. THIS SHORT WAVE ALSO BEGINS TO BREAK DOWN THE
LOW-LEVEL THERMAL RIDGE OVER THE AREA...WITH CLOUDS LIKELY TO
ADVECT/DEVELOP SOUTHWARD INTO THE FORECAST AREA THIS AFTERNOON. IN
ADDITION...TEMPERATURES MAY ALSO PEAK EARLY IN THE AFTERNOON AND
THEN EXPERIENCE A SLOW DROP. TEMPERATURES SHOULD STILL PEAK AROUND
CLIMATOLOGICAL NORMAL /60 TO 65/ WITH THE MORNING SUN. THE CYCLONIC
FLOW OVER THE REGION AND RAPIDLY COOLING 850-925MB TEMPERATURES LOOK
TO SUPPORT CLOUDS OVER MUCH OF THE AREA BY EARLY THIS EVENING AND
UPSTREAM OBSERVATIONAL TRENDS SUPPORT THIS. HAVE GONE WELL ABOVE
MOST GUIDANCE IN SKY COVER FROM LATE TODAY ALL THE WAY THROUGH
TUESDAY MORNING AS HIGH-RESOLUTION MODEL CONDENSATE /SUCH AS THE
4KM SPC WRF/ SEEMS TO WORK BETTER IN SUCH A PATTERN WITH THIN BUT
PROBABLY BROKEN-OVERCAST CLOUD COVER. THE CLOUDS AND NORTH-
NORTHEAST WINDS ON TUESDAY MORNING SHOULD LIMIT WARMING BY QUITE A
BIT WITH SOME LOCATIONS POSSIBLY NOT REACHING 50.

AS THE COOLER AIR AT OR AROUND 0C AT 850MB EXPANDS SOUTHWARD DOWN
THE LAKE LATER TODAY FORESEE DEEPENING LAKE EFFECT CLOUDS AND
SOME SHOWERS DEVELOPING. THESE SHOWERS LOOK TO BE NOT PARTICULARLY
CONCENTRATED WITH LIMITED CONVERGENCE AND MAINLY LIGHT IN
INTENSITY WITH LAKE-INDUCED EQUILIBRIUM LEVELS FORECAST BY THE
NAM OF AROUND 5000 FT. THE BOUNDARY LAYER FLOW FETCH SHOULD FAVOR
NORTHWEST INDIANA FOR THESE SHOWERS TONIGHT INTO EARLY
TUESDAY...THOUGH SOME VEERING TOWARD THE IL/IN STATE LINE AND EVEN
POTENTIALLY CHICAGO TUESDAY MORNING COULD SUPPORT SOME LIGHT
SHOWER ACTIVITY TUESDAY MORNING IN THOSE PLACES. THE HOPWRF-TS
SUPPORTS SUCH A GENERAL EVOLUTION WITH ITS RECENTLY ADDED EXTENDED
HIGH-RES OUTPUT.

TUESDAY NIGHT THROUGH THURSDAY...
SURFACE HIGH PRESSURE WILL BUILD OVER THE AREA FROM THE NORTH DURING
THIS TIME AS THE OVERALL UPPER PATTERN SLOWS THANKS TO AMPLIFICATION
OF A TROUGH ALONG THE WEST COAST OF NORTH AMERICA. OVERALL BENIGN
WEATHER LOOKS TO BE THE RULE WITH TEMPS SLIGHTLY BELOW NORMAL THOUGH
GRADUALLY MODIFYING. MODEL GUIDANCE DOES INDICATE AN ELONGATED SHORT
WAVE TO MOVE INTO THE UPPER MISSISSIPPI VALLEY DURING OR AROUND
THURSDAY NIGHT THOUGH THIS WILL BE MOVING INTO AN UNFAVORABLE
UPPER LEVEL AND MOISTURE SUPPORTIVE PATTERN. SO CONTINUE THE DRY
FORECAST.

FRIDAY INTO NEXT WEEKEND...
THE ONLY CHANGE WITH THIS PORTION OF THE FORECAST WAS TO INCREASE
TEMPERATURES...MAINLY ON SATURDAY. IF CLOUD COVER CAN REMAIN LIMITED
WITH THE PATTERN FORECAST...THE 850MB-925MB TEMPERATURES WOULD
SUPPORT TEMPERATURES POTENTIALLY IN THE 70S WITH A THERMAL RIDGE
STEERED IN FROM THE WEST-SOUTHWEST.

MTF

&&

.AVIATION...

//ORD AND MDW CONCERNS...UPDATED 14Z...

* WESTERLY WINDS BECOMING NORTHWEST LATE MORNING/EARLY THIS
  AFTERNOON AND THEN NORTH/NORTHEAST LATE THIS AFTERNOON...WITH
  GUSTS DEVELOPING BY MIDDAY.

* POSSIBLE MVFR CIGS TODAY AND EVENING.

RODRIGUEZ

//DISCUSSION...UPDATED 12Z...

LINE OF SHRA/TSRA DEVELOPED OVER FAR NORTHEAST IL IN THE PAST HOUR
OR SO AHEAD OF AN UPPER LEVEL WAVE. THIS ACTIVITY WILL CONTINUE TO
MOVE EAST...AFFECTING GYY SHORTLY. THE SURFACE COLD FRONT WILL
MOVE ACROSS THE TERMINALS THIS MORNING SHIFTING WEST/SOUTHWEST
WINDS TO THE NORTHWEST. WINDS WILL CONTINUE TO SLOWLY TURN MORE
NORTH/NORTHWEST BY MID/LATE AFTERNOON. THE GRADIENT IS THEN
EXPECTED TO WEAKEN ENOUGH FOR WIND DIRECTIONS TO SHIFT TO THE
NORTH/NORTHEAST EITHER LATE THIS AFTERNOON OR EARLY THIS EVENING
WITH PREVAILING SPEEDS AT THAT TIME LIKELY UNDER 10KTS. WINDS WILL
TURN BACK TO THE NORTH/NORTHWEST OVERNIGHT.

LOW VFR/HIGH MVFR CIGS ACROSS NORTHERN WI WILL MOVE SOUTH THIS
MORNING REACHING THE TERMINALS LATE THIS MORNING OR EARLY THIS
AFTERNOON. CONFIDENCE REGARDING SPECIFIC CIG HEIGHTS IS FAIRLY LOW
WITH CIGS POSSIBLE DIPPING INTO HIGH MVFR FROM MID AFTERNOON INTO
THE EVENING HOURS.

//ORD AND MDW CONFIDENCE...UPDATED 14Z...

* HIGH CONFIDENCE WITH WIND SPEED/DIRECTION THROUGH EARLY
  AFTERNOON...THEN MEDIUM CONFIDENCE WITH DIRECTION LATER THIS
  AFTERNOON.

* MEDIUM CONFIDENCE WITH MVFR CIGS TODAY AND EVENING.

RODRIGUEZ

//OUTLOOK FOR ORD/MDW FOR 00Z WEDNESDAY-12Z MONDAY...UPDATED 12Z...

* TUESDAY NIGHT...DRY/VFR.
* WEDNESDAY...DRY/VFR. EAST/NORTHEAST WINDS.
* THURSDAY...DRY/VFR. SOUTH WINDS.
* FRIDAY...DRY/VFR. SOUTHWEST WINDS.
* SATURDAY...DRY/VFR. WEST WINDS.
* SUNDAY...DRY/VFR. SOUTH WINDS.

&&

.MARINE...

309 AM...LOW PRESSURE OVER THE UPPER PENINSULA OF MICHIGAN WILL
MOVE SOUTHEAST TODAY AND TONIGHT REACHING THE MID ATLANTIC ON
TUESDAY. A TRAILING COLD FRONT WILL MOVE ACROSS LAKE MICHIGAN THIS
MORNING. SOUTHWEST WINDS WILL TURN NORTHWEST THIS MORNING THEN
NORTH THIS EVENING. THE GRADIENT REMAINS FAIRLY TIGHT ACROSS THE
SOUTHERN THIRD OR SO OF THE LAKE...WITH GUSTS TO 30KT POSSIBLE FOR
A FEW MORE HOURS. HIGH PRESSURE WILL BUILD ACROSS ONTARIO TODAY
AND TONIGHT AS IT STRENGTHENS. WHILE THE CENTER OF THIS HIGH WILL
MOVE EAST INTO QUEBEC TUESDAY NIGHT...A RIDGE WILL EXTEND SOUTH
ACROSS THE WESTERN LAKES TONIGHT AND TUESDAY...THEN MOVE ACROSS
THE LAKE WEDNESDAY. THE GRADIENT WILL TIGHTEN BETWEEN THIS
APPROACHING RIDGE AND THE DEPARTING LOW WITH NORTHERLY WINDS
INCREASING TO 30 KT THIS EVENING AND REMAINING THERE UNTIL TUESDAY
AFTERNOON...AS THE RIDGE SLOWLY WORKS EAST. CMS

&&

.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...SMALL CRAFT ADVISORY...LMZ740-LMZ741-LMZ742-LMZ743-LMZ744-
     LMZ745...10 PM MONDAY TO 7 AM WEDNESDAY.

&&

$$

VISIT US AT HTTP://WEATHER.GOV/CHICAGO (ALL LOWERCASE)

FOLLOW US ON FACEBOOK...TWITTER...AND YOUTUBE AT:
WWW.FACEBOOK.COM/NWSCHICAGO
WWW.TWITTER.COM/NWSCHICAGO
WWW.YOUTUBE.COM/NWSCHICAGO







000
FXUS63 KLOT 201415
AFDLOT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
915 AM CDT MON OCT 20 2014

.DISCUSSION...
557 AM CDT

WE ARE SEEING SCATTERED SHOWERS SPARK NEAR CHICAGO AS OF 555 AM
AHEAD OF THE UPPER DISTURBANCE MENTIONED IN THE PREVIOUS
DISCUSSION. THIS DISTURBANCE HAS A POCKET OF STEEP LAPSE RATES
ALOFT /500MB-750MB/ OF 8C/KM AND GREATER AND THAT IS AIDING SOME
OF THESE SHOWER UPDRAFTS. THIS IS INDICATED BY A COUPLE LIGHTNING
STRIKES OVER LAKE MI AND THE OBSERVERS AT ORD AND MDW REPORTING
INTRA-CLOUD AND CLOUD-TO-AIR LIGHTNING. THE GOOD NEWS IS THIS
UPPER WAVE AND ITS FORCING IS MOVING ABOUT 35-40 MPH SO NOT
EXPECTING THESE TO STICK AROUND THE CHICAGO AREA AFTER 7 AM.
CONTINUE THE SHOWER CHANCES THIS MORNING AS IS IN NORTHWEST
INDIANA AND HAVE ADDED A SLIGHT CHANCE OF THUNDER FOR AREAS NEAR
THE I-80/I-90 CORRIDOR.

MTF

//PREV DISCUSSION...
319 AM CDT

A QUIET WEATHER PATTERN WILL REMAIN IN PLACE IN TERMS OF LACK OF
PRECIPITATION CHANCES AND ANY HIGH IMPACT WEATHER THROUGH NEXT
WEEKEND...THOUGH STILL SEVERAL LITTLE INTERESTS TO TACKLE. THESE
INCLUDED HOW WIDESPREAD CLOUDS WILL REACH LATER TODAY THROUGH
TUESDAY AS WELL AS LAKE EFFECT SHOWER POTENTIAL DURING THAT TIME.
THEN LOOKING AT WHEN AND HOW QUICKLY OF A WARM-UP OCCURS LATE IN
THE WEEK INTO THE WEEKEND.

TODAY THROUGH TUESDAY...
THE CONTINUED AMPLIFIED BUT PROGRESSIVE FLOW OVER CANADA AND THE
NORTHERN CONUS CONTINUES FOR A LITTLE LONGER WITH A PACIFIC/CLIPPER
HYBRID SYSTEM MOVING SOUTHEASTWARD FROM THE CENTRAL GREAT LAKES.
AROUND THIS A WELL-DEFINED SHORT WAVE ON GOES WATER VAPOR IMAGERY IS
MOVING INTO NORTHERN IL EARLY THIS MORNING. THIS IS FAIRLY MOISTURE
STARVED BUT CANNOT RULE OUT A FEW SHOWERS THIS MORNING MAINLY IN
NORTHWEST INDIANA. THIS SHORT WAVE ALSO BEGINS TO BREAK DOWN THE
LOW-LEVEL THERMAL RIDGE OVER THE AREA...WITH CLOUDS LIKELY TO
ADVECT/DEVELOP SOUTHWARD INTO THE FORECAST AREA THIS AFTERNOON. IN
ADDITION...TEMPERATURES MAY ALSO PEAK EARLY IN THE AFTERNOON AND
THEN EXPERIENCE A SLOW DROP. TEMPERATURES SHOULD STILL PEAK AROUND
CLIMATOLOGICAL NORMAL /60 TO 65/ WITH THE MORNING SUN. THE CYCLONIC
FLOW OVER THE REGION AND RAPIDLY COOLING 850-925MB TEMPERATURES LOOK
TO SUPPORT CLOUDS OVER MUCH OF THE AREA BY EARLY THIS EVENING AND
UPSTREAM OBSERVATIONAL TRENDS SUPPORT THIS. HAVE GONE WELL ABOVE
MOST GUIDANCE IN SKY COVER FROM LATE TODAY ALL THE WAY THROUGH
TUESDAY MORNING AS HIGH-RESOLUTION MODEL CONDENSATE /SUCH AS THE
4KM SPC WRF/ SEEMS TO WORK BETTER IN SUCH A PATTERN WITH THIN BUT
PROBABLY BROKEN-OVERCAST CLOUD COVER. THE CLOUDS AND NORTH-
NORTHEAST WINDS ON TUESDAY MORNING SHOULD LIMIT WARMING BY QUITE A
BIT WITH SOME LOCATIONS POSSIBLY NOT REACHING 50.

AS THE COOLER AIR AT OR AROUND 0C AT 850MB EXPANDS SOUTHWARD DOWN
THE LAKE LATER TODAY FORESEE DEEPENING LAKE EFFECT CLOUDS AND
SOME SHOWERS DEVELOPING. THESE SHOWERS LOOK TO BE NOT PARTICULARLY
CONCENTRATED WITH LIMITED CONVERGENCE AND MAINLY LIGHT IN
INTENSITY WITH LAKE-INDUCED EQUILIBRIUM LEVELS FORECAST BY THE
NAM OF AROUND 5000 FT. THE BOUNDARY LAYER FLOW FETCH SHOULD FAVOR
NORTHWEST INDIANA FOR THESE SHOWERS TONIGHT INTO EARLY
TUESDAY...THOUGH SOME VEERING TOWARD THE IL/IN STATE LINE AND EVEN
POTENTIALLY CHICAGO TUESDAY MORNING COULD SUPPORT SOME LIGHT
SHOWER ACTIVITY TUESDAY MORNING IN THOSE PLACES. THE HOPWRF-TS
SUPPORTS SUCH A GENERAL EVOLUTION WITH ITS RECENTLY ADDED EXTENDED
HIGH-RES OUTPUT.

TUESDAY NIGHT THROUGH THURSDAY...
SURFACE HIGH PRESSURE WILL BUILD OVER THE AREA FROM THE NORTH DURING
THIS TIME AS THE OVERALL UPPER PATTERN SLOWS THANKS TO AMPLIFICATION
OF A TROUGH ALONG THE WEST COAST OF NORTH AMERICA. OVERALL BENIGN
WEATHER LOOKS TO BE THE RULE WITH TEMPS SLIGHTLY BELOW NORMAL THOUGH
GRADUALLY MODIFYING. MODEL GUIDANCE DOES INDICATE AN ELONGATED SHORT
WAVE TO MOVE INTO THE UPPER MISSISSIPPI VALLEY DURING OR AROUND
THURSDAY NIGHT THOUGH THIS WILL BE MOVING INTO AN UNFAVORABLE
UPPER LEVEL AND MOISTURE SUPPORTIVE PATTERN. SO CONTINUE THE DRY
FORECAST.

FRIDAY INTO NEXT WEEKEND...
THE ONLY CHANGE WITH THIS PORTION OF THE FORECAST WAS TO INCREASE
TEMPERATURES...MAINLY ON SATURDAY. IF CLOUD COVER CAN REMAIN LIMITED
WITH THE PATTERN FORECAST...THE 850MB-925MB TEMPERATURES WOULD
SUPPORT TEMPERATURES POTENTIALLY IN THE 70S WITH A THERMAL RIDGE
STEERED IN FROM THE WEST-SOUTHWEST.

MTF

&&

.AVIATION...

//ORD AND MDW CONCERNS...UPDATED 14Z...

* WESTERLY WINDS BECOMING NORTHWEST LATE MORNING/EARLY THIS
  AFTERNOON AND THEN NORTH/NORTHEAST LATE THIS AFTERNOON...WITH
  GUSTS DEVELOPING BY MIDDAY.

* POSSIBLE MVFR CIGS TODAY AND EVENING.

RODRIGUEZ

//DISCUSSION...UPDATED 12Z...

LINE OF SHRA/TSRA DEVELOPED OVER FAR NORTHEAST IL IN THE PAST HOUR
OR SO AHEAD OF AN UPPER LEVEL WAVE. THIS ACTIVITY WILL CONTINUE TO
MOVE EAST...AFFECTING GYY SHORTLY. THE SURFACE COLD FRONT WILL
MOVE ACROSS THE TERMINALS THIS MORNING SHIFTING WEST/SOUTHWEST
WINDS TO THE NORTHWEST. WINDS WILL CONTINUE TO SLOWLY TURN MORE
NORTH/NORTHWEST BY MID/LATE AFTERNOON. THE GRADIENT IS THEN
EXPECTED TO WEAKEN ENOUGH FOR WIND DIRECTIONS TO SHIFT TO THE
NORTH/NORTHEAST EITHER LATE THIS AFTERNOON OR EARLY THIS EVENING
WITH PREVAILING SPEEDS AT THAT TIME LIKELY UNDER 10KTS. WINDS WILL
TURN BACK TO THE NORTH/NORTHWEST OVERNIGHT.

LOW VFR/HIGH MVFR CIGS ACROSS NORTHERN WI WILL MOVE SOUTH THIS
MORNING REACHING THE TERMINALS LATE THIS MORNING OR EARLY THIS
AFTERNOON. CONFIDENCE REGARDING SPECIFIC CIG HEIGHTS IS FAIRLY LOW
WITH CIGS POSSIBLE DIPPING INTO HIGH MVFR FROM MID AFTERNOON INTO
THE EVENING HOURS.

//ORD AND MDW CONFIDENCE...UPDATED 14Z...

* HIGH CONFIDENCE WITH WIND SPEED/DIRECTION THROUGH EARLY
  AFTERNOON...THEN MEDIUM CONFIDENCE WITH DIRECTION LATER THIS
  AFTERNOON.

* MEDIUM CONFIDENCE WITH MVFR CIGS TODAY AND EVENING.

RODRIGUEZ

//OUTLOOK FOR ORD/MDW FOR 00Z WEDNESDAY-12Z MONDAY...UPDATED 12Z...

* TUESDAY NIGHT...DRY/VFR.
* WEDNESDAY...DRY/VFR. EAST/NORTHEAST WINDS.
* THURSDAY...DRY/VFR. SOUTH WINDS.
* FRIDAY...DRY/VFR. SOUTHWEST WINDS.
* SATURDAY...DRY/VFR. WEST WINDS.
* SUNDAY...DRY/VFR. SOUTH WINDS.

&&

.MARINE...

309 AM...LOW PRESSURE OVER THE UPPER PENINSULA OF MICHIGAN WILL
MOVE SOUTHEAST TODAY AND TONIGHT REACHING THE MID ATLANTIC ON
TUESDAY. A TRAILING COLD FRONT WILL MOVE ACROSS LAKE MICHIGAN THIS
MORNING. SOUTHWEST WINDS WILL TURN NORTHWEST THIS MORNING THEN
NORTH THIS EVENING. THE GRADIENT REMAINS FAIRLY TIGHT ACROSS THE
SOUTHERN THIRD OR SO OF THE LAKE...WITH GUSTS TO 30KT POSSIBLE FOR
A FEW MORE HOURS. HIGH PRESSURE WILL BUILD ACROSS ONTARIO TODAY
AND TONIGHT AS IT STRENGTHENS. WHILE THE CENTER OF THIS HIGH WILL
MOVE EAST INTO QUEBEC TUESDAY NIGHT...A RIDGE WILL EXTEND SOUTH
ACROSS THE WESTERN LAKES TONIGHT AND TUESDAY...THEN MOVE ACROSS
THE LAKE WEDNESDAY. THE GRADIENT WILL TIGHTEN BETWEEN THIS
APPROACHING RIDGE AND THE DEPARTING LOW WITH NORTHERLY WINDS
INCREASING TO 30 KT THIS EVENING AND REMAINING THERE UNTIL TUESDAY
AFTERNOON...AS THE RIDGE SLOWLY WORKS EAST. CMS

&&

.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...SMALL CRAFT ADVISORY...LMZ740-LMZ741-LMZ742-LMZ743-LMZ744-
     LMZ745...10 PM MONDAY TO 7 AM WEDNESDAY.

&&

$$

VISIT US AT HTTP://WEATHER.GOV/CHICAGO (ALL LOWERCASE)

FOLLOW US ON FACEBOOK...TWITTER...AND YOUTUBE AT:
WWW.FACEBOOK.COM/NWSCHICAGO
WWW.TWITTER.COM/NWSCHICAGO
WWW.YOUTUBE.COM/NWSCHICAGO






000
FXUS63 KLOT 201144
AFDLOT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
644 AM CDT MON OCT 20 2014

.DISCUSSION...
557 AM CDT

WE ARE SEEING SCATTERED SHOWERS SPARK NEAR CHICAGO AS OF 555 AM
AHEAD OF THE UPPER DISTURBANCE MENTIONED IN THE PREVIOUS
DISCUSSION. THIS DISTURBANCE HAS A POCKET OF STEEP LAPSE RATES
ALOFT /500MB-750MB/ OF 8C/KM AND GREATER AND THAT IS AIDING SOME
OF THESE SHOWER UPDRAFTS. THIS IS INDICATED BY A COUPLE LIGHTNING
STRIKES OVER LAKE MI AND THE OBSERVERS AT ORD AND MDW REPORTING
INTRA-CLOUD AND CLOUD-TO-AIR LIGHTNING. THE GOOD NEWS IS THIS
UPPER WAVE AND ITS FORCING IS MOVING ABOUT 35-40 MPH SO NOT
EXPECTING THESE TO STICK AROUND THE CHICAGO AREA AFTER 7 AM.
CONTINUE THE SHOWER CHANCES THIS MORNING AS IS IN NORTHWEST
INDIANA AND HAVE ADDED A SLIGHT CHANCE OF THUNDER FOR AREAS NEAR
THE I-80/I-90 CORRIDOR.

MTF

//PREV DISCUSSION...
319 AM CDT

A QUIET WEATHER PATTERN WILL REMAIN IN PLACE IN TERMS OF LACK OF
PRECIPITATION CHANCES AND ANY HIGH IMPACT WEATHER THROUGH NEXT
WEEKEND...THOUGH STILL SEVERAL LITTLE INTERESTS TO TACKLE. THESE
INCLUDED HOW WIDESPREAD CLOUDS WILL REACH LATER TODAY THROUGH
TUESDAY AS WELL AS LAKE EFFECT SHOWER POTENTIAL DURING THAT TIME.
THEN LOOKING AT WHEN AND HOW QUICKLY OF A WARM-UP OCCURS LATE IN
THE WEEK INTO THE WEEKEND.

TODAY THROUGH TUESDAY...
THE CONTINUED AMPLIFIED BUT PROGRESSIVE FLOW OVER CANADA AND THE
NORTHERN CONUS CONTINUES FOR A LITTLE LONGER WITH A PACIFIC/CLIPPER
HYBRID SYSTEM MOVING SOUTHEASTWARD FROM THE CENTRAL GREAT LAKES.
AROUND THIS A WELL-DEFINED SHORT WAVE ON GOES WATER VAPOR IMAGERY IS
MOVING INTO NORTHERN IL EARLY THIS MORNING. THIS IS FAIRLY MOISTURE
STARVED BUT CANNOT RULE OUT A FEW SHOWERS THIS MORNING MAINLY IN
NORTHWEST INDIANA. THIS SHORT WAVE ALSO BEGINS TO BREAK DOWN THE
LOW-LEVEL THERMAL RIDGE OVER THE AREA...WITH CLOUDS LIKELY TO
ADVECT/DEVELOP SOUTHWARD INTO THE FORECAST AREA THIS AFTERNOON. IN
ADDITION...TEMPERATURES MAY ALSO PEAK EARLY IN THE AFTERNOON AND
THEN EXPERIENCE A SLOW DROP. TEMPERATURES SHOULD STILL PEAK AROUND
CLIMATOLOGICAL NORMAL /60 TO 65/ WITH THE MORNING SUN. THE CYCLONIC
FLOW OVER THE REGION AND RAPIDLY COOLING 850-925MB TEMPERATURES LOOK
TO SUPPORT CLOUDS OVER MUCH OF THE AREA BY EARLY THIS EVENING AND
UPSTREAM OBSERVATIONAL TRENDS SUPPORT THIS. HAVE GONE WELL ABOVE
MOST GUIDANCE IN SKY COVER FROM LATE TODAY ALL THE WAY THROUGH
TUESDAY MORNING AS HIGH-RESOLUTION MODEL CONDENSATE /SUCH AS THE
4KM SPC WRF/ SEEMS TO WORK BETTER IN SUCH A PATTERN WITH THIN BUT
PROBABLY BROKEN-OVERCAST CLOUD COVER. THE CLOUDS AND NORTH-
NORTHEAST WINDS ON TUESDAY MORNING SHOULD LIMIT WARMING BY QUITE A
BIT WITH SOME LOCATIONS POSSIBLY NOT REACHING 50.

AS THE COOLER AIR AT OR AROUND 0C AT 850MB EXPANDS SOUTHWARD DOWN
THE LAKE LATER TODAY FORESEE DEEPENING LAKE EFFECT CLOUDS AND
SOME SHOWERS DEVELOPING. THESE SHOWERS LOOK TO BE NOT PARTICULARLY
CONCENTRATED WITH LIMITED CONVERGENCE AND MAINLY LIGHT IN
INTENSITY WITH LAKE-INDUCED EQUILIBRIUM LEVELS FORECAST BY THE
NAM OF AROUND 5000 FT. THE BOUNDARY LAYER FLOW FETCH SHOULD FAVOR
NORTHWEST INDIANA FOR THESE SHOWERS TONIGHT INTO EARLY
TUESDAY...THOUGH SOME VEERING TOWARD THE IL/IN STATE LINE AND EVEN
POTENTIALLY CHICAGO TUESDAY MORNING COULD SUPPORT SOME LIGHT
SHOWER ACTIVITY TUESDAY MORNING IN THOSE PLACES. THE HOPWRF-TS
SUPPORTS SUCH A GENERAL EVOLUTION WITH ITS RECENTLY ADDED EXTENDED
HIGH-RES OUTPUT.

TUESDAY NIGHT THROUGH THURSDAY...
SURFACE HIGH PRESSURE WILL BUILD OVER THE AREA FROM THE NORTH DURING
THIS TIME AS THE OVERALL UPPER PATTERN SLOWS THANKS TO AMPLIFICATION
OF A TROUGH ALONG THE WEST COAST OF NORTH AMERICA. OVERALL BENIGN
WEATHER LOOKS TO BE THE RULE WITH TEMPS SLIGHTLY BELOW NORMAL THOUGH
GRADUALLY MODIFYING. MODEL GUIDANCE DOES INDICATE AN ELONGATED SHORT
WAVE TO MOVE INTO THE UPPER MISSISSIPPI VALLEY DURING OR AROUND
THURSDAY NIGHT THOUGH THIS WILL BE MOVING INTO AN UNFAVORABLE
UPPER LEVEL AND MOISTURE SUPPORTIVE PATTERN. SO CONTINUE THE DRY
FORECAST.

FRIDAY INTO NEXT WEEKEND...
THE ONLY CHANGE WITH THIS PORTION OF THE FORECAST WAS TO INCREASE
TEMPERATURES...MAINLY ON SATURDAY. IF CLOUD COVER CAN REMAIN LIMITED
WITH THE PATTERN FORECAST...THE 850MB-925MB TEMPERATURES WOULD
SUPPORT TEMPERATURES POTENTIALLY IN THE 70S WITH A THERMAL RIDGE
STEERED IN FROM THE WEST-SOUTHWEST.

MTF

&&

.AVIATION...

//ORD AND MDW CONCERNS...UPDATED 12Z...

* WEST/SOUTHWEST WINDS BECOMING NORTHWEST LATE MORNING/EARLY THIS
  AFTERNOON...THEN NORTH/NORTHEAST LATE THIS AFTERNOON.
* POSSIBLE MVFR CIGS THIS AFTERNOON AND EVENING. CMS

//DISCUSSION...UPDATED 12Z...

LINE OF SHRA/TSRA DEVELOPED OVER FAR NORTHEAST IL IN THE PAST HOUR
OR SO AHEAD OF AN UPPER LEVEL WAVE. THIS ACTIVITY WILL CONTINUE TO
MOVE EAST...AFFECTING GYY SHORTLY. THE SURFACE COLD FRONT WILL
MOVE ACROSS THE TERMINALS THIS MORNING SHIFTING WEST/SOUTHWEST
WINDS TO THE NORTHWEST. WINDS WILL CONTINUE TO SLOWLY TURN MORE
NORTH/NORTHWEST BY MID/LATE AFTERNOON. THE GRADIENT IS THEN
EXPECTED TO WEAKEN ENOUGH FOR WIND DIRECTIONS TO SHIFT TO THE
NORTH/NORTHEAST EITHER LATE THIS AFTERNOON OR EARLY THIS EVENING
WITH PREVAILING SPEEDS AT THAT TIME LIKELY UNDER 10KTS. WINDS WILL
TURN BACK TO THE NORTH/NORTHWEST OVERNIGHT.

LOW VFR/HIGH MVFR CIGS ACROSS NORTHERN WI WILL MOVE SOUTH THIS
MORNING REACHING THE TERMINALS LATE THIS MORNING OR EARLY THIS
AFTERNOON. CONFIDENCE REGARDING SPECIFIC CIG HEIGHTS IS FAIRLY LOW
WITH CIGS POSSIBLE DIPPING INTO HIGH MVFR FROM MID AFTERNOON INTO
THE EVENING HOURS.

//ORD AND MDW CONFIDENCE...UPDATED 12Z...

* HIGH FOR WINDS THRU MID MORNING...THEN MEDIUM FOR DIRECTION AND
  TIMING CHANGES THIS AFTERNOON/EVENING.
* LOW FOR MVFR CIGS THIS AFTERNOON AND EVENING. CMS

//OUTLOOK FOR ORD/MDW FOR 00Z WEDNESDAY-12Z MONDAY...UPDATED 12Z...

* TUESDAY NIGHT...DRY/VFR.
* WEDNESDAY...DRY/VFR. EAST/NORTHEAST WINDS.
* THURSDAY...DRY/VFR. SOUTH WINDS.
* FRIDAY...DRY/VFR. SOUTHWEST WINDS.
* SATURDAY...DRY/VFR. WEST WINDS.
* SUNDAY...DRY/VFR. SOUTH WINDS.

&&

.MARINE...

309 AM...LOW PRESSURE OVER THE UPPER PENINSULA OF MICHIGAN WILL
MOVE SOUTHEAST TODAY AND TONIGHT REACHING THE MID ATLANTIC ON
TUESDAY. A TRAILING COLD FRONT WILL MOVE ACROSS LAKE MICHIGAN THIS
MORNING. SOUTHWEST WINDS WILL TURN NORTHWEST THIS MORNING THEN
NORTH THIS EVENING. THE GRADIENT REMAINS FAIRLY TIGHT ACROSS THE
SOUTHERN THIRD OR SO OF THE LAKE...WITH GUSTS TO 30KT POSSIBLE FOR
A FEW MORE HOURS. HIGH PRESSURE WILL BUILD ACROSS ONTARIO TODAY
AND TONIGHT AS IT STRENGTHENS. WHILE THE CENTER OF THIS HIGH WILL
MOVE EAST INTO QUEBEC TUESDAY NIGHT...A RIDGE WILL EXTEND SOUTH
ACROSS THE WESTERN LAKES TONIGHT AND TUESDAY...THEN MOVE ACROSS
THE LAKE WEDNESDAY. THE GRADIENT WILL TIGHTEN BETWEEN THIS
APPROACHING RIDGE AND THE DEPARTING LOW WITH NORTHERLY WINDS
INCREASING TO 30 KT THIS EVENING AND REMAINING THERE UNTIL TUESDAY
AFTERNOON...AS THE RIDGE SLOWLY WORKS EAST. CMS

&&

.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...SMALL CRAFT ADVISORY...NEARSHORE WATERS UNTIL 7 AM MONDAY.

     SMALL CRAFT ADVISORY...LMZ740-LMZ741-LMZ742-LMZ743-LMZ744-
     LMZ745...10 PM MONDAY TO 7 AM WEDNESDAY.

&&

$$

VISIT US AT HTTP://WEATHER.GOV/CHICAGO (ALL LOWERCASE)

FOLLOW US ON FACEBOOK...TWITTER...AND YOUTUBE AT:
WWW.FACEBOOK.COM/NWSCHICAGO
WWW.TWITTER.COM/NWSCHICAGO
WWW.YOUTUBE.COM/NWSCHICAGO







000
FXUS63 KLOT 201144
AFDLOT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
644 AM CDT MON OCT 20 2014

.DISCUSSION...
557 AM CDT

WE ARE SEEING SCATTERED SHOWERS SPARK NEAR CHICAGO AS OF 555 AM
AHEAD OF THE UPPER DISTURBANCE MENTIONED IN THE PREVIOUS
DISCUSSION. THIS DISTURBANCE HAS A POCKET OF STEEP LAPSE RATES
ALOFT /500MB-750MB/ OF 8C/KM AND GREATER AND THAT IS AIDING SOME
OF THESE SHOWER UPDRAFTS. THIS IS INDICATED BY A COUPLE LIGHTNING
STRIKES OVER LAKE MI AND THE OBSERVERS AT ORD AND MDW REPORTING
INTRA-CLOUD AND CLOUD-TO-AIR LIGHTNING. THE GOOD NEWS IS THIS
UPPER WAVE AND ITS FORCING IS MOVING ABOUT 35-40 MPH SO NOT
EXPECTING THESE TO STICK AROUND THE CHICAGO AREA AFTER 7 AM.
CONTINUE THE SHOWER CHANCES THIS MORNING AS IS IN NORTHWEST
INDIANA AND HAVE ADDED A SLIGHT CHANCE OF THUNDER FOR AREAS NEAR
THE I-80/I-90 CORRIDOR.

MTF

//PREV DISCUSSION...
319 AM CDT

A QUIET WEATHER PATTERN WILL REMAIN IN PLACE IN TERMS OF LACK OF
PRECIPITATION CHANCES AND ANY HIGH IMPACT WEATHER THROUGH NEXT
WEEKEND...THOUGH STILL SEVERAL LITTLE INTERESTS TO TACKLE. THESE
INCLUDED HOW WIDESPREAD CLOUDS WILL REACH LATER TODAY THROUGH
TUESDAY AS WELL AS LAKE EFFECT SHOWER POTENTIAL DURING THAT TIME.
THEN LOOKING AT WHEN AND HOW QUICKLY OF A WARM-UP OCCURS LATE IN
THE WEEK INTO THE WEEKEND.

TODAY THROUGH TUESDAY...
THE CONTINUED AMPLIFIED BUT PROGRESSIVE FLOW OVER CANADA AND THE
NORTHERN CONUS CONTINUES FOR A LITTLE LONGER WITH A PACIFIC/CLIPPER
HYBRID SYSTEM MOVING SOUTHEASTWARD FROM THE CENTRAL GREAT LAKES.
AROUND THIS A WELL-DEFINED SHORT WAVE ON GOES WATER VAPOR IMAGERY IS
MOVING INTO NORTHERN IL EARLY THIS MORNING. THIS IS FAIRLY MOISTURE
STARVED BUT CANNOT RULE OUT A FEW SHOWERS THIS MORNING MAINLY IN
NORTHWEST INDIANA. THIS SHORT WAVE ALSO BEGINS TO BREAK DOWN THE
LOW-LEVEL THERMAL RIDGE OVER THE AREA...WITH CLOUDS LIKELY TO
ADVECT/DEVELOP SOUTHWARD INTO THE FORECAST AREA THIS AFTERNOON. IN
ADDITION...TEMPERATURES MAY ALSO PEAK EARLY IN THE AFTERNOON AND
THEN EXPERIENCE A SLOW DROP. TEMPERATURES SHOULD STILL PEAK AROUND
CLIMATOLOGICAL NORMAL /60 TO 65/ WITH THE MORNING SUN. THE CYCLONIC
FLOW OVER THE REGION AND RAPIDLY COOLING 850-925MB TEMPERATURES LOOK
TO SUPPORT CLOUDS OVER MUCH OF THE AREA BY EARLY THIS EVENING AND
UPSTREAM OBSERVATIONAL TRENDS SUPPORT THIS. HAVE GONE WELL ABOVE
MOST GUIDANCE IN SKY COVER FROM LATE TODAY ALL THE WAY THROUGH
TUESDAY MORNING AS HIGH-RESOLUTION MODEL CONDENSATE /SUCH AS THE
4KM SPC WRF/ SEEMS TO WORK BETTER IN SUCH A PATTERN WITH THIN BUT
PROBABLY BROKEN-OVERCAST CLOUD COVER. THE CLOUDS AND NORTH-
NORTHEAST WINDS ON TUESDAY MORNING SHOULD LIMIT WARMING BY QUITE A
BIT WITH SOME LOCATIONS POSSIBLY NOT REACHING 50.

AS THE COOLER AIR AT OR AROUND 0C AT 850MB EXPANDS SOUTHWARD DOWN
THE LAKE LATER TODAY FORESEE DEEPENING LAKE EFFECT CLOUDS AND
SOME SHOWERS DEVELOPING. THESE SHOWERS LOOK TO BE NOT PARTICULARLY
CONCENTRATED WITH LIMITED CONVERGENCE AND MAINLY LIGHT IN
INTENSITY WITH LAKE-INDUCED EQUILIBRIUM LEVELS FORECAST BY THE
NAM OF AROUND 5000 FT. THE BOUNDARY LAYER FLOW FETCH SHOULD FAVOR
NORTHWEST INDIANA FOR THESE SHOWERS TONIGHT INTO EARLY
TUESDAY...THOUGH SOME VEERING TOWARD THE IL/IN STATE LINE AND EVEN
POTENTIALLY CHICAGO TUESDAY MORNING COULD SUPPORT SOME LIGHT
SHOWER ACTIVITY TUESDAY MORNING IN THOSE PLACES. THE HOPWRF-TS
SUPPORTS SUCH A GENERAL EVOLUTION WITH ITS RECENTLY ADDED EXTENDED
HIGH-RES OUTPUT.

TUESDAY NIGHT THROUGH THURSDAY...
SURFACE HIGH PRESSURE WILL BUILD OVER THE AREA FROM THE NORTH DURING
THIS TIME AS THE OVERALL UPPER PATTERN SLOWS THANKS TO AMPLIFICATION
OF A TROUGH ALONG THE WEST COAST OF NORTH AMERICA. OVERALL BENIGN
WEATHER LOOKS TO BE THE RULE WITH TEMPS SLIGHTLY BELOW NORMAL THOUGH
GRADUALLY MODIFYING. MODEL GUIDANCE DOES INDICATE AN ELONGATED SHORT
WAVE TO MOVE INTO THE UPPER MISSISSIPPI VALLEY DURING OR AROUND
THURSDAY NIGHT THOUGH THIS WILL BE MOVING INTO AN UNFAVORABLE
UPPER LEVEL AND MOISTURE SUPPORTIVE PATTERN. SO CONTINUE THE DRY
FORECAST.

FRIDAY INTO NEXT WEEKEND...
THE ONLY CHANGE WITH THIS PORTION OF THE FORECAST WAS TO INCREASE
TEMPERATURES...MAINLY ON SATURDAY. IF CLOUD COVER CAN REMAIN LIMITED
WITH THE PATTERN FORECAST...THE 850MB-925MB TEMPERATURES WOULD
SUPPORT TEMPERATURES POTENTIALLY IN THE 70S WITH A THERMAL RIDGE
STEERED IN FROM THE WEST-SOUTHWEST.

MTF

&&

.AVIATION...

//ORD AND MDW CONCERNS...UPDATED 12Z...

* WEST/SOUTHWEST WINDS BECOMING NORTHWEST LATE MORNING/EARLY THIS
  AFTERNOON...THEN NORTH/NORTHEAST LATE THIS AFTERNOON.
* POSSIBLE MVFR CIGS THIS AFTERNOON AND EVENING. CMS

//DISCUSSION...UPDATED 12Z...

LINE OF SHRA/TSRA DEVELOPED OVER FAR NORTHEAST IL IN THE PAST HOUR
OR SO AHEAD OF AN UPPER LEVEL WAVE. THIS ACTIVITY WILL CONTINUE TO
MOVE EAST...AFFECTING GYY SHORTLY. THE SURFACE COLD FRONT WILL
MOVE ACROSS THE TERMINALS THIS MORNING SHIFTING WEST/SOUTHWEST
WINDS TO THE NORTHWEST. WINDS WILL CONTINUE TO SLOWLY TURN MORE
NORTH/NORTHWEST BY MID/LATE AFTERNOON. THE GRADIENT IS THEN
EXPECTED TO WEAKEN ENOUGH FOR WIND DIRECTIONS TO SHIFT TO THE
NORTH/NORTHEAST EITHER LATE THIS AFTERNOON OR EARLY THIS EVENING
WITH PREVAILING SPEEDS AT THAT TIME LIKELY UNDER 10KTS. WINDS WILL
TURN BACK TO THE NORTH/NORTHWEST OVERNIGHT.

LOW VFR/HIGH MVFR CIGS ACROSS NORTHERN WI WILL MOVE SOUTH THIS
MORNING REACHING THE TERMINALS LATE THIS MORNING OR EARLY THIS
AFTERNOON. CONFIDENCE REGARDING SPECIFIC CIG HEIGHTS IS FAIRLY LOW
WITH CIGS POSSIBLE DIPPING INTO HIGH MVFR FROM MID AFTERNOON INTO
THE EVENING HOURS.

//ORD AND MDW CONFIDENCE...UPDATED 12Z...

* HIGH FOR WINDS THRU MID MORNING...THEN MEDIUM FOR DIRECTION AND
  TIMING CHANGES THIS AFTERNOON/EVENING.
* LOW FOR MVFR CIGS THIS AFTERNOON AND EVENING. CMS

//OUTLOOK FOR ORD/MDW FOR 00Z WEDNESDAY-12Z MONDAY...UPDATED 12Z...

* TUESDAY NIGHT...DRY/VFR.
* WEDNESDAY...DRY/VFR. EAST/NORTHEAST WINDS.
* THURSDAY...DRY/VFR. SOUTH WINDS.
* FRIDAY...DRY/VFR. SOUTHWEST WINDS.
* SATURDAY...DRY/VFR. WEST WINDS.
* SUNDAY...DRY/VFR. SOUTH WINDS.

&&

.MARINE...

309 AM...LOW PRESSURE OVER THE UPPER PENINSULA OF MICHIGAN WILL
MOVE SOUTHEAST TODAY AND TONIGHT REACHING THE MID ATLANTIC ON
TUESDAY. A TRAILING COLD FRONT WILL MOVE ACROSS LAKE MICHIGAN THIS
MORNING. SOUTHWEST WINDS WILL TURN NORTHWEST THIS MORNING THEN
NORTH THIS EVENING. THE GRADIENT REMAINS FAIRLY TIGHT ACROSS THE
SOUTHERN THIRD OR SO OF THE LAKE...WITH GUSTS TO 30KT POSSIBLE FOR
A FEW MORE HOURS. HIGH PRESSURE WILL BUILD ACROSS ONTARIO TODAY
AND TONIGHT AS IT STRENGTHENS. WHILE THE CENTER OF THIS HIGH WILL
MOVE EAST INTO QUEBEC TUESDAY NIGHT...A RIDGE WILL EXTEND SOUTH
ACROSS THE WESTERN LAKES TONIGHT AND TUESDAY...THEN MOVE ACROSS
THE LAKE WEDNESDAY. THE GRADIENT WILL TIGHTEN BETWEEN THIS
APPROACHING RIDGE AND THE DEPARTING LOW WITH NORTHERLY WINDS
INCREASING TO 30 KT THIS EVENING AND REMAINING THERE UNTIL TUESDAY
AFTERNOON...AS THE RIDGE SLOWLY WORKS EAST. CMS

&&

.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...SMALL CRAFT ADVISORY...NEARSHORE WATERS UNTIL 7 AM MONDAY.

     SMALL CRAFT ADVISORY...LMZ740-LMZ741-LMZ742-LMZ743-LMZ744-
     LMZ745...10 PM MONDAY TO 7 AM WEDNESDAY.

&&

$$

VISIT US AT HTTP://WEATHER.GOV/CHICAGO (ALL LOWERCASE)

FOLLOW US ON FACEBOOK...TWITTER...AND YOUTUBE AT:
WWW.FACEBOOK.COM/NWSCHICAGO
WWW.TWITTER.COM/NWSCHICAGO
WWW.YOUTUBE.COM/NWSCHICAGO






000
FXUS63 KLOT 201058 AAA
AFDLOT

AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
558 AM CDT MON OCT 20 2014

.DISCUSSION...
557 AM CDT

WE ARE SEEING SCATTERED SHOWERS SPARK NEAR CHICAGO AS OF 555 AM
AHEAD OF THE UPPER DISTURBANCE MENTIONED IN THE PREVIOUS
DISCUSSION. THIS DISTURBANCE HAS A POCKET OF STEEP LAPSE RATES
ALOFT /500MB-750MB/ OF 8C/KM AND GREATER AND THAT IS AIDING SOME
OF THESE SHOWER UPDRAFTS. THIS IS INDICATED BY A COUPLE LIGHTNING
STRIKES OVER LAKE MI AND THE OBSERVERS AT ORD AND MDW REPORTING
INTRA-CLOUD AND CLOUD-TO-AIR LIGHTNING. THE GOOD NEWS IS THIS
UPPER WAVE AND ITS FORCING IS MOVING ABOUT 35-40 MPH SO NOT
EXPECTING THESE TO STICK AROUND THE CHICAGO AREA AFTER 7 AM.
CONTINUE THE SHOWER CHANCES THIS MORNING AS IS IN NORTHWEST
INDIANA AND HAVE ADDED A SLIGHT CHANCE OF THUNDER FOR AREAS NEAR
THE I-80/I-90 CORRIDOR.

MTF

&&

.PREV DISCUSSION...
319 AM CDT

A QUIET WEATHER PATTERN WILL REMAIN IN PLACE IN TERMS OF LACK OF
PRECIPITATION CHANCES AND ANY HIGH IMPACT WEATHER THROUGH NEXT
WEEKEND...THOUGH STILL SEVERAL LITTLE INTERESTS TO TACKLE. THESE
INCLUDED HOW WIDESPREAD CLOUDS WILL REACH LATER TODAY THROUGH
TUESDAY AS WELL AS LAKE EFFECT SHOWER POTENTIAL DURING THAT TIME.
THEN LOOKING AT WHEN AND HOW QUICKLY OF A WARM-UP OCCURS LATE IN
THE WEEK INTO THE WEEKEND.

TODAY THROUGH TUESDAY...
THE CONTINUED AMPLIFIED BUT PROGRESSIVE FLOW OVER CANADA AND THE
NORTHERN CONUS CONTINUES FOR A LITTLE LONGER WITH A PACIFIC/CLIPPER
HYBRID SYSTEM MOVING SOUTHEASTWARD FROM THE CENTRAL GREAT LAKES.
AROUND THIS A WELL-DEFINED SHORT WAVE ON GOES WATER VAPOR IMAGERY IS
MOVING INTO NORTHERN IL EARLY THIS MORNING. THIS IS FAIRLY MOISTURE
STARVED BUT CANNOT RULE OUT A FEW SHOWERS THIS MORNING MAINLY IN
NORTHWEST INDIANA. THIS SHORT WAVE ALSO BEGINS TO BREAK DOWN THE
LOW-LEVEL THERMAL RIDGE OVER THE AREA...WITH CLOUDS LIKELY TO
ADVECT/DEVELOP SOUTHWARD INTO THE FORECAST AREA THIS AFTERNOON. IN
ADDITION...TEMPERATURES MAY ALSO PEAK EARLY IN THE AFTERNOON AND
THEN EXPERIENCE A SLOW DROP. TEMPERATURES SHOULD STILL PEAK AROUND
CLIMATOLOGICAL NORMAL /60 TO 65/ WITH THE MORNING SUN. THE CYCLONIC
FLOW OVER THE REGION AND RAPIDLY COOLING 850-925MB TEMPERATURES LOOK
TO SUPPORT CLOUDS OVER MUCH OF THE AREA BY EARLY THIS EVENING AND
UPSTREAM OBSERVATIONAL TRENDS SUPPORT THIS. HAVE GONE WELL ABOVE
MOST GUIDANCE IN SKY COVER FROM LATE TODAY ALL THE WAY THROUGH
TUESDAY MORNING AS HIGH-RESOLUTION MODEL CONDENSATE /SUCH AS THE
4KM SPC WRF/ SEEMS TO WORK BETTER IN SUCH A PATTERN WITH THIN BUT
PROBABLY BROKEN-OVERCAST CLOUD COVER. THE CLOUDS AND NORTH-
NORTHEAST WINDS ON TUESDAY MORNING SHOULD LIMIT WARMING BY QUITE A
BIT WITH SOME LOCATIONS POSSIBLY NOT REACHING 50.

AS THE COOLER AIR AT OR AROUND 0C AT 850MB EXPANDS SOUTHWARD DOWN
THE LAKE LATER TODAY FORESEE DEEPENING LAKE EFFECT CLOUDS AND
SOME SHOWERS DEVELOPING. THESE SHOWERS LOOK TO BE NOT PARTICULARLY
CONCENTRATED WITH LIMITED CONVERGENCE AND MAINLY LIGHT IN
INTENSITY WITH LAKE-INDUCED EQUILIBRIUM LEVELS FORECAST BY THE
NAM OF AROUND 5000 FT. THE BOUNDARY LAYER FLOW FETCH SHOULD FAVOR
NORTHWEST INDIANA FOR THESE SHOWERS TONIGHT INTO EARLY
TUESDAY...THOUGH SOME VEERING TOWARD THE IL/IN STATE LINE AND EVEN
POTENTIALLY CHICAGO TUESDAY MORNING COULD SUPPORT SOME LIGHT
SHOWER ACTIVITY TUESDAY MORNING IN THOSE PLACES. THE HOPWRF-TS
SUPPORTS SUCH A GENERAL EVOLUTION WITH ITS RECENTLY ADDED EXTENDED
HIGH-RES OUTPUT.

TUESDAY NIGHT THROUGH THURSDAY...
SURFACE HIGH PRESSURE WILL BUILD OVER THE AREA FROM THE NORTH DURING
THIS TIME AS THE OVERALL UPPER PATTERN SLOWS THANKS TO AMPLIFICATION
OF A TROUGH ALONG THE WEST COAST OF NORTH AMERICA. OVERALL BENIGN
WEATHER LOOKS TO BE THE RULE WITH TEMPS SLIGHTLY BELOW NORMAL THOUGH
GRADUALLY MODIFYING. MODEL GUIDANCE DOES INDICATE AN ELONGATED SHORT
WAVE TO MOVE INTO THE UPPER MISSISSIPPI VALLEY DURING OR AROUND
THURSDAY NIGHT THOUGH THIS WILL BE MOVING INTO AN UNFAVORABLE
UPPER LEVEL AND MOISTURE SUPPORTIVE PATTERN. SO CONTINUE THE DRY
FORECAST.

FRIDAY INTO NEXT WEEKEND...
THE ONLY CHANGE WITH THIS PORTION OF THE FORECAST WAS TO INCREASE
TEMPERATURES...MAINLY ON SATURDAY. IF CLOUD COVER CAN REMAIN LIMITED
WITH THE PATTERN FORECAST...THE 850MB-925MB TEMPERATURES WOULD
SUPPORT TEMPERATURES POTENTIALLY IN THE 70S WITH A THERMAL RIDGE
STEERED IN FROM THE WEST-SOUTHWEST.

MTF

&&

.AVIATION...

//ORD AND MDW CONCERNS...UPDATED 09Z...

* SOUTHWEST WINDS BECOMING WEST THIS MORNING...NORTHWEST THIS
  AFTERNOON THEN NORTH/NORTHEAST LATE THIS AFTERNOON. CMS

//DISCUSSION...UPDATED 06Z...

A COLD FRONT WILL MOVE ACROSS THE TERMINALS LATER THIS MORNING...
SHIFTING SOUTHWESTERLY WINDS TO THE WEST/NORTHWEST BY MID MORNING
AND THEN TO THE NORTHWEST BY EARLY AFTERNOON. SPEEDS 10-12KTS WITH
A FEW HIGHER GUSTS TO START WILL DIMINISH SOME BY SUNRISE THEN
INCREASE AGAIN TO 10-12KTS THIS AFTERNOON. AS THE FRONT CONTINUES
EAST THIS AFTERNOON...THE GRADIENT BECOMES A BIT WEAKER OVER THE
SOUTHERN END OF LAKE MICHIGAN. THIS WILL LIKELY ALLOW WINDS TO
SHIFT TO THE NORTH/NORTHEAST BY LATE AFTERNOON. CONFIDENCE IN
SPEEDS IS A BIT LOWER...WITH PREVAILING SPEEDS LIKELY TO BE JUST
UNDER 10KTS.

MID CLOUDS WILL SHIFT EAST EARLY THIS MORNING WITH LOWER VFR...
3-5KFT CIGS OVER THE NORTHERN LAKES MOVING SOUTH ACROSS THE AREA
LATER THIS MORNING AND CONTINUING INTO THIS EVENING WITH SOME
POTENTIAL FOR HIGH MVFR CIGS...ESPECIALLY SOUTH OF THE LAKE
AFFECTING GYY. CMS

//ORD AND MDW CONFIDENCE...UPDATED 09Z...

* HIGH FOR WINDS THRU MID MORNING...THEN MEDIUM FOR DIRECTION AND
  TIMING CHANGES THIS AFTERNOON/EVENING. CMS

//OUTLOOK FOR ORD/MDW FOR 12Z TUESDAY-12Z SUNDAY...UPDATED 00Z...

TUESDAY...VFR. BREEZY NORTHEAST WINDS.

WEDNESDAY...VFR. EAST WINDS.

THURSDAY THROUGH SATURDAY...VFR. LIGHT WEST TO SOUTHWEST WINDS.

MDB

&&

.MARINE...

309 AM...LOW PRESSURE OVER THE UPPER PENINSULA OF MICHIGAN WILL
MOVE SOUTHEAST TODAY AND TONIGHT REACHING THE MID ATLANTIC ON
TUESDAY. A TRAILING COLD FRONT WILL MOVE ACROSS LAKE MICHIGAN THIS
MORNING. SOUTHWEST WINDS WILL TURN NORTHWEST THIS MORNING THEN
NORTH THIS EVENING. THE GRADIENT REMAINS FAIRLY TIGHT ACROSS THE
SOUTHERN THIRD OR SO OF THE LAKE...WITH GUSTS TO 30KT POSSIBLE FOR
A FEW MORE HOURS. HIGH PRESSURE WILL BUILD ACROSS ONTARIO TODAY
AND TONIGHT AS IT STRENGTHENS. WHILE THE CENTER OF THIS HIGH WILL
MOVE EAST INTO QUEBEC TUESDAY NIGHT...A RIDGE WILL EXTEND SOUTH
ACROSS THE WESTERN LAKES TONIGHT AND TUESDAY...THEN MOVE ACROSS
THE LAKE WEDNESDAY. THE GRADIENT WILL TIGHTEN BETWEEN THIS
APPROACHING RIDGE AND THE DEPARTING LOW WITH NORTHERLY WINDS
INCREASING TO 30 KT THIS EVENING AND REMAINING THERE UNTIL TUESDAY
AFTERNOON...AS THE RIDGE SLOWLY WORKS EAST. CMS

&&

.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...SMALL CRAFT ADVISORY...NEARSHORE WATERS
     UNTIL 7 AM MONDAY.

     SMALL CRAFT ADVISORY...LMZ740-LMZ741-LMZ742-LMZ743-LMZ744-
     LMZ745...10 PM MONDAY TO 7 AM WEDNESDAY.

&&

$$

VISIT US AT HTTP://WEATHER.GOV/CHICAGO (ALL LOWERCASE)

FOLLOW US ON FACEBOOK...TWITTER...AND YOUTUBE AT:
WWW.FACEBOOK.COM/NWSCHICAGO
WWW.TWITTER.COM/NWSCHICAGO
WWW.YOUTUBE.COM/NWSCHICAGO







000
FXUS63 KLOT 201058 AAA
AFDLOT

AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
558 AM CDT MON OCT 20 2014

.DISCUSSION...
557 AM CDT

WE ARE SEEING SCATTERED SHOWERS SPARK NEAR CHICAGO AS OF 555 AM
AHEAD OF THE UPPER DISTURBANCE MENTIONED IN THE PREVIOUS
DISCUSSION. THIS DISTURBANCE HAS A POCKET OF STEEP LAPSE RATES
ALOFT /500MB-750MB/ OF 8C/KM AND GREATER AND THAT IS AIDING SOME
OF THESE SHOWER UPDRAFTS. THIS IS INDICATED BY A COUPLE LIGHTNING
STRIKES OVER LAKE MI AND THE OBSERVERS AT ORD AND MDW REPORTING
INTRA-CLOUD AND CLOUD-TO-AIR LIGHTNING. THE GOOD NEWS IS THIS
UPPER WAVE AND ITS FORCING IS MOVING ABOUT 35-40 MPH SO NOT
EXPECTING THESE TO STICK AROUND THE CHICAGO AREA AFTER 7 AM.
CONTINUE THE SHOWER CHANCES THIS MORNING AS IS IN NORTHWEST
INDIANA AND HAVE ADDED A SLIGHT CHANCE OF THUNDER FOR AREAS NEAR
THE I-80/I-90 CORRIDOR.

MTF

&&

.PREV DISCUSSION...
319 AM CDT

A QUIET WEATHER PATTERN WILL REMAIN IN PLACE IN TERMS OF LACK OF
PRECIPITATION CHANCES AND ANY HIGH IMPACT WEATHER THROUGH NEXT
WEEKEND...THOUGH STILL SEVERAL LITTLE INTERESTS TO TACKLE. THESE
INCLUDED HOW WIDESPREAD CLOUDS WILL REACH LATER TODAY THROUGH
TUESDAY AS WELL AS LAKE EFFECT SHOWER POTENTIAL DURING THAT TIME.
THEN LOOKING AT WHEN AND HOW QUICKLY OF A WARM-UP OCCURS LATE IN
THE WEEK INTO THE WEEKEND.

TODAY THROUGH TUESDAY...
THE CONTINUED AMPLIFIED BUT PROGRESSIVE FLOW OVER CANADA AND THE
NORTHERN CONUS CONTINUES FOR A LITTLE LONGER WITH A PACIFIC/CLIPPER
HYBRID SYSTEM MOVING SOUTHEASTWARD FROM THE CENTRAL GREAT LAKES.
AROUND THIS A WELL-DEFINED SHORT WAVE ON GOES WATER VAPOR IMAGERY IS
MOVING INTO NORTHERN IL EARLY THIS MORNING. THIS IS FAIRLY MOISTURE
STARVED BUT CANNOT RULE OUT A FEW SHOWERS THIS MORNING MAINLY IN
NORTHWEST INDIANA. THIS SHORT WAVE ALSO BEGINS TO BREAK DOWN THE
LOW-LEVEL THERMAL RIDGE OVER THE AREA...WITH CLOUDS LIKELY TO
ADVECT/DEVELOP SOUTHWARD INTO THE FORECAST AREA THIS AFTERNOON. IN
ADDITION...TEMPERATURES MAY ALSO PEAK EARLY IN THE AFTERNOON AND
THEN EXPERIENCE A SLOW DROP. TEMPERATURES SHOULD STILL PEAK AROUND
CLIMATOLOGICAL NORMAL /60 TO 65/ WITH THE MORNING SUN. THE CYCLONIC
FLOW OVER THE REGION AND RAPIDLY COOLING 850-925MB TEMPERATURES LOOK
TO SUPPORT CLOUDS OVER MUCH OF THE AREA BY EARLY THIS EVENING AND
UPSTREAM OBSERVATIONAL TRENDS SUPPORT THIS. HAVE GONE WELL ABOVE
MOST GUIDANCE IN SKY COVER FROM LATE TODAY ALL THE WAY THROUGH
TUESDAY MORNING AS HIGH-RESOLUTION MODEL CONDENSATE /SUCH AS THE
4KM SPC WRF/ SEEMS TO WORK BETTER IN SUCH A PATTERN WITH THIN BUT
PROBABLY BROKEN-OVERCAST CLOUD COVER. THE CLOUDS AND NORTH-
NORTHEAST WINDS ON TUESDAY MORNING SHOULD LIMIT WARMING BY QUITE A
BIT WITH SOME LOCATIONS POSSIBLY NOT REACHING 50.

AS THE COOLER AIR AT OR AROUND 0C AT 850MB EXPANDS SOUTHWARD DOWN
THE LAKE LATER TODAY FORESEE DEEPENING LAKE EFFECT CLOUDS AND
SOME SHOWERS DEVELOPING. THESE SHOWERS LOOK TO BE NOT PARTICULARLY
CONCENTRATED WITH LIMITED CONVERGENCE AND MAINLY LIGHT IN
INTENSITY WITH LAKE-INDUCED EQUILIBRIUM LEVELS FORECAST BY THE
NAM OF AROUND 5000 FT. THE BOUNDARY LAYER FLOW FETCH SHOULD FAVOR
NORTHWEST INDIANA FOR THESE SHOWERS TONIGHT INTO EARLY
TUESDAY...THOUGH SOME VEERING TOWARD THE IL/IN STATE LINE AND EVEN
POTENTIALLY CHICAGO TUESDAY MORNING COULD SUPPORT SOME LIGHT
SHOWER ACTIVITY TUESDAY MORNING IN THOSE PLACES. THE HOPWRF-TS
SUPPORTS SUCH A GENERAL EVOLUTION WITH ITS RECENTLY ADDED EXTENDED
HIGH-RES OUTPUT.

TUESDAY NIGHT THROUGH THURSDAY...
SURFACE HIGH PRESSURE WILL BUILD OVER THE AREA FROM THE NORTH DURING
THIS TIME AS THE OVERALL UPPER PATTERN SLOWS THANKS TO AMPLIFICATION
OF A TROUGH ALONG THE WEST COAST OF NORTH AMERICA. OVERALL BENIGN
WEATHER LOOKS TO BE THE RULE WITH TEMPS SLIGHTLY BELOW NORMAL THOUGH
GRADUALLY MODIFYING. MODEL GUIDANCE DOES INDICATE AN ELONGATED SHORT
WAVE TO MOVE INTO THE UPPER MISSISSIPPI VALLEY DURING OR AROUND
THURSDAY NIGHT THOUGH THIS WILL BE MOVING INTO AN UNFAVORABLE
UPPER LEVEL AND MOISTURE SUPPORTIVE PATTERN. SO CONTINUE THE DRY
FORECAST.

FRIDAY INTO NEXT WEEKEND...
THE ONLY CHANGE WITH THIS PORTION OF THE FORECAST WAS TO INCREASE
TEMPERATURES...MAINLY ON SATURDAY. IF CLOUD COVER CAN REMAIN LIMITED
WITH THE PATTERN FORECAST...THE 850MB-925MB TEMPERATURES WOULD
SUPPORT TEMPERATURES POTENTIALLY IN THE 70S WITH A THERMAL RIDGE
STEERED IN FROM THE WEST-SOUTHWEST.

MTF

&&

.AVIATION...

//ORD AND MDW CONCERNS...UPDATED 09Z...

* SOUTHWEST WINDS BECOMING WEST THIS MORNING...NORTHWEST THIS
  AFTERNOON THEN NORTH/NORTHEAST LATE THIS AFTERNOON. CMS

//DISCUSSION...UPDATED 06Z...

A COLD FRONT WILL MOVE ACROSS THE TERMINALS LATER THIS MORNING...
SHIFTING SOUTHWESTERLY WINDS TO THE WEST/NORTHWEST BY MID MORNING
AND THEN TO THE NORTHWEST BY EARLY AFTERNOON. SPEEDS 10-12KTS WITH
A FEW HIGHER GUSTS TO START WILL DIMINISH SOME BY SUNRISE THEN
INCREASE AGAIN TO 10-12KTS THIS AFTERNOON. AS THE FRONT CONTINUES
EAST THIS AFTERNOON...THE GRADIENT BECOMES A BIT WEAKER OVER THE
SOUTHERN END OF LAKE MICHIGAN. THIS WILL LIKELY ALLOW WINDS TO
SHIFT TO THE NORTH/NORTHEAST BY LATE AFTERNOON. CONFIDENCE IN
SPEEDS IS A BIT LOWER...WITH PREVAILING SPEEDS LIKELY TO BE JUST
UNDER 10KTS.

MID CLOUDS WILL SHIFT EAST EARLY THIS MORNING WITH LOWER VFR...
3-5KFT CIGS OVER THE NORTHERN LAKES MOVING SOUTH ACROSS THE AREA
LATER THIS MORNING AND CONTINUING INTO THIS EVENING WITH SOME
POTENTIAL FOR HIGH MVFR CIGS...ESPECIALLY SOUTH OF THE LAKE
AFFECTING GYY. CMS

//ORD AND MDW CONFIDENCE...UPDATED 09Z...

* HIGH FOR WINDS THRU MID MORNING...THEN MEDIUM FOR DIRECTION AND
  TIMING CHANGES THIS AFTERNOON/EVENING. CMS

//OUTLOOK FOR ORD/MDW FOR 12Z TUESDAY-12Z SUNDAY...UPDATED 00Z...

TUESDAY...VFR. BREEZY NORTHEAST WINDS.

WEDNESDAY...VFR. EAST WINDS.

THURSDAY THROUGH SATURDAY...VFR. LIGHT WEST TO SOUTHWEST WINDS.

MDB

&&

.MARINE...

309 AM...LOW PRESSURE OVER THE UPPER PENINSULA OF MICHIGAN WILL
MOVE SOUTHEAST TODAY AND TONIGHT REACHING THE MID ATLANTIC ON
TUESDAY. A TRAILING COLD FRONT WILL MOVE ACROSS LAKE MICHIGAN THIS
MORNING. SOUTHWEST WINDS WILL TURN NORTHWEST THIS MORNING THEN
NORTH THIS EVENING. THE GRADIENT REMAINS FAIRLY TIGHT ACROSS THE
SOUTHERN THIRD OR SO OF THE LAKE...WITH GUSTS TO 30KT POSSIBLE FOR
A FEW MORE HOURS. HIGH PRESSURE WILL BUILD ACROSS ONTARIO TODAY
AND TONIGHT AS IT STRENGTHENS. WHILE THE CENTER OF THIS HIGH WILL
MOVE EAST INTO QUEBEC TUESDAY NIGHT...A RIDGE WILL EXTEND SOUTH
ACROSS THE WESTERN LAKES TONIGHT AND TUESDAY...THEN MOVE ACROSS
THE LAKE WEDNESDAY. THE GRADIENT WILL TIGHTEN BETWEEN THIS
APPROACHING RIDGE AND THE DEPARTING LOW WITH NORTHERLY WINDS
INCREASING TO 30 KT THIS EVENING AND REMAINING THERE UNTIL TUESDAY
AFTERNOON...AS THE RIDGE SLOWLY WORKS EAST. CMS

&&

.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...SMALL CRAFT ADVISORY...NEARSHORE WATERS
     UNTIL 7 AM MONDAY.

     SMALL CRAFT ADVISORY...LMZ740-LMZ741-LMZ742-LMZ743-LMZ744-
     LMZ745...10 PM MONDAY TO 7 AM WEDNESDAY.

&&

$$

VISIT US AT HTTP://WEATHER.GOV/CHICAGO (ALL LOWERCASE)

FOLLOW US ON FACEBOOK...TWITTER...AND YOUTUBE AT:
WWW.FACEBOOK.COM/NWSCHICAGO
WWW.TWITTER.COM/NWSCHICAGO
WWW.YOUTUBE.COM/NWSCHICAGO






000
FXUS63 KLOT 201058 AAA
AFDLOT

AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
558 AM CDT MON OCT 20 2014

.DISCUSSION...
557 AM CDT

WE ARE SEEING SCATTERED SHOWERS SPARK NEAR CHICAGO AS OF 555 AM
AHEAD OF THE UPPER DISTURBANCE MENTIONED IN THE PREVIOUS
DISCUSSION. THIS DISTURBANCE HAS A POCKET OF STEEP LAPSE RATES
ALOFT /500MB-750MB/ OF 8C/KM AND GREATER AND THAT IS AIDING SOME
OF THESE SHOWER UPDRAFTS. THIS IS INDICATED BY A COUPLE LIGHTNING
STRIKES OVER LAKE MI AND THE OBSERVERS AT ORD AND MDW REPORTING
INTRA-CLOUD AND CLOUD-TO-AIR LIGHTNING. THE GOOD NEWS IS THIS
UPPER WAVE AND ITS FORCING IS MOVING ABOUT 35-40 MPH SO NOT
EXPECTING THESE TO STICK AROUND THE CHICAGO AREA AFTER 7 AM.
CONTINUE THE SHOWER CHANCES THIS MORNING AS IS IN NORTHWEST
INDIANA AND HAVE ADDED A SLIGHT CHANCE OF THUNDER FOR AREAS NEAR
THE I-80/I-90 CORRIDOR.

MTF

&&

.PREV DISCUSSION...
319 AM CDT

A QUIET WEATHER PATTERN WILL REMAIN IN PLACE IN TERMS OF LACK OF
PRECIPITATION CHANCES AND ANY HIGH IMPACT WEATHER THROUGH NEXT
WEEKEND...THOUGH STILL SEVERAL LITTLE INTERESTS TO TACKLE. THESE
INCLUDED HOW WIDESPREAD CLOUDS WILL REACH LATER TODAY THROUGH
TUESDAY AS WELL AS LAKE EFFECT SHOWER POTENTIAL DURING THAT TIME.
THEN LOOKING AT WHEN AND HOW QUICKLY OF A WARM-UP OCCURS LATE IN
THE WEEK INTO THE WEEKEND.

TODAY THROUGH TUESDAY...
THE CONTINUED AMPLIFIED BUT PROGRESSIVE FLOW OVER CANADA AND THE
NORTHERN CONUS CONTINUES FOR A LITTLE LONGER WITH A PACIFIC/CLIPPER
HYBRID SYSTEM MOVING SOUTHEASTWARD FROM THE CENTRAL GREAT LAKES.
AROUND THIS A WELL-DEFINED SHORT WAVE ON GOES WATER VAPOR IMAGERY IS
MOVING INTO NORTHERN IL EARLY THIS MORNING. THIS IS FAIRLY MOISTURE
STARVED BUT CANNOT RULE OUT A FEW SHOWERS THIS MORNING MAINLY IN
NORTHWEST INDIANA. THIS SHORT WAVE ALSO BEGINS TO BREAK DOWN THE
LOW-LEVEL THERMAL RIDGE OVER THE AREA...WITH CLOUDS LIKELY TO
ADVECT/DEVELOP SOUTHWARD INTO THE FORECAST AREA THIS AFTERNOON. IN
ADDITION...TEMPERATURES MAY ALSO PEAK EARLY IN THE AFTERNOON AND
THEN EXPERIENCE A SLOW DROP. TEMPERATURES SHOULD STILL PEAK AROUND
CLIMATOLOGICAL NORMAL /60 TO 65/ WITH THE MORNING SUN. THE CYCLONIC
FLOW OVER THE REGION AND RAPIDLY COOLING 850-925MB TEMPERATURES LOOK
TO SUPPORT CLOUDS OVER MUCH OF THE AREA BY EARLY THIS EVENING AND
UPSTREAM OBSERVATIONAL TRENDS SUPPORT THIS. HAVE GONE WELL ABOVE
MOST GUIDANCE IN SKY COVER FROM LATE TODAY ALL THE WAY THROUGH
TUESDAY MORNING AS HIGH-RESOLUTION MODEL CONDENSATE /SUCH AS THE
4KM SPC WRF/ SEEMS TO WORK BETTER IN SUCH A PATTERN WITH THIN BUT
PROBABLY BROKEN-OVERCAST CLOUD COVER. THE CLOUDS AND NORTH-
NORTHEAST WINDS ON TUESDAY MORNING SHOULD LIMIT WARMING BY QUITE A
BIT WITH SOME LOCATIONS POSSIBLY NOT REACHING 50.

AS THE COOLER AIR AT OR AROUND 0C AT 850MB EXPANDS SOUTHWARD DOWN
THE LAKE LATER TODAY FORESEE DEEPENING LAKE EFFECT CLOUDS AND
SOME SHOWERS DEVELOPING. THESE SHOWERS LOOK TO BE NOT PARTICULARLY
CONCENTRATED WITH LIMITED CONVERGENCE AND MAINLY LIGHT IN
INTENSITY WITH LAKE-INDUCED EQUILIBRIUM LEVELS FORECAST BY THE
NAM OF AROUND 5000 FT. THE BOUNDARY LAYER FLOW FETCH SHOULD FAVOR
NORTHWEST INDIANA FOR THESE SHOWERS TONIGHT INTO EARLY
TUESDAY...THOUGH SOME VEERING TOWARD THE IL/IN STATE LINE AND EVEN
POTENTIALLY CHICAGO TUESDAY MORNING COULD SUPPORT SOME LIGHT
SHOWER ACTIVITY TUESDAY MORNING IN THOSE PLACES. THE HOPWRF-TS
SUPPORTS SUCH A GENERAL EVOLUTION WITH ITS RECENTLY ADDED EXTENDED
HIGH-RES OUTPUT.

TUESDAY NIGHT THROUGH THURSDAY...
SURFACE HIGH PRESSURE WILL BUILD OVER THE AREA FROM THE NORTH DURING
THIS TIME AS THE OVERALL UPPER PATTERN SLOWS THANKS TO AMPLIFICATION
OF A TROUGH ALONG THE WEST COAST OF NORTH AMERICA. OVERALL BENIGN
WEATHER LOOKS TO BE THE RULE WITH TEMPS SLIGHTLY BELOW NORMAL THOUGH
GRADUALLY MODIFYING. MODEL GUIDANCE DOES INDICATE AN ELONGATED SHORT
WAVE TO MOVE INTO THE UPPER MISSISSIPPI VALLEY DURING OR AROUND
THURSDAY NIGHT THOUGH THIS WILL BE MOVING INTO AN UNFAVORABLE
UPPER LEVEL AND MOISTURE SUPPORTIVE PATTERN. SO CONTINUE THE DRY
FORECAST.

FRIDAY INTO NEXT WEEKEND...
THE ONLY CHANGE WITH THIS PORTION OF THE FORECAST WAS TO INCREASE
TEMPERATURES...MAINLY ON SATURDAY. IF CLOUD COVER CAN REMAIN LIMITED
WITH THE PATTERN FORECAST...THE 850MB-925MB TEMPERATURES WOULD
SUPPORT TEMPERATURES POTENTIALLY IN THE 70S WITH A THERMAL RIDGE
STEERED IN FROM THE WEST-SOUTHWEST.

MTF

&&

.AVIATION...

//ORD AND MDW CONCERNS...UPDATED 09Z...

* SOUTHWEST WINDS BECOMING WEST THIS MORNING...NORTHWEST THIS
  AFTERNOON THEN NORTH/NORTHEAST LATE THIS AFTERNOON. CMS

//DISCUSSION...UPDATED 06Z...

A COLD FRONT WILL MOVE ACROSS THE TERMINALS LATER THIS MORNING...
SHIFTING SOUTHWESTERLY WINDS TO THE WEST/NORTHWEST BY MID MORNING
AND THEN TO THE NORTHWEST BY EARLY AFTERNOON. SPEEDS 10-12KTS WITH
A FEW HIGHER GUSTS TO START WILL DIMINISH SOME BY SUNRISE THEN
INCREASE AGAIN TO 10-12KTS THIS AFTERNOON. AS THE FRONT CONTINUES
EAST THIS AFTERNOON...THE GRADIENT BECOMES A BIT WEAKER OVER THE
SOUTHERN END OF LAKE MICHIGAN. THIS WILL LIKELY ALLOW WINDS TO
SHIFT TO THE NORTH/NORTHEAST BY LATE AFTERNOON. CONFIDENCE IN
SPEEDS IS A BIT LOWER...WITH PREVAILING SPEEDS LIKELY TO BE JUST
UNDER 10KTS.

MID CLOUDS WILL SHIFT EAST EARLY THIS MORNING WITH LOWER VFR...
3-5KFT CIGS OVER THE NORTHERN LAKES MOVING SOUTH ACROSS THE AREA
LATER THIS MORNING AND CONTINUING INTO THIS EVENING WITH SOME
POTENTIAL FOR HIGH MVFR CIGS...ESPECIALLY SOUTH OF THE LAKE
AFFECTING GYY. CMS

//ORD AND MDW CONFIDENCE...UPDATED 09Z...

* HIGH FOR WINDS THRU MID MORNING...THEN MEDIUM FOR DIRECTION AND
  TIMING CHANGES THIS AFTERNOON/EVENING. CMS

//OUTLOOK FOR ORD/MDW FOR 12Z TUESDAY-12Z SUNDAY...UPDATED 00Z...

TUESDAY...VFR. BREEZY NORTHEAST WINDS.

WEDNESDAY...VFR. EAST WINDS.

THURSDAY THROUGH SATURDAY...VFR. LIGHT WEST TO SOUTHWEST WINDS.

MDB

&&

.MARINE...

309 AM...LOW PRESSURE OVER THE UPPER PENINSULA OF MICHIGAN WILL
MOVE SOUTHEAST TODAY AND TONIGHT REACHING THE MID ATLANTIC ON
TUESDAY. A TRAILING COLD FRONT WILL MOVE ACROSS LAKE MICHIGAN THIS
MORNING. SOUTHWEST WINDS WILL TURN NORTHWEST THIS MORNING THEN
NORTH THIS EVENING. THE GRADIENT REMAINS FAIRLY TIGHT ACROSS THE
SOUTHERN THIRD OR SO OF THE LAKE...WITH GUSTS TO 30KT POSSIBLE FOR
A FEW MORE HOURS. HIGH PRESSURE WILL BUILD ACROSS ONTARIO TODAY
AND TONIGHT AS IT STRENGTHENS. WHILE THE CENTER OF THIS HIGH WILL
MOVE EAST INTO QUEBEC TUESDAY NIGHT...A RIDGE WILL EXTEND SOUTH
ACROSS THE WESTERN LAKES TONIGHT AND TUESDAY...THEN MOVE ACROSS
THE LAKE WEDNESDAY. THE GRADIENT WILL TIGHTEN BETWEEN THIS
APPROACHING RIDGE AND THE DEPARTING LOW WITH NORTHERLY WINDS
INCREASING TO 30 KT THIS EVENING AND REMAINING THERE UNTIL TUESDAY
AFTERNOON...AS THE RIDGE SLOWLY WORKS EAST. CMS

&&

.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...SMALL CRAFT ADVISORY...NEARSHORE WATERS
     UNTIL 7 AM MONDAY.

     SMALL CRAFT ADVISORY...LMZ740-LMZ741-LMZ742-LMZ743-LMZ744-
     LMZ745...10 PM MONDAY TO 7 AM WEDNESDAY.

&&

$$

VISIT US AT HTTP://WEATHER.GOV/CHICAGO (ALL LOWERCASE)

FOLLOW US ON FACEBOOK...TWITTER...AND YOUTUBE AT:
WWW.FACEBOOK.COM/NWSCHICAGO
WWW.TWITTER.COM/NWSCHICAGO
WWW.YOUTUBE.COM/NWSCHICAGO







000
FXUS63 KLOT 201058 AAA
AFDLOT

AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
558 AM CDT MON OCT 20 2014

.DISCUSSION...
557 AM CDT

WE ARE SEEING SCATTERED SHOWERS SPARK NEAR CHICAGO AS OF 555 AM
AHEAD OF THE UPPER DISTURBANCE MENTIONED IN THE PREVIOUS
DISCUSSION. THIS DISTURBANCE HAS A POCKET OF STEEP LAPSE RATES
ALOFT /500MB-750MB/ OF 8C/KM AND GREATER AND THAT IS AIDING SOME
OF THESE SHOWER UPDRAFTS. THIS IS INDICATED BY A COUPLE LIGHTNING
STRIKES OVER LAKE MI AND THE OBSERVERS AT ORD AND MDW REPORTING
INTRA-CLOUD AND CLOUD-TO-AIR LIGHTNING. THE GOOD NEWS IS THIS
UPPER WAVE AND ITS FORCING IS MOVING ABOUT 35-40 MPH SO NOT
EXPECTING THESE TO STICK AROUND THE CHICAGO AREA AFTER 7 AM.
CONTINUE THE SHOWER CHANCES THIS MORNING AS IS IN NORTHWEST
INDIANA AND HAVE ADDED A SLIGHT CHANCE OF THUNDER FOR AREAS NEAR
THE I-80/I-90 CORRIDOR.

MTF

&&

.PREV DISCUSSION...
319 AM CDT

A QUIET WEATHER PATTERN WILL REMAIN IN PLACE IN TERMS OF LACK OF
PRECIPITATION CHANCES AND ANY HIGH IMPACT WEATHER THROUGH NEXT
WEEKEND...THOUGH STILL SEVERAL LITTLE INTERESTS TO TACKLE. THESE
INCLUDED HOW WIDESPREAD CLOUDS WILL REACH LATER TODAY THROUGH
TUESDAY AS WELL AS LAKE EFFECT SHOWER POTENTIAL DURING THAT TIME.
THEN LOOKING AT WHEN AND HOW QUICKLY OF A WARM-UP OCCURS LATE IN
THE WEEK INTO THE WEEKEND.

TODAY THROUGH TUESDAY...
THE CONTINUED AMPLIFIED BUT PROGRESSIVE FLOW OVER CANADA AND THE
NORTHERN CONUS CONTINUES FOR A LITTLE LONGER WITH A PACIFIC/CLIPPER
HYBRID SYSTEM MOVING SOUTHEASTWARD FROM THE CENTRAL GREAT LAKES.
AROUND THIS A WELL-DEFINED SHORT WAVE ON GOES WATER VAPOR IMAGERY IS
MOVING INTO NORTHERN IL EARLY THIS MORNING. THIS IS FAIRLY MOISTURE
STARVED BUT CANNOT RULE OUT A FEW SHOWERS THIS MORNING MAINLY IN
NORTHWEST INDIANA. THIS SHORT WAVE ALSO BEGINS TO BREAK DOWN THE
LOW-LEVEL THERMAL RIDGE OVER THE AREA...WITH CLOUDS LIKELY TO
ADVECT/DEVELOP SOUTHWARD INTO THE FORECAST AREA THIS AFTERNOON. IN
ADDITION...TEMPERATURES MAY ALSO PEAK EARLY IN THE AFTERNOON AND
THEN EXPERIENCE A SLOW DROP. TEMPERATURES SHOULD STILL PEAK AROUND
CLIMATOLOGICAL NORMAL /60 TO 65/ WITH THE MORNING SUN. THE CYCLONIC
FLOW OVER THE REGION AND RAPIDLY COOLING 850-925MB TEMPERATURES LOOK
TO SUPPORT CLOUDS OVER MUCH OF THE AREA BY EARLY THIS EVENING AND
UPSTREAM OBSERVATIONAL TRENDS SUPPORT THIS. HAVE GONE WELL ABOVE
MOST GUIDANCE IN SKY COVER FROM LATE TODAY ALL THE WAY THROUGH
TUESDAY MORNING AS HIGH-RESOLUTION MODEL CONDENSATE /SUCH AS THE
4KM SPC WRF/ SEEMS TO WORK BETTER IN SUCH A PATTERN WITH THIN BUT
PROBABLY BROKEN-OVERCAST CLOUD COVER. THE CLOUDS AND NORTH-
NORTHEAST WINDS ON TUESDAY MORNING SHOULD LIMIT WARMING BY QUITE A
BIT WITH SOME LOCATIONS POSSIBLY NOT REACHING 50.

AS THE COOLER AIR AT OR AROUND 0C AT 850MB EXPANDS SOUTHWARD DOWN
THE LAKE LATER TODAY FORESEE DEEPENING LAKE EFFECT CLOUDS AND
SOME SHOWERS DEVELOPING. THESE SHOWERS LOOK TO BE NOT PARTICULARLY
CONCENTRATED WITH LIMITED CONVERGENCE AND MAINLY LIGHT IN
INTENSITY WITH LAKE-INDUCED EQUILIBRIUM LEVELS FORECAST BY THE
NAM OF AROUND 5000 FT. THE BOUNDARY LAYER FLOW FETCH SHOULD FAVOR
NORTHWEST INDIANA FOR THESE SHOWERS TONIGHT INTO EARLY
TUESDAY...THOUGH SOME VEERING TOWARD THE IL/IN STATE LINE AND EVEN
POTENTIALLY CHICAGO TUESDAY MORNING COULD SUPPORT SOME LIGHT
SHOWER ACTIVITY TUESDAY MORNING IN THOSE PLACES. THE HOPWRF-TS
SUPPORTS SUCH A GENERAL EVOLUTION WITH ITS RECENTLY ADDED EXTENDED
HIGH-RES OUTPUT.

TUESDAY NIGHT THROUGH THURSDAY...
SURFACE HIGH PRESSURE WILL BUILD OVER THE AREA FROM THE NORTH DURING
THIS TIME AS THE OVERALL UPPER PATTERN SLOWS THANKS TO AMPLIFICATION
OF A TROUGH ALONG THE WEST COAST OF NORTH AMERICA. OVERALL BENIGN
WEATHER LOOKS TO BE THE RULE WITH TEMPS SLIGHTLY BELOW NORMAL THOUGH
GRADUALLY MODIFYING. MODEL GUIDANCE DOES INDICATE AN ELONGATED SHORT
WAVE TO MOVE INTO THE UPPER MISSISSIPPI VALLEY DURING OR AROUND
THURSDAY NIGHT THOUGH THIS WILL BE MOVING INTO AN UNFAVORABLE
UPPER LEVEL AND MOISTURE SUPPORTIVE PATTERN. SO CONTINUE THE DRY
FORECAST.

FRIDAY INTO NEXT WEEKEND...
THE ONLY CHANGE WITH THIS PORTION OF THE FORECAST WAS TO INCREASE
TEMPERATURES...MAINLY ON SATURDAY. IF CLOUD COVER CAN REMAIN LIMITED
WITH THE PATTERN FORECAST...THE 850MB-925MB TEMPERATURES WOULD
SUPPORT TEMPERATURES POTENTIALLY IN THE 70S WITH A THERMAL RIDGE
STEERED IN FROM THE WEST-SOUTHWEST.

MTF

&&

.AVIATION...

//ORD AND MDW CONCERNS...UPDATED 09Z...

* SOUTHWEST WINDS BECOMING WEST THIS MORNING...NORTHWEST THIS
  AFTERNOON THEN NORTH/NORTHEAST LATE THIS AFTERNOON. CMS

//DISCUSSION...UPDATED 06Z...

A COLD FRONT WILL MOVE ACROSS THE TERMINALS LATER THIS MORNING...
SHIFTING SOUTHWESTERLY WINDS TO THE WEST/NORTHWEST BY MID MORNING
AND THEN TO THE NORTHWEST BY EARLY AFTERNOON. SPEEDS 10-12KTS WITH
A FEW HIGHER GUSTS TO START WILL DIMINISH SOME BY SUNRISE THEN
INCREASE AGAIN TO 10-12KTS THIS AFTERNOON. AS THE FRONT CONTINUES
EAST THIS AFTERNOON...THE GRADIENT BECOMES A BIT WEAKER OVER THE
SOUTHERN END OF LAKE MICHIGAN. THIS WILL LIKELY ALLOW WINDS TO
SHIFT TO THE NORTH/NORTHEAST BY LATE AFTERNOON. CONFIDENCE IN
SPEEDS IS A BIT LOWER...WITH PREVAILING SPEEDS LIKELY TO BE JUST
UNDER 10KTS.

MID CLOUDS WILL SHIFT EAST EARLY THIS MORNING WITH LOWER VFR...
3-5KFT CIGS OVER THE NORTHERN LAKES MOVING SOUTH ACROSS THE AREA
LATER THIS MORNING AND CONTINUING INTO THIS EVENING WITH SOME
POTENTIAL FOR HIGH MVFR CIGS...ESPECIALLY SOUTH OF THE LAKE
AFFECTING GYY. CMS

//ORD AND MDW CONFIDENCE...UPDATED 09Z...

* HIGH FOR WINDS THRU MID MORNING...THEN MEDIUM FOR DIRECTION AND
  TIMING CHANGES THIS AFTERNOON/EVENING. CMS

//OUTLOOK FOR ORD/MDW FOR 12Z TUESDAY-12Z SUNDAY...UPDATED 00Z...

TUESDAY...VFR. BREEZY NORTHEAST WINDS.

WEDNESDAY...VFR. EAST WINDS.

THURSDAY THROUGH SATURDAY...VFR. LIGHT WEST TO SOUTHWEST WINDS.

MDB

&&

.MARINE...

309 AM...LOW PRESSURE OVER THE UPPER PENINSULA OF MICHIGAN WILL
MOVE SOUTHEAST TODAY AND TONIGHT REACHING THE MID ATLANTIC ON
TUESDAY. A TRAILING COLD FRONT WILL MOVE ACROSS LAKE MICHIGAN THIS
MORNING. SOUTHWEST WINDS WILL TURN NORTHWEST THIS MORNING THEN
NORTH THIS EVENING. THE GRADIENT REMAINS FAIRLY TIGHT ACROSS THE
SOUTHERN THIRD OR SO OF THE LAKE...WITH GUSTS TO 30KT POSSIBLE FOR
A FEW MORE HOURS. HIGH PRESSURE WILL BUILD ACROSS ONTARIO TODAY
AND TONIGHT AS IT STRENGTHENS. WHILE THE CENTER OF THIS HIGH WILL
MOVE EAST INTO QUEBEC TUESDAY NIGHT...A RIDGE WILL EXTEND SOUTH
ACROSS THE WESTERN LAKES TONIGHT AND TUESDAY...THEN MOVE ACROSS
THE LAKE WEDNESDAY. THE GRADIENT WILL TIGHTEN BETWEEN THIS
APPROACHING RIDGE AND THE DEPARTING LOW WITH NORTHERLY WINDS
INCREASING TO 30 KT THIS EVENING AND REMAINING THERE UNTIL TUESDAY
AFTERNOON...AS THE RIDGE SLOWLY WORKS EAST. CMS

&&

.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...SMALL CRAFT ADVISORY...NEARSHORE WATERS
     UNTIL 7 AM MONDAY.

     SMALL CRAFT ADVISORY...LMZ740-LMZ741-LMZ742-LMZ743-LMZ744-
     LMZ745...10 PM MONDAY TO 7 AM WEDNESDAY.

&&

$$

VISIT US AT HTTP://WEATHER.GOV/CHICAGO (ALL LOWERCASE)

FOLLOW US ON FACEBOOK...TWITTER...AND YOUTUBE AT:
WWW.FACEBOOK.COM/NWSCHICAGO
WWW.TWITTER.COM/NWSCHICAGO
WWW.YOUTUBE.COM/NWSCHICAGO






000
FXUS63 KLOT 200909
AFDLOT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
409 AM CDT MON OCT 20 2014

.DISCUSSION...
319 AM CDT

A QUIET WEATHER PATTERN WILL REMAIN IN PLACE IN TERMS OF LACK OF
PRECIPITATION CHANCES AND ANY HIGH IMPACT WEATHER THROUGH NEXT
WEEKEND...THOUGH STILL SEVERAL LITTLE INTERESTS TO TACKLE. THESE
INCLUDED HOW WIDESPREAD CLOUDS WILL REACH LATER TODAY THROUGH
TUESDAY AS WELL AS LAKE EFFECT SHOWER POTENTIAL DURING THAT TIME.
THEN LOOKING AT WHEN AND HOW QUICKLY OF A WARM-UP OCCURS LATE IN
THE WEEK INTO THE WEEKEND.

TODAY THROUGH TUESDAY...
THE CONTINUED AMPLIFIED BUT PROGRESSIVE FLOW OVER CANADA AND THE
NORTHERN CONUS CONTINUES FOR A LITTLE LONGER WITH A PACIFIC/CLIPPER
HYBRID SYSTEM MOVING SOUTHEASTWARD FROM THE CENTRAL GREAT LAKES.
AROUND THIS A WELL-DEFINED SHORT WAVE ON GOES WATER VAPOR IMAGERY IS
MOVING INTO NORTHERN IL EARLY THIS MORNING. THIS IS FAIRLY MOISTURE
STARVED BUT CANNOT RULE OUT A FEW SHOWERS THIS MORNING MAINLY IN
NORTHWEST INDIANA. THIS SHORT WAVE ALSO BEGINS TO BREAK DOWN THE
LOW-LEVEL THERMAL RIDGE OVER THE AREA...WITH CLOUDS LIKELY TO
ADVECT/DEVELOP SOUTHWARD INTO THE FORECAST AREA THIS AFTERNOON. IN
ADDITION...TEMPERATURES MAY ALSO PEAK EARLY IN THE AFTERNOON AND
THEN EXPERIENCE A SLOW DROP. TEMPERATURES SHOULD STILL PEAK AROUND
CLIMATOLOGICAL NORMAL /60 TO 65/ WITH THE MORNING SUN. THE CYCLONIC
FLOW OVER THE REGION AND RAPIDLY COOLING 850-925MB TEMPERATURES LOOK
TO SUPPORT CLOUDS OVER MUCH OF THE AREA BY EARLY THIS EVENING AND
UPSTREAM OBSERVATIONAL TRENDS SUPPORT THIS. HAVE GONE WELL ABOVE
MOST GUIDANCE IN SKY COVER FROM LATE TODAY ALL THE WAY THROUGH
TUESDAY MORNING AS HIGH-RESOLUTION MODEL CONDENSATE /SUCH AS THE
4KM SPC WRF/ SEEMS TO WORK BETTER IN SUCH A PATTERN WITH THIN BUT
PROBABLY BROKEN-OVERCAST CLOUD COVER. THE CLOUDS AND NORTH-
NORTHEAST WINDS ON TUESDAY MORNING SHOULD LIMIT WARMING BY QUITE A
BIT WITH SOME LOCATIONS POSSIBLY NOT REACHING 50.

AS THE COOLER AIR AT OR AROUND 0C AT 850MB EXPANDS SOUTHWARD DOWN
THE LAKE LATER TODAY FORESEE DEEPENING LAKE EFFECT CLOUDS AND
SOME SHOWERS DEVELOPING. THESE SHOWERS LOOK TO BE NOT PARTICULARLY
CONCENTRATED WITH LIMITED CONVERGENCE AND MAINLY LIGHT IN
INTENSITY WITH LAKE-INDUCED EQUILIBRIUM LEVELS FORECAST BY THE
NAM OF AROUND 5000 FT. THE BOUNDARY LAYER FLOW FETCH SHOULD FAVOR
NORTHWEST INDIANA FOR THESE SHOWERS TONIGHT INTO EARLY
TUESDAY...THOUGH SOME VEERING TOWARD THE IL/IN STATE LINE AND EVEN
POTENTIALLY CHICAGO TUESDAY MORNING COULD SUPPORT SOME LIGHT
SHOWER ACTIVITY TUESDAY MORNING IN THOSE PLACES. THE HOPWRF-TS
SUPPORTS SUCH A GENERAL EVOLUTION WITH ITS RECENTLY ADDED EXTENDED
HIGH-RES OUTPUT.

TUESDAY NIGHT THROUGH THURSDAY...
SURFACE HIGH PRESSURE WILL BUILD OVER THE AREA FROM THE NORTH DURING
THIS TIME AS THE OVERALL UPPER PATTERN SLOWS THANKS TO AMPLIFICATION
OF A TROUGH ALONG THE WEST COAST OF NORTH AMERICA. OVERALL BENIGN
WEATHER LOOKS TO BE THE RULE WITH TEMPS SLIGHTLY BELOW NORMAL THOUGH
GRADUALLY MODIFYING. MODEL GUIDANCE DOES INDICATE AN ELONGATED SHORT
WAVE TO MOVE INTO THE UPPER MISSISSIPPI VALLEY DURING OR AROUND
THURSDAY NIGHT THOUGH THIS WILL BE MOVING INTO AN UNFAVORABLE
UPPER LEVEL AND MOISTURE SUPPORTIVE PATTERN. SO CONTINUE THE DRY
FORECAST.

FRIDAY INTO NEXT WEEKEND...
THE ONLY CHANGE WITH THIS PORTION OF THE FORECAST WAS TO INCREASE
TEMPERATURES...MAINLY ON SATURDAY. IF CLOUD COVER CAN REMAIN LIMITED
WITH THE PATTERN FORECAST...THE 850MB-925MB TEMPERATURES WOULD
SUPPORT TEMPERATURES POTENTIALLY IN THE 70S WITH A THERMAL RIDGE
STEERED IN FROM THE WEST-SOUTHWEST.

MTF

&&

.AVIATION...

//ORD AND MDW CONCERNS...UPDATED 09Z...

* SOUTHWEST WINDS BECOMING WEST THIS MORNING...NORTHWEST THIS
  AFTERNOON THEN NORTH/NORTHEAST LATE THIS AFTERNOON. CMS

//DISCUSSION...UPDATED 06Z...

A COLD FRONT WILL MOVE ACROSS THE TERMINALS LATER THIS MORNING...
SHIFTING SOUTHWESTERLY WINDS TO THE WEST/NORTHWEST BY MID MORNING
AND THEN TO THE NORTHWEST BY EARLY AFTERNOON. SPEEDS 10-12KTS WITH
A FEW HIGHER GUSTS TO START WILL DIMINISH SOME BY SUNRISE THEN
INCREASE AGAIN TO 10-12KTS THIS AFTERNOON. AS THE FRONT CONTINUES
EAST THIS AFTERNOON...THE GRADIENT BECOMES A BIT WEAKER OVER THE
SOUTHERN END OF LAKE MICHIGAN. THIS WILL LIKELY ALLOW WINDS TO
SHIFT TO THE NORTH/NORTHEAST BY LATE AFTERNOON. CONFIDENCE IN
SPEEDS IS A BIT LOWER...WITH PREVAILING SPEEDS LIKELY TO BE JUST
UNDER 10KTS.

MID CLOUDS WILL SHIFT EAST EARLY THIS MORNING WITH LOWER VFR...
3-5KFT CIGS OVER THE NORTHERN LAKES MOVING SOUTH ACROSS THE AREA
LATER THIS MORNING AND CONTINUING INTO THIS EVENING WITH SOME
POTENTIAL FOR HIGH MVFR CIGS...ESPECIALLY SOUTH OF THE LAKE
AFFECTING GYY. CMS

//ORD AND MDW CONFIDENCE...UPDATED 09Z...

* HIGH FOR WINDS THRU MID MORNING...THEN MEDIUM FOR DIRECTION AND
  TIMING CHANGES THIS AFTERNOON/EVENING. CMS

//OUTLOOK FOR ORD/MDW FOR 12Z TUESDAY-12Z SUNDAY...UPDATED 00Z...

TUESDAY...VFR. BREEZY NORTHEAST WINDS.

WEDNESDAY...VFR. EAST WINDS.

THURSDAY THROUGH SATURDAY...VFR. LIGHT WEST TO SOUTHWEST WINDS.

MDB

&&

.MARINE...

309 AM...LOW PRESSURE OVER THE UPPER PENINSULA OF MICHIGAN WILL
MOVE SOUTHEAST TODAY AND TONIGHT REACHING THE MID ATLANTIC ON
TUESDAY. A TRAILING COLD FRONT WILL MOVE ACROSS LAKE MICHIGAN THIS
MORNING. SOUTHWEST WINDS WILL TURN NORTHWEST THIS MORNING THEN
NORTH THIS EVENING. THE GRADIENT REMAINS FAIRLY TIGHT ACROSS THE
SOUTHERN THIRD OR SO OF THE LAKE...WITH GUSTS TO 30KT POSSIBLE FOR
A FEW MORE HOURS. HIGH PRESSURE WILL BUILD ACROSS ONTARIO TODAY
AND TONIGHT AS IT STRENGTHENS. WHILE THE CENTER OF THIS HIGH WILL
MOVE EAST INTO QUEBEC TUESDAY NIGHT...A RIDGE WILL EXTEND SOUTH
ACROSS THE WESTERN LAKES TONIGHT AND TUESDAY...THEN MOVE ACROSS
THE LAKE WEDNESDAY. THE GRADIENT WILL TIGHTEN BETWEEN THIS
APPROACHING RIDGE AND THE DEPARTING LOW WITH NORTHERLY WINDS
INCREASING TO 30 KT THIS EVENING AND REMAINING THERE UNTIL TUESDAY
AFTERNOON...AS THE RIDGE SLOWLY WORKS EAST. CMS

&&

.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...SMALL CRAFT ADVISORY...NEARSHORE WATERS UNTIL 7 AM MONDAY.

     SMALL CRAFT ADVISORY...LMZ740-LMZ741-LMZ742-LMZ743-LMZ744-
     LMZ745...10 PM MONDAY TO 7 AM WEDNESDAY.

&&

$$

VISIT US AT HTTP://WEATHER.GOV/CHICAGO (ALL LOWERCASE)

FOLLOW US ON FACEBOOK...TWITTER...AND YOUTUBE AT:
WWW.FACEBOOK.COM/NWSCHICAGO
WWW.TWITTER.COM/NWSCHICAGO
WWW.YOUTUBE.COM/NWSCHICAGO






000
FXUS63 KLOT 200909
AFDLOT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
409 AM CDT MON OCT 20 2014

.DISCUSSION...
319 AM CDT

A QUIET WEATHER PATTERN WILL REMAIN IN PLACE IN TERMS OF LACK OF
PRECIPITATION CHANCES AND ANY HIGH IMPACT WEATHER THROUGH NEXT
WEEKEND...THOUGH STILL SEVERAL LITTLE INTERESTS TO TACKLE. THESE
INCLUDED HOW WIDESPREAD CLOUDS WILL REACH LATER TODAY THROUGH
TUESDAY AS WELL AS LAKE EFFECT SHOWER POTENTIAL DURING THAT TIME.
THEN LOOKING AT WHEN AND HOW QUICKLY OF A WARM-UP OCCURS LATE IN
THE WEEK INTO THE WEEKEND.

TODAY THROUGH TUESDAY...
THE CONTINUED AMPLIFIED BUT PROGRESSIVE FLOW OVER CANADA AND THE
NORTHERN CONUS CONTINUES FOR A LITTLE LONGER WITH A PACIFIC/CLIPPER
HYBRID SYSTEM MOVING SOUTHEASTWARD FROM THE CENTRAL GREAT LAKES.
AROUND THIS A WELL-DEFINED SHORT WAVE ON GOES WATER VAPOR IMAGERY IS
MOVING INTO NORTHERN IL EARLY THIS MORNING. THIS IS FAIRLY MOISTURE
STARVED BUT CANNOT RULE OUT A FEW SHOWERS THIS MORNING MAINLY IN
NORTHWEST INDIANA. THIS SHORT WAVE ALSO BEGINS TO BREAK DOWN THE
LOW-LEVEL THERMAL RIDGE OVER THE AREA...WITH CLOUDS LIKELY TO
ADVECT/DEVELOP SOUTHWARD INTO THE FORECAST AREA THIS AFTERNOON. IN
ADDITION...TEMPERATURES MAY ALSO PEAK EARLY IN THE AFTERNOON AND
THEN EXPERIENCE A SLOW DROP. TEMPERATURES SHOULD STILL PEAK AROUND
CLIMATOLOGICAL NORMAL /60 TO 65/ WITH THE MORNING SUN. THE CYCLONIC
FLOW OVER THE REGION AND RAPIDLY COOLING 850-925MB TEMPERATURES LOOK
TO SUPPORT CLOUDS OVER MUCH OF THE AREA BY EARLY THIS EVENING AND
UPSTREAM OBSERVATIONAL TRENDS SUPPORT THIS. HAVE GONE WELL ABOVE
MOST GUIDANCE IN SKY COVER FROM LATE TODAY ALL THE WAY THROUGH
TUESDAY MORNING AS HIGH-RESOLUTION MODEL CONDENSATE /SUCH AS THE
4KM SPC WRF/ SEEMS TO WORK BETTER IN SUCH A PATTERN WITH THIN BUT
PROBABLY BROKEN-OVERCAST CLOUD COVER. THE CLOUDS AND NORTH-
NORTHEAST WINDS ON TUESDAY MORNING SHOULD LIMIT WARMING BY QUITE A
BIT WITH SOME LOCATIONS POSSIBLY NOT REACHING 50.

AS THE COOLER AIR AT OR AROUND 0C AT 850MB EXPANDS SOUTHWARD DOWN
THE LAKE LATER TODAY FORESEE DEEPENING LAKE EFFECT CLOUDS AND
SOME SHOWERS DEVELOPING. THESE SHOWERS LOOK TO BE NOT PARTICULARLY
CONCENTRATED WITH LIMITED CONVERGENCE AND MAINLY LIGHT IN
INTENSITY WITH LAKE-INDUCED EQUILIBRIUM LEVELS FORECAST BY THE
NAM OF AROUND 5000 FT. THE BOUNDARY LAYER FLOW FETCH SHOULD FAVOR
NORTHWEST INDIANA FOR THESE SHOWERS TONIGHT INTO EARLY
TUESDAY...THOUGH SOME VEERING TOWARD THE IL/IN STATE LINE AND EVEN
POTENTIALLY CHICAGO TUESDAY MORNING COULD SUPPORT SOME LIGHT
SHOWER ACTIVITY TUESDAY MORNING IN THOSE PLACES. THE HOPWRF-TS
SUPPORTS SUCH A GENERAL EVOLUTION WITH ITS RECENTLY ADDED EXTENDED
HIGH-RES OUTPUT.

TUESDAY NIGHT THROUGH THURSDAY...
SURFACE HIGH PRESSURE WILL BUILD OVER THE AREA FROM THE NORTH DURING
THIS TIME AS THE OVERALL UPPER PATTERN SLOWS THANKS TO AMPLIFICATION
OF A TROUGH ALONG THE WEST COAST OF NORTH AMERICA. OVERALL BENIGN
WEATHER LOOKS TO BE THE RULE WITH TEMPS SLIGHTLY BELOW NORMAL THOUGH
GRADUALLY MODIFYING. MODEL GUIDANCE DOES INDICATE AN ELONGATED SHORT
WAVE TO MOVE INTO THE UPPER MISSISSIPPI VALLEY DURING OR AROUND
THURSDAY NIGHT THOUGH THIS WILL BE MOVING INTO AN UNFAVORABLE
UPPER LEVEL AND MOISTURE SUPPORTIVE PATTERN. SO CONTINUE THE DRY
FORECAST.

FRIDAY INTO NEXT WEEKEND...
THE ONLY CHANGE WITH THIS PORTION OF THE FORECAST WAS TO INCREASE
TEMPERATURES...MAINLY ON SATURDAY. IF CLOUD COVER CAN REMAIN LIMITED
WITH THE PATTERN FORECAST...THE 850MB-925MB TEMPERATURES WOULD
SUPPORT TEMPERATURES POTENTIALLY IN THE 70S WITH A THERMAL RIDGE
STEERED IN FROM THE WEST-SOUTHWEST.

MTF

&&

.AVIATION...

//ORD AND MDW CONCERNS...UPDATED 09Z...

* SOUTHWEST WINDS BECOMING WEST THIS MORNING...NORTHWEST THIS
  AFTERNOON THEN NORTH/NORTHEAST LATE THIS AFTERNOON. CMS

//DISCUSSION...UPDATED 06Z...

A COLD FRONT WILL MOVE ACROSS THE TERMINALS LATER THIS MORNING...
SHIFTING SOUTHWESTERLY WINDS TO THE WEST/NORTHWEST BY MID MORNING
AND THEN TO THE NORTHWEST BY EARLY AFTERNOON. SPEEDS 10-12KTS WITH
A FEW HIGHER GUSTS TO START WILL DIMINISH SOME BY SUNRISE THEN
INCREASE AGAIN TO 10-12KTS THIS AFTERNOON. AS THE FRONT CONTINUES
EAST THIS AFTERNOON...THE GRADIENT BECOMES A BIT WEAKER OVER THE
SOUTHERN END OF LAKE MICHIGAN. THIS WILL LIKELY ALLOW WINDS TO
SHIFT TO THE NORTH/NORTHEAST BY LATE AFTERNOON. CONFIDENCE IN
SPEEDS IS A BIT LOWER...WITH PREVAILING SPEEDS LIKELY TO BE JUST
UNDER 10KTS.

MID CLOUDS WILL SHIFT EAST EARLY THIS MORNING WITH LOWER VFR...
3-5KFT CIGS OVER THE NORTHERN LAKES MOVING SOUTH ACROSS THE AREA
LATER THIS MORNING AND CONTINUING INTO THIS EVENING WITH SOME
POTENTIAL FOR HIGH MVFR CIGS...ESPECIALLY SOUTH OF THE LAKE
AFFECTING GYY. CMS

//ORD AND MDW CONFIDENCE...UPDATED 09Z...

* HIGH FOR WINDS THRU MID MORNING...THEN MEDIUM FOR DIRECTION AND
  TIMING CHANGES THIS AFTERNOON/EVENING. CMS

//OUTLOOK FOR ORD/MDW FOR 12Z TUESDAY-12Z SUNDAY...UPDATED 00Z...

TUESDAY...VFR. BREEZY NORTHEAST WINDS.

WEDNESDAY...VFR. EAST WINDS.

THURSDAY THROUGH SATURDAY...VFR. LIGHT WEST TO SOUTHWEST WINDS.

MDB

&&

.MARINE...

309 AM...LOW PRESSURE OVER THE UPPER PENINSULA OF MICHIGAN WILL
MOVE SOUTHEAST TODAY AND TONIGHT REACHING THE MID ATLANTIC ON
TUESDAY. A TRAILING COLD FRONT WILL MOVE ACROSS LAKE MICHIGAN THIS
MORNING. SOUTHWEST WINDS WILL TURN NORTHWEST THIS MORNING THEN
NORTH THIS EVENING. THE GRADIENT REMAINS FAIRLY TIGHT ACROSS THE
SOUTHERN THIRD OR SO OF THE LAKE...WITH GUSTS TO 30KT POSSIBLE FOR
A FEW MORE HOURS. HIGH PRESSURE WILL BUILD ACROSS ONTARIO TODAY
AND TONIGHT AS IT STRENGTHENS. WHILE THE CENTER OF THIS HIGH WILL
MOVE EAST INTO QUEBEC TUESDAY NIGHT...A RIDGE WILL EXTEND SOUTH
ACROSS THE WESTERN LAKES TONIGHT AND TUESDAY...THEN MOVE ACROSS
THE LAKE WEDNESDAY. THE GRADIENT WILL TIGHTEN BETWEEN THIS
APPROACHING RIDGE AND THE DEPARTING LOW WITH NORTHERLY WINDS
INCREASING TO 30 KT THIS EVENING AND REMAINING THERE UNTIL TUESDAY
AFTERNOON...AS THE RIDGE SLOWLY WORKS EAST. CMS

&&

.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...SMALL CRAFT ADVISORY...NEARSHORE WATERS UNTIL 7 AM MONDAY.

     SMALL CRAFT ADVISORY...LMZ740-LMZ741-LMZ742-LMZ743-LMZ744-
     LMZ745...10 PM MONDAY TO 7 AM WEDNESDAY.

&&

$$

VISIT US AT HTTP://WEATHER.GOV/CHICAGO (ALL LOWERCASE)

FOLLOW US ON FACEBOOK...TWITTER...AND YOUTUBE AT:
WWW.FACEBOOK.COM/NWSCHICAGO
WWW.TWITTER.COM/NWSCHICAGO
WWW.YOUTUBE.COM/NWSCHICAGO







000
FXUS63 KLOT 200819
AFDLOT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
319 AM CDT MON OCT 20 2014

.DISCUSSION...
319 AM CDT

A QUIET WEATHER PATTERN WILL REMAIN IN PLACE IN TERMS OF LACK OF
PRECIPITATION CHANCES AND ANY HIGH IMPACT WEATHER THROUGH NEXT
WEEKEND...THOUGH STILL SEVERAL LITTLE INTERESTS TO TACKLE. THESE
INCLUDED HOW WIDESPREAD CLOUDS WILL REACH LATER TODAY THROUGH
TUESDAY AS WELL AS LAKE EFFECT SHOWER POTENTIAL DURING THAT TIME.
THEN LOOKING AT WHEN AND HOW QUICKLY OF A WARM-UP OCCURS LATE IN
THE WEEK INTO THE WEEKEND.

TODAY THROUGH TUESDAY...
THE CONTINUED AMPLIFIED BUT PROGRESSIVE FLOW OVER CANADA AND THE
NORTHERN CONUS CONTINUES FOR A LITTLE LONGER WITH A PACIFIC/CLIPPER
HYBRID SYSTEM MOVING SOUTHEASTWARD FROM THE CENTRAL GREAT LAKES.
AROUND THIS A WELL-DEFINED SHORT WAVE ON GOES WATER VAPOR IMAGERY IS
MOVING INTO NORTHERN IL EARLY THIS MORNING. THIS IS FAIRLY MOISTURE
STARVED BUT CANNOT RULE OUT A FEW SHOWERS THIS MORNING MAINLY IN
NORTHWEST INDIANA. THIS SHORT WAVE ALSO BEGINS TO BREAK DOWN THE
LOW-LEVEL THERMAL RIDGE OVER THE AREA...WITH CLOUDS LIKELY TO
ADVECT/DEVELOP SOUTHWARD INTO THE FORECAST AREA THIS AFTERNOON. IN
ADDITION...TEMPERATURES MAY ALSO PEAK EARLY IN THE AFTERNOON AND
THEN EXPERIENCE A SLOW DROP. TEMPERATURES SHOULD STILL PEAK AROUND
CLIMATOLOGICAL NORMAL /60 TO 65/ WITH THE MORNING SUN. THE CYCLONIC
FLOW OVER THE REGION AND RAPIDLY COOLING 850-925MB TEMPERATURES LOOK
TO SUPPORT CLOUDS OVER MUCH OF THE AREA BY EARLY THIS EVENING AND
UPSTREAM OBSERVATIONAL TRENDS SUPPORT THIS. HAVE GONE WELL ABOVE
MOST GUIDANCE IN SKY COVER FROM LATE TODAY ALL THE WAY THROUGH
TUESDAY MORNING AS HIGH-RESOLUTION MODEL CONDENSATE /SUCH AS THE
4KM SPC WRF/ SEEMS TO WORK BETTER IN SUCH A PATTERN WITH THIN BUT
PROBABLY BROKEN-OVERCAST CLOUD COVER. THE CLOUDS AND NORTH-
NORTHEAST WINDS ON TUESDAY MORNING SHOULD LIMIT WARMING BY QUITE A
BIT WITH SOME LOCATIONS POSSIBLY NOT REACHING 50.

AS THE COOLER AIR AT OR AROUND 0C AT 850MB EXPANDS SOUTHWARD DOWN
THE LAKE LATER TODAY FORESEE DEEPENING LAKE EFFECT CLOUDS AND
SOME SHOWERS DEVELOPING. THESE SHOWERS LOOK TO BE NOT PARTICULARLY
CONCENTRATED WITH LIMITED CONVERGENCE AND MAINLY LIGHT IN
INTENSITY WITH LAKE-INDUCED EQUILIBRIUM LEVELS FORECAST BY THE
NAM OF AROUND 5000 FT. THE BOUNDARY LAYER FLOW FETCH SHOULD FAVOR
NORTHWEST INDIANA FOR THESE SHOWERS TONIGHT INTO EARLY
TUESDAY...THOUGH SOME VEERING TOWARD THE IL/IN STATE LINE AND EVEN
POTENTIALLY CHICAGO TUESDAY MORNING COULD SUPPORT SOME LIGHT
SHOWER ACTIVITY TUESDAY MORNING IN THOSE PLACES. THE HOPWRF-TS
SUPPORTS SUCH A GENERAL EVOLUTION WITH ITS RECENTLY ADDED EXTENDED
HIGH-RES OUTPUT.

TUESDAY NIGHT THROUGH THURSDAY...
SURFACE HIGH PRESSURE WILL BUILD OVER THE AREA FROM THE NORTH DURING
THIS TIME AS THE OVERALL UPPER PATTERN SLOWS THANKS TO AMPLIFICATION
OF A TROUGH ALONG THE WEST COAST OF NORTH AMERICA. OVERALL BENIGN
WEATHER LOOKS TO BE THE RULE WITH TEMPS SLIGHTLY BELOW NORMAL THOUGH
GRADUALLY MODIFYING. MODEL GUIDANCE DOES INDICATE AN ELONGATED SHORT
WAVE TO MOVE INTO THE UPPER MISSISSIPPI VALLEY DURING OR AROUND
THURSDAY NIGHT THOUGH THIS WILL BE MOVING INTO AN UNFAVORABLE
UPPER LEVEL AND MOISTURE SUPPORTIVE PATTERN. SO CONTINUE THE DRY
FORECAST.

FRIDAY INTO NEXT WEEKEND...
THE ONLY CHANGE WITH THIS PORTION OF THE FORECAST WAS TO INCREASE
TEMPERATURES...MAINLY ON SATURDAY. IF CLOUD COVER CAN REMAIN LIMITED
WITH THE PATTERN FORECAST...THE 850MB-925MB TEMPERATURES WOULD
SUPPORT TEMPERATURES POTENTIALLY IN THE 70S WITH A THERMAL RIDGE
STEERED IN FROM THE WEST-SOUTHWEST.

MTF

&&

.AVIATION...

//ORD AND MDW CONCERNS...UPDATED 06Z...

* SOUTHWEST WINDS BECOME WEST THIS MORNING...NORTHWEST THIS
  AFTERNOON THEN NORTH/NORTHEAST LATE THIS AFTERNOON. CMS

//DISCUSSION...UPDATED 06Z...

A COLD FRONT WILL MOVE ACROSS THE TERMINALS LATER THIS MORNING...
SHIFTING SOUTHWESTERLY WINDS TO THE WEST/NORTHWEST BY MID MORNING
AND THEN TO THE NORTHWEST BY EARLY AFTERNOON. SPEEDS 10-12KTS WITH
A FEW HIGHER GUSTS TO START WILL DIMINISH SOME BY SUNRISE THEN
INCREASE AGAIN TO 10-12KTS THIS AFTERNOON. AS THE FRONT CONTINUES
EAST THIS AFTERNOON...THE GRADIENT BECOMES A BIT WEAKER OVER THE
SOUTHERN END OF LAKE MICHIGAN. THIS WILL LIKELY ALLOW WINDS TO
SHIFT TO THE NORTH/NORTHEAST BY LATE AFTERNOON. CONFIDENCE IN
SPEEDS IS A BIT LOWER...WITH PREVAILING SPEEDS LIKELY TO BE JUST
UNDER 10KTS.

MID CLOUDS WILL SHIFT EAST EARLY THIS MORNING WITH LOWER VFR...
3-5KFT CIGS OVER THE NORTHERN LAKES MOVING SOUTH ACROSS THE AREA
LATER THIS MORNING AND CONTINUING INTO THIS EVENING WITH SOME
POTENTIAL FOR HIGH MVFR CIGS...ESPECIALLY SOUTH OF THE LAKE
AFFECTING GYY. CMS

//ORD AND MDW CONFIDENCE...UPDATED 06Z...

HIGH FOR WINDS THRU MID MORNING...THEN MEDIUM FOR DIRECTION AND
TIMING CHANGES THIS AFTERNOON/EVENING. CMS

//OUTLOOK FOR ORD/MDW FOR 12Z TUESDAY-12Z SUNDAY...UPDATED 00Z...

TUESDAY...VFR. BREEZY NORTHEAST WINDS.

WEDNESDAY...VFR. EAST WINDS.

THURSDAY THROUGH SATURDAY...VFR. LIGHT WEST TO SOUTHWEST WINDS.

MDB

&&

.MARINE...

309 AM...LOW PRESSURE OVER THE UPPER PENINSULA OF MICHIGAN WILL
MOVE SOUTHEAST TODAY AND TONIGHT REACHING THE MID ATLANTIC ON
TUESDAY. A TRAILING COLD FRONT WILL MOVE ACROSS LAKE MICHIGAN THIS
MORNING. SOUTHWEST WINDS WILL TURN NORTHWEST THIS MORNING THEN
NORTH THIS EVENING. THE GRADIENT REMAINS FAIRLY TIGHT ACROSS THE
SOUTHERN THIRD OR SO OF THE LAKE...WITH GUSTS TO 30KT POSSIBLE FOR
A FEW MORE HOURS. HIGH PRESSURE WILL BUILD ACROSS ONTARIO TODAY
AND TONIGHT AS IT STRENGTHENS. WHILE THE CENTER OF THIS HIGH WILL
MOVE EAST INTO QUEBEC TUESDAY NIGHT...A RIDGE WILL EXTEND SOUTH
ACROSS THE WESTERN LAKES TONIGHT AND TUESDAY...THEN MOVE ACROSS
THE LAKE WEDNESDAY. THE GRADIENT WILL TIGHTEN BETWEEN THIS
APPROACHING RIDGE AND THE DEPARTING LOW WITH NORTHERLY WINDS
INCREASING TO 30 KT THIS EVENING AND REMAINING THERE UNTIL TUESDAY
AFTERNOON...AS THE RIDGE SLOWLY WORKS EAST. CMS

&&

.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...SMALL CRAFT ADVISORY...NEARSHORE WATERS
     UNTIL 7 AM MONDAY.

     SMALL CRAFT ADVISORY...LMZ740-LMZ741-LMZ742-LMZ743-LMZ744-
     LMZ745...10 PM MONDAY TO 7 AM WEDNESDAY.

&&

$$

VISIT US AT HTTP://WEATHER.GOV/CHICAGO (ALL LOWERCASE)

FOLLOW US ON FACEBOOK...TWITTER...AND YOUTUBE AT:
WWW.FACEBOOK.COM/NWSCHICAGO
WWW.TWITTER.COM/NWSCHICAGO
WWW.YOUTUBE.COM/NWSCHICAGO






000
FXUS63 KLOT 200819
AFDLOT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
319 AM CDT MON OCT 20 2014

.DISCUSSION...
319 AM CDT

A QUIET WEATHER PATTERN WILL REMAIN IN PLACE IN TERMS OF LACK OF
PRECIPITATION CHANCES AND ANY HIGH IMPACT WEATHER THROUGH NEXT
WEEKEND...THOUGH STILL SEVERAL LITTLE INTERESTS TO TACKLE. THESE
INCLUDED HOW WIDESPREAD CLOUDS WILL REACH LATER TODAY THROUGH
TUESDAY AS WELL AS LAKE EFFECT SHOWER POTENTIAL DURING THAT TIME.
THEN LOOKING AT WHEN AND HOW QUICKLY OF A WARM-UP OCCURS LATE IN
THE WEEK INTO THE WEEKEND.

TODAY THROUGH TUESDAY...
THE CONTINUED AMPLIFIED BUT PROGRESSIVE FLOW OVER CANADA AND THE
NORTHERN CONUS CONTINUES FOR A LITTLE LONGER WITH A PACIFIC/CLIPPER
HYBRID SYSTEM MOVING SOUTHEASTWARD FROM THE CENTRAL GREAT LAKES.
AROUND THIS A WELL-DEFINED SHORT WAVE ON GOES WATER VAPOR IMAGERY IS
MOVING INTO NORTHERN IL EARLY THIS MORNING. THIS IS FAIRLY MOISTURE
STARVED BUT CANNOT RULE OUT A FEW SHOWERS THIS MORNING MAINLY IN
NORTHWEST INDIANA. THIS SHORT WAVE ALSO BEGINS TO BREAK DOWN THE
LOW-LEVEL THERMAL RIDGE OVER THE AREA...WITH CLOUDS LIKELY TO
ADVECT/DEVELOP SOUTHWARD INTO THE FORECAST AREA THIS AFTERNOON. IN
ADDITION...TEMPERATURES MAY ALSO PEAK EARLY IN THE AFTERNOON AND
THEN EXPERIENCE A SLOW DROP. TEMPERATURES SHOULD STILL PEAK AROUND
CLIMATOLOGICAL NORMAL /60 TO 65/ WITH THE MORNING SUN. THE CYCLONIC
FLOW OVER THE REGION AND RAPIDLY COOLING 850-925MB TEMPERATURES LOOK
TO SUPPORT CLOUDS OVER MUCH OF THE AREA BY EARLY THIS EVENING AND
UPSTREAM OBSERVATIONAL TRENDS SUPPORT THIS. HAVE GONE WELL ABOVE
MOST GUIDANCE IN SKY COVER FROM LATE TODAY ALL THE WAY THROUGH
TUESDAY MORNING AS HIGH-RESOLUTION MODEL CONDENSATE /SUCH AS THE
4KM SPC WRF/ SEEMS TO WORK BETTER IN SUCH A PATTERN WITH THIN BUT
PROBABLY BROKEN-OVERCAST CLOUD COVER. THE CLOUDS AND NORTH-
NORTHEAST WINDS ON TUESDAY MORNING SHOULD LIMIT WARMING BY QUITE A
BIT WITH SOME LOCATIONS POSSIBLY NOT REACHING 50.

AS THE COOLER AIR AT OR AROUND 0C AT 850MB EXPANDS SOUTHWARD DOWN
THE LAKE LATER TODAY FORESEE DEEPENING LAKE EFFECT CLOUDS AND
SOME SHOWERS DEVELOPING. THESE SHOWERS LOOK TO BE NOT PARTICULARLY
CONCENTRATED WITH LIMITED CONVERGENCE AND MAINLY LIGHT IN
INTENSITY WITH LAKE-INDUCED EQUILIBRIUM LEVELS FORECAST BY THE
NAM OF AROUND 5000 FT. THE BOUNDARY LAYER FLOW FETCH SHOULD FAVOR
NORTHWEST INDIANA FOR THESE SHOWERS TONIGHT INTO EARLY
TUESDAY...THOUGH SOME VEERING TOWARD THE IL/IN STATE LINE AND EVEN
POTENTIALLY CHICAGO TUESDAY MORNING COULD SUPPORT SOME LIGHT
SHOWER ACTIVITY TUESDAY MORNING IN THOSE PLACES. THE HOPWRF-TS
SUPPORTS SUCH A GENERAL EVOLUTION WITH ITS RECENTLY ADDED EXTENDED
HIGH-RES OUTPUT.

TUESDAY NIGHT THROUGH THURSDAY...
SURFACE HIGH PRESSURE WILL BUILD OVER THE AREA FROM THE NORTH DURING
THIS TIME AS THE OVERALL UPPER PATTERN SLOWS THANKS TO AMPLIFICATION
OF A TROUGH ALONG THE WEST COAST OF NORTH AMERICA. OVERALL BENIGN
WEATHER LOOKS TO BE THE RULE WITH TEMPS SLIGHTLY BELOW NORMAL THOUGH
GRADUALLY MODIFYING. MODEL GUIDANCE DOES INDICATE AN ELONGATED SHORT
WAVE TO MOVE INTO THE UPPER MISSISSIPPI VALLEY DURING OR AROUND
THURSDAY NIGHT THOUGH THIS WILL BE MOVING INTO AN UNFAVORABLE
UPPER LEVEL AND MOISTURE SUPPORTIVE PATTERN. SO CONTINUE THE DRY
FORECAST.

FRIDAY INTO NEXT WEEKEND...
THE ONLY CHANGE WITH THIS PORTION OF THE FORECAST WAS TO INCREASE
TEMPERATURES...MAINLY ON SATURDAY. IF CLOUD COVER CAN REMAIN LIMITED
WITH THE PATTERN FORECAST...THE 850MB-925MB TEMPERATURES WOULD
SUPPORT TEMPERATURES POTENTIALLY IN THE 70S WITH A THERMAL RIDGE
STEERED IN FROM THE WEST-SOUTHWEST.

MTF

&&

.AVIATION...

//ORD AND MDW CONCERNS...UPDATED 06Z...

* SOUTHWEST WINDS BECOME WEST THIS MORNING...NORTHWEST THIS
  AFTERNOON THEN NORTH/NORTHEAST LATE THIS AFTERNOON. CMS

//DISCUSSION...UPDATED 06Z...

A COLD FRONT WILL MOVE ACROSS THE TERMINALS LATER THIS MORNING...
SHIFTING SOUTHWESTERLY WINDS TO THE WEST/NORTHWEST BY MID MORNING
AND THEN TO THE NORTHWEST BY EARLY AFTERNOON. SPEEDS 10-12KTS WITH
A FEW HIGHER GUSTS TO START WILL DIMINISH SOME BY SUNRISE THEN
INCREASE AGAIN TO 10-12KTS THIS AFTERNOON. AS THE FRONT CONTINUES
EAST THIS AFTERNOON...THE GRADIENT BECOMES A BIT WEAKER OVER THE
SOUTHERN END OF LAKE MICHIGAN. THIS WILL LIKELY ALLOW WINDS TO
SHIFT TO THE NORTH/NORTHEAST BY LATE AFTERNOON. CONFIDENCE IN
SPEEDS IS A BIT LOWER...WITH PREVAILING SPEEDS LIKELY TO BE JUST
UNDER 10KTS.

MID CLOUDS WILL SHIFT EAST EARLY THIS MORNING WITH LOWER VFR...
3-5KFT CIGS OVER THE NORTHERN LAKES MOVING SOUTH ACROSS THE AREA
LATER THIS MORNING AND CONTINUING INTO THIS EVENING WITH SOME
POTENTIAL FOR HIGH MVFR CIGS...ESPECIALLY SOUTH OF THE LAKE
AFFECTING GYY. CMS

//ORD AND MDW CONFIDENCE...UPDATED 06Z...

HIGH FOR WINDS THRU MID MORNING...THEN MEDIUM FOR DIRECTION AND
TIMING CHANGES THIS AFTERNOON/EVENING. CMS

//OUTLOOK FOR ORD/MDW FOR 12Z TUESDAY-12Z SUNDAY...UPDATED 00Z...

TUESDAY...VFR. BREEZY NORTHEAST WINDS.

WEDNESDAY...VFR. EAST WINDS.

THURSDAY THROUGH SATURDAY...VFR. LIGHT WEST TO SOUTHWEST WINDS.

MDB

&&

.MARINE...

309 AM...LOW PRESSURE OVER THE UPPER PENINSULA OF MICHIGAN WILL
MOVE SOUTHEAST TODAY AND TONIGHT REACHING THE MID ATLANTIC ON
TUESDAY. A TRAILING COLD FRONT WILL MOVE ACROSS LAKE MICHIGAN THIS
MORNING. SOUTHWEST WINDS WILL TURN NORTHWEST THIS MORNING THEN
NORTH THIS EVENING. THE GRADIENT REMAINS FAIRLY TIGHT ACROSS THE
SOUTHERN THIRD OR SO OF THE LAKE...WITH GUSTS TO 30KT POSSIBLE FOR
A FEW MORE HOURS. HIGH PRESSURE WILL BUILD ACROSS ONTARIO TODAY
AND TONIGHT AS IT STRENGTHENS. WHILE THE CENTER OF THIS HIGH WILL
MOVE EAST INTO QUEBEC TUESDAY NIGHT...A RIDGE WILL EXTEND SOUTH
ACROSS THE WESTERN LAKES TONIGHT AND TUESDAY...THEN MOVE ACROSS
THE LAKE WEDNESDAY. THE GRADIENT WILL TIGHTEN BETWEEN THIS
APPROACHING RIDGE AND THE DEPARTING LOW WITH NORTHERLY WINDS
INCREASING TO 30 KT THIS EVENING AND REMAINING THERE UNTIL TUESDAY
AFTERNOON...AS THE RIDGE SLOWLY WORKS EAST. CMS

&&

.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...SMALL CRAFT ADVISORY...NEARSHORE WATERS
     UNTIL 7 AM MONDAY.

     SMALL CRAFT ADVISORY...LMZ740-LMZ741-LMZ742-LMZ743-LMZ744-
     LMZ745...10 PM MONDAY TO 7 AM WEDNESDAY.

&&

$$

VISIT US AT HTTP://WEATHER.GOV/CHICAGO (ALL LOWERCASE)

FOLLOW US ON FACEBOOK...TWITTER...AND YOUTUBE AT:
WWW.FACEBOOK.COM/NWSCHICAGO
WWW.TWITTER.COM/NWSCHICAGO
WWW.YOUTUBE.COM/NWSCHICAGO







000
FXUS63 KLOT 200809
AFDLOT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
309 AM CDT MON OCT 20 2014

.DISCUSSION...
152 PM CDT

TONIGHT...
VISIBLE IMAGERY THIS AFTERNOON INDICATES A THIN CIRRUS SHIELD OVER
THE REGION...WITH SOME ENHANCEMENT TO THE CLOUD COVER ACROSS
WISCONSIN AHEAD OF A FRONTAL BOUNDARY THAT IS PUSHING FROM WEST TO
EAST ACROSS THE WESTERN GREAT LAKES. SFC RIDGE HAS DRIFTED SOUTHEAST
OF THE FORECAST AREA...WHICH HAS ALLOWED LLVL FLOW TO TURN
SOUTHWESTERLY. BETWEEN THE NEXT RIDGE OF HIGH PRESSURE AND THE
DEPARTING RIDGE...WEAK TROUGHING WILL SLIDE EAST ACROSS THE UPPER
MIDWEST/GREAT LAKES. THIS HAS PRODUCED A BUMP IN THE GRADIENT AND
RESULTED IN BREEZY CONDS THIS AFTN FROM A GOOD MIXED LAYER.

GUIDANCE HAS SLOWED THE ARRIVAL OF THE FRONTAL BOUNDARY
SLIGHTLY...BUT THERE REMAINS SOME CONSISTENCY THAT THE
MOISTURE/PRECIP WILL BE DISPLACED TO THE NORTHEAST OF THE FORECAST
AREA THRU THE OVERNIGHT PERIOD. TEMPS TONIGHT WILL BE WARMER THAN
THE PRIOR NGT WITH LOWS GENERALLY IN THE LOW/MID 40S.

MONDAY THROUGH THURSDAY...
500MB TROUGH AXIS WILL CONTINUE TO PIVOT EAST OF THE REGION BY
MIDDAY MON...HOWEVER THERE DOES APPEAR TO BE SOME WRAP AROUND
MOISTURE TRYING TO SLIDE SOUTH ACROSS THE LAKE AND MAY PRODUCE SOME
SPRINKLES/LGT RAIN FOR NORTHWEST IN. HAVE MAINTAINED A DRY FORECAST
FOR NORTHEAST IL...HOWEVER LATE MON EVE A FEW SPOTTY SHOWERS COULD
SNEAK INTO THE CHICAGO METRO AREA INTO TUE MORNING. OTHERWISE EXPECT
THE FAR WESTERN FORECAST AREA TO REMAIN DRY. THEN BROAD
ANTI-CYCLONIC FLOW ARRIVES AND IS EXPECTED TO REMAIN IN PLACE THRU
THE SECOND HALF OF THE WEEK. TEMPS MON WILL LIKELY BE THE WARMEST IN
THE UPR 50S TO LOW 60S...THEN COOLING INTO THE LOW/MID 50S FOR
TUE/WED/THUR. WITH HIGH PRES POISED TO BE OVERHEAD TUE
NGT-WED-NGT...LOWS IN MANY AREAS COULD EASILY DIP INTO THE MID 30S.

FRIDAY THROUGH NEXT WEEKEND...
ENSEMBLES CONTINUE WITH THE RATHER BENIGN PATTERN INTO THE WEEKEND.
TROUGH DIGS INTO THE SOUTHWEST CONUS...BUT IS PROGGED TO WEAKEN BY
SAT/SUN. HIGH AMPLITUDE RIDGING OVER THE CENTRAL CONUS WILL
GRADUALLY WEAKEN LATE IN THE WEEK...HOWEVER CURRENT GUIDANCE
SUGGESTS THE DRY PATTERN WILL PERSIST INTO AT LEAST SAT. TEMPS WILL
STEADILY RETURN TO NEAR SEASONAL CONDS WITH HIGHS ARND 60 TO THE LOW
60S BY THE WEEKEND.

BEACHLER

&&

.AVIATION...

//ORD AND MDW CONCERNS...UPDATED 06Z...

* SOUTHWEST WINDS BECOME WEST THIS MORNING...NORTHWEST THIS
  AFTERNOON THEN NORTH/NORTHEAST LATE THIS AFTERNOON. CMS

//DISCUSSION...UPDATED 06Z...

A COLD FRONT WILL MOVE ACROSS THE TERMINALS LATER THIS MORNING...
SHIFTING SOUTHWESTERLY WINDS TO THE WEST/NORTHWEST BY MID MORNING
AND THEN TO THE NORTHWEST BY EARLY AFTERNOON. SPEEDS 10-12KTS WITH
A FEW HIGHER GUSTS TO START WILL DIMINISH SOME BY SUNRISE THEN
INCREASE AGAIN TO 10-12KTS THIS AFTERNOON. AS THE FRONT CONTINUES
EAST THIS AFTERNOON...THE GRADIENT BECOMES A BIT WEAKER OVER THE
SOUTHERN END OF LAKE MICHIGAN. THIS WILL LIKELY ALLOW WINDS TO
SHIFT TO THE NORTH/NORTHEAST BY LATE AFTERNOON. CONFIDENCE IN
SPEEDS IS A BIT LOWER...WITH PREVAILING SPEEDS LIKELY TO BE JUST
UNDER 10KTS.

MID CLOUDS WILL SHIFT EAST EARLY THIS MORNING WITH LOWER VFR...
3-5KFT CIGS OVER THE NORTHERN LAKES MOVING SOUTH ACROSS THE AREA
LATER THIS MORNING AND CONTINUING INTO THIS EVENING WITH SOME
POTENTIAL FOR HIGH MVFR CIGS...ESPECIALLY SOUTH OF THE LAKE
AFFECTING GYY. CMS

//ORD AND MDW CONFIDENCE...UPDATED 06Z...

HIGH FOR WINDS THRU MID MORNING...THEN MEDIUM FOR DIRECTION AND
TIMING CHANGES THIS AFTERNOON/EVENING. CMS

//OUTLOOK FOR ORD/MDW FOR 12Z TUESDAY-12Z SUNDAY...UPDATED 00Z...

TUESDAY...VFR. BREEZY NORTHEAST WINDS.

WEDNESDAY...VFR. EAST WINDS.

THURSDAY THROUGH SATURDAY...VFR. LIGHT WEST TO SOUTHWEST WINDS.

MDB

&&

.MARINE...

309 AM...LOW PRESSURE OVER THE UPPER PENINSULA OF MICHIGAN WILL
MOVE SOUTHEAST TODAY AND TONIGHT REACHING THE MID ATLANTIC ON
TUESDAY. A TRAILING COLD FRONT WILL MOVE ACROSS LAKE MICHIGAN THIS
MORNING. SOUTHWEST WINDS WILL TURN NORTHWEST THIS MORNING THEN
NORTH THIS EVENING. THE GRADIENT REMAINS FAIRLY TIGHT ACROSS THE
SOUTHERN THIRD OR SO OF THE LAKE...WITH GUSTS TO 30KT POSSIBLE FOR
A FEW MORE HOURS. HIGH PRESSURE WILL BUILD ACROSS ONTARIO TODAY
AND TONIGHT AS IT STRENGTHENS. WHILE THE CENTER OF THIS HIGH WILL
MOVE EAST INTO QUEBEC TUESDAY NIGHT...A RIDGE WILL EXTEND SOUTH
ACROSS THE WESTERN LAKES TONIGHT AND TUESDAY...THEN MOVE ACROSS
THE LAKE WEDNESDAY. THE GRADIENT WILL TIGHTEN BETWEEN THIS
APPROACHING RIDGE AND THE DEPARTING LOW WITH NORTHERLY WINDS
INCREASING TO 30 KT THIS EVENING AND REMAINING THERE UNTIL TUESDAY
AFTERNOON...AS THE RIDGE SLOWLY WORKS EAST. CMS

&&

.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...SMALL CRAFT ADVISORY...NEARSHORE WATERS UNTIL 7 AM MONDAY.

     SMALL CRAFT ADVISORY...LMZ740-LMZ741-LMZ742-LMZ743-LMZ744-
     LMZ745...10 PM MONDAY TO 7 AM WEDNESDAY.

&&

$$

VISIT US AT HTTP://WEATHER.GOV/CHICAGO (ALL LOWERCASE)

FOLLOW US ON FACEBOOK...TWITTER...AND YOUTUBE AT:
WWW.FACEBOOK.COM/NWSCHICAGO
WWW.TWITTER.COM/NWSCHICAGO
WWW.YOUTUBE.COM/NWSCHICAGO







000
FXUS63 KLOT 200809
AFDLOT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
309 AM CDT MON OCT 20 2014

.DISCUSSION...
152 PM CDT

TONIGHT...
VISIBLE IMAGERY THIS AFTERNOON INDICATES A THIN CIRRUS SHIELD OVER
THE REGION...WITH SOME ENHANCEMENT TO THE CLOUD COVER ACROSS
WISCONSIN AHEAD OF A FRONTAL BOUNDARY THAT IS PUSHING FROM WEST TO
EAST ACROSS THE WESTERN GREAT LAKES. SFC RIDGE HAS DRIFTED SOUTHEAST
OF THE FORECAST AREA...WHICH HAS ALLOWED LLVL FLOW TO TURN
SOUTHWESTERLY. BETWEEN THE NEXT RIDGE OF HIGH PRESSURE AND THE
DEPARTING RIDGE...WEAK TROUGHING WILL SLIDE EAST ACROSS THE UPPER
MIDWEST/GREAT LAKES. THIS HAS PRODUCED A BUMP IN THE GRADIENT AND
RESULTED IN BREEZY CONDS THIS AFTN FROM A GOOD MIXED LAYER.

GUIDANCE HAS SLOWED THE ARRIVAL OF THE FRONTAL BOUNDARY
SLIGHTLY...BUT THERE REMAINS SOME CONSISTENCY THAT THE
MOISTURE/PRECIP WILL BE DISPLACED TO THE NORTHEAST OF THE FORECAST
AREA THRU THE OVERNIGHT PERIOD. TEMPS TONIGHT WILL BE WARMER THAN
THE PRIOR NGT WITH LOWS GENERALLY IN THE LOW/MID 40S.

MONDAY THROUGH THURSDAY...
500MB TROUGH AXIS WILL CONTINUE TO PIVOT EAST OF THE REGION BY
MIDDAY MON...HOWEVER THERE DOES APPEAR TO BE SOME WRAP AROUND
MOISTURE TRYING TO SLIDE SOUTH ACROSS THE LAKE AND MAY PRODUCE SOME
SPRINKLES/LGT RAIN FOR NORTHWEST IN. HAVE MAINTAINED A DRY FORECAST
FOR NORTHEAST IL...HOWEVER LATE MON EVE A FEW SPOTTY SHOWERS COULD
SNEAK INTO THE CHICAGO METRO AREA INTO TUE MORNING. OTHERWISE EXPECT
THE FAR WESTERN FORECAST AREA TO REMAIN DRY. THEN BROAD
ANTI-CYCLONIC FLOW ARRIVES AND IS EXPECTED TO REMAIN IN PLACE THRU
THE SECOND HALF OF THE WEEK. TEMPS MON WILL LIKELY BE THE WARMEST IN
THE UPR 50S TO LOW 60S...THEN COOLING INTO THE LOW/MID 50S FOR
TUE/WED/THUR. WITH HIGH PRES POISED TO BE OVERHEAD TUE
NGT-WED-NGT...LOWS IN MANY AREAS COULD EASILY DIP INTO THE MID 30S.

FRIDAY THROUGH NEXT WEEKEND...
ENSEMBLES CONTINUE WITH THE RATHER BENIGN PATTERN INTO THE WEEKEND.
TROUGH DIGS INTO THE SOUTHWEST CONUS...BUT IS PROGGED TO WEAKEN BY
SAT/SUN. HIGH AMPLITUDE RIDGING OVER THE CENTRAL CONUS WILL
GRADUALLY WEAKEN LATE IN THE WEEK...HOWEVER CURRENT GUIDANCE
SUGGESTS THE DRY PATTERN WILL PERSIST INTO AT LEAST SAT. TEMPS WILL
STEADILY RETURN TO NEAR SEASONAL CONDS WITH HIGHS ARND 60 TO THE LOW
60S BY THE WEEKEND.

BEACHLER

&&

.AVIATION...

//ORD AND MDW CONCERNS...UPDATED 06Z...

* SOUTHWEST WINDS BECOME WEST THIS MORNING...NORTHWEST THIS
  AFTERNOON THEN NORTH/NORTHEAST LATE THIS AFTERNOON. CMS

//DISCUSSION...UPDATED 06Z...

A COLD FRONT WILL MOVE ACROSS THE TERMINALS LATER THIS MORNING...
SHIFTING SOUTHWESTERLY WINDS TO THE WEST/NORTHWEST BY MID MORNING
AND THEN TO THE NORTHWEST BY EARLY AFTERNOON. SPEEDS 10-12KTS WITH
A FEW HIGHER GUSTS TO START WILL DIMINISH SOME BY SUNRISE THEN
INCREASE AGAIN TO 10-12KTS THIS AFTERNOON. AS THE FRONT CONTINUES
EAST THIS AFTERNOON...THE GRADIENT BECOMES A BIT WEAKER OVER THE
SOUTHERN END OF LAKE MICHIGAN. THIS WILL LIKELY ALLOW WINDS TO
SHIFT TO THE NORTH/NORTHEAST BY LATE AFTERNOON. CONFIDENCE IN
SPEEDS IS A BIT LOWER...WITH PREVAILING SPEEDS LIKELY TO BE JUST
UNDER 10KTS.

MID CLOUDS WILL SHIFT EAST EARLY THIS MORNING WITH LOWER VFR...
3-5KFT CIGS OVER THE NORTHERN LAKES MOVING SOUTH ACROSS THE AREA
LATER THIS MORNING AND CONTINUING INTO THIS EVENING WITH SOME
POTENTIAL FOR HIGH MVFR CIGS...ESPECIALLY SOUTH OF THE LAKE
AFFECTING GYY. CMS

//ORD AND MDW CONFIDENCE...UPDATED 06Z...

HIGH FOR WINDS THRU MID MORNING...THEN MEDIUM FOR DIRECTION AND
TIMING CHANGES THIS AFTERNOON/EVENING. CMS

//OUTLOOK FOR ORD/MDW FOR 12Z TUESDAY-12Z SUNDAY...UPDATED 00Z...

TUESDAY...VFR. BREEZY NORTHEAST WINDS.

WEDNESDAY...VFR. EAST WINDS.

THURSDAY THROUGH SATURDAY...VFR. LIGHT WEST TO SOUTHWEST WINDS.

MDB

&&

.MARINE...

309 AM...LOW PRESSURE OVER THE UPPER PENINSULA OF MICHIGAN WILL
MOVE SOUTHEAST TODAY AND TONIGHT REACHING THE MID ATLANTIC ON
TUESDAY. A TRAILING COLD FRONT WILL MOVE ACROSS LAKE MICHIGAN THIS
MORNING. SOUTHWEST WINDS WILL TURN NORTHWEST THIS MORNING THEN
NORTH THIS EVENING. THE GRADIENT REMAINS FAIRLY TIGHT ACROSS THE
SOUTHERN THIRD OR SO OF THE LAKE...WITH GUSTS TO 30KT POSSIBLE FOR
A FEW MORE HOURS. HIGH PRESSURE WILL BUILD ACROSS ONTARIO TODAY
AND TONIGHT AS IT STRENGTHENS. WHILE THE CENTER OF THIS HIGH WILL
MOVE EAST INTO QUEBEC TUESDAY NIGHT...A RIDGE WILL EXTEND SOUTH
ACROSS THE WESTERN LAKES TONIGHT AND TUESDAY...THEN MOVE ACROSS
THE LAKE WEDNESDAY. THE GRADIENT WILL TIGHTEN BETWEEN THIS
APPROACHING RIDGE AND THE DEPARTING LOW WITH NORTHERLY WINDS
INCREASING TO 30 KT THIS EVENING AND REMAINING THERE UNTIL TUESDAY
AFTERNOON...AS THE RIDGE SLOWLY WORKS EAST. CMS

&&

.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...SMALL CRAFT ADVISORY...NEARSHORE WATERS UNTIL 7 AM MONDAY.

     SMALL CRAFT ADVISORY...LMZ740-LMZ741-LMZ742-LMZ743-LMZ744-
     LMZ745...10 PM MONDAY TO 7 AM WEDNESDAY.

&&

$$

VISIT US AT HTTP://WEATHER.GOV/CHICAGO (ALL LOWERCASE)

FOLLOW US ON FACEBOOK...TWITTER...AND YOUTUBE AT:
WWW.FACEBOOK.COM/NWSCHICAGO
WWW.TWITTER.COM/NWSCHICAGO
WWW.YOUTUBE.COM/NWSCHICAGO






000
FXUS63 KLOT 200809
AFDLOT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
309 AM CDT MON OCT 20 2014

.DISCUSSION...
152 PM CDT

TONIGHT...
VISIBLE IMAGERY THIS AFTERNOON INDICATES A THIN CIRRUS SHIELD OVER
THE REGION...WITH SOME ENHANCEMENT TO THE CLOUD COVER ACROSS
WISCONSIN AHEAD OF A FRONTAL BOUNDARY THAT IS PUSHING FROM WEST TO
EAST ACROSS THE WESTERN GREAT LAKES. SFC RIDGE HAS DRIFTED SOUTHEAST
OF THE FORECAST AREA...WHICH HAS ALLOWED LLVL FLOW TO TURN
SOUTHWESTERLY. BETWEEN THE NEXT RIDGE OF HIGH PRESSURE AND THE
DEPARTING RIDGE...WEAK TROUGHING WILL SLIDE EAST ACROSS THE UPPER
MIDWEST/GREAT LAKES. THIS HAS PRODUCED A BUMP IN THE GRADIENT AND
RESULTED IN BREEZY CONDS THIS AFTN FROM A GOOD MIXED LAYER.

GUIDANCE HAS SLOWED THE ARRIVAL OF THE FRONTAL BOUNDARY
SLIGHTLY...BUT THERE REMAINS SOME CONSISTENCY THAT THE
MOISTURE/PRECIP WILL BE DISPLACED TO THE NORTHEAST OF THE FORECAST
AREA THRU THE OVERNIGHT PERIOD. TEMPS TONIGHT WILL BE WARMER THAN
THE PRIOR NGT WITH LOWS GENERALLY IN THE LOW/MID 40S.

MONDAY THROUGH THURSDAY...
500MB TROUGH AXIS WILL CONTINUE TO PIVOT EAST OF THE REGION BY
MIDDAY MON...HOWEVER THERE DOES APPEAR TO BE SOME WRAP AROUND
MOISTURE TRYING TO SLIDE SOUTH ACROSS THE LAKE AND MAY PRODUCE SOME
SPRINKLES/LGT RAIN FOR NORTHWEST IN. HAVE MAINTAINED A DRY FORECAST
FOR NORTHEAST IL...HOWEVER LATE MON EVE A FEW SPOTTY SHOWERS COULD
SNEAK INTO THE CHICAGO METRO AREA INTO TUE MORNING. OTHERWISE EXPECT
THE FAR WESTERN FORECAST AREA TO REMAIN DRY. THEN BROAD
ANTI-CYCLONIC FLOW ARRIVES AND IS EXPECTED TO REMAIN IN PLACE THRU
THE SECOND HALF OF THE WEEK. TEMPS MON WILL LIKELY BE THE WARMEST IN
THE UPR 50S TO LOW 60S...THEN COOLING INTO THE LOW/MID 50S FOR
TUE/WED/THUR. WITH HIGH PRES POISED TO BE OVERHEAD TUE
NGT-WED-NGT...LOWS IN MANY AREAS COULD EASILY DIP INTO THE MID 30S.

FRIDAY THROUGH NEXT WEEKEND...
ENSEMBLES CONTINUE WITH THE RATHER BENIGN PATTERN INTO THE WEEKEND.
TROUGH DIGS INTO THE SOUTHWEST CONUS...BUT IS PROGGED TO WEAKEN BY
SAT/SUN. HIGH AMPLITUDE RIDGING OVER THE CENTRAL CONUS WILL
GRADUALLY WEAKEN LATE IN THE WEEK...HOWEVER CURRENT GUIDANCE
SUGGESTS THE DRY PATTERN WILL PERSIST INTO AT LEAST SAT. TEMPS WILL
STEADILY RETURN TO NEAR SEASONAL CONDS WITH HIGHS ARND 60 TO THE LOW
60S BY THE WEEKEND.

BEACHLER

&&

.AVIATION...

//ORD AND MDW CONCERNS...UPDATED 06Z...

* SOUTHWEST WINDS BECOME WEST THIS MORNING...NORTHWEST THIS
  AFTERNOON THEN NORTH/NORTHEAST LATE THIS AFTERNOON. CMS

//DISCUSSION...UPDATED 06Z...

A COLD FRONT WILL MOVE ACROSS THE TERMINALS LATER THIS MORNING...
SHIFTING SOUTHWESTERLY WINDS TO THE WEST/NORTHWEST BY MID MORNING
AND THEN TO THE NORTHWEST BY EARLY AFTERNOON. SPEEDS 10-12KTS WITH
A FEW HIGHER GUSTS TO START WILL DIMINISH SOME BY SUNRISE THEN
INCREASE AGAIN TO 10-12KTS THIS AFTERNOON. AS THE FRONT CONTINUES
EAST THIS AFTERNOON...THE GRADIENT BECOMES A BIT WEAKER OVER THE
SOUTHERN END OF LAKE MICHIGAN. THIS WILL LIKELY ALLOW WINDS TO
SHIFT TO THE NORTH/NORTHEAST BY LATE AFTERNOON. CONFIDENCE IN
SPEEDS IS A BIT LOWER...WITH PREVAILING SPEEDS LIKELY TO BE JUST
UNDER 10KTS.

MID CLOUDS WILL SHIFT EAST EARLY THIS MORNING WITH LOWER VFR...
3-5KFT CIGS OVER THE NORTHERN LAKES MOVING SOUTH ACROSS THE AREA
LATER THIS MORNING AND CONTINUING INTO THIS EVENING WITH SOME
POTENTIAL FOR HIGH MVFR CIGS...ESPECIALLY SOUTH OF THE LAKE
AFFECTING GYY. CMS

//ORD AND MDW CONFIDENCE...UPDATED 06Z...

HIGH FOR WINDS THRU MID MORNING...THEN MEDIUM FOR DIRECTION AND
TIMING CHANGES THIS AFTERNOON/EVENING. CMS

//OUTLOOK FOR ORD/MDW FOR 12Z TUESDAY-12Z SUNDAY...UPDATED 00Z...

TUESDAY...VFR. BREEZY NORTHEAST WINDS.

WEDNESDAY...VFR. EAST WINDS.

THURSDAY THROUGH SATURDAY...VFR. LIGHT WEST TO SOUTHWEST WINDS.

MDB

&&

.MARINE...

309 AM...LOW PRESSURE OVER THE UPPER PENINSULA OF MICHIGAN WILL
MOVE SOUTHEAST TODAY AND TONIGHT REACHING THE MID ATLANTIC ON
TUESDAY. A TRAILING COLD FRONT WILL MOVE ACROSS LAKE MICHIGAN THIS
MORNING. SOUTHWEST WINDS WILL TURN NORTHWEST THIS MORNING THEN
NORTH THIS EVENING. THE GRADIENT REMAINS FAIRLY TIGHT ACROSS THE
SOUTHERN THIRD OR SO OF THE LAKE...WITH GUSTS TO 30KT POSSIBLE FOR
A FEW MORE HOURS. HIGH PRESSURE WILL BUILD ACROSS ONTARIO TODAY
AND TONIGHT AS IT STRENGTHENS. WHILE THE CENTER OF THIS HIGH WILL
MOVE EAST INTO QUEBEC TUESDAY NIGHT...A RIDGE WILL EXTEND SOUTH
ACROSS THE WESTERN LAKES TONIGHT AND TUESDAY...THEN MOVE ACROSS
THE LAKE WEDNESDAY. THE GRADIENT WILL TIGHTEN BETWEEN THIS
APPROACHING RIDGE AND THE DEPARTING LOW WITH NORTHERLY WINDS
INCREASING TO 30 KT THIS EVENING AND REMAINING THERE UNTIL TUESDAY
AFTERNOON...AS THE RIDGE SLOWLY WORKS EAST. CMS

&&

.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...SMALL CRAFT ADVISORY...NEARSHORE WATERS UNTIL 7 AM MONDAY.

     SMALL CRAFT ADVISORY...LMZ740-LMZ741-LMZ742-LMZ743-LMZ744-
     LMZ745...10 PM MONDAY TO 7 AM WEDNESDAY.

&&

$$

VISIT US AT HTTP://WEATHER.GOV/CHICAGO (ALL LOWERCASE)

FOLLOW US ON FACEBOOK...TWITTER...AND YOUTUBE AT:
WWW.FACEBOOK.COM/NWSCHICAGO
WWW.TWITTER.COM/NWSCHICAGO
WWW.YOUTUBE.COM/NWSCHICAGO






000
FXUS63 KLOT 200809
AFDLOT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
309 AM CDT MON OCT 20 2014

.DISCUSSION...
152 PM CDT

TONIGHT...
VISIBLE IMAGERY THIS AFTERNOON INDICATES A THIN CIRRUS SHIELD OVER
THE REGION...WITH SOME ENHANCEMENT TO THE CLOUD COVER ACROSS
WISCONSIN AHEAD OF A FRONTAL BOUNDARY THAT IS PUSHING FROM WEST TO
EAST ACROSS THE WESTERN GREAT LAKES. SFC RIDGE HAS DRIFTED SOUTHEAST
OF THE FORECAST AREA...WHICH HAS ALLOWED LLVL FLOW TO TURN
SOUTHWESTERLY. BETWEEN THE NEXT RIDGE OF HIGH PRESSURE AND THE
DEPARTING RIDGE...WEAK TROUGHING WILL SLIDE EAST ACROSS THE UPPER
MIDWEST/GREAT LAKES. THIS HAS PRODUCED A BUMP IN THE GRADIENT AND
RESULTED IN BREEZY CONDS THIS AFTN FROM A GOOD MIXED LAYER.

GUIDANCE HAS SLOWED THE ARRIVAL OF THE FRONTAL BOUNDARY
SLIGHTLY...BUT THERE REMAINS SOME CONSISTENCY THAT THE
MOISTURE/PRECIP WILL BE DISPLACED TO THE NORTHEAST OF THE FORECAST
AREA THRU THE OVERNIGHT PERIOD. TEMPS TONIGHT WILL BE WARMER THAN
THE PRIOR NGT WITH LOWS GENERALLY IN THE LOW/MID 40S.

MONDAY THROUGH THURSDAY...
500MB TROUGH AXIS WILL CONTINUE TO PIVOT EAST OF THE REGION BY
MIDDAY MON...HOWEVER THERE DOES APPEAR TO BE SOME WRAP AROUND
MOISTURE TRYING TO SLIDE SOUTH ACROSS THE LAKE AND MAY PRODUCE SOME
SPRINKLES/LGT RAIN FOR NORTHWEST IN. HAVE MAINTAINED A DRY FORECAST
FOR NORTHEAST IL...HOWEVER LATE MON EVE A FEW SPOTTY SHOWERS COULD
SNEAK INTO THE CHICAGO METRO AREA INTO TUE MORNING. OTHERWISE EXPECT
THE FAR WESTERN FORECAST AREA TO REMAIN DRY. THEN BROAD
ANTI-CYCLONIC FLOW ARRIVES AND IS EXPECTED TO REMAIN IN PLACE THRU
THE SECOND HALF OF THE WEEK. TEMPS MON WILL LIKELY BE THE WARMEST IN
THE UPR 50S TO LOW 60S...THEN COOLING INTO THE LOW/MID 50S FOR
TUE/WED/THUR. WITH HIGH PRES POISED TO BE OVERHEAD TUE
NGT-WED-NGT...LOWS IN MANY AREAS COULD EASILY DIP INTO THE MID 30S.

FRIDAY THROUGH NEXT WEEKEND...
ENSEMBLES CONTINUE WITH THE RATHER BENIGN PATTERN INTO THE WEEKEND.
TROUGH DIGS INTO THE SOUTHWEST CONUS...BUT IS PROGGED TO WEAKEN BY
SAT/SUN. HIGH AMPLITUDE RIDGING OVER THE CENTRAL CONUS WILL
GRADUALLY WEAKEN LATE IN THE WEEK...HOWEVER CURRENT GUIDANCE
SUGGESTS THE DRY PATTERN WILL PERSIST INTO AT LEAST SAT. TEMPS WILL
STEADILY RETURN TO NEAR SEASONAL CONDS WITH HIGHS ARND 60 TO THE LOW
60S BY THE WEEKEND.

BEACHLER

&&

.AVIATION...

//ORD AND MDW CONCERNS...UPDATED 06Z...

* SOUTHWEST WINDS BECOME WEST THIS MORNING...NORTHWEST THIS
  AFTERNOON THEN NORTH/NORTHEAST LATE THIS AFTERNOON. CMS

//DISCUSSION...UPDATED 06Z...

A COLD FRONT WILL MOVE ACROSS THE TERMINALS LATER THIS MORNING...
SHIFTING SOUTHWESTERLY WINDS TO THE WEST/NORTHWEST BY MID MORNING
AND THEN TO THE NORTHWEST BY EARLY AFTERNOON. SPEEDS 10-12KTS WITH
A FEW HIGHER GUSTS TO START WILL DIMINISH SOME BY SUNRISE THEN
INCREASE AGAIN TO 10-12KTS THIS AFTERNOON. AS THE FRONT CONTINUES
EAST THIS AFTERNOON...THE GRADIENT BECOMES A BIT WEAKER OVER THE
SOUTHERN END OF LAKE MICHIGAN. THIS WILL LIKELY ALLOW WINDS TO
SHIFT TO THE NORTH/NORTHEAST BY LATE AFTERNOON. CONFIDENCE IN
SPEEDS IS A BIT LOWER...WITH PREVAILING SPEEDS LIKELY TO BE JUST
UNDER 10KTS.

MID CLOUDS WILL SHIFT EAST EARLY THIS MORNING WITH LOWER VFR...
3-5KFT CIGS OVER THE NORTHERN LAKES MOVING SOUTH ACROSS THE AREA
LATER THIS MORNING AND CONTINUING INTO THIS EVENING WITH SOME
POTENTIAL FOR HIGH MVFR CIGS...ESPECIALLY SOUTH OF THE LAKE
AFFECTING GYY. CMS

//ORD AND MDW CONFIDENCE...UPDATED 06Z...

HIGH FOR WINDS THRU MID MORNING...THEN MEDIUM FOR DIRECTION AND
TIMING CHANGES THIS AFTERNOON/EVENING. CMS

//OUTLOOK FOR ORD/MDW FOR 12Z TUESDAY-12Z SUNDAY...UPDATED 00Z...

TUESDAY...VFR. BREEZY NORTHEAST WINDS.

WEDNESDAY...VFR. EAST WINDS.

THURSDAY THROUGH SATURDAY...VFR. LIGHT WEST TO SOUTHWEST WINDS.

MDB

&&

.MARINE...

309 AM...LOW PRESSURE OVER THE UPPER PENINSULA OF MICHIGAN WILL
MOVE SOUTHEAST TODAY AND TONIGHT REACHING THE MID ATLANTIC ON
TUESDAY. A TRAILING COLD FRONT WILL MOVE ACROSS LAKE MICHIGAN THIS
MORNING. SOUTHWEST WINDS WILL TURN NORTHWEST THIS MORNING THEN
NORTH THIS EVENING. THE GRADIENT REMAINS FAIRLY TIGHT ACROSS THE
SOUTHERN THIRD OR SO OF THE LAKE...WITH GUSTS TO 30KT POSSIBLE FOR
A FEW MORE HOURS. HIGH PRESSURE WILL BUILD ACROSS ONTARIO TODAY
AND TONIGHT AS IT STRENGTHENS. WHILE THE CENTER OF THIS HIGH WILL
MOVE EAST INTO QUEBEC TUESDAY NIGHT...A RIDGE WILL EXTEND SOUTH
ACROSS THE WESTERN LAKES TONIGHT AND TUESDAY...THEN MOVE ACROSS
THE LAKE WEDNESDAY. THE GRADIENT WILL TIGHTEN BETWEEN THIS
APPROACHING RIDGE AND THE DEPARTING LOW WITH NORTHERLY WINDS
INCREASING TO 30 KT THIS EVENING AND REMAINING THERE UNTIL TUESDAY
AFTERNOON...AS THE RIDGE SLOWLY WORKS EAST. CMS

&&

.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...SMALL CRAFT ADVISORY...NEARSHORE WATERS UNTIL 7 AM MONDAY.

     SMALL CRAFT ADVISORY...LMZ740-LMZ741-LMZ742-LMZ743-LMZ744-
     LMZ745...10 PM MONDAY TO 7 AM WEDNESDAY.

&&

$$

VISIT US AT HTTP://WEATHER.GOV/CHICAGO (ALL LOWERCASE)

FOLLOW US ON FACEBOOK...TWITTER...AND YOUTUBE AT:
WWW.FACEBOOK.COM/NWSCHICAGO
WWW.TWITTER.COM/NWSCHICAGO
WWW.YOUTUBE.COM/NWSCHICAGO







000
FXUS63 KLOT 200524
AFDLOT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
1224 AM CDT MON OCT 20 2014

.DISCUSSION...
152 PM CDT

TONIGHT...
VISIBLE IMAGERY THIS AFTERNOON INDICATES A THIN CIRRUS SHIELD OVER
THE REGION...WITH SOME ENHANCEMENT TO THE CLOUD COVER ACROSS
WISCONSIN AHEAD OF A FRONTAL BOUNDARY THAT IS PUSHING FROM WEST TO
EAST ACROSS THE WESTERN GREAT LAKES. SFC RIDGE HAS DRIFTED SOUTHEAST
OF THE FORECAST AREA...WHICH HAS ALLOWED LLVL FLOW TO TURN
SOUTHWESTERLY. BETWEEN THE NEXT RIDGE OF HIGH PRESSURE AND THE
DEPARTING RIDGE...WEAK TROUGHING WILL SLIDE EAST ACROSS THE UPPER
MIDWEST/GREAT LAKES. THIS HAS PRODUCED A BUMP IN THE GRADIENT AND
RESULTED IN BREEZY CONDS THIS AFTN FROM A GOOD MIXED LAYER.

GUIDANCE HAS SLOWED THE ARRIVAL OF THE FRONTAL BOUNDARY
SLIGHTLY...BUT THERE REMAINS SOME CONSISTENCY THAT THE
MOISTURE/PRECIP WILL BE DISPLACED TO THE NORTHEAST OF THE FORECAST
AREA THRU THE OVERNIGHT PERIOD. TEMPS TONIGHT WILL BE WARMER THAN
THE PRIOR NGT WITH LOWS GENERALLY IN THE LOW/MID 40S.

MONDAY THROUGH THURSDAY...
500MB TROUGH AXIS WILL CONTINUE TO PIVOT EAST OF THE REGION BY
MIDDAY MON...HOWEVER THERE DOES APPEAR TO BE SOME WRAP AROUND
MOISTURE TRYING TO SLIDE SOUTH ACROSS THE LAKE AND MAY PRODUCE SOME
SPRINKLES/LGT RAIN FOR NORTHWEST IN. HAVE MAINTAINED A DRY FORECAST
FOR NORTHEAST IL...HOWEVER LATE MON EVE A FEW SPOTTY SHOWERS COULD
SNEAK INTO THE CHICAGO METRO AREA INTO TUE MORNING. OTHERWISE EXPECT
THE FAR WESTERN FORECAST AREA TO REMAIN DRY. THEN BROAD
ANTI-CYCLONIC FLOW ARRIVES AND IS EXPECTED TO REMAIN IN PLACE THRU
THE SECOND HALF OF THE WEEK. TEMPS MON WILL LIKELY BE THE WARMEST IN
THE UPR 50S TO LOW 60S...THEN COOLING INTO THE LOW/MID 50S FOR
TUE/WED/THUR. WITH HIGH PRES POISED TO BE OVERHEAD TUE
NGT-WED-NGT...LOWS IN MANY AREAS COULD EASILY DIP INTO THE MID 30S.

FRIDAY THROUGH NEXT WEEKEND...
ENSEMBLES CONTINUE WITH THE RATHER BENIGN PATTERN INTO THE WEEKEND.
TROUGH DIGS INTO THE SOUTHWEST CONUS...BUT IS PROGGED TO WEAKEN BY
SAT/SUN. HIGH AMPLITUDE RIDGING OVER THE CENTRAL CONUS WILL
GRADUALLY WEAKEN LATE IN THE WEEK...HOWEVER CURRENT GUIDANCE
SUGGESTS THE DRY PATTERN WILL PERSIST INTO AT LEAST SAT. TEMPS WILL
STEADILY RETURN TO NEAR SEASONAL CONDS WITH HIGHS ARND 60 TO THE LOW
60S BY THE WEEKEND.

BEACHLER

&&

.AVIATION...

//ORD AND MDW CONCERNS...UPDATED 06Z...

* SOUTHWEST WINDS BECOME WEST THIS MORNING...NORTHWEST THIS
  AFTERNOON THEN NORTH/NORTHEAST LATE THIS AFTERNOON. CMS

//DISCUSSION...UPDATED 06Z...

A COLD FRONT WILL MOVE ACROSS THE TERMINALS LATER THIS MORNING...
SHIFTING SOUTHWESTERLY WINDS TO THE WEST/NORTHWEST BY MID MORNING
AND THEN TO THE NORTHWEST BY EARLY AFTERNOON. SPEEDS 10-12KTS WITH
A FEW HIGHER GUSTS TO START WILL DIMINISH SOME BY SUNRISE THEN
INCREASE AGAIN TO 10-12KTS THIS AFTERNOON. AS THE FRONT CONTINUES
EAST THIS AFTERNOON...THE GRADIENT BECOMES A BIT WEAKER OVER THE
SOUTHERN END OF LAKE MICHIGAN. THIS WILL LIKELY ALLOW WINDS TO
SHIFT TO THE NORTH/NORTHEAST BY LATE AFTERNOON. CONFIDENCE IN
SPEEDS IS A BIT LOWER...WITH PREVAILING SPEEDS LIKELY TO BE JUST
UNDER 10KTS.

MID CLOUDS WILL SHIFT EAST EARLY THIS MORNING WITH LOWER VFR...
3-5KFT CIGS OVER THE NORTHERN LAKES MOVING SOUTH ACROSS THE AREA
LATER THIS MORNING AND CONTINUING INTO THIS EVENING WITH SOME
POTENTIAL FOR HIGH MVFR CIGS...ESPECIALLY SOUTH OF THE LAKE
AFFECTING GYY. CMS

//ORD AND MDW CONFIDENCE...UPDATED 06Z...

HIGH FOR WINDS THRU MID MORNING...THEN MEDIUM FOR DIRECTION AND
TIMING CHANGES THIS AFTERNOON/EVENING. CMS

//OUTLOOK FOR ORD/MDW FOR 12Z TUESDAY-12Z SUNDAY...UPDATED 00Z...

TUESDAY...VFR. BREEZY NORTHEAST WINDS.

WEDNESDAY...VFR. EAST WINDS.

THURSDAY THROUGH SATURDAY...VFR. LIGHT WEST TO SOUTHWEST WINDS.

MDB

&&

.MARINE...
324 PM CDT

LOW PRESSURE MOVING THROUGH ONTARIO TONIGHT WILL DRAG A COLD
FRONT ACROSS THE LAKE AND TIGHTEN THE PRESSURE GRADIENT THIS
EVENING. GALE FORCE GUSTS ARE POSSIBLE FOR A TIME BUT GENERALLY
WINDS SHOULD STAY BELOW GALE WARNING CRITERIA. A SMALL CRAFT
ADVISORY CONTINUES FOR NEARSHORE WATERS THIS EVENING AND THROUGH
THE EARLY OVERNIGHT HOURS DUE TO STRONG OFFSHORE WINDS...BUT WAVES
SHOULD NOT BE A BIG PROBLEM UNTIL WINDS TURN NORTHWEST AND THEN
NORTH BY LATE MONDAY...INCREASING AGAIN IN A GRADIENT BETWEEN AN
APPROACHING HIGH AND THE SLOWLY DEPARTING LOW. THESE STRONG
NORTHERLY WINDS PERSIST THROUGH TUESDAY AFTER WHICH TIME THE RIDGE
MOVES OVER THE LAKE BRINGING FAIRLY QUIET CONDITIONS.

LENNING

&&

.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...SMALL CRAFT ADVISORY...NEARSHORE WATERS UNTIL 3 AM MONDAY.

&&

$$

VISIT US AT HTTP://WEATHER.GOV/CHICAGO (ALL LOWERCASE)

FOLLOW US ON FACEBOOK...TWITTER...AND YOUTUBE AT:
WWW.FACEBOOK.COM/NWSCHICAGO
WWW.TWITTER.COM/NWSCHICAGO
WWW.YOUTUBE.COM/NWSCHICAGO







000
FXUS63 KLOT 200524
AFDLOT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
1224 AM CDT MON OCT 20 2014

.DISCUSSION...
152 PM CDT

TONIGHT...
VISIBLE IMAGERY THIS AFTERNOON INDICATES A THIN CIRRUS SHIELD OVER
THE REGION...WITH SOME ENHANCEMENT TO THE CLOUD COVER ACROSS
WISCONSIN AHEAD OF A FRONTAL BOUNDARY THAT IS PUSHING FROM WEST TO
EAST ACROSS THE WESTERN GREAT LAKES. SFC RIDGE HAS DRIFTED SOUTHEAST
OF THE FORECAST AREA...WHICH HAS ALLOWED LLVL FLOW TO TURN
SOUTHWESTERLY. BETWEEN THE NEXT RIDGE OF HIGH PRESSURE AND THE
DEPARTING RIDGE...WEAK TROUGHING WILL SLIDE EAST ACROSS THE UPPER
MIDWEST/GREAT LAKES. THIS HAS PRODUCED A BUMP IN THE GRADIENT AND
RESULTED IN BREEZY CONDS THIS AFTN FROM A GOOD MIXED LAYER.

GUIDANCE HAS SLOWED THE ARRIVAL OF THE FRONTAL BOUNDARY
SLIGHTLY...BUT THERE REMAINS SOME CONSISTENCY THAT THE
MOISTURE/PRECIP WILL BE DISPLACED TO THE NORTHEAST OF THE FORECAST
AREA THRU THE OVERNIGHT PERIOD. TEMPS TONIGHT WILL BE WARMER THAN
THE PRIOR NGT WITH LOWS GENERALLY IN THE LOW/MID 40S.

MONDAY THROUGH THURSDAY...
500MB TROUGH AXIS WILL CONTINUE TO PIVOT EAST OF THE REGION BY
MIDDAY MON...HOWEVER THERE DOES APPEAR TO BE SOME WRAP AROUND
MOISTURE TRYING TO SLIDE SOUTH ACROSS THE LAKE AND MAY PRODUCE SOME
SPRINKLES/LGT RAIN FOR NORTHWEST IN. HAVE MAINTAINED A DRY FORECAST
FOR NORTHEAST IL...HOWEVER LATE MON EVE A FEW SPOTTY SHOWERS COULD
SNEAK INTO THE CHICAGO METRO AREA INTO TUE MORNING. OTHERWISE EXPECT
THE FAR WESTERN FORECAST AREA TO REMAIN DRY. THEN BROAD
ANTI-CYCLONIC FLOW ARRIVES AND IS EXPECTED TO REMAIN IN PLACE THRU
THE SECOND HALF OF THE WEEK. TEMPS MON WILL LIKELY BE THE WARMEST IN
THE UPR 50S TO LOW 60S...THEN COOLING INTO THE LOW/MID 50S FOR
TUE/WED/THUR. WITH HIGH PRES POISED TO BE OVERHEAD TUE
NGT-WED-NGT...LOWS IN MANY AREAS COULD EASILY DIP INTO THE MID 30S.

FRIDAY THROUGH NEXT WEEKEND...
ENSEMBLES CONTINUE WITH THE RATHER BENIGN PATTERN INTO THE WEEKEND.
TROUGH DIGS INTO THE SOUTHWEST CONUS...BUT IS PROGGED TO WEAKEN BY
SAT/SUN. HIGH AMPLITUDE RIDGING OVER THE CENTRAL CONUS WILL
GRADUALLY WEAKEN LATE IN THE WEEK...HOWEVER CURRENT GUIDANCE
SUGGESTS THE DRY PATTERN WILL PERSIST INTO AT LEAST SAT. TEMPS WILL
STEADILY RETURN TO NEAR SEASONAL CONDS WITH HIGHS ARND 60 TO THE LOW
60S BY THE WEEKEND.

BEACHLER

&&

.AVIATION...

//ORD AND MDW CONCERNS...UPDATED 06Z...

* SOUTHWEST WINDS BECOME WEST THIS MORNING...NORTHWEST THIS
  AFTERNOON THEN NORTH/NORTHEAST LATE THIS AFTERNOON. CMS

//DISCUSSION...UPDATED 06Z...

A COLD FRONT WILL MOVE ACROSS THE TERMINALS LATER THIS MORNING...
SHIFTING SOUTHWESTERLY WINDS TO THE WEST/NORTHWEST BY MID MORNING
AND THEN TO THE NORTHWEST BY EARLY AFTERNOON. SPEEDS 10-12KTS WITH
A FEW HIGHER GUSTS TO START WILL DIMINISH SOME BY SUNRISE THEN
INCREASE AGAIN TO 10-12KTS THIS AFTERNOON. AS THE FRONT CONTINUES
EAST THIS AFTERNOON...THE GRADIENT BECOMES A BIT WEAKER OVER THE
SOUTHERN END OF LAKE MICHIGAN. THIS WILL LIKELY ALLOW WINDS TO
SHIFT TO THE NORTH/NORTHEAST BY LATE AFTERNOON. CONFIDENCE IN
SPEEDS IS A BIT LOWER...WITH PREVAILING SPEEDS LIKELY TO BE JUST
UNDER 10KTS.

MID CLOUDS WILL SHIFT EAST EARLY THIS MORNING WITH LOWER VFR...
3-5KFT CIGS OVER THE NORTHERN LAKES MOVING SOUTH ACROSS THE AREA
LATER THIS MORNING AND CONTINUING INTO THIS EVENING WITH SOME
POTENTIAL FOR HIGH MVFR CIGS...ESPECIALLY SOUTH OF THE LAKE
AFFECTING GYY. CMS

//ORD AND MDW CONFIDENCE...UPDATED 06Z...

HIGH FOR WINDS THRU MID MORNING...THEN MEDIUM FOR DIRECTION AND
TIMING CHANGES THIS AFTERNOON/EVENING. CMS

//OUTLOOK FOR ORD/MDW FOR 12Z TUESDAY-12Z SUNDAY...UPDATED 00Z...

TUESDAY...VFR. BREEZY NORTHEAST WINDS.

WEDNESDAY...VFR. EAST WINDS.

THURSDAY THROUGH SATURDAY...VFR. LIGHT WEST TO SOUTHWEST WINDS.

MDB

&&

.MARINE...
324 PM CDT

LOW PRESSURE MOVING THROUGH ONTARIO TONIGHT WILL DRAG A COLD
FRONT ACROSS THE LAKE AND TIGHTEN THE PRESSURE GRADIENT THIS
EVENING. GALE FORCE GUSTS ARE POSSIBLE FOR A TIME BUT GENERALLY
WINDS SHOULD STAY BELOW GALE WARNING CRITERIA. A SMALL CRAFT
ADVISORY CONTINUES FOR NEARSHORE WATERS THIS EVENING AND THROUGH
THE EARLY OVERNIGHT HOURS DUE TO STRONG OFFSHORE WINDS...BUT WAVES
SHOULD NOT BE A BIG PROBLEM UNTIL WINDS TURN NORTHWEST AND THEN
NORTH BY LATE MONDAY...INCREASING AGAIN IN A GRADIENT BETWEEN AN
APPROACHING HIGH AND THE SLOWLY DEPARTING LOW. THESE STRONG
NORTHERLY WINDS PERSIST THROUGH TUESDAY AFTER WHICH TIME THE RIDGE
MOVES OVER THE LAKE BRINGING FAIRLY QUIET CONDITIONS.

LENNING

&&

.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...SMALL CRAFT ADVISORY...NEARSHORE WATERS UNTIL 3 AM MONDAY.

&&

$$

VISIT US AT HTTP://WEATHER.GOV/CHICAGO (ALL LOWERCASE)

FOLLOW US ON FACEBOOK...TWITTER...AND YOUTUBE AT:
WWW.FACEBOOK.COM/NWSCHICAGO
WWW.TWITTER.COM/NWSCHICAGO
WWW.YOUTUBE.COM/NWSCHICAGO






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