000
FXUS63 KDVN 181130
AFDDVN

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE QUAD CITIES IA IL
630 AM CDT SAT MAY 18 2013

.SYNOPSIS...
ISSUED AT 245 AM CDT SAT MAY 18 2013

06Z SFC ANALYSIS HAS A MESO WAKE LOW NEAR KPHP WITH A MESO HIGH
NORTH OF KONL. NUMEROUS OUTFLOW BOUNDARIES WERE ACROSS THE DAKOTAS
FROM THE MCS. THE MAIN FRONTAL BOUNDARY RAN FROM CENTRAL OHIO...
ACROSS NORTHERN ILLINOIS...AND THEN INTO SOUTHWEST MINNESOTA. DEW
POINTS SOUTH OF THE FRONTAL BOUNDARY WERE MAINLY IN THE 60S. NORTH
OF THE FRONTAL BOUNDARY DEW POINTS WERE IN THE 40S AND 50S.

&&

.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 245 AM CDT SAT MAY 18 2013

QUIET AND DRY CONDITIONS WILL BE SEEN ACROSS THE AREA TODAY AS THE
UPPER RIDGE MOVES EAST FROM THE PLAINS. CLOUDS FROM THE NORTHERN
PLAINS MCS SHOULD INITIALLY PROVIDE FILTERED SUNSHINE BEFORE
BREAKING UP DURING THE DAY.

TONIGHT...QUIET AND DRY CONDITIONS WILL BE SEEN DURING THE EVENING
AS THE UPPER RIDGE MOVES INTO THE WESTERN GREAT LAKES. AFTER
MIDNIGHT THE MCS AND LIFT TOOLS SUGGEST ELEVATED SHRA WITH POSSIBLY
SOME THUNDER SHOULD BEGIN DEVELOPING ACROSS THE WESTERN CWFA AS THE
LLJ BEGINS TO VEER SLIGHTLY INTO EASTERN IOWA WITH BETTER WAA ALOFT
AND MOISTURE.

08

.LONG TERM...(SUNDAY THROUGH FRIDAY)
ISSUED AT 245 AM CDT SAT MAY 18 2013

LOWER END SEVERE WEATHER RISKS LATE SUNDAY AND AGAIN MONDAY THE
MAIN FORECAST ISSUES WITH DECENT RAINS LASTING INTO WEDNESDAY.

OVERVIEW...INITIALIZATION AND VERIFICATION ADEQUATE ON SYNOPTIC
SCALES BUT POOR ON BL MOISTURE AND ESPECIALLY CONVECTIVE EVENTS.
THIS IMPACTS FORECAST WITH CONCEPTUAL FORCING TOOLS WEIGHTED
TOWARD HI-RES ECMWF BEST WITH GFS SERIOUS CONVECTIVE FEEDBACK AND
NAM-WRF NOT MUCH BETTER. D_PROG_DT SUPPORTS USE OF MORE STABLE
HI-RES ECMWF ENTIRE PERIOD WITH INPUTS FROM GEM-RH AND UKMET.

SUNDAY...TRENDS OF JET SUPPORT LOWER END SEVERE RISK MAINLY IN
THE LATE PM INTO EVENING HOURS. JET AXIS AND FORCING ARE DELAYED AND
BETTER FOCUSED WELL SW OF AREA WITH LITTLE SURFACE BASED FORCING
NOTED AT THIS TIME. PROBABLE STORMS AND SHOWERS TO MOVE INTO AREA
LATE PM AND MORE LIKELY IN THE EVENING. SBCAPES AOA 2000+ J/KG
SUGGESTED AND WBZ OF ~11K AGL WITH 35-45KT LOW LEVEL JET OF A
CONVECTIVE SYSTEM OR LINE WITH SOME BOWING SEGMENTS. IF SURFACE
TEMPERATURES/DEWPOINTS ARE AOA 78/65 THEN SOME WINDS OF 60 TO
POSSIBLY NEAR 70 MPH MAY OCCUR. LIMITED SCL SHEAR NOTED TO
PRECLUDE TORNADIC THREAT ATTM. STORMS THAT CAN ENTRAIN MID/UPPER
DRY LEVEL AIR MAY PRODUCE SOME LARGE HAIL UP TO 1.5 INCHES BUT
THIS MAY NOT OCCUR IF MCS IS IN MATURE STAGES AS SUGGESTED. HIGHS
SUNDAY WITH PARTLY SUNNY SKIES 83-88F NW TO SE. SUNDAY NIGHT TO BE
MILD WITH 64-68F READINGS FOR MINS. RAIN AMOUNTS MOST AREAS TO BE
LIGHT TO MODERATE WITH ISOLATED HEAVY AMOUNTS WITH ANY TRAINING OF
STORMS WHICH ARE MARGINAL ATTM WITH FAST FLOW ATTM. `POPS HIGH
CHANCE TO LOWER END LIKELIES AROUND 60 PERCENT.

MONDAY...FRONT NEARBY WITH FAST UPPER FLOW SUPPORTS PM SCATTERED
REDEVELOPMENT WITH POTENTIALLY HIGHER RISK OF SEVERE WEATHER IN PM
HOURS THAN SUNDAY AND ANY FORCING. T/TD PROFILES A FEW DEGREES
LOWER THAN SUNDAY BUT MORE FAVORABLE SHEAR PROFILES FOR SEVERE
WITH STRAIGHT LINE WINDS OF 60-70+ MPH DUE TO GOOD MOMENTUM
TRANSFER AND EVEN ISOLATED TORNADO AS JET AXIS IMPINGES IN WITH
DECENT SCL SHEAR. HAIL OVER 1.75" POSSIBLE IF MID LEVELS ARE AS
DRY AS CURRENTLY SUGGESTED. POPS 40-50 DURING DAY AND LIKELIES
MONDAY NIGHT WITH ANOTHER MCS PROBABLY TO MOVE ACROSS AREA. SEVERE
RISK SHOULD WANE BY MID TO LATE EVENING HOURS. MAX TEMPS 78-83
WITH MINS OF 60-65. RAIN AMOUNTS MOSTLY LIGHT TO MODERATE WITH
ISOLATED HEAVY AMOUNTS AND GREATER RISK OF TRAINING OF STORMS WITH
PARALLEL FLOW.

TUESDAY INTO WEDNESDAY...SHOWERS AND ISOLATED STORMS LIKELY WITH
WAVE TO ROTATE NORTH FROM SOUTHERN PLAINS. THIS SHOULD BE A
WIDESPREAD RAIN EVENT OF MODERATE TO HEAVY TOTALS BASED ON UPPER
FORCING. TOTAL RAIN AMOUNTS OVER THE NEXT 96 HOURS SHOULD BE 1-3
INCHES OVER THE FORECAST AREA. HIGHS IN THE 70S BOTH DAYS WITH
WEDNESDAY A FEW DEGREES COOLER THAN WEDNESDAY AS UPPER LOW MOVES
OVERHEAD. MINS MID 50S TO LOWER 60S.

THURSDAY AND FRIDAY...LARGE CANADIAN HIGH PRESSURE TO BRING COOL
AND DRY AIR INTO REGION WITH HIGHS UPPER 60S TO LOWER 70S AND LOWS
UPPER 40S TO LOWER 50S WITH LOWS FRIDAY AM POSSIBLY STILL AT LEAST
A CATEGORY LOWER SUGGESTED.

NICHOLS

&&

.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z SUNDAY MORNING)
ISSUED AT 626 AM CDT SAT MAY 18 2013

FRONTAL BOUNDARY RUNNING FROM NEAR KIND...TO KMLI...AND KMIW HAS
RESULTED IN MVFR/IFR CONDITIONS ALONG AND SOUTH OF THE FRONT.
CONDITIONS WILL IMPROVE TO VFR BY 18Z/18 AND REMAIN VFR THROUGH
06Z/19. AFT 06Z/19 THE POTENTIAL FOR NOCTURNAL SHRA/TSRA WILL BE
ON THE INCREASE ACROSS EASTERN IOWA WITH THE POTENTIAL FOR MVFR
CONDITIONS PRIOR TO SUNRISE.              ..08..

&&

.DVN WATCHES/WARNINGS/ADVISORIES...
IA...NONE.
IL...NONE.
MO...NONE.
&&

$$

SYNOPSIS...08
SHORT TERM...08
LONG TERM...NICHOLS
AVIATION...08

000
FXUS63 KDMX 181128
AFDDMX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE DES MOINES IA
628 AM CDT SAT MAY 18 2013

.SHORT TERM.../TODAY /...
ISSUED AT 352 AM CDT SAT MAY 18 2013

UPPER LEVEL RIDGING TO BUILD OVER THE STATE TODAY...WITH SOUTHERLY
FLOW AHEAD OF A DEVELOPING AREA OF SFC LOW PRESSURE ACROSS THE
WESTERN HIGH PLAINS OF SD/NE/CO. DRY CONDITIONS ARE EXPECTED ACROSS
THE CWA TODAY...HOWEVER PUSH OF MOISTURE ADVECTION COULD ALLOW FOR
SOME THUNDERSTORM DEVELOPMENT JUST TO THE WEST OF THE CWA BY LATE
AFTERNOON/EARLY EVENING. FOR NOW LOOKS LIKE ANY ACTIVITY WILL HOLD
OFF UNTIL AFTER 00Z ACROSS THE AREA...SO HAVE KEPT THE GRIDS DRY.
TEMPS ARE TRICKY TODAY...WITH CLOUD SHIELD INITIALLY OVER PORTIONS
OF THE CWA FROM ONGOING MCS ACTIVITY ACROSS CNTRL NE/SD/MN. DO
EXPECT SKIES TO CLEAR SOME THROUGH THE MORNING...WITH DECENT MIXING
ALLOWING TEMPS TO PUSH INTO THE 80S ACROSS THE CWA. COULD ALSO SEE
SOME BREEZY CONDITIONS AS STRONGER WINDS ALOFT MIX DOWN THROUGH THE
DAY.

.LONG TERM.../TONIGHT THROUGH FRIDAY/...
ISSUED AT 352 AM CDT SAT MAY 18 2013

SHORTWAVE WILL EJECT TOWARDS THE STATE TONIGHT WITH MID LEVEL QG
FORCING INCREASING. INSTABILITY WILL ALREADY BE IN PLACE WITH THE
ARRIVAL OF THE FORCING AND ANTICIPATE CONVECTION DEVELOPING/MOVING
INTO THE WEST AND SPREADING NORTHEAST WITH TIME. THIS CONVECTION
PERSIST INTO SUNDAY MORNING ACROSS A BROAD SWATH OF THE FORECAST
AREA BEFORE THE FORCING PASSES TO THE NORTHEAST. WILL LIKELY SEE
SOME BREAK IN THE ACTIVITY LATE SUNDAY MORNING INTO THE EARLY
AFTERNOON IN SUBSIDENCE BEHIND THIS INITIAL WAVE AND HAVE
DECREASED POPS EARLY IN THE AFTERNOON. HOWEVER...NEXT SHORTWAVE
WILL BE QUICKLY APPROACHING BY LATE AFTERNOON/EVENING WITH VERY
GOOD UPPER LEVEL DIVERGENCE. GOOD MID LEVEL LAPSE RATES MOVE INTO
THE STATE DURING THIS TIME AS SURFACE LOW MOVES INTO EASTERN
NEBRASKA. STILL SOME QUESTION AS TO RECOVERY BEHIND DEPARTING
CONVECTION DURING THE MORNING BUT THE SOUTHWEST SHOULD SEE THE
BEST CHANCE OF THIS OCCURRING BY LATE AFTERNOON. SPC HAS ALSO
HIGHLIGHTED THIS AREA WITH BEST POTENTIAL FOR SEVERE CONVECTION
DURING THE AFTERNOON AS BULK SHEAR WILL BE INCREASING WITH
APPROACHING MID LEVEL SPEED MAX AND LOW LEVEL HELICITY WILL ALSO
BE INCREASING AS SURFACE LOW MOVES INTO NEBRASKA. SOME CONCERN
WITH A WARM LAYER IN THE LOW LEVELS OF FORECAST SOUNDINGS THAT MAY
AT LEAST SLOW PARCEL ACCELERATION IN THE 0-3KM LAYER. OVERALL
STILL PLENTY UNCERTAINTY AS TO THE EVENTUAL EVOLUTION...BUT SEVERE
WEATHER WITH AT LEAST LARGE HAIL APPEARS A GOOD BET WITH THE
POSSIBILITY OF A FEW TORNADOES IN THE SOUTH LATE AFTERNOON/EVENING
TIMEFRAME.

THE THREAT OF CONVECTION WILL PERSIST INTO SUNDAY NIGHT...ALTHOUGH
DRY SLOT MOVING UP INTO THE STATE MAY BEGIN TO CUT OFF MORE
SIGNIFICANT PRECIPITATION WITH TIME. UPPER LOW WILL THEN SIT AND
SPIN NEAR IOWA THROUGH WEDNESDAY WITH ONGOING THREATS OF PCPN
DURING THIS TIME. MAY SEE THE POTENTIAL FOR MORE SEVERE WEATHER IN
THE SOUTHEAST ON MONDAY WITH OTHER CONVECTION ACROSS FAR NORTHERN
IOWA UNDERNEATH THE UPPER LOW. CHANCES OF SHOWERS/ISOLD THUNDER
WILL LINGER INTO TUESDAY/WEDNESDAY AS LOW SLOWLY MOVES THROUGH THE
STATE WITH QUIET WEATHER ARRIVING LATE IN THE WEEK.

&&

.AVIATION...18/12Z
ISSUED AT 628 AM CDT SAT MAY 18 2013

SOME LIGHT FOG AROUND MAY BRIEFLY DROP VSBYS INTO THE MVFR/IFR
CATEGORY FOR A FEW HOURS THIS MORNING AT THE EASTERN TAF SITES.
SOME MID LEVEL LOWER VFR CLOUDS TO MOVE IN THROUGHOUT THE
DAY...WITH SOUTHEASTERLY WINDS PICKING UP WITH MIXING TODAY AND
THEN DIMINISHING WITH SUNSET. CHANCE FOR THUNDERSTORMS LATE
TONIGHT...WITH BEST CHANCE AT KFOD AND KDSM. THEREFORE WENT WITH
VCSH FOR NOW UNTIL TIMING OF THUNDER CAN BE BETTER DETERMINED.

&&

.DMX WATCHES/WARNINGS/ADVISORIES...NONE.

&&

$$

SHORT TERM...BEERENDS
LONG TERM...COGIL
AVIATION...BEERENDS

000
FXUS63 KDMX 180852
AFDDMX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE DES MOINES IA
352 AM CDT SAT MAY 18 2013

.SHORT TERM.../TODAY /...
ISSUED AT 352 AM CDT SAT MAY 18 2013

UPPER LEVEL RIDGING TO BUILD OVER THE STATE TODAY...WITH SOUTHERLY
FLOW AHEAD OF A DEVELOPING AREA OF SFC LOW PRESSURE ACROSS THE
WESTERN HIGH PLAINS OF SD/NE/CO. DRY CONDITIONS ARE EXPECTED ACROSS
THE CWA TODAY...HOWEVER PUSH OF MOISTURE ADVECTION COULD ALLOW FOR
SOME THUNDERSTORM DEVELOPMENT JUST TO THE WEST OF THE CWA BY LATE
AFTERNOON/EARLY EVENING. FOR NOW LOOKS LIKE ANY ACTIVITY WILL HOLD
OFF UNTIL AFTER 00Z ACROSS THE AREA...SO HAVE KEPT THE GRIDS DRY.
TEMPS ARE TRICKY TODAY...WITH CLOUD SHIELD INITIALLY OVER PORTIONS
OF THE CWA FROM ONGOING MCS ACTIVITY ACROSS CNTRL NE/SD/MN. DO
EXPECT SKIES TO CLEAR SOME THROUGH THE MORNING...WITH DECENT MIXING
ALLOWING TEMPS TO PUSH INTO THE 80S ACROSS THE CWA. COULD ALSO SEE
SOME BREEZY CONDITIONS AS STRONGER WINDS ALOFT MIX DOWN THROUGH THE
DAY.

.LONG TERM.../TONIGHT THROUGH FRIDAY/...
ISSUED AT 352 AM CDT SAT MAY 18 2013

SHORTWAVE WILL EJECT TOWARDS THE STATE TONIGHT WITH MID LEVEL QG
FORCING INCREASING. INSTABILITY WILL ALREADY BE IN PLACE WITH THE
ARRIVAL OF THE FORCING AND ANTICIPATE CONVECTION DEVELOPING/MOVING
INTO THE WEST AND SPREADING NORTHEAST WITH TIME. THIS CONVECTION
PERSIST INTO SUNDAY MORNING ACROSS A BROAD SWATH OF THE FORECAST
AREA BEFORE THE FORCING PASSES TO THE NORTHEAST. WILL LIKELY SEE
SOME BREAK IN THE ACTIVITY LATE SUNDAY MORNING INTO THE EARLY
AFTERNOON IN SUBSIDENCE BEHIND THIS INITIAL WAVE AND HAVE
DECREASED POPS EARLY IN THE AFTERNOON. HOWEVER...NEXT SHORTWAVE
WILL BE QUICKLY APPROACHING BY LATE AFTERNOON/EVENING WITH VERY
GOOD UPPER LEVEL DIVERGENCE. GOOD MID LEVEL LAPSE RATES MOVE INTO
THE STATE DURING THIS TIME AS SURFACE LOW MOVES INTO EASTERN
NEBRASKA. STILL SOME QUESTION AS TO RECOVERY BEHIND DEPARTING
CONVECTION DURING THE MORNING BUT THE SOUTHWEST SHOULD SEE THE
BEST CHANCE OF THIS OCCURRING BY LATE AFTERNOON. SPC HAS ALSO
HIGHLIGHTED THIS AREA WITH BEST POTENTIAL FOR SEVERE CONVECTION
DURING THE AFTERNOON AS BULK SHEAR WILL BE INCREASING WITH
APPROACHING MID LEVEL SPEED MAX AND LOW LEVEL HELICITY WILL ALSO
BE INCREASING AS SURFACE LOW MOVES INTO NEBRASKA. SOME CONCERN
WITH A WARM LAYER IN THE LOW LEVELS OF FORECAST SOUNDINGS THAT MAY
AT LEAST SLOW PARCEL ACCELERATION IN THE 0-3KM LAYER. OVERALL
STILL PLENTY UNCERTAINTY AS TO THE EVENTUAL EVOLUTION...BUT SEVERE
WEATHER WITH AT LEAST LARGE HAIL APPEARS A GOOD BET WITH THE
POSSIBILITY OF A FEW TORNADOES IN THE SOUTH LATE AFTERNOON/EVENING
TIMEFRAME.

THE THREAT OF CONVECTION WILL PERSIST INTO SUNDAY NIGHT...ALTHOUGH
DRY SLOT MOVING UP INTO THE STATE MAY BEGIN TO CUT OFF MORE
SIGNIFICANT PRECIPITATION WITH TIME. UPPER LOW WILL THEN SIT AND
SPIN NEAR IOWA THROUGH WEDNESDAY WITH ONGOING THREATS OF PCPN
DURING THIS TIME. MAY SEE THE POTENTIAL FOR MORE SEVERE WEATHER IN
THE SOUTHEAST ON MONDAY WITH OTHER CONVECTION ACROSS FAR NORTHERN
IOWA UNDERNEATH THE UPPER LOW. CHANCES OF SHOWERS/ISOLD THUNDER
WILL LINGER INTO TUESDAY/WEDNESDAY AS LOW SLOWLY MOVES THROUGH THE
STATE WITH QUIET WEATHER ARRIVING LATE IN THE WEEK.

&&

.AVIATION...18/06Z
ISSUED AT 1240 PM CDT FRI MAY 17 2013

LOW LEVEL MOISTURE WORKING ITS WAY NORTHWARD WILL MOISTEN UP THE
ATMOSPHERE OVERNIGHT PRODUCING SOME MVFR CONDITIONS IN PATCHY
FOG...ESPECIALLY ALONG A BOUNDARY THAT EXISTS ALONG AND NORTH OF
HIGHWAY 20.  MID/HI LEVEL CLOUDS FROM A HUGE THUNDERSTORM COMPLEX TO
THE WEST WILL KEEP VFR CIGS OVER TAF LOCATIONS AND COULD KEEP FOG
LIMITED TO EASTERN LOCATIONS WHERE BETTER RADIATIONAL COOLING WILL
OCCUR DUE TO LESS CLOUD COVER.  AFTER 19/00Z AND ESPECIALLY AFTER
19/06Z THUNDERSTORMS WILL DEVELOP ACROSS THE MISSOURI RIVER VALLEY
AND DRIFT EAST OVERNIGHT.

&&

.DMX WATCHES/WARNINGS/ADVISORIES...NONE.

&&

$$

SHORT TERM...BEERENDS
LONG TERM...COGIL
AVIATION...FAB

000
FXUS63 KDVN 180818
AFDDVN

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE QUAD CITIES IA IL
318 AM CDT SAT MAY 18 2013

.SYNOPSIS...
ISSUED AT 245 AM CDT SAT MAY 18 2013

06Z SFC ANALYSIS HAS A MESO WAKE LOW NEAR KPHP WITH A MESO HIGH
NORTH OF KONL. NUMEROUS OUTFLOW BOUNDARIES WERE ACROSS THE DAKOTAS
FROM THE MCS. THE MAIN FRONTAL BOUNDARY RAN FROM CENTRAL OHIO...
ACROSS NORTHERN ILLINOIS...AND THEN INTO SOUTHWEST MINNESOTA. DEW
POINTS SOUTH OF THE FRONTAL BOUNDARY WERE MAINLY IN THE 60S. NORTH
OF THE FRONTAL BOUNDARY DEW POINTS WERE IN THE 40S AND 50S.

&&

.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 245 AM CDT SAT MAY 18 2013

QUIET AND DRY CONDITIONS WILL BE SEEN ACROSS THE AREA TODAY AS THE
UPPER RIDGE MOVES EAST FROM THE PLAINS. CLOUDS FROM THE NORTHERN
PLAINS MCS SHOULD INITIALLY PROVIDE FILTERED SUNSHINE BEFORE
BREAKING UP DURING THE DAY.

TONIGHT...QUIET AND DRY CONDITIONS WILL BE SEEN DURING THE EVENING
AS THE UPPER RIDGE MOVES INTO THE WESTERN GREAT LAKES. AFTER
MIDNIGHT THE MCS AND LIFT TOOLS SUGGEST ELEVATED SHRA WITH POSSIBLY
SOME THUNDER SHOULD BEGIN DEVELOPING ACROSS THE WESTERN CWFA AS THE
LLJ BEGINS TO VEER SLIGHTLY INTO EASTERN IOWA WITH BETTER WAA ALOFT
AND MOISTURE.

08

.LONG TERM...(SUNDAY THROUGH FRIDAY)
ISSUED AT 245 AM CDT SAT MAY 18 2013

LOWER END SEVERE WEATHER RISKS LATE SUNDAY AND AGAIN MONDAY THE
MAIN FORECAST ISSUES WITH DECENT RAINS LASTING INTO WEDNESDAY.

OVERVIEW...INITIALIZATION AND VERIFICATION ADEQUATE ON SYNOPTIC
SCALES BUT POOR ON BL MOISTURE AND ESPECIALLY CONVECTIVE EVENTS.
THIS IMPACTS FORECAST WITH CONCEPTUAL FORCING TOOLS WEIGHTED
TOWARD HI-RES ECMWF BEST WITH GFS SERIOUS CONVECTIVE FEEDBACK AND
NAM-WRF NOT MUCH BETTER. D_PROG_DT SUPPORTS USE OF MORE STABLE
HI-RES ECMWF ENTIRE PERIOD WITH INPUTS FROM GEM-RH AND UKMET.

SUNDAY...TRENDS OF JET SUPPORT LOWER END SEVERE RISK MAINLY IN
THE LATE PM INTO EVENING HOURS. JET AXIS AND FORCING ARE DELAYED AND
BETTER FOCUSED WELL SW OF AREA WITH LITTLE SURFACE BASED FORCING
NOTED AT THIS TIME. PROBABLE STORMS AND SHOWERS TO MOVE INTO AREA
LATE PM AND MORE LIKELY IN THE EVENING. SBCAPES AOA 2000+ J/KG
SUGGESTED AND WBZ OF ~11K AGL WITH 35-45KT LOW LEVEL JET OF A
CONVECTIVE SYSTEM OR LINE WITH SOME BOWING SEGMENTS. IF SURFACE
TEMPERATURES/DEWPOINTS ARE AOA 78/65 THEN SOME WINDS OF 60 TO
POSSIBLY NEAR 70 MPH MAY OCCUR. LIMITED SCL SHEAR NOTED TO
PRECLUDE TORNADIC THREAT ATTM. STORMS THAT CAN ENTRAIN MID/UPPER
DRY LEVEL AIR MAY PRODUCE SOME LARGE HAIL UP TO 1.5 INCHES BUT
THIS MAY NOT OCCUR IF MCS IS IN MATURE STAGES AS SUGGESTED. HIGHS
SUNDAY WITH PARTLY SUNNY SKIES 83-88F NW TO SE. SUNDAY NIGHT TO BE
MILD WITH 64-68F READINGS FOR MINS. RAIN AMOUNTS MOST AREAS TO BE
LIGHT TO MODERATE WITH ISOLATED HEAVY AMOUNTS WITH ANY TRAINING OF
STORMS WHICH ARE MARGINAL ATTM WITH FAST FLOW ATTM. `POPS HIGH
CHANCE TO LOWER END LIKELIES AROUND 60 PERCENT.

MONDAY...FRONT NEARBY WITH FAST UPPER FLOW SUPPORTS PM SCATTERED
REDEVELOPMENT WITH POTENTIALLY HIGHER RISK OF SEVERE WEATHER IN PM
HOURS THAN SUNDAY AND ANY FORCING. T/TD PROFILES A FEW DEGREES
LOWER THAN SUNDAY BUT MORE FAVORABLE SHEAR PROFILES FOR SEVERE
WITH STRAIGHT LINE WINDS OF 60-70+ MPH DUE TO GOOD MOMENTUM
TRANSFER AND EVEN ISOLATED TORNADO AS JET AXIS IMPINGES IN WITH
DECENT SCL SHEAR. HAIL OVER 1.75" POSSIBLE IF MID LEVELS ARE AS
DRY AS CURRENTLY SUGGESTED. POPS 40-50 DURING DAY AND LIKELIES
MONDAY NIGHT WITH ANOTHER MCS PROBABLY TO MOVE ACROSS AREA. SEVERE
RISK SHOULD WANE BY MID TO LATE EVENING HOURS. MAX TEMPS 78-83
WITH MINS OF 60-65. RAIN AMOUNTS MOSTLY LIGHT TO MODERATE WITH
ISOLATED HEAVY AMOUNTS AND GREATER RISK OF TRAINING OF STORMS WITH
PARALLEL FLOW.

TUESDAY INTO WEDNESDAY...SHOWERS AND ISOLATED STORMS LIKELY WITH
WAVE TO ROTATE NORTH FROM SOUTHERN PLAINS. THIS SHOULD BE A
WIDESPREAD RAIN EVENT OF MODERATE TO HEAVY TOTALS BASED ON UPPER
FORCING. TOTAL RAIN AMOUNTS OVER THE NEXT 96 HOURS SHOULD BE 1-3
INCHES OVER THE FORECAST AREA. HIGHS IN THE 70S BOTH DAYS WITH
WEDNESDAY A FEW DEGREES COOLER THAN WEDNESDAY AS UPPER LOW MOVES
OVERHEAD. MINS MID 50S TO LOWER 60S.

THURSDAY AND FRIDAY...LARGE CANADIAN HIGH PRESSURE TO BRING COOL
AND DRY AIR INTO REGION WITH HIGHS UPPER 60S TO LOWER 70S AND LOWS
UPPER 40S TO LOWER 50S WITH LOWS FRIDAY AM POSSIBLY STILL AT LEAST
A CATEGORY LOWER SUGGESTED.

NICHOLS


&&

.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z SATURDAY NIGHT)
ISSUED AT 245 AM CDT SAT MAY 18 2013

A FRONTAL BOUNDARY FROM ROUGHLY KGYY TO KCID IS CREATING MVFR VSBYS
AT KCID/KMLI. THESE LOWER VSBYS WILL CONTINUE THROUGH SUNRISE AND
MAY AFFECT KDBQ. CIGS ARE EXPECTED TO REMAIN VFR BUT RECENT
SATELLITE TRENDS SHOW SPOTTY MVFR CIGS DVLPG ACROSS IOWA AND
ILLINOIS. AFT 12Z/18 VFR CONDITIONS ARE EXPECTED THROUGH 06Z/19. AFT
06Z/19 VFR CONDITIONS SHOULD CONTINUE BUT THE THREAT OF NOCTURNAL
SHRA/TSRA WILL BE ON THE INCREASE ACROSS EASTERN IOWA.

08

&&

.DVN WATCHES/WARNINGS/ADVISORIES...
IA...NONE.
IL...NONE.
MO...NONE.
&&

$$

SYNOPSIS...08
SHORT TERM...08
LONG TERM...NICHOLS
AVIATION...08

000
FXUS63 KDMX 180448 AAB
AFDDMX

AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE DES MOINES IA
1146 PM CDT FRI MAY 17 2013

.UPDATED FOR 18/06Z AVIATION DISCUSSION...

.SHORT TERM.../TONIGHT/
ISSUED AT 354 PM CDT FRI MAY 17 2013

AREAS OF SHOWERS AND THUNDERSTORMS WHICH HAVE DEVELOPED ACROSS
PORTIONS OF NORTHERN CWA ALONG WEAK BOUNDARY WILL PERSIST THROUGH
THE EVENING HOURS...AS SYSTEM CONTINUES TO PUSH SLOWLY EASTWARD.
ANTICIPATE DEVELOPMENT TO TAPER OFF AFTER PEAK HEATING...BUT WILL
CONTINUE TO SEE ISOLATED THUNDERSTORMS. VERY LIMITED SHEAR WITH
STORMS...AND DO NOT ANTICIPATE SEVERE WEATHER...THOUGH A STORM MAY
BRIEFLY PRODUCE HAIL OR GUSTY WINDS. IN ADDITION...STORMS HAVE BEEN
EFFICIENT RAINFALL PRODUCERS...AND MAY SEE A RISK FOR FLASH FLOODING
ACROSS THE NORTH WERE SOILS ARE SATURATED...IF STORMS TRAIN OR MOVE
SLOWLY ACROSS THE REGION. WILL NOT PUT OUT A FLASH FLOOD WATCH GIVEN
THE ISOLATED NATURE OF STORMS. PRECIPITATION CHANCES WILL DIMINISH
THROUGH 06Z AS SYSTEM LIFTS NORTHEAST. OVERNIGHT LOWS AGAIN ARE
TRICKY WITH CLOUD COVER. HAVE DROPPED TEMPERATURES A FEW DEGREES
ACROSS THE NORTHEAST WHERE HIGH TEMPERATURES WERE COOLER WITH CLOUD
COVER. SOME STRONGER WAA BEGINS TO PUSH INTO THE WEST LATE IN THE
OVERNIGHT...AND MAY SEE SLIGHTLY WARMER TEMPERATURES THERE...HOWEVER
HAVE KEPT TEMPS BELOW GUIDANCE THERE.

.LONG TERM.../SATURDAY THROUGH FRIDAY/
ISSUED AT 354 PM CDT FRI MAY 17 2013

PRIMARY CONCERN REMAINS PRECIP TRENDS THROUGH THE
PERIOD...ESPECIALLY SUNDAY INTO MONDAY. THE WEEKEND WILL BEGIN
FAIRLY TRANQUIL HOWEVER WITH WARM AND HUMID WEATHER AS IA IS
INFLUENCED BY THE WARM SECTOR. THETA-E ADVECTION WILL SPREAD SW-
NE INTO SAT NIGHT HOWEVER INCREASING OUR CHANCES FOR
CONVECTION.,.WHICH LOOKS LIKE IT WILL LINGER INTO AT LEAST SUNDAY
MORNING. STEEP LAPSE RATES AND SOME FORM OF AN ELEVATED MIXED
LAYER EARLY MAY KEEP THE CONVECTION QUITE ELEVATED
INITIALLY...HOWEVER SOUNDINGS SHOW THE COLUMN MOISTENING TOWARD
DAYBREAK. MORE FAVORABLE CAPE/CIN PARCELS LOWER IN SOUNDINGS
LEADING TO CONVECTION POTENTIALLY BEING ROOTED LOWER INTO SUNDAY.
ESTIMATED EFFECTIVE SHEAR IS NOT GREAT AT THIS POINT...BUT WOULD
STILL BE SUFFICIENT FOR LOW END SEVERE THREAT CONSIDERING MUCAPES
APPROACHING 2000 J/KG AT TIMES.

THIS LEADS INTO LATER SUNDAY WHERE SOME QUESTIONS ABOUT SURFACE
BASED EVENT COMING TOGETHER STILL EXIST. THETA-E ADVECTION STILL
LINGERS INTO IA BY MIDDAY LEADING TO QUESTIONS RAISED YESTERDAY
REGARDING RECOVERY TIME BETWEEN ELEVATED CONVECTION AND PEAK HEATING
SURFACE BASED POTENTIAL. MODELS ARE STILL IN SOME DISAGREEMENT
WITH REGARD TO PLACEMENT OF SURFACE FEATURES AS WELL...ON BOTH THE
SYNOPTIC AND MESOSCALE. 12Z GFS AND ECMWF FAVOR A SURFACE LOW
BEING CENTERED OVER ERN NE...WHILE 12Z NAM SUGGESTS LOWER PRESSURE
FROM NE INTO MN ALONG INVERTED TROUGH. NAM ALSO SHOW FRONT
ENHANCED BY OUTFLOW ACROSS MO. THIS OUTFLOW FROM EARLIER
CONVECTION COULD VERY WELL AFFECT NORTHWARD EXTENT OF
THERMODYNAMIC RECOVERY AND WHERE LOCALIZED 0-1KM SHEAR AND TORNADO
THREAT IS ENHANCED. EVEN WITH THESE QUESTIONS IT STILL APPEARS
THAT CURRENT SPC DAY 3 OUTLOOK HAS FAVORED AREA IN PLACE WHICH IS
ON THE NOSE OF THE UPPER LEVEL JET AND POTENTIAL FOR BETTER DEEP
SHEAR. LOOKED AT SLU CIPS 12Z ANALOGS TO SEE IF THEY OFFERED ANY
INSIGHT...BUT 60HR FORECAST UTILIZES THE NAM AS A BASELINE WHICH
MAY BE TOO FAR NORTH WITH SURFACE FEATURES. 00Z GFS ANALOGS MAY BE
TOO FAR NORTH AS WELL...AS GFS HAS NOW TRENDED CLOSER TO PREVIOUS
ERN NE ECMWF SOLUTIONS.

SITUATION CHANGES SOMEWHAT MONDAY WITH LOWER DEWPOINTS DROPPING
INSTABILITY SOMEWHAT AS WELL. SOUNDINGS APPEAR WELL MIXED WITH
LITTLE CINH HOWEVER SO STILL EXPECT CONVECTION TO DEVELOP
DIURNALLY. DAMAGING WINDS POTENTIAL MAY BE SOMEWHAT HIGHER DUE TO
STRONGER MIXED LAYER WINDS AND BETTER DCAPES AS LOW LAYERS DRY OUT
SOMEWHAT. SYSTEM THEN OCCLUDES INTO TUE AND IS IN NO HURRY TO
DEPART. MID/LATE MAY SOLAR HEATING NEAR THIS UPPER LOW WILL KEEP
POTENTIAL FOR MAINLY DIURNALLY BASED CONVECTION IN THE FORECAST TO
SOME EXTENT UNTIL THU WHEN SYSTEM FINALLY OPENS UP AND EXITS.

&&

.AVIATION...18/06Z
ISSUED AT 1240 PM CDT FRI MAY 17 2013

LOW LEVEL MOISTURE WORKING ITS WAY NORTHWARD WILL MOISTEN UP THE
ATMOSPHERE OVERNIGHT PRODUCING SOME MVFR CONDITIONS IN PATCHY
FOG...ESPECIALLY ALONG A BOUNDARY THAT EXISTS ALONG AND NORTH OF
HIGHWAY 20.  MID/HI LEVEL CLOUDS FROM A HUGE THUNDERSTORM COMPLEX TO
THE WEST WILL KEEP VFR CIGS OVER TAF LOCATIONS AND COULD KEEP FOG
LIMITED TO EASTERN LOCATIONS WHERE BETTER RADIATIONAL COOLING WILL
OCCUR DUE TO LESS CLOUD COVER.  AFTER 19/00Z AND ESPECIALLY AFTER
19/06Z THUNDERSTORMS WILL DEVELOP ACROSS THE MISSOURI RIVER VALLEY
AND DRIFT EAST OVERNIGHT.

&&

.DMX WATCHES/WARNINGS/ADVISORIES...NONE.

&&

$$

SHORT TERM...AWB
LONG TERM...SMALL
AVIATION...FAB

000
FXUS63 KDVN 180431
AFDDVN

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE QUAD CITIES IA IL
1131 PM CDT FRI MAY 17 2013

.SYNOPSIS...
ISSUED AT 256 PM CDT FRI MAY 17 2013

500 MB ANALYSIS SHOWS WEAK RIDGING OVER THE CENTRAL US WITH A LOW
MOVING INTO THE OHIO VALLEY...AND A SHORT WAVE CROSSING IOWA.  AT
THE SURFACE LOW PRESSURE IS CENTERED OVER SE WY WITH A STATIONARY
FRONT EXTENDING ACROSS NORTHERN IOWA AND ILLINOIS.  BOUNDARY WAS
REINFORCED BY OUTFLOW FROM THUNDERSTORMS TO THE NORTH OVER MN AND
WI OVERNIGHT AND WARM SOUTHERLY WINDS TO ITS SOUTH. GULF IS WIDE
OPEN WITH DEW POINTS IN THE 60S IN THE WARM SECTOR.

&&

.SHORT TERM...(THIS EVENING THROUGH SATURDAY)
ISSUED AT 256 PM CDT FRI MAY 17 2013

ON THE RADAR THIS AFTERNOON...SCATTERED DIURNAL THUNDERSTORMS HAVE
DEVELOPED IN THE WARM SECTOR OVER NORTHERN ILLINOIS IN THE VICINITY
OF THE SURFACE BOUNDARY.  MEANWHILE...A SECOND AREA OF STORMS OVER
NORTH CENTRAL AND CENTRAL IOWA HAS DEVELOPED WITH THE SUPPORT OF THE
PASSING SHORT WAVE.  BOTH OF THESE AREAS ARE EXPECTED TO WEAKEN AND
DISSIPATE WITH LOSS OF DAYTIME HEATING AFTER 00Z. TONIGHT THE FRONT
IS PROGGED TO MOVE LITTLE...THEN PUSH NORTHWARD SATURDAY AND BEGIN
TO WASH OUT. WITH THE CWFA FIRMLY ENTRENCHED IN THE WARM SECTOR...
TEMPERATURES SATURDAY WILL RISE TO NEAR TODAYS HIGHS.

.LONG TERM...(SATURDAY NIGHT THROUGH FRIDAY)
ISSUED AT 256 PM CDT FRI MAY 17 2013

SUNDAY AFTERNOON AND EVENING CONTINUE TO LOOK ACTIVE ACROSS THE
PLAINS AND MID MISSISSIPPI VALLEY AS A NEGATIVELY TILTED TROF LIFTS
FROM THE SOUTHERN PLAINS INTO THE MID/UPPER MISSISSIPPI VALLEY BY
MONDAY MORNING.

PRIOR TO SUNDAYS EVENT...THE UPPER TROF WILL BE LOCATED OVER THE
ROCKIES WITH A SURFACE TROF/FRONT OVER THE CENTRAL AND NORTHERN
PLAINS.  MODELS SUGGEST AN MCS WILL DEVELOP OVER THE CENTRAL PLAINS
AHEAD OF THE SURFACE BOUNDARY IN RESPONSE TO THE LLJ STRENGTHENING
TO 40 TO 50KTS SATURDAY EVENING.  THE FAVORED AREA FOR MCS
DEVELOPMENT LOOKS TO BE EASTERN NE WITH THE COMPLEX LIFTING
NORTHEAST POSSIBLY BRUSHING THE NORTHWESTERN CWFA EARLY SUNDAY
MORNING.

FOR SUNDAY AND SUNDAY NIGHT MODELS ARE IN AGREEMENT THAT THE BEST
UPPER FORCING WILL LIFT NORTH THROUGH THE AREA SUNDAY EVENING. AT
THE SAME TIME A SURFACE LOW MOVES NORTH THROUGH EASTERN NE/WESTERN
IA DRAGGING THE WARM FRONT NORTH THROUGH THE AREA.  WITH THE
LOW/UPPER LEVEL FORCING PHASED  THE BIG QUESTION WILL BE THE AMOUNT
OF INSTABILITY THE SYSTEM HAS TO WORK WITH.  AT THIS POINT EXPECT
TEMPERATURES TO BE IN THE THE MID 80S OVER MOST OF THE AREA BY LATE
AFTERNOON WITH ANY DEBRIS CLOUDS FROM THE OVERNIGHT MCS MIXING OUT
EARLY IN THE DAY.  THE NAM/GFS LOOK TOO MOIST WITH THEIR LOW TO MID
70 SURFACE DEW POINTS SUNDAY AFTERNOON. THE ECMWF/S MID OR UPPER 60S
LOOK MORE REASONABLE.  THESE TEMPS/DEW POINTS SHOULD SUPPORT LATE
AFTERNOON/EARLY EVENING CAPES AROUND 2000J/KG OVER EASTERN IA.
GIVEN THE FORCING AND 30 TO 50 KTS DEEP LAYER SHEAR OVER THE
AREA...SEVERE STORMS STILL LOOK PROBABLE WITH HAIL AND DAMAGING WINDS
THE MAIN THREATS.  ISOLATED TORNADOES CAN/T BE RULED OUT ESPECIALLY
IN THE SOUTH DURING THE EVENING AS THE WARM FRONT MOVES THROUGH.
P/W/S WILL BE IN THE 1.5 TO 2.0 INCH RANGE SO ANY STRONG STORMS WILL
PRODUCE LOCALLY HEAVY RAINS.

THE UPPER TROF CLOSES OFF AND THE SYSTEM  OCCLUDES AND STALLS JUST
NORTH OF THE FORECAST AREA MONDAY THROUGH WEDNESDAY OR THURSDAY.
THIS WILL KEEP OF THREAT OF SHOWERS AND THUNDERSTORMS OVER THE
AREA...ALTHOUGH ORGANIZED STRONG OR SEVERE CONVECTION DOES NOT LOOK
LIKELY.  BY FRIDAY MODELS MOVE THE UPPER TROF EAST AS RIDGING BUILDS
OVER THE PLAINS AND A SURFACE HIGH MOVES INTO THE WESTERN GREAT
LAKES.  WITH THIS SYNOPTIC PATTERN COOL NORTHEAST WINDS OFF THE
LAKES COULD GET THE MEMORIAL DAY WEEKEND OFF TO A COOL...DRY START.

&&

.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z SATURDAY NIGHT)
ISSUED AT 1129 PM CDT FRI MAY 17 2013

SOUTHEASTERLY WINDS AROUND 5 TO 10 KTS WILL CONTINUE THROUGH
LATE SATURDAY EVENING...AS A WARM FRONT LIFTS INTO WISCONSIN. CONDITIONS
WILL BE VFR WITH CIGS ABOVE 12KFT PRIMARY. LATER TONIGHT...AFTER
08Z...SOME MVFR FOG IS EXPECTED.  AFTER 13Z SATURDAY...A RETURN
TO VFR WEATHER WITH PARTLY CLOUDY SKIES AND LIGHT SOUTHEAST WINDS.
THIS VFR WEATHER SHOULD PERSIST THROUGH THE REMAINDER OF THE
PERIOD. THERE WILL BE A THREAT FOR A SHOWER AFTER 06Z SUNDAY IN IOWA.
ERVIN

&&

.DVN WATCHES/WARNINGS/ADVISORIES...
IA...NONE.
IL...NONE.
MO...NONE.
&&

$$

SYNOPSIS...DMD
SHORT TERM...DMD
LONG TERM...DLF
AVIATION...ERVIN

000
FXUS63 KDMX 172346 AAA
AFDDMX

AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE DES MOINES IA
642 PM CDT FRI MAY 17 2013

.UPDATED FOR 18/00Z AVIATION DISCUSSION...

.SHORT TERM.../TONIGHT/
ISSUED AT 354 PM CDT FRI MAY 17 2013

AREAS OF SHOWERS AND THUNDERSTORMS WHICH HAVE DEVELOPED ACROSS
PORTIONS OF NORTHERN CWA ALONG WEAK BOUNDARY WILL PERSIST THROUGH
THE EVENING HOURS...AS SYSTEM CONTINUES TO PUSH SLOWLY EASTWARD.
ANTICIPATE DEVELOPMENT TO TAPER OFF AFTER PEAK HEATING...BUT WILL
CONTINUE TO SEE ISOLATED THUNDERSTORMS. VERY LIMITED SHEAR WITH
STORMS...AND DO NOT ANTICIPATE SEVERE WEATHER...THOUGH A STORM MAY
BRIEFLY PRODUCE HAIL OR GUSTY WINDS. IN ADDITION...STORMS HAVE BEEN
EFFICIENT RAINFALL PRODUCERS...AND MAY SEE A RISK FOR FLASH FLOODING
ACROSS THE NORTH WERE SOILS ARE SATURATED...IF STORMS TRAIN OR MOVE
SLOWLY ACROSS THE REGION. WILL NOT PUT OUT A FLASH FLOOD WATCH GIVEN
THE ISOLATED NATURE OF STORMS. PRECIPITATION CHANCES WILL DIMINISH
THROUGH 06Z AS SYSTEM LIFTS NORTHEAST. OVERNIGHT LOWS AGAIN ARE
TRICKY WITH CLOUD COVER. HAVE DROPPED TEMPERATURES A FEW DEGREES
ACROSS THE NORTHEAST WHERE HIGH TEMPERATURES WERE COOLER WITH CLOUD
COVER. SOME STRONGER WAA BEGINS TO PUSH INTO THE WEST LATE IN THE
OVERNIGHT...AND MAY SEE SLIGHTLY WARMER TEMPERATURES THERE...HOWEVER
HAVE KEPT TEMPS BELOW GUIDANCE THERE.

.LONG TERM.../SATURDAY THROUGH FRIDAY/
ISSUED AT 354 PM CDT FRI MAY 17 2013

PRIMARY CONCERN REMAINS PRECIP TRENDS THROUGH THE
PERIOD...ESPECIALLY SUNDAY INTO MONDAY. THE WEEKEND WILL BEGIN
FAIRLY TRANQUIL HOWEVER WITH WARM AND HUMID WEATHER AS IA IS
INFLUENCED BY THE WARM SECTOR. THETA-E ADVECTION WILL SPREAD SW-
NE INTO SAT NIGHT HOWEVER INCREASING OUR CHANCES FOR
CONVECTION.,.WHICH LOOKS LIKE IT WILL LINGER INTO AT LEAST SUNDAY
MORNING. STEEP LAPSE RATES AND SOME FORM OF AN ELEVATED MIXED
LAYER EARLY MAY KEEP THE CONVECTION QUITE ELEVATED
INITIALLY...HOWEVER SOUNDINGS SHOW THE COLUMN MOISTENING TOWARD
DAYBREAK. MORE FAVORABLE CAPE/CIN PARCELS LOWER IN SOUNDINGS
LEADING TO CONVECTION POTENTIALLY BEING ROOTED LOWER INTO SUNDAY.
ESTIMATED EFFECTIVE SHEAR IS NOT GREAT AT THIS POINT...BUT WOULD
STILL BE SUFFICIENT FOR LOW END SEVERE THREAT CONSIDERING MUCAPES
APPROACHING 2000 J/KG AT TIMES.

THIS LEADS INTO LATER SUNDAY WHERE SOME QUESTIONS ABOUT SURFACE
BASED EVENT COMING TOGETHER STILL EXIST. THETA-E ADVECTION STILL
LINGERS INTO IA BY MIDDAY LEADING TO QUESTIONS RAISED YESTERDAY
REGARDING RECOVERY TIME BETWEEN ELEVATED CONVECTION AND PEAK HEATING
SURFACE BASED POTENTIAL. MODELS ARE STILL IN SOME DISAGREEMENT
WITH REGARD TO PLACEMENT OF SURFACE FEATURES AS WELL...ON BOTH THE
SYNOPTIC AND MESOSCALE. 12Z GFS AND ECMWF FAVOR A SURFACE LOW
BEING CENTERED OVER ERN NE...WHILE 12Z NAM SUGGESTS LOWER PRESSURE
FROM NE INTO MN ALONG INVERTED TROUGH. NAM ALSO SHOW FRONT
ENHANCED BY OUTFLOW ACROSS MO. THIS OUTFLOW FROM EARLIER
CONVECTION COULD VERY WELL AFFECT NORTHWARD EXTENT OF
THERMODYNAMIC RECOVERY AND WHERE LOCALIZED 0-1KM SHEAR AND TORNADO
THREAT IS ENHANCED. EVEN WITH THESE QUESTIONS IT STILL APPEARS
THAT CURRENT SPC DAY 3 OUTLOOK HAS FAVORED AREA IN PLACE WHICH IS
ON THE NOSE OF THE UPPER LEVEL JET AND POTENTIAL FOR BETTER DEEP
SHEAR. LOOKED AT SLU CIPS 12Z ANALOGS TO SEE IF THEY OFFERED ANY
INSIGHT...BUT 60HR FORECAST UTILIZES THE NAM AS A BASELINE WHICH
MAY BE TOO FAR NORTH WITH SURFACE FEATURES. 00Z GFS ANALOGS MAY BE
TOO FAR NORTH AS WELL...AS GFS HAS NOW TRENDED CLOSER TO PREVIOUS
ERN NE ECMWF SOLUTIONS.

SITUATION CHANGES SOMEWHAT MONDAY WITH LOWER DEWPOINTS DROPPING
INSTABILITY SOMEWHAT AS WELL. SOUNDINGS APPEAR WELL MIXED WITH
LITTLE CINH HOWEVER SO STILL EXPECT CONVECTION TO DEVELOP
DIURNALLY. DAMAGING WINDS POTENTIAL MAY BE SOMEWHAT HIGHER DUE TO
STRONGER MIXED LAYER WINDS AND BETTER DCAPES AS LOW LAYERS DRY OUT
SOMEWHAT. SYSTEM THEN OCCLUDES INTO TUE AND IS IN NO HURRY TO
DEPART. MID/LATE MAY SOLAR HEATING NEAR THIS UPPER LOW WILL KEEP
POTENTIAL FOR MAINLY DIURNALLY BASED CONVECTION IN THE FORECAST TO
SOME EXTENT UNTIL THU WHEN SYSTEM FINALLY OPENS UP AND EXITS.

&&

.AVIATION...18/00Z
ISSUED AT 642 PM CDT FRI MAY 17 2013

A WEAK UPPER LEVEL DISTURBANCE RIDING ATOP A RIDGE OF HIGH PRESSURE
COMBINED WITH A WEAK SURFACE BOUNDARY HAS ALLOWED ISOLATED
THUNDERSTORMS TO DEVELOP OVER NORTH CENTRAL IOWA.  THESE ARE
EXPECTED TO DIMINISH BY 02-03Z.  SOUNDINGS INDICATED SOME LOW LEVEL
MOISTURE IN THE VICINITY OF A WARM FRONT WILL ALLOW FOR SOME FOG
DEVELOPMENT FROM ROUGHLY 09Z-13Z SO TAF SITES INCLUDE A PERIOD OF
MVFR CONDITIONS DURING THIS TIME.  THE REST OF THE FORECAST PERIOD
WILL BE VFR CONDITIONS WITH A S TO SE WIND AT 5-15KTS.

&&

.DMX WATCHES/WARNINGS/ADVISORIES...NONE.

&&

$$

SHORT TERM...AWB
LONG TERM...SMALL
AVIATION...FAB

000
FXUS63 KDVN 172308
AFDDVN

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE QUAD CITIES IA IL
608 PM CDT FRI MAY 17 2013

.SYNOPSIS...
ISSUED AT 256 PM CDT FRI MAY 17 2013

500 MB ANALYSIS SHOWS WEAK RIDGING OVER THE CENTRAL US WITH A LOW
MOVING INTO THE OHIO VALLEY...AND A SHORT WAVE CROSSING IOWA.  AT
THE SURFACE LOW PRESSURE IS CENTERED OVER SE WY WITH A STATIONARY
FRONT EXTENDING ACROSS NORTHERN IOWA AND ILLINOIS.  BOUNDARY WAS
REINFORCED BY OUTFLOW FROM THUNDERSTORMS TO THE NORTH OVER MN AND
WI OVERNIGHT AND WARM SOUTHERLY WINDS TO ITS SOUTH. GULF IS WIDE
OPEN WITH DEW POINTS IN THE 60S IN THE WARM SECTOR.

&&

.SHORT TERM...(THIS EVENING THROUGH SATURDAY)
ISSUED AT 256 PM CDT FRI MAY 17 2013

ON THE RADAR THIS AFTERNOON...SCATTERED DIURNAL THUNDERSTORMS HAVE
DEVELOPED IN THE WARM SECTOR OVER NORTHERN ILLINOIS IN THE VICINITY
OF THE SURFACE BOUNDARY.  MEANWHILE...A SECOND AREA OF STORMS OVER
NORTH CENTRAL AND CENTRAL IOWA HAS DEVELOPED WITH THE SUPPORT OF THE
PASSING SHORT WAVE.  BOTH OF THESE AREAS ARE EXPECTED TO WEAKEN AND
DISSIPATE WITH LOSS OF DAYTIME HEATING AFTER 00Z. TONIGHT THE FRONT
IS PROGGED TO MOVE LITTLE...THEN PUSH NORTHWARD SATURDAY AND BEGIN
TO WASH OUT. WITH THE CWFA FIRMLY ENTRENCHED IN THE WARM SECTOR...
TEMPERATURES SATURDAY WILL RISE TO NEAR TODAYS HIGHS.

.LONG TERM...(SATURDAY NIGHT THROUGH FRIDAY)
ISSUED AT 256 PM CDT FRI MAY 17 2013

SUNDAY AFTERNOON AND EVENING CONTINUE TO LOOK ACTIVE ACROSS THE
PLAINS AND MID MISSISSIPPI VALLEY AS A NEGATIVELY TILTED TROF LIFTS
FROM THE SOUTHERN PLAINS INTO THE MID/UPPER MISSISSIPPI VALLEY BY
MONDAY MORNING.

PRIOR TO SUNDAYS EVENT...THE UPPER TROF WILL BE LOCATED OVER THE
ROCKIES WITH A SURFACE TROF/FRONT OVER THE CENTRAL AND NORTHERN
PLAINS.  MODELS SUGGEST AN MCS WILL DEVELOP OVER THE CENTRAL PLAINS
AHEAD OF THE SURFACE BOUNDARY IN RESPONSE TO THE LLJ STRENGTHENING
TO 40 TO 50KTS SATURDAY EVENING.  THE FAVORED AREA FOR MCS
DEVELOPMENT LOOKS TO BE EASTERN NE WITH THE COMPLEX LIFTING
NORTHEAST POSSIBLY BRUSHING THE NORTHWESTERN CWFA EARLY SUNDAY
MORNING.

FOR SUNDAY AND SUNDAY NIGHT MODELS ARE IN AGREEMENT THAT THE BEST
UPPER FORCING WILL LIFT NORTH THROUGH THE AREA SUNDAY EVENING. AT
THE SAME TIME A SURFACE LOW MOVES NORTH THROUGH EASTERN NE/WESTERN
IA DRAGGING THE WARM FRONT NORTH THROUGH THE AREA.  WITH THE
LOW/UPPER LEVEL FORCING PHASED  THE BIG QUESTION WILL BE THE AMOUNT
OF INSTABILITY THE SYSTEM HAS TO WORK WITH.  AT THIS POINT EXPECT
TEMPERATURES TO BE IN THE THE MID 80S OVER MOST OF THE AREA BY LATE
AFTERNOON WITH ANY DEBRIS CLOUDS FROM THE OVERNIGHT MCS MIXING OUT
EARLY IN THE DAY.  THE NAM/GFS LOOK TOO MOIST WITH THEIR LOW TO MID
70 SURFACE DEW POINTS SUNDAY AFTERNOON. THE ECMWF/S MID OR UPPER 60S
LOOK MORE REASONABLE.  THESE TEMPS/DEW POINTS SHOULD SUPPORT LATE
AFTERNOON/EARLY EVENING CAPES AROUND 2000J/KG OVER EASTERN IA.
GIVEN THE FORCING AND 30 TO 50 KTS DEEP LAYER SHEAR OVER THE
AREA...SEVERE STORMS STILL LOOK PROBABLE WITH HAIL AND DAMAGING WINDS
THE MAIN THREATS.  ISOLATED TORNADOES CAN/T BE RULED OUT ESPECIALLY
IN THE SOUTH DURING THE EVENING AS THE WARM FRONT MOVES THROUGH.
P/W/S WILL BE IN THE 1.5 TO 2.0 INCH RANGE SO ANY STRONG STORMS WILL
PRODUCE LOCALLY HEAVY RAINS.

THE UPPER TROF CLOSES OFF AND THE SYSTEM  OCCLUDES AND STALLS JUST
NORTH OF THE FORECAST AREA MONDAY THROUGH WEDNESDAY OR THURSDAY.
THIS WILL KEEP OF THREAT OF SHOWERS AND THUNDERSTORMS OVER THE
AREA...ALTHOUGH ORGANIZED STRONG OR SEVERE CONVECTION DOES NOT LOOK
LIKELY.  BY FRIDAY MODELS MOVE THE UPPER TROF EAST AS RIDGING BUILDS
OVER THE PLAINS AND A SURFACE HIGH MOVES INTO THE WESTERN GREAT
LAKES.  WITH THIS SYNOPTIC PATTERN COOL NORTHEAST WINDS OFF THE
LAKES COULD GET THE MEMORIAL DAY WEEKEND OFF TO A COOL...DRY START.

&&

.AVIATION...(FOR THE 00Z TAFS THROUGH 00Z SATURDAY EVENING)
ISSUED AT 604 PM CDT FRI MAY 17 2013

SOUTHEASTERLY WINDS AROUND 5 TO 10 KTS WILL CONTINUE THROUGH
SATURDAY EVENING...AS A WARM FRONT LIFTS INTO WISCONSIN. AS THIS
OCCURS EARLY THIS EVENING...ANY REMAINING ISOLATED SHOWERS IN
ILLINOIS WILL DISSIPATE AND MOVE NORTH INTO WISCONSIN.
THEREFORE...CONDITIONS WILL BE VFR WITH CIGS ABOVE 12KFT PRIMARY.
LATER TONIGHT...AFTER 06Z...SOME MVFR FOG IS LIKELY AS WINDS
BECOME LIGHT UNDER A PERIOD OF MOSTLY CLEAR SKIES. THE STRATUS
THAT HAD BEEN INCLUDED IN PRIOR ISSUANCES HAS BEEN REMOVED AS IT
APPEARS MODELS ARE TOO MOIST IN A FORECAST OF MOISTURE LEVELS.
AFTER 13Z SATURDAY...A RETURN TO VFR WEATHER WITH PARTLY CLOUDY
SKIES AND LIGHT SOUTHEAST WINDS.
ERVIN

&&

.DVN WATCHES/WARNINGS/ADVISORIES...
IA...NONE.
IL...NONE.
MO...NONE.
&&

$$

SYNOPSIS...DMD
SHORT TERM...DMD
LONG TERM...DLF
AVIATION...ERVIN

000
FXUS63 KDMX 172059
AFDDMX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE DES MOINES IA
359 PM CDT FRI MAY 17 2013

.SHORT TERM.../TONIGHT/
ISSUED AT 354 PM CDT FRI MAY 17 2013

AREAS OF SHOWERS AND THUNDERSTORMS WHICH HAVE DEVELOPED ACROSS
PORTIONS OF NORTHERN CWA ALONG WEAK BOUNDARY WILL PERSIST THROUGH
THE EVENING HOURS...AS SYSTEM CONTINUES TO PUSH SLOWLY EASTWARD.
ANTICIPATE DEVELOPMENT TO TAPER OFF AFTER PEAK HEATING...BUT WILL
CONTINUE TO SEE ISOLATED THUNDERSTORMS. VERY LIMITED SHEAR WITH
STORMS...AND DO NOT ANTICIPATE SEVERE WEATHER...THOUGH A STORM MAY
BRIEFLY PRODUCE HAIL OR GUSTY WINDS. IN ADDITION...STORMS HAVE BEEN
EFFICIENT RAINFALL PRODUCERS...AND MAY SEE A RISK FOR FLASH FLOODING
ACROSS THE NORTH WERE SOILS ARE SATURATED...IF STORMS TRAIN OR MOVE
SLOWLY ACROSS THE REGION. WILL NOT PUT OUT A FLASH FLOOD WATCH GIVEN
THE ISOLATED NATURE OF STORMS. PRECIPITATION CHANCES WILL DIMINISH
THROUGH 06Z AS SYSTEM LIFTS NORTHEAST. OVERNIGHT LOWS AGAIN ARE
TRICKY WITH CLOUD COVER. HAVE DROPPED TEMPERATURES A FEW DEGREES
ACROSS THE NORTHEAST WHERE HIGH TEMPERATURES WERE COOLER WITH CLOUD
COVER. SOME STRONGER WAA BEGINS TO PUSH INTO THE WEST LATE IN THE
OVERNIGHT...AND MAY SEE SLIGHTLY WARMER TEMPERATURES THERE...HOWEVER
HAVE KEPT TEMPS BELOW GUIDANCE THERE.

.LONG TERM.../SATURDAY THROUGH FRIDAY/
ISSUED AT 354 PM CDT FRI MAY 17 2013

PRIMARY CONCERN REMAINS PRECIP TRENDS THROUGH THE
PERIOD...ESPECIALLY SUNDAY INTO MONDAY. THE WEEKEND WILL BEGIN
FAIRLY TRANQUIL HOWEVER WITH WARM AND HUMID WEATHER AS IA IS
INFLUENCED BY THE WARM SECTOR. THETA-E ADVECTION WILL SPREAD SW-
NE INTO SAT NIGHT HOWEVER INCREASING OUR CHANCES FOR
CONVECTION.,.WHICH LOOKS LIKE IT WILL LINGER INTO AT LEAST SUNDAY
MORNING. STEEP LAPSE RATES AND SOME FORM OF AN ELEVATED MIXED
LAYER EARLY MAY KEEP THE CONVECTION QUITE ELEVATED
INITIALLY...HOWEVER SOUNDINGS SHOW THE COLUMN MOISTENING TOWARD
DAYBREAK. MORE FAVORABLE CAPE/CIN PARCELS LOWER IN SOUNDINGS
LEADING TO CONVECTION POTENTIALLY BEING ROOTED LOWER INTO SUNDAY.
ESTIMATED EFFECTIVE SHEAR IS NOT GREAT AT THIS POINT...BUT WOULD
STILL BE SUFFICIENT FOR LOW END SEVERE THREAT CONSIDERING MUCAPES
APPROACHING 2000 J/KG AT TIMES.

THIS LEADS INTO LATER SUNDAY WHERE SOME QUESTIONS ABOUT SURFACE
BASED EVENT COMING TOGETHER STILL EXIST. THETA-E ADVECTION STILL
LINGERS INTO IA BY MIDDAY LEADING TO QUESTIONS RAISED YESTERDAY
REGARDING RECOVERY TIME BETWEEN ELEVATED CONVECTION AND PEAK HEATING
SURFACE BASED POTENTIAL. MODELS ARE STILL IN SOME DISAGREEMENT
WITH REGARD TO PLACEMENT OF SURFACE FEATURES AS WELL...ON BOTH THE
SYNOPTIC AND MESOSCALE. 12Z GFS AND ECMWF FAVOR A SURFACE LOW
BEING CENTERED OVER ERN NE...WHILE 12Z NAM SUGGESTS LOWER PRESSURE
FROM NE INTO MN ALONG INVERTED TROUGH. NAM ALSO SHOW FRONT
ENHANCED BY OUTLOW ACROSS MO. THIS OUTFLOW FROM EARLIER
CONVECTION COULD VERY WELL AFFECT NORTHWARD EXTENT OF
THERMODYNAMIC RECOVERY AND WHERE LOCALIZED 0-1KM SHEAR AND TORNADO
THREAT IS ENHANCED. EVEN WITH THESE QUESTIONS IT STILL APPEARS
THAT CURRENT SPC DAY 3 OUTLOOK HAS FAVORED AREA IN PLACE WHICH IS
ON THE NOSE OF THE UPPER LEVEL JET AND POTENTIAL FOR BETTER DEEP
SHEAR. LOOKED AT SLU CIPS 12Z ANALOGS TO SEE IF THEY OFFERED ANY
INSIGHT...BUT 60HR FORECAST UTILIZES THE NAM AS A BASELINE WHICH
MAY BE TOO FAR NORTH WITH SURFACE FEATURES. 00Z GFS ANALOGS MAY BE
TOO FAR NORTH AS WELL...AS GFS HAS NOW TRENDED CLOSER TO PREVIOUS
ERN NE ECMWF SOLUTIONS.

SITUATION CHANGES SOMEWHAT MONDAY WITH LOWER DEWPOINTS DROPPING
INSTABILITY SOMEWHAT AS WELL. SOUNDINGS APPEAR WELL MIXED WITH
LITTLE CINH HOWEVER SO STILL EXPECT CONVECTION TO DEVELOP
DIURNALLY. DAMAGING WINDS POTENTIAL MAY BE SOMEWHAT HIGHER DUE TO
STRONGER MIXED LAYER WINDS AND BETTER DCAPES AS LOW LAYERS DRY OUT
SOMEWHAT. SYSTEM THEN OCCLUDES INTO TUE AND IS IN NO HURRY TO
DEPART. MID/LATE MAY SOLAR HEATING NEAR THIS UPPER LOW WILL KEEP
POTENTIAL FOR MAINLY DIURNALLY BASED CONVECTION IN THE FORECAST TO
SOME EXTENT UNTIL THU WHEN SYSTEM FINALLY OPENS UP AND EXITS.

&&

.AVIATION...17/18Z
ISSUED AT 1217 PM CDT FRI MAY 17 2013

CEILINGS WILL REMAIN PRIMARILY VFR...WITH ISOLATED THUNDERSTORMS
BETWEEN18-00Z WHICH MAY BRING LOWER MVFR CEILINGS TO
SITES...ESPECIALLY NORTHERN SITES KFOD/KMCW/KDSM. HOWEVER...IMPACT
WILL BE BRIEF. HAVE INCLUDED MENTION OF VCTS...WITH ISOLATED
NATURE OF STORMS. CEILINGS WILL BE LIFTING AS SYSTEM PUSHES
FURTHER EAST WITH WINDS BECOMING MORE SOUTHERLY AND LIGHT
OVERNIGHT.


&&

.DMX WATCHES/WARNINGS/ADVISORIES...NONE.

&&

$$

SHORT TERM...AWB
LONG TERM...SMALL
AVIATION...AWB

000
FXUS63 KDVN 171958
AFDDVN

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE QUAD CITIES IA IL
258 PM CDT FRI MAY 17 2013

.SYNOPSIS...
ISSUED AT 256 PM CDT FRI MAY 17 2013

500 MB ANALYSIS SHOWS WEAK RIDGING OVER THE CENTRAL US WITH A LOW
MOVING INTO THE OHIO VALLEY...AND A SHORT WAVE CROSSING IOWA.  AT
THE SURFACE LOW PRESSURE IS CENTERED OVER SE WY WITH A STATIONARY
FRONT EXTENDING ACROSS NORTHERN IOWA AND ILLINOIS.  BOUNDARY WAS
REINFORCED BY OUTFLOW FROM THUNDERSTORMS TO THE NORTH OVER MN AND
WI OVERNIGHT AND WARM SOUTHERLY WINDS TO ITS SOUTH. GULF IS WIDE
OPEN WITH DEW POINTS IN THE 60S IN THE WARM SECTOR.

&&

.SHORT TERM...(THIS EVENING THROUGH SATURDAY)
ISSUED AT 256 PM CDT FRI MAY 17 2013

ON THE RADAR THIS AFTERNOON...SCATTERED DIURNAL THUNDERSTORMS HAVE
DEVELOPED IN THE WARM SECTOR OVER NORTHERN ILLINOIS IN THE VICINITY
OF THE SURFACE BOUNDARY.  MEANWHILE...A SECOND AREA OF STORMS OVER
NORTH CENTRAL AND CENTRAL IOWA HAS DEVELOPED WITH THE SUPPORT OF THE
PASSING SHORT WAVE.  BOTH OF THESE AREAS ARE EXPECTED TO WEAKEN AND
DISSIPATE WITH LOSS OF DAYTIME HEATING AFTER 00Z. TONIGHT THE FRONT
IS PROGGED TO MOVE LITTLE...THEN PUSH NORTHWARD SATURDAY AND BEGIN
TO WASH OUT. WITH THE CWFA FIRMLY ENTRENCHED IN THE WARM SECTOR...
TEMPERATURES SATURDAY WILL RISE TO NEAR TODAYS HIGHS.

.LONG TERM...(SATURDAY NIGHT THROUGH FRIDAY)
ISSUED AT 256 PM CDT FRI MAY 17 2013

SUNDAY AFTERNOON AND EVENING CONTINUE TO LOOK ACTIVE ACROSS THE
PLAINS AND MID MISSISSIPPI VALLEY AS A NEGATIVELY TILTED TROF LIFTS
FROM THE SOUTHERN PLAINS INTO THE MID/UPPER MISSISSIPPI VALLEY BY
MONDAY MORNING.

PRIOR TO SUNDAYS EVENT...THE UPPER TROF WILL BE LOCATED OVER THE
ROCKIES WITH A SURFACE TROF/FRONT OVER THE CENTRAL AND NORTHERN
PLAINS.  MODELS SUGGEST AN MCS WILL DEVELOP OVER THE CENTRAL PLAINS
AHEAD OF THE SURFACE BOUNDARY IN RESPONSE TO THE LLJ STRENGTHENING
TO 40 TO 50KTS SATURDAY EVENING.  THE FAVORED AREA FOR MCS
DEVELOPMENT LOOKS TO BE EASTERN NE WITH THE COMPLEX LIFTING
NORTHEAST POSSIBLY BRUSHING THE NORTHWESTERN CWFA EARLY SUNDAY
MORNING.

FOR SUNDAY AND SUNDAY NIGHT MODELS ARE IN AGREEMENT THAT THE BEST
UPPER FORCING WILL LIFT NORTH THROUGH THE AREA SUNDAY EVENING. AT
THE SAME TIME A SURFACE LOW MOVES NORTH THROUGH EASTERN NE/WESTERN
IA DRAGGING THE WARM FRONT NORTH THROUGH THE AREA.  WITH THE
LOW/UPPER LEVEL FORCING PHASED  THE BIG QUESTION WILL BE THE AMOUNT
OF INSTABILITY THE SYSTEM HAS TO WORK WITH.  AT THIS POINT EXPECT
TEMPERATURES TO BE IN THE THE MID 80S OVER MOST OF THE AREA BY LATE
AFTERNOON WITH ANY DEBRIS CLOUDS FROM THE OVERNIGHT MCS MIXING OUT
EARLY IN THE DAY.  THE NAM/GFS LOOK TOO MOIST WITH THEIR LOW TO MID
70 SURFACE DEW POINTS SUNDAY AFTERNOON. THE ECMWF/S MID OR UPPER 60S
LOOK MORE REASONABLE.  THESE TEMPS/DEW POINTS SHOULD SUPPORT LATE
AFTERNOON/EARLY EVENING CAPES AROUND 2000J/KG OVER EASTERN IA.
GIVEN THE FORCING AND 30 TO 50 KTS DEEP LAYER SHEAR OVER THE
AREA...SEVERE STORMS STILL LOOK PROBABLE WITH HAIL AND DAMAGING WINDS
THE MAIN THREATS.  ISOLATED TORNADOES CAN/T BE RULED OUT ESPECIALLY
IN THE SOUTH DURING THE EVENING AS THE WARM FRONT MOVES THROUGH.
P/W/S WILL BE IN THE 1.5 TO 2.0 INCH RANGE SO ANY STRONG STORMS WILL
PRODUCE LOCALLY HEAVY RAINS.

THE UPPER TROF CLOSES OFF AND THE SYSTEM  OCCLUDES AND STALLS JUST
NORTH OF THE FORECAST AREA MONDAY THROUGH WEDNESDAY OR THURSDAY.
THIS WILL KEEP OF THREAT OF SHOWERS AND THUNDERSTORMS OVER THE
AREA...ALTHOUGH ORGANIZED STRONG OR SEVERE CONVECTION DOES NOT LOOK
LIKELY.  BY FRIDAY MODELS MOVE THE UPPER TROF EAST AS RIDGING BUILDS
OVER THE PLAINS AND A SURFACE HIGH MOVES INTO THE WESTERN GREAT
LAKES.  WITH THIS SYNOPTIC PATTERN COOL NORTHEAST WINDS OFF THE
LAKES COULD GET THE MEMORIAL DAY WEEKEND OFF TO A COOL...DRY START.

&&

.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z SATURDAY AFTERNOON)
ISSUED AT 1214 PM CDT FRI MAY 17 2013

SCATTERED SHOWERS AND THUNDERSTORMS WILL DEVELOP THIS AFTERNOON...
PRODUCING ISOLATED HEAVY RAINFALL AND LOCAL MVFR CIGS AND VSBYS.
OUTSIDE OF THUNDERSTORMS...VFR CONDITIONS WILL CONTINUE THROUGH THE
EVENING. OVERNIGHT AREAS OF FOG AND IFR CIGS ARE EXPECTED TO SETTLE
ACROSS THE REGION...IMPROVING ONCE AGAIN TO VFR AFTER 14Z/18.

&&

.DVN WATCHES/WARNINGS/ADVISORIES...
IA...NONE.
IL...NONE.
MO...NONE.
&&

$$

SYNOPSIS...DMD
SHORT TERM...DMD
LONG TERM...DLF
AVIATION...DMD

000
FXUS63 KDVN 171730
AFDDVN

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE QUAD CITIES IA IL
1230 PM CDT FRI MAY 17 2013

.UPDATE...
ISSUED AT 649 AM CDT FRI MAY 17 2013

THE NOCTURNAL MCS WILL CONTINUE MOVING EAST FROM MN INTO WI THIS
MORNING BEFORE SLOWLY DISSIPATING. BOUNDARIES LEFT OVER FROM THAT
CONVECTION WILL BE THE PRIMARY FOCUS FOR DIURNAL CONVECTION TODAY.

MCS AND LIFT TOOLS PER RAP TRENDS SHOW THE THETA E GRADIENT AND
ASSOCIATED CONVERGENCE/LIFT IS JUST NORTH OF THE AREA. THUS DRY
CONDITIONS ARE EXPECTED THROUGH MID DAY ACROSS THE AREA. THE
CURRENT FCST HAS CONVECTION DEVELOPING IN THE AFTERNOON BUT IT IS
DEPENDENT ON WHEN CONVECTIVE TEMPERATURE IS ACHIEVED. IF THE RAP IS
CORRECT WE WOULD REMAIN BELOW CONVECTIVE TEMPERATURE. HOWEVER...
THE RAP TRENDS DO SHOW AREAS OF CONVERGENCE DEVELOPING DURING THE
AFTERNOON ALONG WITH WEAK THETA E GRADIENTS.

SO...ISOLATED TO SCATTERED CONVECTION IS EXPECTED THIS AFTERNOON
WITH THE NORTH THIRD MORE FAVORED DUE TO THE PROXIMITY OF THE
FRONTAL BOUNDARY. STORMS WILL BE SLOW MOVING DUE TO THE UPPER
RIDGE SO ANY THUNDERSTORM THAT DEVELOPS WILL HAVE THE POTENTIAL TO
PRODUCE VERY LOCALIZED HEAVY RAINFALL OF AN INCH OR MORE.  ..08..

&&

.SYNOPSIS...
ISSUED AT 229 AM CDT FRI MAY 17 2013

06Z SFC ANALYSIS HAS A WEAK LOW IN WESTERN IOWA JUST EAST OF KSUX
AND ANOTHER IN SOUTHERN SOUTH DAKOTA. AN EAST/WEST FRONTAL BOUNDARY
RAN FROM NORTHERN OHIO...THROUGH CENTRAL INDIANA...AND TO THE LOW
NEAR KSUX. FLOW OFF LAKE MICHIGAN HAD DEW POINTS RANGING FROM THE
UPPER 30S NORTH OF THE FRONT TO 50S AND LOW 60S SOUTH OF THE FRONT.

&&

.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 229 AM CDT FRI MAY 17 2013

THE CURRENT CONVECTION ON RADAR IS OCCURRING ALONG A THETA E
GRADIENT AND MOISTURE/TEMPERATURE GRADIENTS FROM THE 850MB FRONT.
MOST OF THE AREA WILL REMAIN DRY THROUGH SUNRISE EXCEPT FOR VERY
ISOLATED CONVECTION IN THE HWY 20 CORRIDOR.

THE MORNING HOURS ARE EXPECTED TO BE MAINLY DRY WITH PASSING CLOUDS
AS THE THETA E GRADIENT MOVES NORTH INTO WISCONSIN. DIFFERENTIAL
HEATING COMBINED WITH AN APPROACHING VORT MAX SHOULD RESULT IN
ISOLATED TO SCATTERED CONVECTION DEVELOPING BY LATE MORNING IN THE
EASTERN CWFA.

DURING THE AFTERNOON HOURS...ISOLATED TO SCATTERED CONVECTION WILL
EXPAND TO MOST OF THE CWFA AS CONVECTIVE TEMPERATURES ARE REACHED.

THE PROXIMITY OF THE UPPER RIDGE MEANS THAT STEERING CURRENTS FOR
THE CONVECTION ARE VERY WEAK. THUS THOSE AREAS THAT DO SEE RAIN THIS
AFTERNOON WILL HAVE THE POTENTIAL TO SEE LOCALLY HEAVY RAINFALL.

CONVECTION WILL SLOWLY DIMINISH WITH SUNSET BUT ISOLATED TO
SCATTERED CONVECTION IS EXPECTED TO CONTINUE INTO THE EVENING OVER
ROUGHLY THE NORTHEAST HALF OF THE CWFA. BY LATE EVENING MAINLY DRY
CONDITIONS ARE EXPECTED WITH LITTLE IF ANY CONVECTION AFTER
MIDNIGHT.

08

.LONG TERM...(SATURDAY THROUGH THURSDAY)
ISSUED AT 229 AM CDT FRI MAY 17 2013

MAIN CHALLENGE IS THE PROBABLE SEVERE WEATHER RISKS SUN/MON.

OVERVIEW...INITIALIZATION AND VERIFICATION FAIR WITH ALL SOLUTIONS
HAVING DIFFICULTY WITH ONGOING CENTRAL IOWA MCS EVENT. COUPLED
WITH BL DEWPOINT ISSUES SUGGEST AGAIN USE OF CONCEPTUAL
PRECIPITATION EVOLUTION TOOLS DERIVED FROM THE FORCING OF A BLEND
OF GEM-NH /HI-RES ECMWF/GFS. THIS SUPPORTS A DECENT RISK OF SEVERE
STORMS SUN/MON WITH PHASING AND CONVECTIVE ISSUES THAT SHOULD
BETTER CLARIFIED IN THE NEXT 24 HOURS. HIGHER END SEVERE STORM
EVENTS FOR REGION APPEAR MARGINAL ATTM FOR THE AREA WITH LOW/MODERATE
SEVERE EVENTS SUGGESTED ATTM.

SATURDAY...MINOR CHANGES WITH AREA LIKELY PARTLY SUNNY AND DRY AHEAD
OF SEASONABLY STRONG UPPER LEVEL SYSTEM MOVING INTO WEST CENTRAL
PLAINS. WARM AND A BIT HUMID WITH HIGHS IN THE LOWER 80S AND LOWS
MOSTLY IN THE LOWER 60S WITH DEWPOINTS 60-64F. SOME PATCHY FOG
POSSIBLE WITH ANY CLEARING FOR LATER SHIFTS TO CONSIDER.

SUNDAY AND MONDAY. GOOD SHEAR AND AT LEAST MODERATE INSTABILITY
SUPPORT ONE OR MORE CONVECTIVE EVENTS SUGGESTED WITH ENVIRONMENT
MOSTLY FAVORABLE FOR CONVECTIVE BOWING SEGMENTS ATTM. SEVERE
WEATHER AREAL TOOL AND BLEP/HELP ALGORITHMS SUGGEST WITH T/TDS
AOA 83/63 OF 60-70 MPH STRAIGHT LINE WINDS AND SOME HAIL THAT
COULD APPROACH 1.75 INCHES WITH WBZ OF ~11K AGL AND SBCAPE OF
2000-3000 J/KG. IF ANY WAVE FORMS IN LATE PM/EVENING THERE IS A
RISK OF ISOLATED TORNADOES BUT THIS APPEARS MARGINAL DUE TO
CURRENT JET STRUCTURE AND TIMING. HIGHS SUGGESTED BASED ON PARTLY
SUNNY SKIES SHOULD BE IN THE LOWER/MIDDLE 80S AND MINS MOSTLY IN
THE MIDDLE 60S. PW/S OF 1.25+ INCHES DO SUPPORT LOCALLY HEAVY
RAINFALL WITH ANY TRAINING OF STORMS. POPS IN THE LIKELY CATEGORY TO THE
MID/HIGH CHANCE WITH TIMING MAIN ISSUE. LOCAL FORCING AND HEAVY
RAIN TECHNIQUES DO SUPPORT MOST AREAS TO PICK UP AN INCH OR MORE
OF RAIN WITH PASSAGE OF UPPER LEVEL SYSTEM OVER NEXT 96+ HOURS.

TUESDAY...A CHALLENGE WITH WAVE BASED ON CONVECTION FIRING OVER
SOUTHERN PLAINS THE KEY ISSUE. JET STRUCTURE SUPPORTS DECENT RAIN
EVENT WITH LOTS OF CLOUDS AND THIS WOULD IMPACT HIGH TEMPERATURES
FOR LATER SHIFTS THAT MAY NEED LOWERING OVER CENTRAL AND SE SECTIONS.
POPS MAY NEED RAISING AS WELL BY 10-20 PERCENT WITH MODERATE TO
LOW END HEAVY AMOUNTS SUGGESTED. CONVECTIVE FEEDBACK QUESTION
SHOULD BE CLARIFIED MORE IN THE NEXT 24-36 HOURS. TUESDAY
NIGHT...UPPER LOW MOVES INTO AREA WITH CHANCE OF LOW TOP CONVECTION
OF SHOWERS AND BRIEF THUNDERSTORMS. MINS OF 55-60F WITH TEMPS
POSSIBLY A BIT TOO COOL IN FAR SE SECTIONS WITH CLOUDS.

WEDNESDAY AND THURSDAY...UPPER LOW TO SLIDE SLOWLY EAST WITH CHANCE
SHOWERS AND POSSIBLY ISOLATED THUNDER WITH PARTLY TO MOSTLY CLOUDY
SKIES. HIGH TEMPERATURES 67-77F SUGGESTED.  LOWS IN THE 50S WED AM
AND MID/UPPER 40S TO LOWER 50S SE SECTIONS THU AM. SEASONABLY STRONG
CANADIAN HIGH PRESSURE TO THEN DOMINATE AND KEEP AREA COOL WITH LOW
DEWPOINTS AND BELOW NORMAL INTO NEXT WEEKEND.

NICHOLS

&&

.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z SATURDAY AFTERNOON)
ISSUED AT 1214 PM CDT FRI MAY 17 2013

SCATTERED SHOWERS AND THUNDERSTORMS WILL DEVELOP THIS AFTERNOON...
PRODUCING ISOLATED HEAVY RAINFALL AND LOCAL MVFR CIGS AND VSBYS.
OUTSIDE OF THUNDERSTORMS...VFR CONDITIONS WILL CONTINUE THROUGH THE
EVENING. OVERNIGHT AREAS OF FOG AND IFR CIGS ARE EXPECTED TO SETTLE
ACROSS THE REGION...IMPROVING ONCE AGAIN TO VFR AFTER 14Z/18.

&&

.DVN WATCHES/WARNINGS/ADVISORIES...
IA...NONE.
IL...NONE.
MO...NONE.
&&

$$

UPDATE...08
SYNOPSIS...08
SHORT TERM...08
LONG TERM...NICHOLS
AVIATION...DMD

000
FXUS63 KDMX 171723
AFDDMX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE DES MOINES IA
1223 PM CDT FRI MAY 17 2013

.UPDATE...
ISSUED AT 1217 PM CDT FRI MAY 17 2013

AREAS OF ISOLATED THUNDERSTORMS HAVE DEVELOPED ALONG A WEAK
BOUNDARY...LIKELY REMNANT FROM OVERNIGHT/EARLY MORNING CONVECTION
ACROSS WESTERN PORTIONS OF THE CWA. HAVE UPDATED FORECAST TO
ACCOUNT FOR THESE THUNDERSTORMS...AS THEY ARE LIKELY TO CONTINUE
THROUGHOUT THE DAY...WITH LITTLE INHIBITION TO SUPPRESS
DEVELOPMENT. IN ADDITION...ANTICIPATE AN EASTWARD PUSH OF
DEVELOPMENT AND HAVE INCLUDED ISOLATED MENTION FURTHER EAST.

&&

.SHORT TERM.../TODAY /...
ISSUED AT 400 AM CDT FRI MAY 17 2013

CONVECTION ONGOING ACROSS THE NORTH ON THE NOSE OF 850MB THETA-E
ADVECTION IN ADVANCE OF A WEAKENING SHORTWAVE TROUGH LIFTING THROUGH
THE WEAK UPPER LEVEL RIDGE. OVERALL WEAK SHEAR AND OK
INSTABILITY...SO SEVERE THREAT IS LIMITED. HOWEVER DUAL-POL ANALYSIS
CONTINUES TO INDICATE SOME SMALL HAIL WITHIN THE STRONGER STORMS AND
MAIN THREAT OF STORMS TO BE HEAVY RAIN ESPECIALLY WITH CELLS NOW
TRAINING SOME WITH EASTERLY MOVEMENT. EXPECT CHANCE FOR PRECIP TO
CONTINUE LINGER INTO THE MORNING ACROSS THE NORTHERN CWA...WITH
FORCING WEAKENING TOWARD LATE MORNING INTO THE AFTERNOON HOURS.
ENERGY ROTATING AROUND A WEAK UPPER LEVEL SYSTEM MOVING THROUGH
MISSOURI. MAY SEE SOME SHOWER/THUNDERSTORM DEVELOPMENT WITH THIS
SYSTEM TOWARD THIS AFTERNOON...WITH STORMS LIFTING NORTHWARD INTO
THE FAR SOUTHEASTERN CWA. OVERALL THOUGH BEST CHANCES FOR PRECIP
TODAY...WILL BE WITH THE LINGERING CONVECTION THIS MORNING. AIR MASS
ALOFT AGAIN SIMILAR TO PREVIOUS DAYS...SO STICK NEAR PERSISTENCE
WITH MAX TEMPS EXCEPT KEPT THE NORTH A BIT COOLER WITH CLOUDS/PRECIP
CHANCES.

.LONG TERM.../TONIGHT THROUGH THURSDAY/...
ISSUED AT 400 AM CDT FRI MAY 17 2013

UPPER LEVEL RIDGE BUILDING INTO THE CENTRAL PLAINS WILL BRING AN
END TO PRECIPITATION CHANCES TONIGHT INTO SATURDAY AS THE WARM
SECTOR SPREADS ACROSS THE STATE. THE RIDGE WILL SHIFT EAST
SATURDAY NIGHT AS A VIGOROUS UPPER LEVEL SYSTEM DIVES INTO THE
NORTHERN HIGH PLAINS. THIS WILL CREATE AN ACTIVE SOUTHWEST FLOW
ACROSS THE STATE. STRONG MOISTURE TRANSPORT WILL LIFT INTO
SOUTHWEST IOWA AS THE LOW LEVEL JET INCREASES ACROSS EASTERN
KANSAS AND POINTS INTO THE STATE. A GOOD ELEVATED MIXED LAYER WILL
BE IN PLACE WITH A FAIR AMOUNT OF DRY AIR TO OVERCOME AND THIS
MAY LIMIT OVERALL COVERAGE BUT STILL SOME STORMS SHOULD DEVELOP
AND WILL BRING THE THREAT FOR LARGE HAIL AND HEAVY RAIN GIVEN
INCREASING PWATS TO 1.5 INCHES AND STORM MOVEMENT AT 25 TO 30 KTS
TO THE NORTHEAST.

THE BEST SEVERE WEATHER THREAT THROUGH THE PERIOD WILL BE ON
SUNDAY AS A STRONG UPPER WAVE ROTATES AROUND THE DEVELOPING CLOSED
LOW TO THE WEST. THE GREATEST THREAT WILL BE DURING THE AFTERNOON
AND EVENING. THE SURFACE LOW IS EXPECTED TO BE OVER EASTERN
NEBRASKA TO FAR WEST CENTRAL IOWA WITH THE WARM FRONT EXTENDING
INTO SOUTHERN OR CENTRAL IOWA. CONDITIONS CONTINUE TO LOOK
FAVORABLE FOR SUPERCELLULAR DEVELOPMENT WITH VERY LARGE HAIL
EXPECTED. TORNADO THREAT STILL LOOKS FAVORABLE ACROSS THE
SOUTHWEST HALF WITH INCREASING CONFIDENCE THAT THE SFC WINDS WILL
BACK LEADING TO INCREASED LOW LEVEL SHEAR. THE MID LEVEL FLOW IS
NOT REAL STRONG AND COULD BE A LIMITING FACTOR HOWEVER LATEST
FORECAST MODELS SOUNDINGS SUGGEST LCLS WILL BE LOWER THAN
PREVIOUSLY EXPECTED. HEAVY RAIN WILL REMAIN A THREAT WITH PWATS UP
TO 1.75 INCHES AND RIGHT MOVER SUPERCELL MOTIONS OF 20 TO 30 KTS.
COULD CERTAINLY DEVELOP INTO A VOLATILE SITUATION.

THE DRY SLOT WILL THEN LIFT SOUTHWEST TO NORTHEAST SUNDAY NIGHT
AND INTO A PORTION OF MONDAY. A FEW SEVERE STORMS ARE POSSIBLE
YET MONDAY BY THE PRIMARY SHOW WILL BE SUNDAY. THE UPPER LOW WILL
SLOWLY FILL AND ROTATE THROUGH THE AREA THROUGH MID WEEK AND WILL
KEEP PRECIPITATION CHANCES IN THE FORECAST. UPPER RIDGE FINALLY
SHIFTS INTO THE REGION TOWARD THE END OF THE PERIOD AND BRING
DRIER WEATHER AND WARMER TEMPERATURES.

&&

.AVIATION...17/18Z
 ISSUED AT 1217 PM CDT FRI MAY 17 2013

CEILINGS WILL REMAIN PRIMARILY VFR...WITH ISOLATED THUNDERSTORMS
BETWEEN18-00Z WHICH MAY BRING LOWER MVFR CEILINGS TO
SITES...ESPECIALLY NORTHERN SITES KFOD/KMCW/KDSM. HOWEVER...IMPACT
WILL BE BRIEF. HAVE INCLUDED MENTION OF VCTS...WITH ISOLATED
NATURE OF STORMS. CEILINGS WILL BE LIFTING AS SYSTEM PUSHES
FURTHER EAST WITH WINDS BECOMING MORE SOUTHERLY AND LIGHT
OVERNIGHT.

&&

.DMX WATCHES/WARNINGS/ADVISORIES...NONE.

&&

$$

UPDATE...AWB
SHORT TERM...BEERENDS
LONG TERM...DONAVON
AVIATION...AWB

000
FXUS63 KDVN 171201
AFDDVN

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE QUAD CITIES IA IL
701 AM CDT FRI MAY 17 2013

.UPDATE...
ISSUED AT 649 AM CDT FRI MAY 17 2013

THE NOCTURNAL MCS WILL CONTINUE MOVING EAST FROM MN INTO WI THIS
MORNING BEFORE SLOWLY DISSIPATING. BOUNDARIES LEFT OVER FROM THAT
CONVECTION WILL BE THE PRIMARY FOCUS FOR DIURNAL CONVECTION TODAY.

MCS AND LIFT TOOLS PER RAP TRENDS SHOW THE THETA E GRADIENT AND
ASSOCIATED CONVERGENCE/LIFT IS JUST NORTH OF THE AREA. THUS DRY
CONDITIONS ARE EXPECTED THROUGH MID DAY ACROSS THE AREA. THE
CURRENT FCST HAS CONVECTION DEVELOPING IN THE AFTERNOON BUT IT IS
DEPENDENT ON WHEN CONVECTIVE TEMPERATURE IS ACHIEVED. IF THE RAP IS
CORRECT WE WOULD REMAIN BELOW CONVECTIVE TEMPERATURE. HOWEVER...
THE RAP TRENDS DO SHOW AREAS OF CONVERGENCE DEVELOPING DURING THE
AFTERNOON ALONG WITH WEAK THETA E GRADIENTS.

SO...ISOLATED TO SCATTERED CONVECTION IS EXPECTED THIS AFTERNOON
WITH THE NORTH THIRD MORE FAVORED DUE TO THE PROXIMITY OF THE
FRONTAL BOUNDARY. STORMS WILL BE SLOW MOVING DUE TO THE UPPER
RIDGE SO ANY THUNDERSTORM THAT DEVELOPS WILL HAVE THE POTENTIAL TO
PRODUCE VERY LOCALIZED HEAVY RAINFALL OF AN INCH OR MORE.  ..08..

&&

.SYNOPSIS...
ISSUED AT 229 AM CDT FRI MAY 17 2013

06Z SFC ANALYSIS HAS A WEAK LOW IN WESTERN IOWA JUST EAST OF KSUX
AND ANOTHER IN SOUTHERN SOUTH DAKOTA. AN EAST/WEST FRONTAL BOUNDARY
RAN FROM NORTHERN OHIO...THROUGH CENTRAL INDIANA...AND TO THE LOW
NEAR KSUX. FLOW OFF LAKE MICHIGAN HAD DEW POINTS RANGING FROM THE
UPPER 30S NORTH OF THE FRONT TO 50S AND LOW 60S SOUTH OF THE FRONT.

&&

.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 229 AM CDT FRI MAY 17 2013

THE CURRENT CONVECTION ON RADAR IS OCCURRING ALONG A THETA E
GRADIENT AND MOISTURE/TEMPERATURE GRADIENTS FROM THE 850MB FRONT.
MOST OF THE AREA WILL REMAIN DRY THROUGH SUNRISE EXCEPT FOR VERY
ISOLATED CONVECTION IN THE HWY 20 CORRIDOR.

THE MORNING HOURS ARE EXPECTED TO BE MAINLY DRY WITH PASSING CLOUDS
AS THE THETA E GRADIENT MOVES NORTH INTO WISCONSIN. DIFFERENTIAL
HEATING COMBINED WITH AN APPROACHING VORT MAX SHOULD RESULT IN
ISOLATED TO SCATTERED CONVECTION DEVELOPING BY LATE MORNING IN THE
EASTERN CWFA.

DURING THE AFTERNOON HOURS...ISOLATED TO SCATTERED CONVECTION WILL
EXPAND TO MOST OF THE CWFA AS CONVECTIVE TEMPERATURES ARE REACHED.

THE PROXIMITY OF THE UPPER RIDGE MEANS THAT STEERING CURRENTS FOR
THE CONVECTION ARE VERY WEAK. THUS THOSE AREAS THAT DO SEE RAIN THIS
AFTERNOON WILL HAVE THE POTENTIAL TO SEE LOCALLY HEAVY RAINFALL.

CONVECTION WILL SLOWLY DIMINISH WITH SUNSET BUT ISOLATED TO
SCATTERED CONVECTION IS EXPECTED TO CONTINUE INTO THE EVENING OVER
ROUGHLY THE NORTHEAST HALF OF THE CWFA. BY LATE EVENING MAINLY DRY
CONDITIONS ARE EXPECTED WITH LITTLE IF ANY CONVECTION AFTER
MIDNIGHT.

08

.LONG TERM...(SATURDAY THROUGH THURSDAY)
ISSUED AT 229 AM CDT FRI MAY 17 2013

MAIN CHALLENGE IS THE PROBABLE SEVERE WEATHER RISKS SUN/MON.

OVERVIEW...INITIALIZATION AND VERIFICATION FAIR WITH ALL SOLUTIONS
HAVING DIFFICULTY WITH ONGOING CENTRAL IOWA MCS EVENT. COUPLED
WITH BL DEWPOINT ISSUES SUGGEST AGAIN USE OF CONCEPTUAL
PRECIPITATION EVOLUTION TOOLS DERIVED FROM THE FORCING OF A BLEND
OF GEM-NH /HI-RES ECMWF/GFS. THIS SUPPORTS A DECENT RISK OF SEVERE
STORMS SUN/MON WITH PHASING AND CONVECTIVE ISSUES THAT SHOULD
BETTER CLARIFIED IN THE NEXT 24 HOURS. HIGHER END SEVERE STORM
EVENTS FOR REGION APPEAR MARGINAL ATTM FOR THE AREA WITH LOW/MODERATE
SEVERE EVENTS SUGGESTED ATTM.

SATURDAY...MINOR CHANGES WITH AREA LIKELY PARTLY SUNNY AND DRY AHEAD
OF SEASONABLY STRONG UPPER LEVEL SYSTEM MOVING INTO WEST CENTRAL
PLAINS. WARM AND A BIT HUMID WITH HIGHS IN THE LOWER 80S AND LOWS
MOSTLY IN THE LOWER 60S WITH DEWPOINTS 60-64F. SOME PATCHY FOG
POSSIBLE WITH ANY CLEARING FOR LATER SHIFTS TO CONSIDER.

SUNDAY AND MONDAY. GOOD SHEAR AND AT LEAST MODERATE INSTABILITY
SUPPORT ONE OR MORE CONVECTIVE EVENTS SUGGESTED WITH ENVIRONMENT
MOSTLY FAVORABLE FOR CONVECTIVE BOWING SEGMENTS ATTM. SEVERE
WEATHER AREAL TOOL AND BLEP/HELP ALGORITHMS SUGGEST WITH T/TDS
AOA 83/63 OF 60-70 MPH STRAIGHT LINE WINDS AND SOME HAIL THAT
COULD APPROACH 1.75 INCHES WITH WBZ OF ~11K AGL AND SBCAPE OF
2000-3000 J/KG. IF ANY WAVE FORMS IN LATE PM/EVENING THERE IS A
RISK OF ISOLATED TORNADOES BUT THIS APPEARS MARGINAL DUE TO
CURRENT JET STRUCTURE AND TIMING. HIGHS SUGGESTED BASED ON PARTLY
SUNNY SKIES SHOULD BE IN THE LOWER/MIDDLE 80S AND MINS MOSTLY IN
THE MIDDLE 60S. PW/S OF 1.25+ INCHES DO SUPPORT LOCALLY HEAVY
RAINFALL WITH ANY TRAINING OF STORMS. POPS IN THE LIKELY CATEGORY TO THE
MID/HIGH CHANCE WITH TIMING MAIN ISSUE. LOCAL FORCING AND HEAVY
RAIN TECHNIQUES DO SUPPORT MOST AREAS TO PICK UP AN INCH OR MORE
OF RAIN WITH PASSAGE OF UPPER LEVEL SYSTEM OVER NEXT 96+ HOURS.

TUESDAY...A CHALLENGE WITH WAVE BASED ON CONVECTION FIRING OVER
SOUTHERN PLAINS THE KEY ISSUE. JET STRUCTURE SUPPORTS DECENT RAIN
EVENT WITH LOTS OF CLOUDS AND THIS WOULD IMPACT HIGH TEMPERATURES
FOR LATER SHIFTS THAT MAY NEED LOWERING OVER CENTRAL AND SE SECTIONS.
POPS MAY NEED RAISING AS WELL BY 10-20 PERCENT WITH MODERATE TO
LOW END HEAVY AMOUNTS SUGGESTED. CONVECTIVE FEEDBACK QUESTION
SHOULD BE CLARIFIED MORE IN THE NEXT 24-36 HOURS. TUESDAY
NIGHT...UPPER LOW MOVES INTO AREA WITH CHANCE OF LOW TOP CONVECTION
OF SHOWERS AND BRIEF THUNDERSTORMS. MINS OF 55-60F WITH TEMPS
POSSIBLY A BIT TOO COOL IN FAR SE SECTIONS WITH CLOUDS.

WEDNESDAY AND THURSDAY...UPPER LOW TO SLIDE SLOWLY EAST WITH CHANCE
SHOWERS AND POSSIBLY ISOLATED THUNDER WITH PARTLY TO MOSTLY CLOUDY
SKIES. HIGH TEMPERATURES 67-77F SUGGESTED.  LOWS IN THE 50S WED AM
AND MID/UPPER 40S TO LOWER 50S SE SECTIONS THU AM. SEASONABLY STRONG
CANADIAN HIGH PRESSURE TO THEN DOMINATE AND KEEP AREA COOL WITH LOW
DEWPOINTS AND BELOW NORMAL INTO NEXT WEEKEND.

NICHOLS

&&

.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z SATURDAY MORNING)
ISSUED AT 649 AM CDT FRI MAY 17 2013

VFR WX WILL BE SEEN THROUGH 12Z/18. NEW CONVECTION WILL DVLP AFT
18Z/17 BUT THE PROBABILITY OF A SHRA OR TSRA AFFECTING A TAF SITE
IS 15 PERCENT. VCTS OR VCSH WAS INCLUDED IN THE 12Z TAFS TO
REFLECT THE POTENTIAL FOR NEARBY CONVECTION FROM 20Z/17 TO 03Z/18.
IF A SHRA/TSRA AFFECTS A TAF SITE CIGS SHOULD REMAIN VFR. VSBYS
MAY DROP TO MVFR OR IFR FROM HEAVY RAIN.          ..08..

&&

.DVN WATCHES/WARNINGS/ADVISORIES...
IA...NONE.
IL...NONE.
MO...NONE.
&&

$$

UPDATE...08
SYNOPSIS...08
SHORT TERM...08
LONG TERM...NICHOLS
AVIATION...08

000
FXUS63 KDMX 171119 CCA
AFDDMX

AREA FORECAST DISCUSSION...CORRECTED
NATIONAL WEATHER SERVICE DES MOINES IA
616 AM CDT FRI MAY 17 2013

.SHORT TERM.../TODAY /...
ISSUED AT 400 AM CDT FRI MAY 17 2013

CONVECTION ONGOING ACROSS THE NORTH ON THE NOSE OF 850MB THETA-E
ADVECTION IN ADVANCE OF A WEAKENING SHORTWAVE TROUGH LIFTING THROUGH
THE WEAK UPPER LEVEL RIDGE. OVERALL WEAK SHEAR AND OK
INSTABILITY...SO SEVERE THREAT IS LIMITED. HOWEVER DUAL-POL ANALYSIS
CONTINUES TO INDICATE SOME SMALL HAIL WITHIN THE STRONGER STORMS AND
MAIN THREAT OF STORMS TO BE HEAVY RAIN ESPECIALLY WITH CELLS NOW
TRAINING SOME WITH EASTERLY MOVEMENT. EXPECT CHANCE FOR PRECIP TO
CONTINUE LINGER INTO THE MORNING ACROSS THE NORTHERN CWA...WITH
FORCING WEAKENING TOWARD LATE MORNING INTO THE AFTERNOON HOURS.
ENERGY ROTATING AROUND A WEAK UPPER LEVEL SYSTEM MOVING THROUGH
MISSOURI. MAY SEE SOME SHOWER/THUNDERSTORM DEVELOPMENT WITH THIS
SYSTEM TOWARD THIS AFTERNOON...WITH STORMS LIFTING NORTHWARD INTO
THE FAR SOUTHEASTERN CWA. OVERALL THOUGH BEST CHANCES FOR PRECIP
TODAY...WILL BE WITH THE LINGERING CONVECTION THIS MORNING. AIR MASS
ALOFT AGAIN SIMILAR TO PREVIOUS DAYS...SO STICK NEAR PERSISTENCE
WITH MAX TEMPS EXCEPT KEPT THE NORTH A BIT COOLER WITH CLOUDS/PRECIP
CHANCES.

.LONG TERM.../TONIGHT THROUGH THURSDAY/...
ISSUED AT 400 AM CDT FRI MAY 17 2013

UPPER LEVEL RIDGE BUILDING INTO THE CENTRAL PLAINS WILL BRING AN
END TO PRECIPITATION CHANCES TONIGHT INTO SATURDAY AS THE WARM
SECTOR SPREADS ACROSS THE STATE. THE RIDGE WILL SHIFT EAST
SATURDAY NIGHT AS A VIGOROUS UPPER LEVEL SYSTEM DIVES INTO THE
NORTHERN HIGH PLAINS. THIS WILL CREATE AN ACTIVE SOUTHWEST FLOW
ACROSS THE STATE. STRONG MOISTURE TRANSPORT WILL LIFT INTO
SOUTHWEST IOWA AS THE LOW LEVEL JET INCREASES ACROSS EASTERN
KANSAS AND POINTS INTO THE STATE. A GOOD ELEVATED MIXED LAYER WILL
BE IN PLACE WITH A FAIR AMOUNT OF DRY AIR TO OVERCOME AND THIS
MAY LIMIT OVERALL COVERAGE BUT STILL SOME STORMS SHOULD DEVELOP
AND WILL BRING THE THREAT FOR LARGE HAIL AND HEAVY RAIN GIVEN
INCREASING PWATS TO 1.5 INCHES AND STORM MOVEMENT AT 25 TO 30 KTS
TO THE NORTHEAST.

THE BEST SEVERE WEATHER THREAT THROUGH THE PERIOD WILL BE ON
SUNDAY AS A STRONG UPPER WAVE ROTATES AROUND THE DEVELOPING CLOSED
LOW TO THE WEST. THE GREATEST THREAT WILL BE DURING THE AFTERNOON
AND EVENING. THE SURFACE LOW IS EXPECTED TO BE OVER EASTERN
NEBRASKA TO FAR WEST CENTRAL IOWA WITH THE WARM FRONT EXTENDING
INTO SOUTHERN OR CENTRAL IOWA. CONDITIONS CONTINUE TO LOOK
FAVORABLE FOR SUPERCELLULAR DEVELOPMENT WITH VERY LARGE HAIL
EXPECTED. TORNADO THREAT STILL LOOKS FAVORABLE ACROSS THE
SOUTHWEST HALF WITH INCREASING CONFIDENCE THAT THE SFC WINDS WILL
BACK LEADING TO INCREASED LOW LEVEL SHEAR. THE MID LEVEL FLOW IS
NOT REAL STRONG AND COULD BE A LIMITING FACTOR HOWEVER LATEST
FORECAST MODELS SOUNDINGS SUGGEST LCLS WILL BE LOWER THAN
PREVIOUSLY EXPECTED. HEAVY RAIN WILL REMAIN A THREAT WITH PWATS UP
TO 1.75 INCHES AND RIGHT MOVER SUPERCELL MOTIONS OF 20 TO 30 KTS.
COULD CERTAINLY DEVELOP INTO A VOLATILE SITUATION.

THE DRY SLOT WILL THEN LIFT SOUTHWEST TO NORTHEAST SUNDAY NIGHT
AND INTO A PORTION OF MONDAY. A FEW SEVERE STORMS ARE POSSIBLE
YET MONDAY BY THE PRIMARY SHOW WILL BE SUNDAY. THE UPPER LOW WILL
SLOWLY FILL AND ROTATE THROUGH THE AREA THROUGH MID WEEK AND WILL
KEEP PRECIPITATION CHANCES IN THE FORECAST. UPPER RIDGE FINALLY
SHIFTS INTO THE REGION TOWARD THE END OF THE PERIOD AND BRING
DRIER WEATHER AND WARMER TEMPERATURES.

&&

.AVIATION...17/12Z
ISSUED AT 619 AM CDT FRI MAY 17 2013

VFR CONDITIONS EXPECTED THROUGHOUT THE TAF PERIOD AT MOST
LOCATIONS...EXCEPTION WILL BE AT KOTM WITH SOME MVFR CIGS IN PLACE
INITIALLY. EASTERLY TO SOUTHEASTERLY WINDS BECOMING SOUTHERLY TODAY.
SOME ISOLATED SHOWERS MOVING THROUGH THE NORTHERN HALF OF THE
STATE...COULD IMPACT KFOD AND KMCW OVER THE NEXT FEW HOURS. COVERAGE
IS SPOTTY...SO STUCK WITH VCSH FOR NOW. CHANCES FOR AN ISOLATED
SHOWER OR THUNDERSTORM CONTINUE ACROSS THE NORTH INTO THIS
AFTERNOON...BUT UNCERTAINTY ABOUT
TIMING/PLACEMENT/DEVELOPMENT IS HIGH SO HAVE GONE DRY PAST MID
MORNING. COULD ALSO SEE AN ISOLATED STORM AROUND KOTM THIS
AFTERNOON...BUT STICK WITH DRY CONDITIONS FOR NOW AS WELL.


&&

.DMX WATCHES/WARNINGS/ADVISORIES...NONE.

&&

$$

SHORT TERM...BEERENDS
LONG TERM...DONAVON
AVIATION...BEERENDS

000
FXUS63 KDMX 171116
AFDDMX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE DES MOINES IA
616 AM CDT FRI MAY 17 2013

.SHORT TERM.../TODAY /...
ISSUED AT 400 AM CDT FRI MAY 17 2013

CONVECTION ONGOING ACROSS THE NORTH ON THE NOSE OF 850MB THETA-E
ADVECTION IN ADVANCE OF A WEAKENING SHORTWAVE TROUGH LIFTING THROUGH
THE WEAK UPPER LEVEL RIDGE. OVERALL WEAK SHEAR AND OK
INSTABILITY...SO SEVERE THREAT IS LIMITED. HOWEVER DUAL-POL ANALYSIS
CONTINUES TO INDICATE SOME SMALL HAIL WITHIN THE STRONGER STORMS AND
MAIN THREAT OF STORMS TO BE HEAVY RAIN ESPECIALLY WITH CELLS NOW
TRAINING SOME WITH EASTERLY MOVEMENT. EXPECT CHANCE FOR PRECIP TO
CONTINUE LINGER INTO THE MORNING ACROSS THE NORTHERN CWA...WITH
FORCING WEAKENING TOWARD LATE MORNING INTO THE AFTERNOON HOURS.
ENERGY ROTATING AROUND A WEAK UPPER LEVEL SYSTEM MOVING THROUGH
MISSOURI. MAY SEE SOME SHOWER/THUNDERSTORM DEVELOPMENT WITH THIS
SYSTEM TOWARD THIS AFTERNOON...WITH STORMS LIFTING NORTHWARD INTO
THE FAR SOUTHEASTERN CWA. OVERALL THOUGH BEST CHANCES FOR PRECIP
TODAY...WILL BE WITH THE LINGERING CONVECTION THIS MORNING. AIR MASS
ALOFT AGAIN SIMILAR TO PREVIOUS DAYS...SO STICK NEAR PERSISTENCE
WITH MAX TEMPS EXCEPT KEPT THE NORTH A BIT COOLER WITH CLOUDS/PRECIP
CHANCES.

.LONG TERM.../TONIGHT THROUGH THURSDAY/...
ISSUED AT 400 AM CDT FRI MAY 17 2013

UPPER LEVEL RIDGE BUILDING INTO THE CENTRAL PLAINS WILL BRING AN
END TO PRECIPITATION CHANCES TONIGHT INTO SATURDAY AS THE WARM
SECTOR SPREADS ACROSS THE STATE. THE RIDGE WILL SHIFT EAST
SATURDAY NIGHT AS A VIGOROUS UPPER LEVEL SYSTEM DIVES INTO THE
NORTHERN HIGH PLAINS. THIS WILL CREATE AN ACTIVE SOUTHWEST FLOW
ACROSS THE STATE. STRONG MOISTURE TRANSPORT WILL LIFT INTO
SOUTHWEST IOWA AS THE LOW LEVEL JET INCREASES ACROSS EASTERN
KANSAS AND POINTS INTO THE STATE. A GOOD ELEVATED MIXED LAYER WILL
BE IN PLACE WITH A FAIR AMOUNT OF DRY AIR TO OVERCOME AND THIS
MAY LIMIT OVERALL COVERAGE BUT STILL SOME STORMS SHOULD DEVELOP
AND WILL BRING THE THREAT FOR LARGE HAIL AND HEAVY RAIN GIVEN
INCREASING PWATS TO 1.5 INCHES AND STORM MOVEMENT AT 25 TO 30 KTS
TO THE NORTHEAST.

THE BEST SEVERE WEATHER THREAT THROUGH THE PERIOD WILL BE ON
SUNDAY AS A STRONG UPPER WAVE ROTATES AROUND THE DEVELOPING CLOSED
LOW TO THE WEST. THE GREATEST THREAT WILL BE DURING THE AFTERNOON
AND EVENING. THE SURFACE LOW IS EXPECTED TO BE OVER EASTERN
NEBRASKA TO FAR WEST CENTRAL IOWA WITH THE WARM FRONT EXTENDING
INTO SOUTHERN OR CENTRAL IOWA. CONDITIONS CONTINUE TO LOOK
FAVORABLE FOR SUPERCELLULAR DEVELOPMENT WITH VERY LARGE HAIL
EXPECTED. TORNADO THREAT STILL LOOKS FAVORABLE ACROSS THE
SOUTHWEST HALF WITH INCREASING CONFIDENCE THAT THE SFC WINDS WILL
BACK LEADING TO INCREASED LOW LEVEL SHEAR. THE MID LEVEL FLOW IS
NOT REAL STRONG AND COULD BE A LIMITING FACTOR HOWEVER LATEST
FORECAST MODELS SOUNDINGS SUGGEST LCLS WILL BE LOWER THAN
PREVIOUSLY EXPECTED. HEAVY RAIN WILL REMAIN A THREAT WITH PWATS UP
TO 1.75 INCHES AND RIGHT MOVER SUPERCELL MOTIONS OF 20 TO 30 KTS.
COULD CERTAINLY DEVELOP INTO A VOLATILE SITUATION.

THE DRY SLOT WILL THEN LIFT SOUTHWEST TO NORTHEAST SUNDAY NIGHT
AND INTO A PORTION OF MONDAY. A FEW SEVERE STORMS ARE POSSIBLE
YET MONDAY BY THE PRIMARY SHOW WILL BE SUNDAY. THE UPPER LOW WILL
SLOWLY FILL AND ROTATE THROUGH THE AREA THROUGH MID WEEK AND WILL
KEEP PRECIPITATION CHANCES IN THE FORECAST. UPPER RIDGE FINALLY
SHIFTS INTO THE REGION TOWARD THE END OF THE PERIOD AND BRING
DRIER WEATHER AND WARMER TEMPERATURES.

&&

.AVIATION...17/12Z
ISSUED AT 616 AM CDT FRI MAY 17 2013

VFR CONDITIONS EXPECTED THROUGHOUT THE TAF PERIOD...WITH
EASTERLY TO SOUTHEASTERLY WINDS BECOMING SOUTHERLY TODAY.
SOME ISOLATED SHOWERS MOVING THROUGH THE NORTHERN HALF OF THE
STATE...COULD IMPACT KFOD AND KMCW OVER THE NEXT FEW HOURS.
COVERAGE IS SPOTTY...SO STUCK WITH VCSH FOR NOW. CHANCES FOR AN
ISOLATED SHOWER OR THUNDERSTORM CONTINUE ACROSS THE NORTH INTO
THIS AFTERNOON...BUT UNCERTAINTY ABOUT
TIMING/PLACEMENT/DEVELOPMENT IS HIGH SO HAVE GONE DRY PAST MID
MORNING. COULD ALSO SEE AN ISOLATED STORM AROUND KOTM THIS
AFTERNOON...BUT STICK WITH DRY CONDITIONS FOR NOW AS WELL.


&&

.DMX WATCHES/WARNINGS/ADVISORIES...NONE.

&&

$$

SHORT TERM...BEERENDS
LONG TERM...DONAVON
AVIATION...BEERENDS

000
FXUS63 KDMX 170901
AFDDMX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE DES MOINES IA
401 AM CDT FRI MAY 17 2013

.SHORT TERM.../TODAY /...
ISSUED AT 400 AM CDT FRI MAY 17 2013

CONVECTION ONGOING ACROSS THE NORTH ON THE NOSE OF 850MB THETA-E
ADVECTION IN ADVANCE OF A WEAKENING SHORTWAVE TROUGH LIFTING THROUGH
THE WEAK UPPER LEVEL RIDGE. OVERALL WEAK SHEAR AND OK
INSTABILITY...SO SEVERE THREAT IS LIMITED. HOWEVER DUAL-POL ANALYSIS
CONTINUES TO INDICATE SOME SMALL HAIL WITHIN THE STRONGER STORMS AND
MAIN THREAT OF STORMS TO BE HEAVY RAIN ESPECIALLY WITH CELLS NOW
TRAINING SOME WITH EASTERLY MOVEMENT. EXPECT CHANCE FOR PRECIP TO
CONTINUE LINGER INTO THE MORNING ACROSS THE NORTHERN CWA...WITH
FORCING WEAKENING TOWARD LATE MORNING INTO THE AFTERNOON HOURS.
ENERGY ROTATING AROUND A WEAK UPPER LEVEL SYSTEM MOVING THROUGH
MISSOURI. MAY SEE SOME SHOWER/THUNDERSTORM DEVELOPMENT WITH THIS
SYSTEM TOWARD THIS AFTERNOON...WITH STORMS LIFTING NORTHWARD INTO
THE FAR SOUTHEASTERN CWA. OVERALL THOUGH BEST CHANCES FOR PRECIP
TODAY...WILL BE WITH THE LINGERING CONVECTION THIS MORNING. AIR MASS
ALOFT AGAIN SIMILAR TO PREVIOUS DAYS...SO STICK NEAR PERSISTENCE
WITH MAX TEMPS EXCEPT KEPT THE NORTH A BIT COOLER WITH CLOUDS/PRECIP
CHANCES.

.LONG TERM.../TONIGHT THROUGH THURSDAY/...
ISSUED AT 400 AM CDT FRI MAY 17 2013

UPPER LEVEL RIDGE BUILDING INTO THE CENTRAL PLAINS WILL BRING AN
END TO PRECIPITATION CHANCES TONIGHT INTO SATURDAY AS THE WARM
SECTOR SPREADS ACROSS THE STATE. THE RIDGE WILL SHIFT EAST
SATURDAY NIGHT AS A VIGOROUS UPPER LEVEL SYSTEM DIVES INTO THE
NORTHERN HIGH PLAINS. THIS WILL CREATE AN ACTIVE SOUTHWEST FLOW
ACROSS THE STATE. STRONG MOISTURE TRANSPORT WILL LIFT INTO
SOUTHWEST IOWA AS THE LOW LEVEL JET INCREASES ACROSS EASTERN
KANSAS AND POINTS INTO THE STATE. A GOOD ELEVATED MIXED LAYER WILL
BE IN PLACE WITH A FAIR AMOUNT OF DRY AIR TO OVERCOME AND THIS
MAY LIMIT OVERALL COVERAGE BUT STILL SOME STORMS SHOULD DEVELOP
AND WILL BRING THE THREAT FOR LARGE HAIL AND HEAVY RAIN GIVEN
INCREASING PWATS TO 1.5 INCHES AND STORM MOVEMENT AT 25 TO 30 KTS
TO THE NORTHEAST.

THE BEST SEVERE WEATHER THREAT THROUGH THE PERIOD WILL BE ON
SUNDAY AS A STRONG UPPER WAVE ROTATES AROUND THE DEVELOPING CLOSED
LOW TO THE WEST. THE GREATEST THREAT WILL BE DURING THE AFTERNOON
AND EVENING. THE SURFACE LOW IS EXPECTED TO BE OVER EASTERN
NEBRASKA TO FAR WEST CENTRAL IOWA WITH THE WARM FRONT EXTENDING
INTO SOUTHERN OR CENTRAL IOWA. CONDITIONS CONTINUE TO LOOK
FAVORABLE FOR SUPERCELLULAR DEVELOPMENT WITH VERY LARGE HAIL
EXPECTED. TORNADO THREAT STILL LOOKS FAVORABLE ACROSS THE
SOUTHWEST HALF WITH INCREASING CONFIDENCE THAT THE SFC WINDS WILL
BACK LEADING TO INCREASED LOW LEVEL SHEAR. THE MID LEVEL FLOW IS
NOT REAL STRONG AND COULD BE A LIMITING FACTOR HOWEVER LATEST
FORECAST MODELS SOUNDINGS SUGGEST LCLS WILL BE LOWER THAN
PREVIOUSLY EXPECTED. HEAVY RAIN WILL REMAIN A THREAT WITH PWATS UP
TO 1.75 INCHES AND RIGHT MOVER SUPERCELL MOTIONS OF 20 TO 30 KTS.
COULD CERTAINLY DEVELOP INTO A VOLATILE SITUATION.

THE DRY SLOT WILL THEN LIFT SOUTHWEST TO NORTHEAST SUNDAY NIGHT
AND INTO A PORTION OF MONDAY. A FEW SEVERE STORMS ARE POSSIBLE
YET MONDAY BY THE PRIMARY SHOW WILL BE SUNDAY. THE UPPER LOW WILL
SLOWLY FILL AND ROTATE THROUGH THE AREA THROUGH MID WEEK AND WILL
KEEP PRECIPITATION CHANCES IN THE FORECAST. UPPER RIDGE FINALLY
SHIFTS INTO THE REGION TOWARD THE END OF THE PERIOD AND BRING
DRIER WEATHER AND WARMER TEMPERATURES.

&&

.AVIATION...17/06Z
ISSUED AT 1154 PM CDT THU MAY 16 2013

SHOWERS AND A FEW THUNDERSTORMS WILL PERSIST ACROSS NORTHERN IOWA
AND POSSIBLY AFFECT KMCW DURING THE EARLY MORNING HOURS...BUT THE
PROBABILITY IS LOW AND EVEN IF A STORM DOES PASS OVER THE TERMINAL
CONDITIONS WOULD EITHER REMAIN VFR OR GO BELOW ONLY VERY BRIEFLY.
THUS HAVE HANDLED IT WITH ONLY A VCSH IN THE 06Z TAFS.
OTHERWISE...LIGHT WINDS AND VFR CIGS EXPECTED AT ALL TERMINALS
THROUGH THE TAF PERIOD. LIGHT BR MAY DEVELOP LATE
TONIGHT...MAINLY AT KDSM/KOTM...BUT CONFIDENCE IS TOO LOW FOR
INCLUSION IN THE TAFS AT THIS TIME.


&&

.DMX WATCHES/WARNINGS/ADVISORIES...NONE.

&&

$$

SHORT TERM...BEERENDS
LONG TERM...DONAVON
AVIATION...LEE

000
FXUS63 KDVN 170823
AFDDVN

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE QUAD CITIES IA IL
323 AM CDT FRI MAY 17 2013

.SYNOPSIS...
ISSUED AT 229 AM CDT FRI MAY 17 2013

06Z SFC ANALYSIS HAS A WEAK LOW IN WESTERN IOWA JUST EAST OF KSUX
AND ANOTHER IN SOUTHERN SOUTH DAKOTA. AN EAST/WEST FRONTAL BOUNDARY
RAN FROM NORTHERN OHIO...THROUGH CENTRAL INDIANA...AND TO THE LOW
NEAR KSUX. FLOW OFF LAKE MICHIGAN HAD DEW POINTS RANGING FROM THE
UPPER 30S NORTH OF THE FRONT TO 50S AND LOW 60S SOUTH OF THE FRONT.

&&

.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 229 AM CDT FRI MAY 17 2013

THE CURRENT CONVECTION ON RADAR IS OCCURRING ALONG A THETA E
GRADIENT AND MOISTURE/TEMPERATURE GRADIENTS FROM THE 850MB FRONT.
MOST OF THE AREA WILL REMAIN DRY THROUGH SUNRISE EXCEPT FOR VERY
ISOLATED CONVECTION IN THE HWY 20 CORRIDOR.

THE MORNING HOURS ARE EXPECTED TO BE MAINLY DRY WITH PASSING CLOUDS
AS THE THETA E GRADIENT MOVES NORTH INTO WISCONSIN. DIFFERENTIAL
HEATING COMBINED WITH AN APPROACHING VORT MAX SHOULD RESULT IN
ISOLATED TO SCATTERED CONVECTION DEVELOPING BY LATE MORNING IN THE
EASTERN CWFA.

DURING THE AFTERNOON HOURS...ISOLATED TO SCATTERED CONVECTION WILL
EXPAND TO MOST OF THE CWFA AS CONVECTIVE TEMPERATURES ARE REACHED.

THE PROXIMITY OF THE UPPER RIDGE MEANS THAT STEERING CURRENTS FOR
THE CONVECTION ARE VERY WEAK. THUS THOSE AREAS THAT DO SEE RAIN THIS
AFTERNOON WILL HAVE THE POTENTIAL TO SEE LOCALLY HEAVY RAINFALL.

CONVECTION WILL SLOWLY DIMINISH WITH SUNSET BUT ISOLATED TO
SCATTERED CONVECTION IS EXPECTED TO CONTINUE INTO THE EVENING OVER
ROUGHLY THE NORTHEAST HALF OF THE CWFA. BY LATE EVENING MAINLY DRY
CONDITIONS ARE EXPECTED WITH LITTLE IF ANY CONVECTION AFTER
MIDNIGHT.

08

.LONG TERM...(SATURDAY THROUGH THURSDAY)
ISSUED AT 229 AM CDT FRI MAY 17 2013

MAIN CHALLENGE IS THE PROBABLE SEVERE WEATHER RISKS SUN/MON.

OVERVIEW...INITIALIZATION AND VERIFICATION FAIR WITH ALL SOLUTIONS
HAVING DIFFICULTY WITH ONGOING CENTRAL IOWA MCS EVENT. COUPLED
WITH BL DEWPOINT ISSUES SUGGEST AGAIN USE OF CONCEPTUAL
PRECIPITATION EVOLUTION TOOLS DERIVED FROM THE FORCING OF A BLEND
OF GEM-NH /HI-RES ECMWF/GFS. THIS SUPPORTS A DECENT RISK OF SEVERE
STORMS SUN/MON WITH PHASING AND CONVECTIVE ISSUES THAT SHOULD
BETTER CLARIFIED IN THE NEXT 24 HOURS. HIGHER END SEVERE STORM
EVENTS FOR REGION APPEAR MARGINAL ATTM FOR THE AREA WITH LOW/MODERATE
SEVERE EVENTS SUGGESTED ATTM.

SATURDAY...MINOR CHANGES WITH AREA LIKELY PARTLY SUNNY AND DRY AHEAD
OF SEASONABLY STRONG UPPER LEVEL SYSTEM MOVING INTO WEST CENTRAL
PLAINS. WARM AND A BIT HUMID WITH HIGHS IN THE LOWER 80S AND LOWS
MOSTLY IN THE LOWER 60S WITH DEWPOINTS 60-64F. SOME PATCHY FOG
POSSIBLE WITH ANY CLEARING FOR LATER SHIFTS TO CONSIDER.

SUNDAY AND MONDAY. GOOD SHEAR AND AT LEAST MODERATE INSTABILITY
SUPPORT ONE OR MORE CONVECTIVE EVENTS SUGGESTED WITH ENVIRONMENT
MOSTLY FAVORABLE FOR CONVECTIVE BOWING SEGMENTS ATTM. SEVERE
WEATHER AREAL TOOL AND BLEP/HELP ALGORITHMS SUGGEST WITH T/TDS
AOA 83/63 OF 60-70 MPH STRAIGHT LINE WINDS AND SOME HAIL THAT
COULD APPROACH 1.75 INCHES WITH WBZ OF ~11K AGL AND SBCAPE OF
2000-3000 J/KG. IF ANY WAVE FORMS IN LATE PM/EVENING THERE IS A
RISK OF ISOLATED TORNADOES BUT THIS APPEARS MARGINAL DUE TO
CURRENT JET STRUCTURE AND TIMING. HIGHS SUGGESTED BASED ON PARTLY
SUNNY SKIES SHOULD BE IN THE LOWER/MIDDLE 80S AND MINS MOSTLY IN
THE MIDDLE 60S. PW/S OF 1.25+ INCHES DO SUPPORT LOCALLY HEAVY
RAINFALL WITH ANY TRAINING OF STORMS. POPS IN THE LIKELY CATEGORY TO THE
MID/HIGH CHANCE WITH TIMING MAIN ISSUE. LOCAL FORCING AND HEAVY
RAIN TECHNIQUES DO SUPPORT MOST AREAS TO PICK UP AN INCH OR MORE
OF RAIN WITH PASSAGE OF UPPER LEVEL SYSTEM OVER NEXT 96+ HOURS.

TUESDAY...A CHALLENGE WITH WAVE BASED ON CONVECTION FIRING OVER
SOUTHERN PLAINS THE KEY ISSUE. JET STRUCTURE SUPPORTS DECENT RAIN
EVENT WITH LOTS OF CLOUDS AND THIS WOULD IMPACT HIGH TEMPERATURES
FOR LATER SHIFTS THAT MAY NEED LOWERING OVER CENTRAL AND SE SECTIONS.
POPS MAY NEED RAISING AS WELL BY 10-20 PERCENT WITH MODERATE TO
LOW END HEAVY AMOUNTS SUGGESTED. CONVECTIVE FEEDBACK QUESTION
SHOULD BE CLARIFIED MORE IN THE NEXT 24-36 HOURS. TUESDAY
NIGHT...UPPER LOW MOVES INTO AREA WITH CHANCE OF LOW TOP CONVECTION
OF SHOWERS AND BRIEF THUNDERSTORMS. MINS OF 55-60F WITH TEMPS
POSSIBLY A BIT TOO COOL IN FAR SE SECTIONS WITH CLOUDS.

WEDNESDAY AND THURSDAY...UPPER LOW TO SLIDE SLOWLY EAST WITH CHANCE
SHOWERS AND POSSIBLY ISOLATED THUNDER WITH PARTLY TO MOSTLY CLOUDY
SKIES. HIGH TEMPERATURES 67-77F SUGGESTED.  LOWS IN THE 50S WED AM
AND MID/UPPER 40S TO LOWER 50S SE SECTIONS THU AM. SEASONABLY STRONG
CANADIAN HIGH PRESSURE TO THEN DOMINATE AND KEEP AREA COOL WITH LOW
DEWPOINTS AND BELOW NORMAL INTO NEXT WEEKEND.

NICHOLS

&&

.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z FRIDAY NIGHT)
ISSUED AT 229 AM CDT FRI MAY 17 2013

VFR WX IS EXPECTED THROUGH 00Z/18. MAINLY ISOLD CONVECTION WITH TSRA
IS EXPECTED AFT 16Z/17 BUT THE PROBABILITY OF A SHRA OR TSRA HITTING
A TAF SITE IS 10-15 PERCENT. CONVECTION THAT DOES AFFECT A TAF SITE
SHOULD RESULT IN VFR CIGS BUT VSBYS MAY BE MVFR OR IFR IN STRONGER
STORMS.

08

&&

.DVN WATCHES/WARNINGS/ADVISORIES...
IA...NONE.
IL...NONE.
MO...NONE.
&&

$$

SYNOPSIS...08
SHORT TERM...08
LONG TERM...NICHOLS
AVIATION...08

000
FXUS63 KDMX 170454
AFDDMX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE DES MOINES IA
1154 PM CDT THU MAY 16 2013

.SHORT TERM.../TONIGHT/
ISSUED AT 410 PM CDT THU MAY 16 2013

FORECAST CONCERN FOR PERIOD AGAIN BECOMES POPS AND CHANCES FOR
CONVECTION ACROSS THE AREA THIS EVENING AND OVERNIGHT. WEAK BOUNDARY
LOCATED ACROSS NORTHERN MISSOURI/SOUTHERN AND WESTERN IOWA HAS
BECOME FOCUS FOR STORM DEVELOPMENT LATE IN THE AFTERNOON ACROSS THE
EAST. ACROSS SOUTH CENTRAL IOWA...REMNANT CIRRUS FROM MORNING
CONVECTION HAS PREVENTS CU FIELD FROM FORMING...WHICH MAY HELP LIMIT
CONVECTION POTENTIAL FOR THE LATE AFTERNOON AND EVENING HOURS.
HOWEVER..CAPE VALUES REMAIN HIGH ACROSS THE AREA...AND BOUNDARY MAY
BE ENOUGH FORCING TO GET STORMS. SHEAR IS EXTREMELY LIMITED...BUT
WITH HIGH CAPE VALUES ANY STORMS MAY BE ABLE TO MAINTAIN
THEMSELVES...AND MAY BECOME BRIEFLY SEVERE. HAVE THEREFORE KEPT
ISOLATED THUNDER CHANCES ACROSS THE SOUTH AND WEST.

FOR THE REST OF THE OVERNIGHT PERIOD...APPROACHING FRONTAL BOUNDARY
CURRENTLY PRODUCING PRECIPITATION ACROSS EASTERN NEBRASKA AND SOUTH
DAKOTA WILL CONTINUE TO PUSH EASTWARD OVERNIGHT. HOWEVER...BEST
FORCING AND TRACK OF SYSTEM AND EMBEDDED SHORTWAVE WILL TAKE BEST
PRECIP NORTHEAST OF CWA. MAY SEE SOME HEAVIER PRECIP AMOUNTS IN THE
FAR NORTHEAST OVERNIGHT...BUT BEST CHANCES WILL BE OUTSIDE THE CWA.
HAVE KEPT HIGH POPS FOR THE NORTH OVERNIGHT HOWEVER WITH GOOD
CONFIDENCE IN TRACK OF SYSTEM CONTINUING INTO IOWA. HAVE LESS
CONFIDENCE FURTHER SOUTH ACROSS CENTRAL IOWA OVERNIGHT...BUT MAY SEE
AT LEAST LIGHT PRECIPITATION.

OVERNIGHT LOW BECOME TRICKY WITH CLOUD INFLUENCES AS CLOUDS INCREASE
ACROSS THE AREA. HOWEVER...HAVE KEPT NEAR GOING AND NEAR
GUIDANCE...EXCEPT IN THE NORTH WHERE TEMPERATURES WARMED INTO THE
MID 80S TODAY...AND WILL BE SLOW TO FALL OFF BEFORE CLOUDS ARRIVE.
HAVE THEREFORE BUMPED LOWS UP A FEW DEGREES ACROSS THE NORTH.

.LONG TERM.../FRIDAY THROUGH THURSDAY/
ISSUED AT 410 PM CDT THU MAY 16 2013

CONVECTIVE TRENDS WILL OBVIOUSLY BE THE PRIMARY CONCERN THROUGH
MUCH OF THE PERIOD.  EXPECT REMNANTS OF CURRENT NE MCS TO STILL BE
AFFECTING NRN IA BY BEGINNING OF THE PERIOD. KINEMATIC FORCING
COMPONENT WILL HAVE LIKELY PASSED INTO THE UPPER MS VALLEY WITH
CURRENT NE SHORT WAVE...HOWEVER LINGERING WARM ADVECTION SHOULD
SUSTAIN CONVECTION FARTHER WEST INTO FRI AS WARM FRONT ESTABLISHES
ITSELF ALONG OR JUST NORTH OF THE IA/MN BORDER. EXAMINATION OF
ELEVATED CAPE SUGGESTS LITTLE INHIBITION WITH CAPES 500-1000 J/KG.
ESTIMATED EFFECTIVE SHEAR ALSO LOOKS SUFFICIENT TO MAINTAIN
MINIMAL SEVERE POTENTIAL EARLY...MAINLY IN THE FORM OF LARGE
HAIL. REMAINDER OF DAY SHOULD SEE TYPICAL DIURNAL DECREASE IN WARM
ADVECTION FORCED PRECIP ALTHOUGH HAVE KEPT LOW POPS GOING LATE.
FORECAST SOUNDINGS AND PROJECTED CAPES/CINS SUGGEST SURFACE BASED
CONVECTION WILL BE POSSIBLE...BUT SYNOPTIC BOUNDARY WILL LIKELY BE
INTO MN BY THAT TIME WITH NEXT ROUND OF THETA-E ADVECTION HEADING
INTO THE NIGHT FARTHER NORTH AS WELL. TRIGGER WOULD LIKELY HAVE TO
ORIGINATE FROM LINGERING OUTFLOW BOUNDARY.

CONVECTION POTENTIAL SHOULD PUSH NORTHWARD BY FRI NIGHT AND SAT WITH
IA IN THE WARM SECTOR AND INFLUENCED BY PASSAGE OF UPPER LEVEL
RIDGE.  ATTENTION THEN TURNS UPSTREAM STARTING SAT NIGHT.
THERMODYNAMIC AND KINEMATIC FORCING WILL BOTH INCREASE AHEAD OF
APPROACHING LONG WAVE TROUGH.  THIS WILL SPREAD PRECIP INTO THE MO
VALLEY LATER SAT NIGHT AND INTO SUN.  QUESTION THEN BECOMES
SEPARATION AND RECOVERY BETWEEN THIS EVENT AND POTENTIAL SURFACE
BASED CONVECTION ALONG FRONT DURING PEAK HEATING.  SEVERE POTENTIAL
IS CERTAINLY THERE IF ANYTHING DEVELOPS...ESPECIALLY FROM
SOUTHERN IA FARTHER SOUTH NEAR PROXIMITY TO SURFACE WARM FRONT
DEPICTED BY 12Z ECMWF AND ALSO CLOSER TO SRN PLAINS JET. ALL MODES
OF SEVERE WEATHER WOULD BE POSSIBLE INCLUDING TORNADOES AND CANNOT
ARGUE WITH CURRENT SPC DAY 4 OUTLOOK. ALTHOUGH SYSTEM WILL BE
SOMEWHAT LESS IMPRESSIVE BY MON...SEVERE POTENTIAL WILL STILL BE
THERE AS SURFACE LOW LIFTS INTO ERN SD. INSTABILITY MAY BE
SOMEWHAT LESS BUT ANYTHING THAT DEVELOPS COULD CERTAINLY BE
ORGANIZED AND SUPERCELLULAR AS UPPER LEVEL JET LIFTS NORTHWARD
INCREASING DEEP SHEAR.

UPPER LEVEL SYSTEM OPENS UP AND DRIFTS EASTWARD TUE INTO LATE WED
KEEPING RELATIVELY UNSTABLE AIRMASS IN PLACE AND THE POTENTIAL FOR
ADDITIONAL CONVECTION. LITTLE AIRMASS CHANGE BEHIND THIS SYSTEM
WITH AT LEAST SEASONAL TEMPERATURES INTO NEXT WEEK.

&&

.AVIATION...17/06Z
 ISSUED AT 1154 PM CDT THU MAY 16 2013

SHOWERS AND A FEW THUNDERSTORMS WILL PERSIST ACROSS NORTHERN IOWA
AND POSSIBLY AFFECT KMCW DURING THE EARLY MORNING HOURS...BUT THE
PROBABILITY IS LOW AND EVEN IF A STORM DOES PASS OVER THE TERMINAL
CONDITIONS WOULD EITHER REMAIN VFR OR GO BELOW ONLY VERY BRIEFLY.
THUS HAVE HANDLED IT WITH ONLY A VCSH IN THE 06Z TAFS.
OTHERWISE...LIGHT WINDS AND VFR CIGS EXPECTED AT ALL TERMINALS
THROUGH THE TAF PERIOD. LIGHT BR MAY DEVELOP LATE
TONIGHT...MAINLY AT KDSM/KOTM...BUT CONFIDENCE IS TOO LOW FOR
INCLUSION IN THE TAFS AT THIS TIME.

&&

.DMX WATCHES/WARNINGS/ADVISORIES...NONE.

&&

$$

SHORT TERM...AWB
LONG TERM...SMALL
AVIATION...LEE

000
FXUS63 KDVN 170436
AFDDVN

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE QUAD CITIES IA IL
1136 PM CDT THU MAY 16 2013

.SYNOPSIS...
ISSUED AT 325 PM CDT THU MAY 16 2013

SURFACE FRONT EARLY THIS AFTERNOON REMAINED STALLED FROM SOUTHERN OH
AND IN...W-NW ACROSS CENTRAL IL THROUGH THE FAR SE TIP OF IA TO NEAR
OMAHA. TEMPERATURES WERE IN THE 80S OVER MUCH OF THE AREA...WITH THE
FRONT ACTING PRIMARILY AS A MOISTURE BOUNDARY. SURFACE DEWPOINTS
WERE IN THE 60S TO ITS SOUTH...WHILE 40S ENCOMPASSED MOST OF THE
DVN FORECAST AREA TO THE NORTH. AREA RADARS SHOW THIS BOUNDARY LIT
UP WITH SCATTERED THUNDERSTORMS FROM SOUTHERN INDIANA TO NEAR KEOKUK.
IN THE BIGGER PICTURE...A SLOW MOVING UPPER LOW WAS ROLLING INTO
NORTHEAST AR...HELPING MAINTAIN AN AXIS OF GULF MOISTURE AT 850 MB
FROM KS THROUGH MO INTO THE OHIO RIVER VALLEY. TO THE WEST...A
SHORTWAVE AND ACCOMPANYING MCS WAS OVER NORTHEAST NEB. A SECONDARY...
PERHAPS STRONGER STRONGER SHORTWAVE AND THUNDERSTORM COMPLEX WAS
MOVING INTO SW NEB. THESE FEATURES CREATE A CHALLENGING FORECAST
FOR PRECIPITATION CHANCES IN THE IN THE SHORT TERM THROUGH
FRIDAY...THEN ATTENTION TURNS TO A MORE SIGNIFICANT SYSTEM AND
POSSIBLE SEVERE WEATHER OUTBREAK LATE IN THE WEEKEND INTO EARLY
NEXT WEEK.

&&

.SHORT TERM...(THIS EVENING THROUGH FRIDAY)
ISSUED AT 325 PM CDT THU MAY 16 2013

POOR INITIALIZATION AND HANDLING OF CONVECTIVE TRENDS IN BOTH THE SHORT
TERM MODELS AND SYNOPTIC SCALE MODELS...ALONG WITH A COMPLEX
INTERACTION OF LARGE SCALE FEATURES LENDS TO A LOW CONFIDENCE
FORECAST IN THE EVOLUTION OF THUNDERSTORM CHANCES THROUGH FRIDAY.
IN THE SHORT TERM...HIGH RESOLUTION MODELS DEPICT THE FRONT
LIFTING NORTH THIS EVENING IN ADVANCE OF THE NORTHEAST NEB
THUNDERSTORM COMPLEX MOVING INTO NW IA. THE POTENTIAL FOR
SUSTAINED THUNDERSTORMS WILL BE LIMITED BY A WEAK...SUBSIDENT FLOW
ALOFT AND WEAK MID LEVEL RIDGING IN PLACE OVER THE AREA INDUCED BY
THE UPPER LOW PASSING TO THE NORTH THIS EVENING. FOR NOW...WILL
FOLLOW TRENDS FROM 12Z MODELS...THAT WERE LESS BULLISH ON
THUNDERSTORMS ALONG WARM FRONT THIS EVENING...KEEPING SLIGHT
CHANCES GOING THROUGH MID EVENING SOUTH OF I-80. NONE OF THE 12Z
MODELS HAD A DECENT HANDLE ON THE LOCATIONS OF THE MCS COMPLEXES
MOVING THROUGH THE PLAINS AT 18Z. AS EVIDENT BY THE RECENT
OBSERVATION WITH .69 INCHES OF RAIN IN LESS THAN AN HOUR FROM A
SMALL CELL OVER KEOKUK...AND PUBLIC REPORT OF 1.09 IN HANCOCK
COUNTY...WHERE RAIN DOES FALL...LOCALLY MODERATE TO HEAVY RAINFALL
WILL BE POSSIBLE. STORMS LATE THIS AFTERNOON AND EARLY EVENING
WILL WILL BE PULSE TYPE AND SLOW MOVING. LATER TONIGHT...HAVE
POPS RAMPING BACK UP AS THE LEAD SHORTWAVE PASSES TO THE
NORTH...POSSIBLY REINVIGORATING CONVECTION ON THE SURFACE AND 850
MB FRONT OVER THE CENTRAL AND NORTHERN HALF OF THE FORECAST AREA.
OVERNIGHT LOWS WILL RANGE FROM THE LOWER 50S IN THE DRIER AIRMASS
MAINTAINED OVER FAR NW IL...TO THE LOWER 60S ACROSS THE SOUTH.

FRIDAY...THE SECONDARY SHORTWAVE IN WESTERN NEBRASKA ROLLS ACROSS
NORTHERN IA AROUND MIDDAY WHILE THE CENTRAL MS VALLEY LOW PASSES
INTO THE OHIO RIVER VALLEY. THE BULK OF THE FORCING IS AGAIN
DEPICTED NORTH OF THE AREA...BUT ANY LIFT OVER THE FORECAST AREA
WILL HAVE A HIGHER PW AIRMASS TO PRODUCE SCATTERED SHOWERS AND
THUNDERSTORMS...ESPECIALLY DURING PEAK HEATING. SEVERE WEATHER IS
NOT EXPECTED DUE TO A LACK OF SHEAR OR STRONG BOUNDARIES.THE AIRMASS
CURRENTLY ACROSS SOUTHERN IL AND MO WILL BE IN PLACE OVER THE
FORECAST AREA BY AFTERNOON...SUPPORTING HIGHS FROM THE UPPER 70S TO
LOWER 80S WITH HIGHER HUMIDITY AS DEWPOINTS SHOULD BE IN THE UPPER
50S TO LOWER 60S.

.LONG TERM...(FRIDAY NIGHT THROUGH THURSDAY)
ISSUED AT 325 PM CDT THU MAY 16 2013

...SEVERE WEATHER POSSIBLE SUNDAY AND MONDAY...

FRIDAY NIGHT THROUGH NEXT THURSDAY...
SATURDAY WILL BE A WARM DAY WITH A SHORTWAVE RIDGE ALOFT OVER THE
MIDWEST. MODEL SHOW SURFACE BASED CAPES ARE AROUND 2000 J/KG BUT
TEMPERATURES ALOFT ARE WARM ENOUGH TO KEEP THE AREA CAPPED SO
CONVECTIVE INITIATION IS NOT ANTICIPATED. HIGH TEMPERATURES WILL
RANGE AROUND 80 DEGREES.

SUNDAY...SHORT RANGE MODELS SHOW NEGATIVE TILTED UPPER TROF WITH A
SURFACE LOW OVER THE UPPER MIDWEST THAT WILL LIKELY PRODUCE STRONG
THUNDERSTORMS IN OR NEAR THE FORECAST AREA DURING THE AFTERNOON.
SUNDAY MORNING LOOKS TO BE MUGGY WITH TEMPERATURES RISING INTO THE
MID TO UPPER 80S BY AFTERNOON WITH SURFACE DEWPOINTS CLIMBING INTO
THE LOW TO MID 60S. THESE TEMPERATURES WILL DESTABILIZE THE
ATMOSPHERE AND INCREASE CAPES BETWEEN 2500 TO 3000 J/KG. CURRENT
MODELS INDICATE LATE DAY CONVECTION MAY BEGIN OVER WESTERN IOWA AND
MOVE EAST TOWARD THE MISSISSIPPI VALLEY SUNDAY NIGHT. STRONG OR
SEVERE THUNDERSTORMS WITH HEAVY RAIN ARE LIKELY OVERNIGHT. I WILL
CONTINUE TO CARRY CURRENT FORECAST LIKELY POPS.

MONDAY...LATEST MODELS INDICATE THERE IS AN INCREASING CHANCE FOR
SEVERE THUNDERSTORMS/SUPERCELLS MONDAY AFTERNOON WHEN THE STRONGEST
UPPER LEVEL FORCING OCCURS...ALONG WITH A WELL DESTABILIZED
ATMOSPHERE AND SURFACE FRONT MOVING ACROSS THE AREA. MODEL SOLUTIONS
VARY AS TO WHERE THE LOCATION AND TIMING OF THE BEST SYNOPTIC
FORCING WILL BE...BUT THEY ALL CONTINUE TO MAINTAIN A NEGATIVELY
TILTED TROF OVER THE UPPER MID WEST. THE LOW BECOMES NEARLY
VERTICALLY STACKED AS IT MOVES TOWARD MINNESOTA. WITH A WARM FRONT
HAVING PASSED WELL NORTH OF THE REGION ON SUNDAY..AMPLE MOISTURE
ADVECTION FROM THE GULF OF MEXICO WILL KEEP DEWPOINTS IN THE MID 60S
WITH HIGH TEMPERATURES IN THE MID TO UPPER 70S PRODUCING HIGH CAPE
VALUES. KEEPING LIKELY POPS IN THE CURRENT FORECAST SEEMS REASONABLE.

DUE TO VARYING MODEL SOLUTIONS AND THE LOCATION OF BOUNDARIES LEFT
OVER FROM SUNDAYS CONVECTION...CONFIDENCE IS HIGH SEVERE WEATHER
WILL OCCUR IN OR NEAR THE FORECAST AREA. CONFIDENCE IS LOW AS TO THE
EXACT LOCATION.

TUESDAY THROUGH THURSDAY...CONSENSUS MODEL SOLUTIONS DIVERGE IN
EVOLUTION OF THE CLOSED UPPER LOW BUT THE OVERALL TREND IS FOR THE
SYSTEM TO MEANDER OVER THE MISSISSIPPI VALLEY. WITH WEAK VORT MAXES
ROTATING AROUND THE UPPER LOW AND COOL TEMPERATURES ALOFT THERE WILL
BE A CHANCE OF THUNDERSTORMS TUESDAY AND WEDNESDAY. BY
THURSDAY...THE MODELS MOVE THE UPPER LOW SOUTHEAST AND BUILD A LONG
WAVE RIDGE OVER THE MIDWEST. TEMPERATURES WILL BE AROUND 80 ON
WEDNESDAY BUT WILL BEGIN TO RISE AS AS HEIGHTS CONTINUE TO BUILD

&&

.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z FRIDAY NIGHT)
ISSUED AT 1134 PM CDT THU MAY 16 2013

A CHALLENGING NEXT 24 HOURS OF AVIATION IS EXPECTED AS WE SEE A
WEAK WARM FRONT GRADUALLY LIFT FROM SOUTHEAST IOWA INTO WISCONSIN FROM
EARLY THIS MORNING THROUGH THIS AFTERNOON. AS THIS
OCCURS...CONDITIONS WILL REMAIN MAINLY VFR ON A WIDESPREAD
NATURE...HOWEVER...ISOLATED TO SCATTERED SHOWERS AND THUNDERSTORMS
WILL CONTINUE TO BE A THREAT ALONG THE FRONT. THIS WILL BE MAINLY
THIS EVENING AROUND BRL...AND FROM LATE TONIGHT THROUGH THE
AFTERNOON HOURS FRIDAY AT MLI...CID...AND DBQ. THE COVERAGE OF
STORMS IS NOT WIDESPREAD ENOUGH TO WARRANT MORE THAN A VICINITY
MENTION WITHIN TAF FORECASTS.CONVECTIVE TRENDS WILL BE WATCHED
CAREFULLY...AND UPDATES TO TAFS WILL BE ISSUED AS NEEDED. ERVIN

&&

.DVN WATCHES/WARNINGS/ADVISORIES...
IA...NONE.
IL...NONE.
MO...NONE.
&&

$$

SYNOPSIS...SHEETS
SHORT TERM...SHEETS
LONG TERM...KUHL
AVIATION...ERVIN

000
FXUS63 KDMX 162327
AFDDMX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE DES MOINES IA
627 PM CDT THU MAY 16 2013

.SHORT TERM.../TONIGHT/
ISSUED AT 410 PM CDT THU MAY 16 2013

FORECAST CONCERN FOR PERIOD AGAIN BECOMES POPS AND CHANCES FOR
CONVECTION ACROSS THE AREA THIS EVENING AND OVERNIGHT. WEAK BOUNDARY
LOCATED ACROSS NORTHERN MISSOURI/SOUTHERN AND WESTERN IOWA HAS
BECOME FOCUS FOR STORM DEVELOPMENT LATE IN THE AFTERNOON ACROSS THE
EAST. ACROSS SOUTH CENTRAL IOWA...REMNANT CIRRUS FROM MORNING
CONVECTION HAS PREVENTS CU FIELD FROM FORMING...WHICH MAY HELP LIMIT
CONVECTION POTENTIAL FOR THE LATE AFTERNOON AND EVENING HOURS.
HOWEVER..CAPE VALUES REMAIN HIGH ACROSS THE AREA...AND BOUNDARY MAY
BE ENOUGH FORCING TO GET STORMS. SHEAR IS EXTREMELY LIMITED...BUT
WITH HIGH CAPE VALUES ANY STORMS MAY BE ABLE TO MAINTAIN
THEMSELVES...AND MAY BECOME BRIEFLY SEVERE. HAVE THEREFORE KEPT
ISOLATED THUNDER CHANCES ACROSS THE SOUTH AND WEST.

FOR THE REST OF THE OVERNIGHT PERIOD...APPROACHING FRONTAL BOUNDARY
CURRENTLY PRODUCING PRECIPITATION ACROSS EASTERN NEBRASKA AND SOUTH
DAKOTA WILL CONTINUE TO PUSH EASTWARD OVERNIGHT. HOWEVER...BEST
FORCING AND TRACK OF SYSTEM AND EMBEDDED SHORTWAVE WILL TAKE BEST
PRECIP NORTHEAST OF CWA. MAY SEE SOME HEAVIER PRECIP AMOUNTS IN THE
FAR NORTHEAST OVERNIGHT...BUT BEST CHANCES WILL BE OUTSIDE THE CWA.
HAVE KEPT HIGH POPS FOR THE NORTH OVERNIGHT HOWEVER WITH GOOD
CONFIDENCE IN TRACK OF SYSTEM CONTINUING INTO IOWA. HAVE LESS
CONFIDENCE FURTHER SOUTH ACROSS CENTRAL IOWA OVERNIGHT...BUT MAY SEE
AT LEAST LIGHT PRECIPITATION.

OVERNIGHT LOW BECOME TRICKY WITH CLOUD INFLUENCES AS CLOUDS INCREASE
ACROSS THE AREA. HOWEVER...HAVE KEPT NEAR GOING AND NEAR
GUIDANCE...EXCEPT IN THE NORTH WHERE TEMPERATURES WARMED INTO THE
MID 80S TODAY...AND WILL BE SLOW TO FALL OFF BEFORE CLOUDS ARRIVE.
HAVE THEREFORE BUMPED LOWS UP A FEW DEGREES ACROSS THE NORTH.

.LONG TERM.../FRIDAY THROUGH THURSDAY/
ISSUED AT 410 PM CDT THU MAY 16 2013

CONVECTIVE TRENDS WILL OBVIOUSLY BE THE PRIMARY CONCERN THROUGH
MUCH OF THE PERIOD.  EXPECT REMNANTS OF CURRENT NE MCS TO STILL BE
AFFECTING NRN IA BY BEGINNING OF THE PERIOD. KINEMATIC FORCING
COMPONENT WILL HAVE LIKELY PASSED INTO THE UPPER MS VALLEY WITH
CURRENT NE SHORT WAVE...HOWEVER LINGERING WARM ADVECTION SHOULD
SUSTAIN CONVECTION FARTHER WEST INTO FRI AS WARM FRONT ESTABLISHES
ITSELF ALONG OR JUST NORTH OF THE IA/MN BORDER. EXAMINATION OF
ELEVATED CAPE SUGGESTS LITTLE INHIBITION WITH CAPES 500-1000 J/KG.
ESTIMATED EFFECTIVE SHEAR ALSO LOOKS SUFFICIENT TO MAINTAIN
MINIMAL SEVERE POTENTIAL EARLY...MAINLY IN THE FORM OF LARGE
HAIL. REMAINDER OF DAY SHOULD SEE TYPICAL DIURNAL DECREASE IN WARM
ADVECTION FORCED PRECIP ALTHOUGH HAVE KEPT LOW POPS GOING LATE.
FORECAST SOUNDINGS AND PROJECTED CAPES/CINS SUGGEST SURFACE BASED
CONVECTION WILL BE POSSIBLE...BUT SYNOPTIC BOUNDARY WILL LIKELY BE
INTO MN BY THAT TIME WITH NEXT ROUND OF THETA-E ADVECTION HEADING
INTO THE NIGHT FARTHER NORTH AS WELL. TRIGGER WOULD LIKELY HAVE TO
ORIGINATE FROM LINGERING OUTFLOW BOUNDARY.

CONVECTION POTENTIAL SHOULD PUSH NORTHWARD BY FRI NIGHT AND SAT WITH
IA IN THE WARM SECTOR AND INFLUENCED BY PASSAGE OF UPPER LEVEL
RIDGE.  ATTENTION THEN TURNS UPSTREAM STARTING SAT NIGHT.
THERMODYNAMIC AND KINEMATIC FORCING WILL BOTH INCREASE AHEAD OF
APPROACHING LONG WAVE TROUGH.  THIS WILL SPREAD PRECIP INTO THE MO
VALLEY LATER SAT NIGHT AND INTO SUN.  QUESTION THEN BECOMES
SEPARATION AND RECOVERY BETWEEN THIS EVENT AND POTENTIAL SURFACE
BASED CONVECTION ALONG FRONT DURING PEAK HEATING.  SEVERE POTENTIAL
IS CERTAINLY THERE IF ANYTHING DEVELOPS...ESPECIALLY FROM
SOUTHERN IA FARTHER SOUTH NEAR PROXIMITY TO SURFACE WARM FRONT
DEPICTED BY 12Z ECMWF AND ALSO CLOSER TO SRN PLAINS JET. ALL MODES
OF SEVERE WEATHER WOULD BE POSSIBLE INCLUDING TORNADOES AND CANNOT
ARGUE WITH CURRENT SPC DAY 4 OUTLOOK. ALTHOUGH SYSTEM WILL BE
SOMEWHAT LESS IMPRESSIVE BY MON...SEVERE POTENTIAL WILL STILL BE
THERE AS SURFACE LOW LIFTS INTO ERN SD. INSTABILITY MAY BE
SOMEWHAT LESS BUT ANYTHING THAT DEVELOPS COULD CERTAINLY BE
ORGANIZED AND SUPERCELLULAR AS UPPER LEVEL JET LIFTS NORTHWARD
INCREASING DEEP SHEAR.

UPPER LEVEL SYSTEM OPENS UP AND DRIFTS EASTWARD TUE INTO LATE WED
KEEPING RELATIVELY UNSTABLE AIRMASS IN PLACE AND THE POTENTIAL FOR
ADDITIONAL CONVECTION. LITTLE AIRMASS CHANGE BEHIND THIS SYSTEM
WITH AT LEAST SEASONAL TEMPERATURES INTO NEXT WEEK.

&&

.AVIATION...17/00Z
 ISSUED AT 625 PM CDT THU MAY 16 2013

THUNDERSTORMS WILL AFFECT THE AREA TONIGHT BUT REMAIN ISOLATED AT
IN SOUTHERN AND EASTERN AREAS. AT KFOD/KMCW WHERE THUNDERSTORMS
ARE MORE LIKELY HAVE INCLUDED VCTS AND A TEMPO AT KFOD...BUT
AMENDMENTS ARE A DISTINCT POSSIBILITY DUE TO THE UNPREDICTABLE AND
PULSEY NATURE OF THE STORMS. ASIDE FROM THAT...LIGHT BR IS POSSIBLE
DURING THE EARLY MORNING HOURS FRIDAY BUT GIVEN CURRENT DEWPOINT
DEPRESSIONS AND LACK OF RECENT RAINFALL IN MANY AREAS HAVE NOT
GONE LOWER THAN 6SM BR FOR NOW AND WILL REASSESS FOR THE 06Z
ISSUANCE. VFR CONDITIONS ARE EXPECTED TO PREVAIL ON FRIDAY.

&&

.DMX WATCHES/WARNINGS/ADVISORIES...NONE.

&&

$$

SHORT TERM...AWB
LONG TERM...SMALL
AVIATION...LEE

000
FXUS63 KDVN 162323
AFDDVN

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE QUAD CITIES IA IL
623 PM CDT THU MAY 16 2013

.SYNOPSIS...
ISSUED AT 325 PM CDT THU MAY 16 2013

SURFACE FRONT EARLY THIS AFTERNOON REMAINED STALLED FROM SOUTHERN OH
AND IN...W-NW ACROSS CENTRAL IL THROUGH THE FAR SE TIP OF IA TO NEAR
OMAHA. TEMPERATURES WERE IN THE 80S OVER MUCH OF THE AREA...WITH THE
FRONT ACTING PRIMARILY AS A MOISTURE BOUNDARY. SURFACE DEWPOINTS
WERE IN THE 60S TO ITS SOUTH...WHILE 40S ENCOMPASSED MOST OF THE
DVN FORECAST AREA TO THE NORTH. AREA RADARS SHOW THIS BOUNDARY LIT
UP WITH SCATTERED THUNDERSTORMS FROM SOUTHERN INDIANA TO NEAR KEOKUK.
IN THE BIGGER PICTURE...A SLOW MOVING UPPER LOW WAS ROLLING INTO
NORTHEAST AR...HELPING MAINTAIN AN AXIS OF GULF MOISTURE AT 850 MB
FROM KS THROUGH MO INTO THE OHIO RIVER VALLEY. TO THE WEST...A
SHORTWAVE AND ACCOMPANYING MCS WAS OVER NORTHEAST NEB. A SECONDARY...
PERHAPS STRONGER STRONGER SHORTWAVE AND THUNDERSTORM COMPLEX WAS
MOVING INTO SW NEB. THESE FEATURES CREATE A CHALLENGING FORECAST
FOR PRECIPITATION CHANCES IN THE IN THE SHORT TERM THROUGH
FRIDAY...THEN ATTENTION TURNS TO A MORE SIGNIFICANT SYSTEM AND
POSSIBLE SEVERE WEATHER OUTBREAK LATE IN THE WEEKEND INTO EARLY
NEXT WEEK.

&&

.SHORT TERM...(THIS EVENING THROUGH FRIDAY)
ISSUED AT 325 PM CDT THU MAY 16 2013

POOR INITIALIZATION AND HANDLING OF CONVECTIVE TRENDS IN BOTH THE SHORT
TERM MODELS AND SYNOPTIC SCALE MODELS...ALONG WITH A COMPLEX
INTERACTION OF LARGE SCALE FEATURES LENDS TO A LOW CONFIDENCE
FORECAST IN THE EVOLUTION OF THUNDERSTORM CHANCES THROUGH FRIDAY.
IN THE SHORT TERM...HIGH RESOLUTION MODELS DEPICT THE FRONT
LIFTING NORTH THIS EVENING IN ADVANCE OF THE NORTHEAST NEB
THUNDERSTORM COMPLEX MOVING INTO NW IA. THE POTENTIAL FOR
SUSTAINED THUNDERSTORMS WILL BE LIMITED BY A WEAK...SUBSIDENT FLOW
ALOFT AND WEAK MID LEVEL RIDGING IN PLACE OVER THE AREA INDUCED BY
THE UPPER LOW PASSING TO THE NORTH THIS EVENING. FOR NOW...WILL
FOLLOW TRENDS FROM 12Z MODELS...THAT WERE LESS BULLISH ON
THUNDERSTORMS ALONG WARM FRONT THIS EVENING...KEEPING SLIGHT
CHANCES GOING THROUGH MID EVENING SOUTH OF I-80. NONE OF THE 12Z
MODELS HAD A DECENT HANDLE ON THE LOCATIONS OF THE MCS COMPLEXES
MOVING THROUGH THE PLAINS AT 18Z. AS EVIDENT BY THE RECENT
OBSERVATION WITH .69 INCHES OF RAIN IN LESS THAN AN HOUR FROM A
SMALL CELL OVER KEOKUK...AND PUBLIC REPORT OF 1.09 IN HANCOCK
COUNTY...WHERE RAIN DOES FALL...LOCALLY MODERATE TO HEAVY RAINFALL
WILL BE POSSIBLE. STORMS LATE THIS AFTERNOON AND EARLY EVENING
WILL WILL BE PULSE TYPE AND SLOW MOVING. LATER TONIGHT...HAVE
POPS RAMPING BACK UP AS THE LEAD SHORTWAVE PASSES TO THE
NORTH...POSSIBLY REINVIGORATING CONVECTION ON THE SURFACE AND 850
MB FRONT OVER THE CENTRAL AND NORTHERN HALF OF THE FORECAST AREA.
OVERNIGHT LOWS WILL RANGE FROM THE LOWER 50S IN THE DRIER AIRMASS
MAINTAINED OVER FAR NW IL...TO THE LOWER 60S ACROSS THE SOUTH.

FRIDAY...THE SECONDARY SHORTWAVE IN WESTERN NEBRASKA ROLLS ACROSS
NORTHERN IA AROUND MIDDAY WHILE THE CENTRAL MS VALLEY LOW PASSES
INTO THE OHIO RIVER VALLEY. THE BULK OF THE FORCING IS AGAIN
DEPICTED NORTH OF THE AREA...BUT ANY LIFT OVER THE FORECAST AREA
WILL HAVE A HIGHER PW AIRMASS TO PRODUCE SCATTERED SHOWERS AND
THUNDERSTORMS...ESPECIALLY DURING PEAK HEATING. SEVERE WEATHER IS
NOT EXPECTED DUE TO A LACK OF SHEAR OR STRONG BOUNDARIES.THE AIRMASS
CURRENTLY ACROSS SOUTHERN IL AND MO WILL BE IN PLACE OVER THE
FORECAST AREA BY AFTERNOON...SUPPORTING HIGHS FROM THE UPPER 70S TO
LOWER 80S WITH HIGHER HUMIDITY AS DEWPOINTS SHOULD BE IN THE UPPER
50S TO LOWER 60S.

.LONG TERM...(FRIDAY NIGHT THROUGH THURSDAY)
ISSUED AT 325 PM CDT THU MAY 16 2013

...SEVERE WEATHER POSSIBLE SUNDAY AND MONDAY...

FRIDAY NIGHT THROUGH NEXT THURSDAY...
SATURDAY WILL BE A WARM DAY WITH A SHORTWAVE RIDGE ALOFT OVER THE
MIDWEST. MODEL SHOW SURFACE BASED CAPES ARE AROUND 2000 J/KG BUT
TEMPERATURES ALOFT ARE WARM ENOUGH TO KEEP THE AREA CAPPED SO
CONVECTIVE INITIATION IS NOT ANTICIPATED. HIGH TEMPERATURES WILL
RANGE AROUND 80 DEGREES.

SUNDAY...SHORT RANGE MODELS SHOW NEGATIVE TILTED UPPER TROF WITH A
SURFACE LOW OVER THE UPPER MIDWEST THAT WILL LIKELY PRODUCE STRONG
THUNDERSTORMS IN OR NEAR THE FORECAST AREA DURING THE AFTERNOON.
SUNDAY MORNING LOOKS TO BE MUGGY WITH TEMPERATURES RISING INTO THE
MID TO UPPER 80S BY AFTERNOON WITH SURFACE DEWPOINTS CLIMBING INTO
THE LOW TO MID 60S. THESE TEMPERATURES WILL DESTABILIZE THE
ATMOSPHERE AND INCREASE CAPES BETWEEN 2500 TO 3000 J/KG. CURRENT
MODELS INDICATE LATE DAY CONVECTION MAY BEGIN OVER WESTERN IOWA AND
MOVE EAST TOWARD THE MISSISSIPPI VALLEY SUNDAY NIGHT. STRONG OR
SEVERE THUNDERSTORMS WITH HEAVY RAIN ARE LIKELY OVERNIGHT. I WILL
CONTINUE TO CARRY CURRENT FORECAST LIKELY POPS.

MONDAY...LATEST MODELS INDICATE THERE IS AN INCREASING CHANCE FOR
SEVERE THUNDERSTORMS/SUPERCELLS MONDAY AFTERNOON WHEN THE STRONGEST
UPPER LEVEL FORCING OCCURS...ALONG WITH A WELL DESTABILIZED
ATMOSPHERE AND SURFACE FRONT MOVING ACROSS THE AREA. MODEL SOLUTIONS
VARY AS TO WHERE THE LOCATION AND TIMING OF THE BEST SYNOPTIC
FORCING WILL BE...BUT THEY ALL CONTINUE TO MAINTAIN A NEGATIVELY
TILTED TROF OVER THE UPPER MID WEST. THE LOW BECOMES NEARLY
VERTICALLY STACKED AS IT MOVES TOWARD MINNESOTA. WITH A WARM FRONT
HAVING PASSED WELL NORTH OF THE REGION ON SUNDAY..AMPLE MOISTURE
ADVECTION FROM THE GULF OF MEXICO WILL KEEP DEWPOINTS IN THE MID 60S
WITH HIGH TEMPERATURES IN THE MID TO UPPER 70S PRODUCING HIGH CAPE
VALUES. KEEPING LIKELY POPS IN THE CURRENT FORECAST SEEMS REASONABLE.

DUE TO VARYING MODEL SOLUTIONS AND THE LOCATION OF BOUNDARIES LEFT
OVER FROM SUNDAYS CONVECTION...CONFIDENCE IS HIGH SEVERE WEATHER
WILL OCCUR IN OR NEAR THE FORECAST AREA. CONFIDENCE IS LOW AS TO THE
EXACT LOCATION.

TUESDAY THROUGH THURSDAY...CONSENSUS MODEL SOLUTIONS DIVERGE IN
EVOLUTION OF THE CLOSED UPPER LOW BUT THE OVERALL TREND IS FOR THE
SYSTEM TO MEANDER OVER THE MISSISSIPPI VALLEY. WITH WEAK VORT MAXES
ROTATING AROUND THE UPPER LOW AND COOL TEMPERATURES ALOFT THERE WILL
BE A CHANCE OF THUNDERSTORMS TUESDAY AND WEDNESDAY. BY
THURSDAY...THE MODELS MOVE THE UPPER LOW SOUTHEAST AND BUILD A LONG
WAVE RIDGE OVER THE MIDWEST. TEMPERATURES WILL BE AROUND 80 ON
WEDNESDAY BUT WILL BEGIN TO RISE AS AS HEIGHTS CONTINUE TO BUILD

&&

.AVIATION...(FOR THE 00Z TAFS THROUGH 00Z FRIDAY EVENING)
ISSUED AT 618 PM CDT THU MAY 16 2013

A CHALLENGING NEXT 24 HOURS OF AVIATION IS EXPECTED AS WE SEE A
WEAK WARM FRONT GRADUALLY LIFT FROM SOUTHEAST IOWA INTO NORTHERN
ILLINOIS FROM TONIGHT THROUGH FRIDAY AFTERNOON. AS THIS
OCCURS...CONDITIONS WILL REMAIN MAINLY VFR ON A WIDESPREAD
NATURE...HOWEVER...ISOLATED TO SCATTERED SHOWERS AND THUNDERSTORMS
WILL CONTINUE TO BE A THREAT ALONG THE FRONT. THIS WILL BE MAINLY
THIS EVENING AROUND BRL...AND FROM LATE TONIGHT THROUGH THE
AFTERNOON HOURS FRIDAY AT MLI...CID...AND DBQ. THE COVERAGE OF
STORMS IS NOT WIDESPREAD ENOUGH TO WARRANT MORE THAN A VICINITY
MENTION WITHIN TAF FORECASTS. THAT SAID...INDIVIDUAL STORMS WILL
CERTAINLY BE CAPABLE OF BRIEF HEAVY RAINFALL...AND THUS COULD
RESTRICT VISIBILITIES TO UNDER 2 MILES FOR A BRIEF PERIOD. CURRENT
TRENDS WILL BE WATCHED CAREFULLY...AND UPDATES TO TAFS WILL BE
ISSUED AS CONVECTIVE TRENDS EVOLVE.
ERVIN

&&

.DVN WATCHES/WARNINGS/ADVISORIES...
IA...NONE.
IL...NONE.
MO...NONE.
&&

$$

SYNOPSIS...SHEETS
SHORT TERM...SHEETS
LONG TERM...KUHL
AVIATION...ERVIN

000
FXUS63 KDMX 162110
AFDDMX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE DES MOINES IA
410 PM CDT THU MAY 16 2013

.SHORT TERM.../TONIGHT/
ISSUED AT 410 PM CDT THU MAY 16 2013

FORECAST CONCERN FOR PERIOD AGAIN BECOMES POPS AND CHANCES FOR
CONVECTION ACROSS THE AREA THIS EVENING AND OVERNIGHT. WEAK BOUNDARY
LOCATED ACROSS NORTHERN MISSOURI/SOUTHERN AND WESTERN IOWA HAS
BECOME FOCUS FOR STORM DEVELOPMENT LATE IN THE AFTERNOON ACROSS THE
EAST. ACROSS SOUTH CENTRAL IOWA...REMNANT CIRRUS FROM MORNING
CONVECTION HAS PREVENTS CU FIELD FROM FORMING...WHICH MAY HELP LIMIT
CONVECTION POTENTIAL FOR THE LATE AFTERNOON AND EVENING HOURS.
HOWEVER..CAPE VALUES REMAIN HIGH ACROSS THE AREA...AND BOUNDARY MAY
BE ENOUGH FORCING TO GET STORMS. SHEAR IS EXTREMELY LIMITED...BUT
WITH HIGH CAPE VALUES ANY STORMS MAY BE ABLE TO MAINTAIN
THEMSELVES...AND MAY BECOME BRIEFLY SEVERE. HAVE THEREFORE KEPT
ISOLATED THUNDER CHANCES ACROSS THE SOUTH AND WEST.

FOR THE REST OF THE OVERNIGHT PERIOD...APPROACHING FRONTAL BOUNDARY
CURRENTLY PRODUCING PRECIPITATION ACROSS EASTERN NEBRASKA AND SOUTH
DAKOTA WILL CONTINUE TO PUSH EASTWARD OVERNIGHT. HOWEVER...BEST
FORCING AND TRACK OF SYSTEM AND EMBEDDED SHORTWAVE WILL TAKE BEST
PRECIP NORTHEAST OF CWA. MAY SEE SOME HEAVIER PRECIP AMOUNTS IN THE
FAR NORTHEAST OVERNIGHT...BUT BEST CHANCES WILL BE OUTSIDE THE CWA.
HAVE KEPT HIGH POPS FOR THE NORTH OVERNIGHT HOWEVER WITH GOOD
CONFIDENCE IN TRACK OF SYSTEM CONTINUING INTO IOWA. HAVE LESS
CONFIDENCE FURTHER SOUTH ACROSS CENTRAL IOWA OVERNIGHT...BUT MAY SEE
AT LEAST LIGHT PRECIPITATION.

OVERNIGHT LOW BECOME TRICKY WITH CLOUD INFLUENCES AS CLOUDS INCREASE
ACROSS THE AREA. HOWEVER...HAVE KEPT NEAR GOING AND NEAR
GUIDANCE...EXCEPT IN THE NORTH WHERE TEMPERATURES WARMED INTO THE
MID 80S TODAY...AND WILL BE SLOW TO FALL OFF BEFORE CLOUDS ARRIVE.
HAVE THEREFORE BUMPED LOWS UP A FEW DEGREES ACROSS THE NORTH.

.LONG TERM.../FRIDAY THROUGH THURSDAY/
ISSUED AT 410 PM CDT THU MAY 16 2013

CONVECTIVE TRENDS WILL OBVIOUSLY BE THE PRIMARY CONCERN THROUGH
MUCH OF THE PERIOD.  EXPECT REMNANTS OF CURRENT NE MCS TO STILL BE
AFFECTING NRN IA BY BEGINNING OF THE PERIOD. KINEMATIC FORCING
COMPONENT WILL HAVE LIKELY PASSED INTO THE UPPER MS VALLEY WITH
CURRENT NE SHORT WAVE...HOWEVER LINGERING WARM ADVECTION SHOULD
SUSTAIN CONVECTION FARTHER WEST INTO FRI AS WARM FRONT ESTABLISHES
ITSELF ALONG OR JUST NORTH OF THE IA/MN BORDER. EXAMINATION OF
ELEVATED CAPE SUGGESTS LITTLE INHIBITION WITH CAPES 500-1000 J/KG.
ESTIMATED EFFECTIVE SHEAR ALSO LOOKS SUFFICIENT TO MAINTAIN
MINIMAL SEVERE POTENTIAL EARLY...MAINLY IN THE FORM OF LARGE
HAIL. REMAINDER OF DAY SHOULD SEE TYPICAL DIURNAL DECREASE IN WARM
ADVECTION FORCED PRECIP ALTHOUGH HAVE KEPT LOW POPS GOING LATE.
FORECAST SOUNDINGS AND PROJECTED CAPES/CINS SUGGEST SURFACE BASED
CONVECTION WILL BE POSSIBLE...BUT SYNOPTIC BOUNDARY WILL LIKELY BE
INTO MN BY THAT TIME WITH NEXT ROUND OF THETA-E ADVECTION HEADING
INTO THE NIGHT FARTHER NORTH AS WELL. TRIGGER WOULD LIKELY HAVE TO
ORIGINATE FROM LINGERING OUTFLOW BOUNDARY.

CONVECTION POTENTIAL SHOULD PUSH NORTHWARD BY FRI NIGHT AND SAT WITH
IA IN THE WARM SECTOR AND INFLUENCED BY PASSAGE OF UPPER LEVEL
RIDGE.  ATTENTION THEN TURNS UPSTREAM STARTING SAT NIGHT.
THERMODYNAMIC AND KINEMATIC FORCING WILL BOTH INCREASE AHEAD OF
APPROACHING LONG WAVE TROUGH.  THIS WILL SPREAD PRECIP INTO THE MO
VALLEY LATER SAT NIGHT AND INTO SUN.  QUESTION THEN BECOMES
SEPARATION AND RECOVERY BETWEEN THIS EVENT AND POTENTIAL SURFACE
BASED CONVECTION ALONG FRONT DURING PEAK HEATING.  SEVERE POTENTIAL
IS CERTAINLY THERE IF ANYTHING DEVELOPS...ESPECIALLY FROM
SOUTHERN IA FARTHER SOUTH NEAR PROXIMITY TO SURFACE WARM FRONT
DEPICTED BY 12Z ECMWF AND ALSO CLOSER TO SRN PLAINS JET. ALL MODES
OF SEVERE WEATHER WOULD BE POSSIBLE INCLUDING TORNADOES AND CANNOT
ARGUE WITH CURRENT SPC DAY 4 OUTLOOK. ALTHOUGH SYSTEM WILL BE
SOMEWHAT LESS IMPRESSIVE BY MON...SEVERE POTENTIAL WILL STILL BE
THERE AS SURFACE LOW LIFTS INTO ERN SD. INSTABILITY MAY BE
SOMEWHAT LESS BUT ANYTHING THAT DEVELOPS COULD CERTAINLY BE
ORGANIZED AND SUPERCELLULAR AS UPPER LEVEL JET LIFTS NORTHWARD
INCREASING DEEP SHEAR.

UPPER LEVEL SYSTEM OPENS UP AND DRIFTS EASTWARD TUE INTO LATE WED
KEEPING RELATIVELY UNSTABLE AIRMASS IN PLACE AND THE POTENTIAL FOR
ADDITIONAL CONVECTION. LITTLE AIRMASS CHANGE BEHIND THIS SYSTEM
WITH AT LEAST SEASONAL TEMPERATURES INTO NEXT WEEK.

&&

.AVIATION...16/18Z
ISSUED AT 1237 PM CDT THU MAY 16 2013

CEILINGS WILL REMAIN VFR THROUGH BEGINNING OF PERIOD WITH WINDS
FROM THE SE...AND MAY BE GUSTY BEFORE 00Z. APPROACHING BOUNDARY
WILL BRING AN INCREASE IN CLOUDS AND MAY SEE CEILINGS DROP TO LOW
VFR. IN ADDITION...PRECIPITATION CHANCES AT SITES INCREASING FROM
WEST TO EAST FOR LATE IN THE PERIOD. HAVE NOT INCLUDED MENTION
RA/TSRA AT SITES WITH UNCERTAINTY IN TIMING AND LOCATION ATTM...BUT
HAVE CONTINUED TREND OF LOWER CLINGS. MAY SEE MVFR OR LOWER
CEILINGS IF PRECIP IMPACTS SITES OVERNIGHT...BEFORE CONDITIONS
IMPROVE EARLY FRIDAY.

&&

.DMX WATCHES/WARNINGS/ADVISORIES...NONE.

&&

$$

SHORT TERM...AWB
LONG TERM...SMALL
AVIATION...AWB

000
FXUS63 KDVN 162034
AFDDVN

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE QUAD CITIES IA IL
334 PM CDT THU MAY 16 2013

.SYNOPSIS...
ISSUED AT 325 PM CDT THU MAY 16 2013

SURFACE FRONT EARLY THIS AFTERNOON REMAINED STALLED FROM SOUTHERN OH
AND IN...W-NW ACROSS CENTRAL IL THROUGH THE FAR SE TIP OF IA TO NEAR
OMAHA. TEMPERATURES WERE IN THE 80S OVER MUCH OF THE AREA...WITH THE
FRONT ACTING PRIMARILY AS A MOISTURE BOUNDARY. SURFACE DEWPOINTS
WERE IN THE 60S TO ITS SOUTH...WHILE 40S ENCOMPASSED MOST OF THE
DVN FORECAST AREA TO THE NORTH. AREA RADARS SHOW THIS BOUNDARY LIT
UP WITH SCATTERED THUNDERSTORMS FROM SOUTHERN INDIANA TO NEAR KEOKUK.
IN THE BIGGER PICTURE...A SLOW MOVING UPPER LOW WAS ROLLING INTO
NORTHEAST AR...HELPING MAINTAIN AN AXIS OF GULF MOISTURE AT 850 MB
FROM KS THROUGH MO INTO THE OHIO RIVER VALLEY. TO THE WEST...A
SHORTWAVE AND ACCOMPANYING MCS WAS OVER NORTHEAST NEB. A SECONDARY...
PERHAPS STRONGER STRONGER SHORTWAVE AND THUNDERSTORM COMPLEX WAS
MOVING INTO SW NEB. THESE FEATURES CREATE A CHALLENGING FORECAST
FOR PRECIPITATION CHANCES IN THE IN THE SHORT TERM THROUGH
FRIDAY...THEN ATTENTION TURNS TO A MORE SIGNIFICANT SYSTEM AND
POSSIBLE SEVERE WEATHER OUTBREAK LATE IN THE WEEKEND INTO EARLY
NEXT WEEK.

&&

.SHORT TERM...(THIS EVENING THROUGH FRIDAY)
ISSUED AT 325 PM CDT THU MAY 16 2013

POOR INITIALIZATION AND HANDLING OF CONVECTIVE TRENDS IN BOTH THE SHORT
TERM MODELS AND SYNOPTIC SCALE MODELS...ALONG WITH A COMPLEX
INTERACTION OF LARGE SCALE FEATURES LENDS TO A LOW CONFIDENCE
FORECAST IN THE EVOLUTION OF THUNDERSTORM CHANCES THROUGH FRIDAY.
IN THE SHORT TERM...HIGH RESOLUTION MODELS DEPICT THE FRONT
LIFTING NORTH THIS EVENING IN ADVANCE OF THE NORTHEAST NEB
THUNDERSTORM COMPLEX MOVING INTO NW IA. THE POTENTIAL FOR
SUSTAINED THUNDERSTORMS WILL BE LIMITED BY A WEAK...SUBSIDENT FLOW
ALOFT AND WEAK MID LEVEL RIDGING IN PLACE OVER THE AREA INDUCED BY
THE UPPER LOW PASSING TO THE NORTH THIS EVENING. FOR NOW...WILL
FOLLOW TRENDS FROM 12Z MODELS...THAT WERE LESS BULLISH ON
THUNDERSTORMS ALONG WARM FRONT THIS EVENING...KEEPING SLIGHT
CHANCES GOING THROUGH MID EVENING SOUTH OF I-80. NONE OF THE 12Z
MODELS HAD A DECENT HANDLE ON THE LOCATIONS OF THE MCS COMPLEXES
MOVING THROUGH THE PLAINS AT 18Z. AS EVIDENT BY THE RECENT
OBSERVATION WITH .69 INCHES OF RAIN IN LESS THAN AN HOUR FROM A
SMALL CELL OVER KEOKUK...AND PUBLIC REPORT OF 1.09 IN HANCOCK
COUNTY...WHERE RAIN DOES FALL...LOCALLY MODERATE TO HEAVY RAINFALL
WILL BE POSSIBLE. STORMS LATE THIS AFTERNOON AND EARLY EVENING
WILL WILL BE PULSE TYPE AND SLOW MOVING. LATER TONIGHT...HAVE
POPS RAMPING BACK UP AS THE LEAD SHORTWAVE PASSES TO THE
NORTH...POSSIBLY REINVIGORATING CONVECTION ON THE SURFACE AND 850
MB FRONT OVER THE CENTRAL AND NORTHERN HALF OF THE FORECAST AREA.
OVERNIGHT LOWS WILL RANGE FROM THE LOWER 50S IN THE DRIER AIRMASS
MAINTAINED OVER FAR NW IL...TO THE LOWER 60S ACROSS THE SOUTH.

FRIDAY...THE SECONDARY SHORTWAVE IN WESTERN NEBRASKA ROLLS ACROSS
NORTHERN IA AROUND MIDDAY WHILE THE CENTRAL MS VALLEY LOW PASSES
INTO THE OHIO RIVER VALLEY. THE BULK OF THE FORCING IS AGAIN
DEPICTED NORTH OF THE AREA...BUT ANY LIFT OVER THE FORECAST AREA
WILL HAVE A HIGHER PW AIRMASS TO PRODUCE SCATTERED SHOWERS AND
THUNDERSTORMS...ESPECIALLY DURING PEAK HEATING. SEVERE WEATHER IS
NOT EXPECTED DUE TO A LACK OF SHEAR OR STRONG BOUNDARIES.THE AIRMASS
CURRENTLY ACROSS SOUTHERN IL AND MO WILL BE IN PLACE OVER THE
FORECAST AREA BY AFTERNOON...SUPPORTING HIGHS FROM THE UPPER 70S TO
LOWER 80S WITH HIGHER HUMIDITY AS DEWPOINTS SHOULD BE IN THE UPPER
50S TO LOWER 60S.

.LONG TERM...(FRIDAY NIGHT THROUGH THURSDAY)
ISSUED AT 325 PM CDT THU MAY 16 2013

...SEVERE WEATHER POSSIBLE SUNDAY AND MONDAY...

FRIDAY NIGHT THROUGH NEXT THURSDAY...
SATURDAY WILL BE A WARM DAY WITH A SHORTWAVE RIDGE ALOFT OVER THE
MIDWEST. MODEL SHOW SURFACE BASED CAPES ARE AROUND 2000 J/KG BUT
TEMPERATURES ALOFT ARE WARM ENOUGH TO KEEP THE AREA CAPPED SO
CONVECTIVE INITIATION IS NOT ANTICIPATED. HIGH TEMPERATURES WILL
RANGE AROUND 80 DEGREES.

SUNDAY...SHORT RANGE MODELS SHOW NEGATIVE TILTED UPPER TROF WITH A
SURFACE LOW OVER THE UPPER MIDWEST THAT WILL LIKELY PRODUCE STRONG
THUNDERSTORMS IN OR NEAR THE FORECAST AREA DURING THE AFTERNOON.
SUNDAY MORNING LOOKS TO BE MUGGY WITH TEMPERATURES RISING INTO THE
MID TO UPPER 80S BY AFTERNOON WITH SURFACE DEWPOINTS CLIMBING INTO
THE LOW TO MID 60S. THESE TEMPERATURES WILL DESTABILIZE THE
ATMOSPHERE AND INCREASE CAPES BETWEEN 2500 TO 3000 J/KG. CURRENT
MODELS INDICATE LATE DAY CONVECTION MAY BEGIN OVER WESTERN IOWA AND
MOVE EAST TOWARD THE MISSISSIPPI VALLEY SUNDAY NIGHT. STRONG OR
SEVERE THUNDERSTORMS WITH HEAVY RAIN ARE LIKELY OVERNIGHT. I WILL
CONTINUE TO CARRY CURRENT FORECAST LIKELY POPS.

MONDAY...LATEST MODELS INDICATE THERE IS AN INCREASING CHANCE FOR
SEVERE THUNDERSTORMS/SUPERCELLS MONDAY AFTERNOON WHEN THE STRONGEST
UPPER LEVEL FORCING OCCURS...ALONG WITH A WELL DESTABILIZED
ATMOSPHERE AND SURFACE FRONT MOVING ACROSS THE AREA. MODEL SOLUTIONS
VARY AS TO WHERE THE LOCATION AND TIMING OF THE BEST SYNOPTIC
FORCING WILL BE...BUT THEY ALL CONTINUE TO MAINTAIN A NEGATIVELY
TILTED TROF OVER THE UPPER MID WEST. THE LOW BECOMES NEARLY
VERTICALLY STACKED AS IT MOVES TOWARD MINNESOTA. WITH A WARM FRONT
HAVING PASSED WELL NORTH OF THE REGION ON SUNDAY..AMPLE MOISTURE
ADVECTION FROM THE GULF OF MEXICO WILL KEEP DEWPOINTS IN THE MID 60S
WITH HIGH TEMPERATURES IN THE MID TO UPPER 70S PRODUCING HIGH CAPE
VALUES. KEEPING LIKELY POPS IN THE CURRENT FORECAST SEEMS REASONABLE.

DUE TO VARYING MODEL SOLUTIONS AND THE LOCATION OF BOUNDARIES LEFT
OVER FROM SUNDAYS CONVECTION...CONFIDENCE IS HIGH SEVERE WEATHER
WILL OCCUR IN OR NEAR THE FORECAST AREA. CONFIDENCE IS LOW AS TO THE
EXACT LOCATION.

TUESDAY THROUGH THURSDAY...CONSENSUS MODEL SOLUTIONS DIVERGE IN
EVOLUTION OF THE CLOSED UPPER LOW BUT THE OVERALL TREND IS FOR THE
SYSTEM TO MEANDER OVER THE MISSISSIPPI VALLEY. WITH WEAK VORT MAXES
ROTATING AROUND THE UPPER LOW AND COOL TEMPERATURES ALOFT THERE WILL
BE A CHANCE OF THUNDERSTORMS TUESDAY AND WEDNESDAY. BY
THURSDAY...THE MODELS MOVE THE UPPER LOW SOUTHEAST AND BUILD A LONG
WAVE RIDGE OVER THE MIDWEST. TEMPERATURES WILL BE AROUND 80 ON
WEDNESDAY BUT WILL BEGIN TO RISE AS AS HEIGHTS CONTINUE TO BUILD
OVER OUR AREA AS THE UPPER RIDGE MOVES EAST. ..KUHL..
&&

.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z FRIDAY AFTERNOON)
ISSUED AT 1218 PM CDT THU MAY 16 2013

VFR AND LIGHT SOUTHEAST CONDITIONS TO PREVAIL THIS AFTERNOON
THROUGH FRIDAY MORNING. A STALLED SURFACE FRONT ACROSS FAR SOUTHERN
IA INTO CENTRAL IL WILL BE THE FOCUS FOR SHOWERS AND THUNDERSTORMS
THIS AFTERNOON...WHICH MAY IMPACT THE BRL SITE. OVERNIGHT...THERE
IS A LOW CHANCE OF THUNDERSTORMS AT ESPECIALLY CID AND DBQ AS THIS
BOUNDARY ADVANCES NORTHWARD. THIS IS HANDLED WITH PROB30 GROUPS
FOR LATE TONIGHT AND EARLY FRIDAY MORNING IN THE LATEST FORECAST
FOR CID AND DBQ.

&&

.DVN WATCHES/WARNINGS/ADVISORIES...
IA...NONE.
IL...NONE.
MO...NONE.
&&

$$

SYNOPSIS...SHEETS
SHORT TERM...SHEETS
LONG TERM...KUHL
AVIATION...SHEETS

000
FXUS63 KDMX 161740
AFDDMX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE DES MOINES IA
1240 PM CDT THU MAY 16 2013

.SHORT TERM.../TODAY /...
ISSUED AT 411 AM CDT THU MAY 16 2013

CLUSTER OF WEAK THUNDERSTORMS CONTINUES ACROSS THE SOUTHEASTERN CWA
IN AREA OF MOISTURE CONVERGENCE AND MOISTURE ADVECTION ALOFT. THIS
ACTIVITY IS EXPECTED TO WANE OVER THE NEXT FEW HOURS...AS MOISTURE
TRANSPORT ALOFT BECOMES ORIENTED FURTHER TO THE WEST AHEAD OF AN
APPROACHING MID LEVEL SHORTWAVE TROUGH. MOISTURE ADVECTION TO
INCREASE AND BECOME ORIENTED INTO THE SOUTHWESTERN TO WEST CENTRAL
CWA TOWARD MID MORNING TO MID AFTERNOON. THEREFORE COULD STILL SEE
SOME ISOLATED TO SCATTERED SHOWERS/THUNDERSTORMS ACROSS THE FAR
SOUTH THROUGHOUT THE MORNING...AND THEN WESTERN CWA THIS AFTERNOON.
BETTER CHANCES REMAIN WEST/NORTH OF THE CWA CLOSER TO THE UPPER
LEVEL SHORTWAVE TROUGH...SO STUCK WITH SLIGHT CHANCE/CHANCE POPS
ACROSS THE AREA. ANY ACTIVITY TO REMAIN ELEVATED FOR THE MOST
PART...HOWEVER NAM SOUNDINGS DO SUGGEST POTENTIAL FOR A FEW SURFACE
BASED STORMS THIS AFTERNOON. HOWEVER DEEP LAYER SHEAR REMAINS WEAK
SO ANY SEVERE POTENTIAL IS MINIMAL.

AIR MASS ALOFT IS SIMILAR TO YESTERDAY...BUT CLOUD COVER EXPECTED TO
BE HIGHER THUS KEPT MAX TEMPS NEAR PERSISTENCE FOR TODAY BUT WENT A
DEGREE OR TWO COOLER DUE TO CLOUD COVER/PRECIP CHANCES.

.LONG TERM.../TONIGHT THROUGH WEDNESDAY/...
ISSUED AT 411 AM CDT THU MAY 16 2013

VIGOROUS SHORT WAVE LIFTING NORTHEAST THROUGH COLORADO THIS
MORNING AND WILL ARRIVE OVER THE NORTHWEST PORTIONS OF THE REGION
TONIGHT. THE PREFERRED TRACK OF THIS SYSTEM HAS BEEN TRENDING
FARTHER TO THE NORTHWEST. THE FARTHEST NORTHWEST TRACKS WOULD KEEP
MUCH OF THE FORECAST AREA MOSTLY DRY TONIGHT INTO FRIDAY. THE LOW
LEVEL JET WILL BECOME RE-ESTABLISHED WEST OF IOWA THEN LEANING
NORTHEAST INTO MINNESOTA AS THE UPPER WAVE ARRIVES. AT THIS
POINT...HAVE KEPT POPS IN ESPECIALLY ACROSS THE NORTH WITH
GENERAL STEERING FLOW AND CORFIDI VECTORS POINTING EAST/SOUTHEAST.
THE WARM SECTOR WILL THEN BECOME ESTABLISHED OVER IOWA FRIDAY NIGHT
INTO SATURDAY.

THE UPPER RIDGE WILL BEGIN TO SHIFT EAST IN RESPONSE THE THE
DEEPENING TROUGH TO THE WEST WITH A CLOSE LOW EVENTUALLY
DEVELOPING ACROSS THE NORTHERN HIGH PLAINS ON SUNDAY. THIS WILL
BRING SOUTHWEST FLOW TO IOWA WITH SEVERAL PIECES OF ENERGY
RIPPLING THROUGH. THUNDERSTORMS WILL BEGIN TO ENTER WESTERN IOWA
AFTER MIDNIGHT SATURDAY THEN MORE PRONOUNCED CHANCES FOR
THUNDERSTORMS FOR LATE SUNDAY THROUGH MONDAY. THE POTENTIAL FOR
SEVERE WEATHER SUNDAY AND MONDAY STILL LOOKS THE BEST IT HAS THIS
SPRING. THE ENVIRONMENT WILL BE FAVORABLE FOR SUPERCELLS DURING
THIS PERIOD WITH GOOD INSTABILITY AND INCREASING SHEAR. AT THIS
TIME IT APPEARS FAVORABLE FOR TORNADIC ACTIVITY WHICH COULD PUT AN
END TO THE CURRENT TORNADO FREE STREAK ONGOING ACROSS IOWA.
TEMPERATURES THROUGH THE WEEKEND WILL BE ABOVE NORMAL AND IN THE
80S FOR SEVERAL DAYS. THE BOUNDARY WILL MOVE THROUGH MONDAY THEN
MORE SEASONAL WEATHER TO FOLLOW.

&&

.AVIATION...16/18Z
 ISSUED AT 1237 PM CDT THU MAY 16 2013

CEILINGS WILL REMAIN VFR THROUGH BEGINNING OF PERIOD WITH WINDS
FROM THE SE...AND MAY BE GUSTY BEFORE 00Z. APPROACHING BOUNDARY
WILL BRING AN INCREASE IN CLOUDS AND MAY SEE CEILINGS DROP TO LOW
VFR. IN ADDITION...PRECIPITATION CHANCES AT SITES INCREASING FROM
WEST TO EAST FOR LATE IN THE PERIOD. HAVE NOT INCLUDED MENTION
RA/TSRA AT SITES WITH UNCERTAINTY IN TIMING AND LOCATION ATTM...BUT
HAVE CONTINUED TREND OF LOWER CLINGS. MAY SEE MVFR OR LOWER
CEILINGS IF PRECIP IMPACTS SITES OVERNIGHT...BEFORE CONDITIONS
IMPROVE EARLY FRIDAY.

&&

.DMX WATCHES/WARNINGS/ADVISORIES...NONE.

&&

$$

SHORT TERM...BEERENDS
LONG TERM...DONAVON
AVIATION...AWB

000
FXUS63 KDVN 161740
AFDDVN

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE QUAD CITIES IA IL
1240 PM CDT THU MAY 16 2013

.UPDATE...
ISSUED AT 1218 PM CDT THU MAY 16 2013

SURFACE ANALYSIS FROM 15Z INDICATED THE PRIMARY STATIONARY FRONT
AT THE SURFACE REACHED FROM JUST SOUTH OF SPRINGFIELD IL THROUGH
KEOKUK...THEN W-NW TO NEAR OMAHA. THE REMNANTS OF THE OVERNIGHT
SHOWERS AND THUNDERSTORMS ACROSS THE SOUTH HAVE SINCE ZIPPERED
WEST AND FINALLY DISSIPATED ALONG THIS BOUNDARY OVER S CENTRAL AND
SW IA OVER THE LAST OUR. HOWEVER...NEW DEVELOPMENT WAS INDICATED
BY KILX 88D ALONG THE SURFACE BOUNDARY NEAR KSPI AND VISIBLE
SATELLITE IMAGERY REVEALED AN AGITATED CU FIELD EXTENDING
NORTHWEST FROM INTO FAR NE MO AND THE IA/MO BORDER REGION.

SHORT TERM HIGH RES MODELS AND LATEST TRENDS SUPPORT REDEVELOPMENT
OF SCATTERED SHOWERS AND THUNDERSTORMS ALONG AND NORTH OF THIS
BOUNDARY ACROSS THE FAR SOUTH THIS AFTERNOON. WEAK MID LEVEL
SUBSIDENCE INDUCED NORTH OF THE UPPER LOW OVER NE OK...ALONG WITH
DRY AIR AT 850 MB...HAS LIKELY HELPED DISSIPATE THE MID LEVEL CLOUDS
OVER THE NORTHERN HALF OF THE FORECAST AREA...AND WILL LIKELY KEEP
RAIN CHANCES LOW THERE THIS AFTERNOON. FORECAST THEN BECOMES MORE
COMPLEX TONIGHT AS AN ADVANCING SHORTWAVE AND THUNDERSTORM COMPLEX
ACROSS NORTH CENTRAL NEB CONTINUES TO ADVANCE EASTWARD...BUT WILL
BE HINDERED SOME ITS INTERACTION WITH THE LOW MOVING INTO THE MID
MS VALLEY. FOR NOW...WILL KEEP LOW CHANCES FOR THUNDERSTORMS GOING
OVER THE ENTIRE FORECAST AREA AS THE SURFACE FRONT WASHES OUT AND ADVANCES
NORTHWARD.

&&

.SYNOPSIS...
ISSUED AT 330 AM CDT THU MAY 16 2013

A STATIONARY FRONT IS DRAPED ALONG THE KANSAS/NEBRASKA
BORDER...ACROSS FAR NORTHERN MISSOURI...AND CONTINUING EAST ACROSS
CENTRAL ILLINOIS AND INDIANA.  THIS FRONT SERVED AS THE FOCUS FOR
SURFACE BASED CONVECTION LAST EVENING.  AT 850MB THE FRONT SURFACE
IS JUST A LITTLE WAYS NORTH OF THE SURFACE BOUNDARY...AND IS BEING
NICELY DEPICTED BY THE CONVECTION OVER SOUTHERN IOWA..AND ALSO
CONTINUING EAST INTO ILLINOIS AND INDIANA.  FROM THE 00Z UPPER AIR
ANALYSIS IT ALSO CONTINUES WEST TO NORTHEAST COLORADO...GENERALLY
NEAR OR JUST NORTH OF THE SURFACE BOUNDARY.  THE 850MB ANALYSIS ALSO
SHOWS PLENTY OF LOW LEVEL MOISTURE BEING ADVECTED NORTH AND
IMPINGING ON THE 850MB BOUNDARY...BUT NOT VERY STRONGLY AND IS ONLY
JUST ENOUGH TO PRODUCE THE SHOWERS AND THUNDERSTORMS WE HAVE ON THE
RADAR NOW.   LE

&&

.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 330 AM CDT THU MAY 16 2013

THE MAIN CONCERN THE NEXT 24 HOURS IS WHERE AND WHEN THE SHOWERS AND
THUNDERSTORMS WILL FORM.

TODAY...EXPECT THAT THIS CURRENT BAND OF CONVECTION IS GOING TO
GRADUALLY WEAKEN TOWARDS SUNRISE...THOUGH IT MAY FLARE A LITTLE
PERIODICALLY.  THEN...EXPECT SOME ISOLATED TO SCATTERED ACTIVITY
ALONG THE BOUNDARY DURING THE MORNING AND EARLY AFTERNOON AS STORMS
SETTLE DOWN AND THEN REFOCUS UPON THE SURFACE BOUNDARY DURING THE
AFTERNOON.  HOWEVER...BY THEN IT WILL BE SLOWLY PUSHING NORTH IN
RESPONSE TO A SHORTWAVE MOVING ACROSS THE PLAINS...AND NEW
CONVECTION FIRING OUT OVER NEBRASKA AND SOUTH DAKOTA THIS AFTERNOON.
SOME MODELS ARE HINTING THAT WE WILL HAVE LITTLE/NO CONVECTION OVER
THE AREA THIS AFTERNOON...BUT CANNOT RULE OUT SOME ISOLATED TO
SCATTERED ACTIVITY AS LOW LEVEL CAPES SHOULD APPROACH 1000-1500 SOUTH
OF THE FRONT AND WEAK LOW LEVEL CONVERGENCE ALONG IT SHOULD SERVE AS
A FOCUS.  DO NOT EXPECT ANY SEVERE STORMS OUT OF THIS...BUT SLOW
MOVING GARDEN VARIETY SHOWERS AND THUNDERSTORMS. HIGH TEMPERATURES
TODAY SHOULD BE FAIRLY CLOSE TO WHAT WE HAD YESTERDAY...IF SLIGHTLY
COOLER SOUTH WHERE MORE CLOUD COVER IS EXPECTED.

TONIGHT EXPECT THAT THE FRONT WILL CONTINUE TO SLOWLY PULL NORTH AS
THE CONVECTION OUT WEST FORMS INTO AN MCS OVER EASTERN SOUTH DAKOTA
AND NORTHEAST NEBRASKA AS WELL.  HAVE KEPT THE SLIGHT CHANCE POPS
GOING OVER THE CWA AS THE FRONT PULLS NORTH..BUT CONFIDENCE IS NOT
VERY HIGH.  IN FACT...THERE IS SOME RISK THAT THE MCS WILL MOVE EAST
AND BEGIN TO MOVE INTO THE FORECAST AREA BY 12Z...ESPECIALLY IF IT
CAN CAUSE SOME ACTIVITY TO ZIPPER ALONG THE FRONT TOWARDS US.
THUS...THE EVENING POPS ARE FAIRLY LOW...BUT HAVE RAMPED POPS UP TO
CHANCE CATEGORY AFTER MIDNIGHT.   MIN TEMPS IN THE 50S AND LOW 60S
CAN BE EXPECTED. HAVE COOLED OFF THE NORTHEAST AS WE MAY GET SOME
LAKE EFFECTS IN THERE AS THE WINDS TURN MORE NORTHEAST.    LE

.LONG TERM...(FRIDAY THROUGH NEXT WEDNESDAY)
ISSUED AT 330 AM CDT THU MAY 16 2013

FRIDAY AND SATURDAY...WILL CONTINUE TO KEEP CHC POPS FOR SHOWERS AND
THUNDERSTORMS ACRS THE CWA ON FRI WITH HIGHEST CHC AXIS ORIENTED
FROM NW-TO-SE ACRS FCST AREA. THIS IN AREA OF WARM AIR ADVECTION
WING ASSOCIATED WITH PROBABLY MCS MOVING ACRS FAR NORTHERN IA...MN
AND INTO WI. STILL A CHANCE FOR THE SOUTHEAST FLANK OF THE MAIN
SYSTEM ITSELF TO GRAZE THE FAR NORTHERN CWA FRI MORNING. ACTIVITY
SHOULD DIURNALLY WANE FRI AFTERNOON. SOME MODERATE AMOUNTS OF
RAINFALL POSSIBLE IN THE FAR NORTHERN CWA OR UNDER WAA WING AXIS.
LULLS OR BREAKS IN THE PRECIP TO ALLOW TEMPS TO WARM TO AROUND 80
BUT THEY MAY STAY COOLER IN THE 70S ACRS THE FAR NORTH IN
LINGERING CONVECTIVE ZONE AND CLOUD DEBRIS...EAST BOUNDARY LAYER
FLOW AS WELL NORTH OF LINGERING LLVL BOUNDARY. LATEST SUITE OF 00Z
MODEL RUNS AND ENSEMBLES CONTINUE TO TREND IN HANDLING OF L/W
UPPER TROF ESTABLISHING ACRS THE ROCKIES EFFECTIVELY ENHANCING
UPPER RIDGING TO TH EAST OF IT ACRS MUCH OF THE MID AND UPPER MS
RVR VALLEY REGIONS THROUGH SAT. THUS AFTER A CHANCE OF LINGERING
SHOWERS/STORMS EARLY FRI EVENING...THE DVN CWA MAY BE MAINLY DRY
THROUGH 12Z SUNDAY. FCST SOUNDINGS SUGGESTING BUILDING CAPPING
WARM WEDGE ALOFT ON SAT WILL ALSO HAMPER AMBIENT HEATING INDUCED
THUNDERSTORMS. LLVL MOISTURE FEED/WARM CONVEYOR UP TO THE LEE OF
SHEARING L/W TROF SUGGESTS THE SIGNIFICANT CONVECTION TO OCCUR
ACRS MAINLY THE CENTRAL INTO NORTHERN PLAINS DURING THE SECOND
HALF OF THIS PERIOD. WITH LACK OF PRECIP..SAT HIGHS WIDESPREAD IN
THE 80-85 DEGREE RANGE EXCEPT ALONG AND NORTH OF THE HWY 20
CORRIDOR.

SUNDAY AND MONDAY...ASSESSING THE LATEST RUNS...INCREASING NEG
TILTED UPPER TROF AND DEEPENING LLVL CYCLONE SOMEWHERE OVER THE
NORTHEASTERN PLAINS OR WESTERN MN THIS PERIOD STILL SUGGESTS A
POTENTIALLY SIGNIFICANT CONVECTIVE EVENT OR TWO MAY OCCUR IN OR
NEAR THE DVN CWA THIS PERIOD. BEST GUESS AT THIS POINT SUGGESTS MUCH
OF THE DAY SUNDAY TO BE DRY AND HEAT UP INTO THE MID TO UPPER 80S
WITH SFC DPTS MAKING IT INTO THE 60S FOR DECENT CAPE VALUES.
AFTERNOON CONVECTION MAY STILL LOOK TO TAKE OFF ACRS WESTERN INTO
CENTRAL IA...THEN LOOK TO PROPAGATE INTO THE DVN CWA SUNDAY NIGHT.
STRONG TO SVR CONVECTION POSSIBLE AS IT ARRIVES...AS WELL AS
LOCALLY HEAVY RAINFALL POSSIBLE OF OVER AN INCH BY MONDAY MORNING.
MONDAY STILL APPEARS A QUESTION MARK VERY MUCH DEPENDING ON WHAT
OCCURS OR LINGERS OUT OF SUNDAY NIGHT. CONVECTIVE DEBRIS AND OUTFLOW
LASTING LONG ENOUGH TO LIMIT INSTABILITY LOCALLY AND SHIFTING
STORM INITIATION JUST OFF TO THE EAST AND SOUTH...OR THE MORNING
DEBRIS CLEARS OFF IN TIME FOR RAPID DESTABILIZATION. THIS WOULD BE
TROUBLE AS SYNOPTICALLY STRONGEST FORCING OF THE PERIOD AND POSSIBLE
SUPERCELL/TORNADIC SET-UP WOULD LOOK TO TAKE PLACE AHEAD OF INCOMING
DRY SLOT ACRS AT LEAST THE EASTERN OF SOUTHEASTERN HALF OF THE DVN
CWA BY MONDAY AFTERNOON AND EVENING. HIGH CHC POPS OR EVEN SOME
LIKELY/S TO CONTINUE FROM SUNDAY NIGHT THROUGH MON...ALTHOUGH PLENTY
OF QUESTIONS CONTINUE BUT THE SIGNALS HAVE BEEN THERE FOR A FEW DAYS
NOW. DRY SLOT ASSOCIATED WITH A STRONG WRAPPED UP SYSTEM MAY BRING
LULL IN THE ACTIVITY LATE MON NIGHT INTO TUE.

TUESDAY AND WEDNESDAY...CLOSED OFF UPPER LOW BEING HANDLED
DIFFERENTLY BY SEVERAL OF THE MEDIUM RANGE MODELS THIS PERIOD...BUT
LONG RANGE SIGNALS SUGGEST IT TO BE BLOCKED OR GYRATE SLOWLY TOWARD
THE MID/UPPER MS RVR VALLEY THROUGH THE END OF THE LONG RANGE FOR
MORE SHOWERS AS IT BECOMES COOL CORE AND INDUCING UNSTABLE PARCELS.
HOW COOL CORE THE CLOSED LOW BECOMES AND WHERE IS VERY MUCH UP TO
DEBATE BETWEEN THE THE VARIOUS SOLUTIONS.    ..12..

&&

.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z FRIDAY AFTERNOON)
ISSUED AT 1218 PM CDT THU MAY 16 2013

VFR AND LIGHT SOUTHEAST CONDITIONS TO PREVAIL THIS AFTERNOON
THROUGH FRIDAY MORNING. A STALLED SURFACE FRONT ACROSS FAR SOUTHERN
IA INTO CENTRAL IL WILL BE THE FOCUS FOR SHOWERS AND THUNDERTORMS
THIS AFTERNOON...WHICH MAY IMPACT THE BRL SITE. OVERNIGHT...THERE
IS A LOW CHANCE OF THUNDERSTORMS AT ESPECIALLY CID AND DBQ AS THIS
BOUNDARY ADVANCES NORTHWARD. THIS IS HANDLED WITH PROB30 GROUPS
FOR LATE TONIGHT AND EARLY FRIDAY MORNING IN THE LATEST FORECAST
FOR CID AND DBQ.

&&

.DVN WATCHES/WARNINGS/ADVISORIES...
IA...NONE.
IL...NONE.
MO...NONE.
&&

$$

UPDATE...SHEETS
SYNOPSIS...LE
SHORT TERM...LE
LONG TERM...12
AVIATION...SHEETS