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000
FXUS66 KMTR 252155
AFDMTR

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SAN FRANCISCO BAY AREA
255 PM PDT SAT OCT 25 2014

.SYNOPSIS...A PACIFIC STORM WILL MOVE EAST OF THE AREA LATER
TONIGHT AND SUNDAY WITH A COOLER AND DRIER AIRMASS OVER THE AREA
SUNDAY. HIGH PRESSURE WILL BUILD OVER THE STATE FROM MONDAY
THROUGH MIDWEEK WITH A WARMING TREND EXPECTED. THE NEXT PACIFIC
STORM SHOULD REACH THE COAST BY LATE FRIDAY OR SATURDAY WITH
AN INCREASING CHANCE OF RAIN.

&&

.DISCUSSION...AS OF 02:28 PM PDT SATURDAY...LIGHT SHOWERS CONTINUE
TO DEVELOP OVER THE COASTAL MOUNTAINS ESPECIALLY NORTH BAY. EVEN A
COUPLE SHOWERS SHOWING UP IN THE MONTEREY BAY AND SPREADING
EASTWARD. NOTED ONLY ONE LIGHTNING STRIKE SO FAR IN SONOMA
COUNTY...BUT POTENTIAL EXISTS THROUGH THE EARLY EVENING FOR
ADDITIONAL STRIKES FROM ABOUT THE SANTA CRUZ MOUNTAINS NORTHWARD.
IN ADDITION...OFFSHORE SHOWERS APPROACHING MARIN COUNTY AND NORTH
BAY COULD EVEN IMPACT CENTRAL AND NORTHERN SF BAY OVER THE NEXT
FEW HOURS. NOT EXPECTING ANY HEAVY AMOUNTS FROM THESE
SHOWERS...BUT COULD SEE A QUICK TENTH OF AN INCH OF SO FROM
STRONGER CELLS. MOST AREAS WILL SEE ONLY LIGHT PRECIPITATION IF ANY.

HRRR GUIDANCE SHOWS SURFACE WIND SHIFT WITH TROF AXIS MOVING
ONSHORE AROUND 02Z THIS EVENING. SUSPECT GREATEST CONCENTRATION OF
CONVECTION SHOULD OCCUR WITH THIS AXIS AS IT MOVES ONSHORE AND
THRU THE BAY AREA. HIT AND MISS SHOWERS WITH AN OUTSIDE CHANCE OF
A LATE AFTERNOON OR EVENING THUNDERSTORM SHOULD COME TO AN END BY
MIDNIGHT MOST AREAS.

DRIER AND COOLER AIRMASS WILL SET UP OVER THE CENTRAL COAST AREA
SUNDAY WITH 850 MB TEMPERATURES ONLY AROUND 6C. THE RIDGE
GRADUALLY BUILDS OVER CALIFORNIA INTO MIDWEEK WITH A WARMING
TREND. ATMOSPHERIC RIVER ENERGY SHOULD REMAIN NORTH OF OUR
FORECAST AREA WITH THE CLOSEST BRUSH WITH SONOMA COUNTY LATE
TUESDAY AND WEDNESDAY. KEEPING FORECAST DRY FOR NOW.

MAIN CONCERN IS NEXT PACIFIC TROF MOVING INTO THE AREA FRIDAY AND
SATURDAY. MODELS COMING INTO BETTER AGREEMENT ON PROGRESSING A
COLD FRONT THROUGH THE AREA. THERE ARE MINOR TIMING DIFFERENCES
WITH THE ECMWF FASTEST AND WEAKEST FORCING A COLD FRONT THROUGH
THE AREA FRIDAY. GFS SLIGHTLY SLOWER AND STRONGER WITH THE FRONT
FRIDAY NIGHT OR EARLY SATURDAY. GEM IS IN BETWEEN THE TWO OTHER
MODELS. THIS TROF IS DEEPER AND COLDER AND SHOULD BRING MUCH
NEEDED PRECIPITATION A LITTLE FURTHER SOUTH. STILL SEVERAL DAYS
AWAY SO DETAILS MAY CHANGE WITH FUTURE MODEL RUNS.

&&

.AVIATION...AS OF 4:45 AM PDT SATURDAY...A PRE-FRONTAL BOUNDARY
CONTINUES TO PUSH INLAND THIS MORNING WITH LIGHT RAIN IMPACTING
THE MONTEREY BAY AREA TERMINALS. FURTHER NORTH...RAIN SHOWERS ARE
DEVELOPING ALONG THE COLD FRONT THAT WILL PUSH INLAND THROUGH THE
AFTERNOON. IN ADDITION...A FEW THUNDERSTORMS WILL BE POSSIBLE
OVER THE NORTH BAY TERMINALS THIS AFTERNOON AND EVENING. WINDS
WILL INCREASE SLIGHTLY THIS AFTERNOON AND SHIFT TO THE NORTHWEST
IN WAKE OF THE FRONTAL PASSAGE. PRECIPITATION CHANCES DIMINISH
THROUGH THE LATE EVENING.

VICINITY OF KSFO...VFR WITH BRIEF MVFR CONDITIONS THROUGH THE
AFTERNOON/EVENING BENEATH SHOWER ACTIVITY. WIND SPEEDS WILL LIKELY
INCREASE THIS AFTERNOON AND BECOME MORE WESTERLY THROUGH THE
EVENING. MODERATE CONFIDENCE.

KSFO BRIDGE APPROACH...SIMILAR TO KSFO.

MONTEREY BAY AREA TERMINALS...VFR WITH BRIEF MVFR CONDITIONS
THROUGH THE LATE MORNING BENEATH SHOWER ACTIVITY. VFR CONDITIONS
EXPECTED AFTER 21Z WITH A SLIGHT INCREASE IN WESTERLY WIND SPEEDS.
WINDS BECOME LIGHT OVERNIGHT WITH PATCHY STRATUS POSSIBLE...YET
WILL KEEP SCT CLOUDS AT THIS TIME. MODERATE CONFIDENCE.

&&

.MARINE...AS OF 02:50 PM PDT SATURDAY...WEST TO NORTHWEST WINDS
WILL CONTINUE TO DIMINISH THROUGH TONIGHT AS A STRONG SURFACE LOW
PRESSURE PULLS AWAY FROM THE REGION. IN ADDITION...A LARGE
WESTERLY SWELL MOVING THROUGH THE WATERS WILL SLOWLY SUBSIDE
OVERNIGHT. WIND SPEEDS WILL THEN INCREASE AGAIN SUNDAY AFTERNOON
AND EVENING OVER THE COASTAL WATERS AS HIGH PRESSURE BUILDS OFF
THE CALIFORNIA COAST.

&&

.MTR WATCHES/WARNINGS/ADVISORIES...
     .TNGT...SCA...SF BAY SOUTH OF THE BAY BRIDGE UNTIL 3 PM
             SCA...PT REYES TO PIGEON PT 0-10 NM UNTIL 3 PM
             SCA...PIGEON PT TO PT PINOS 0-10 NM UNTIL 3 PM
             SCA...PT PINOS TO PT PIEDRAS BLANCAS 0-10 NM UNTIL 3 PM
             SCA...PIGEON PT TO PT PINOS 10-60 NM UNTIL 3 PM
             SCA...PT PINOS TO PT PIEDRAS BLANCAS 10-60 NM UNTIL 3 PM
             SCA...SF BAY NORTH OF THE BAY BRIDGE UNTIL 9 PM
             SCA...PT ARENA TO PT REYES 0-10 NM UNTIL 9 PM
             SCA...PT ARENA TO PT REYES 10-60 NM UNTIL 9 PM
             SCA...PT REYES TO PIGEON PT 10-60 NM UNTIL 9 PM
             SCA...ROUGH BAR ADVISORY FOR SF BAR UNTIL 9 PM

&&

$$

PUBLIC FORECAST: KBB
AVIATION/MARINE: RGASS

VISIT US AT WEATHER.GOV/SANFRANCISCO

FOLLOW US ON FACEBOOK, TWITTER, AND YOUTUBE AT:
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000
FXUS66 KMTR 251753
AFDMTR

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SAN FRANCISCO BAY AREA
1053 AM PDT SAT OCT 25 2014

.SYNOPSIS...A PACIFIC STORM WILL CONTINUE TO IMPACT THE AREA TODAY
BEFORE LIFTING QUICKLY NORTHEAST OUT OF THE AREA BY SUNDAY MORNING.
A COLD FRONT WILL MOVE EAST OF THE AREA THIS AFTERNOON. GUSTY
SOUTHERLY WINDS ALONG THE COAST AND OVER THE MOUNTAINS SHOULD
GRADUALLY DECREASE THIS AFTERNOON AND EVENING. BEHIND THE COLD FRONT
AND ASSOCIATED RAIN BANDS... COOLER UNSTABLE AIR WILL BRING
SCATTERED SHOWERS TO MUCH OF THE AREA THIS AFTERNOON AND EVENING. A
FEW THUNDERSTORMS MAY DEVELOP AS WELL...ESPECIALLY FROM THE SANTA
CRUZ MOUNTAINS NORTHWARD. DRIER AND COOLER WEATHER IS EXPECTED
SUNDAY WITH A WARMING TREND BEGINNING MONDAY AS HIGH PRESSURE
REBUILDS ALONG THE COAST.

&&

.DISCUSSION...AS OF 08:35 AM PDT SATURDAY...FINE TUNING DETAILS IN
THE FORECAST FOR TODAY AND THIS EVENING. FRONTAL BAND IS
PROGRESSING EASTWARD AND HAS MARCHED INTO EAST BAY AND EXTENDS
SOUTH INTO MONTEREY COUNTY. GOOD BREAK IN PRECIPITATION BEHIND THE
FRONT WITH SF BAY LOOKING FOR A PERIOD OF DRY WEATHER BEFORE
COOLER MORE UNSTABLE AIR MASS MOVES ONSHORE. BACKED OFF
PRECIPITATION AND CLOUD COVER SOMEWHAT THIS MORNING CENTRAL AND
NORTH BAY.

BROAD BRUSHED MUCH OF AREA WITH SCATTERED SHOWERS AND EVEN
NUMEROUS SHOWERS NORTH BAY THIS AFTERNOON AS BREAKS IN CLOUDS AND
SOLAR HEATING WORK ON THE MOIST DESTABILIZING AIR MASS. ISOLATED
THUNDERSTORMS IN THE CARDS AS WELL FROM ABOUT SANTA CRUZ MOUNTAINS
NORTHWARD THIS AFTERNOON. BEST CHANCE OF ANY THREAT OF THUNDER
INTO THE BAY AREA WOULD BE MID AFTERNOON THRU EARLY EVENING. NORTH BAY
COULD EASILY SEE THUNDER ANYTIME THIS AFTERNOON. WOULD NOT RULE
OUT SMALL HAIL WITH SOME OF THE STORMS GIVEN RELATIVELY HIGH CAPE
VALUES. NAM FORECAST SOUNDING FOR STS THIS AFTERNOON SHOWS CAPES
OVER 500J WHICH IS PRETTY IMPRESSIVE FOR THIS AREA...BUT HELICITY
IS MUCH LOWER THAN WAS FORECAST YESTERDAY. WIND SHEAR STILL PRETTY
STRONG...BUT DIRECTIONAL SHEAR BREAKS DOWN ABOUT THE TIME
CONVECTION GETS GOING.

WIND ADVISORY IS MARGINAL GIVEN CURRENT WIND SPEEDS AND TREND IN
WIND WILL BE DOWNWARD THIS AFTERNOON. GIVEN POTENTIAL IMPACTS WITH
DROUGHT STRESSED TREES AND LACK OF SIGNIFICANT WINDS FOR SOME TIME
NOW...WILL LEAVE THE ADVISORY RIDE FOR NOW WITH GUSTS OVER 35 MPH
STILL LIKELY IN ELEVATED TERRAIN.

&&

.PREV DISCUSSION...AS OF 02:28 AM PDT SATURDAY...THE FORECAST
FOCUS TODAY IS ON RAIN CHANCES AND PROBABILITY OF THUNDERSTORMS
AND ANY SEVERE WEATHER POTENTIAL.

AS OF 09Z...A LOW PRESSURE CENTERED NEAR 40N/130W IS WELL EVIDENT
ON IR SATELLITE IMAGERY. THIS LOW IS EXPECTED TO LIFT
NORTHEASTWARD TODAY...AND INTO SOUTHWEST WASHINGTON BY 00Z SUN.
CURRENT RADAR SHOWS AN INITIAL BAND OF RAIN SHOWERS MOVING INTO
THE COASTAL NORTH BAY PRESENTLY. MODEL CONSENSUS CONTINUES TO BE
FOR LIGHT RAIN TO PUSH QUICKLY THROUGH THE AREA THIS MORNING.
TIMING IS FAIRLY CONSISTENT FROM PREVIOUS RUNS WHICH INDICATES
THAT SHOWERS WILL MOVE INTO THE IMMEDIATE SAN FRANCISCO BAY AREA
BY 12Z AND THE MONTEREY BAY AREA AROUND 15Z. HRRR INDICATES JUST A
QUICK SHOT...ABOUT 3-5 HOURS...OF LIGHT RAIN WITH RAPID MOVING
FRONTAL BANDS. AFTER THESE BANDS CLEAR THERE WILL BE A FEW HOURS
OF DRY WEATHER AS THE ATMOSPHERE DESTABILIZES WITH COLD ADVECTION
NOTED. THIS WILL PROVIDE THE BASIC INGREDIENTS NEEDED FOR
SCATTERED SHOWERS AND THUNDERSTORMS THIS AFTERNOON ESPECIALLY OVER
THE NORTH BAY. AN ANALYSIS OF FORECAST SOUNDINGS SHOWED A
MODERATELY UNSTABLE AIR MASS WITH SOME SURFACE BASED INSTABILITY.
THE PROFILE REMAINS MOIST ENOUGH TO SUPPORT CONVECTION AS WELL.
THERE WILL BE A VIGOROUS WIND FIELD WITH 0-6KM SHEAR IN EXCESS OF
30KTS AND NOTED LOW LEVEL SHEAR AS WELL. IN ADDITION...A JET
STREAK WILL PASS THROUGH NORTHERN CALIFORNIA AND LEAVE THE NORTH
BAY IN THE FAVORABLE RIGHT ENTRANCE REGION THIS AFTERNOON. THE
SURFACE BASED INSTABILITY WILL BE SOMEWHAT LIMITED HOWEVER NOTING
500 MB HEIGHT FALLS ASSOCIATED WITH A SHORTWAVE AT THAT LEVEL.
THIS WILL BE SUFFICIENT LIFT AND INSTABILITY TO SUPPORT SCATTERED
STORMS THIS AFTERNOON AND EVENING IN THE NORTH BAY
ESPECIALLY...WITH ISOLATED STORMS POSSIBLE EVEN AS FAR SOUTH AS
THE SANTA CRUZ MOUNTAINS. AGREE WITH SPC DAY 1 OUTLOOK OF MARGINAL
SEVERE THREAT IN THE NORTH BAY...AND THEIR FORECAST OF POTENTIAL
LOW TOPPED SUPERCELL STRUCTURE IS REASONABLE GIVEN LOW FREEZING
HEIGHTS AND AMPLE SHEAR. NOTED FAVORABLE HODOGRAPH AS WELL TO
SUPPORT THIS FORECAST. LOW FREEZING HEIGHT WILL SUPPORT SMALL HAIL
POTENTIAL. SHEAR BECOMES MORE UNIDIRECTIONAL AFTER 21Z...AND NOTED
STORM MOTION WILL BE QUICK FROM THE SOUTHWEST. 0-6KM MEAN WIND OF
35-40KTS BY 21Z TO ALSO INDICATE POTENTIAL FOR GUSTY WINDS IN
STORMS.

OTHER FACTOR OF NOTE TODAY IS WIND ADVISORY WHICH HAS BEEN
EXTENDED A FEW HOURS IN THE ELEVATED TERRAIN. MARGINAL EVENT WILL
HAVE POTENTIAL TO PRODUCE GREATER IMPACT GIVEN THAT IT IS THE FIRST
WIND OF THE SEASON...AND DROUGHT CONDITIONS HAVE PRODUCED MORE DEAD
OR DYING TREES AND VEGETATION THIS YEAR. MODELS CONTINUE TO SUGGEST
GUSTS NEAR 50 MPH OR HIGHER IN THE HIGH TERRAIN AND COAST. CURRENT
GUSTS ALREADY NEAR 50 MPH IN SOME AREAS SO THIS LOOKS REASONABLE.

HEIGHTS WILL BEGIN TO RISE OVERNIGHT AS THE LOW EXITS THE AREA.
SHOWERS WILL TAPER OFF OVERNIGHT AND DRYING CONDITIONS ARE
EXPECTED. RIDGING WILL GRADUALLY BUILD BACK INTO THE AREA AND
PRODUCE WARMING TEMPERATURES. BUT COOL NIGHTTIME LOWS EXPECTED IN
THE AREA SUNDAY NIGHT BEFORE THE WARMING TREND. LIKELY TO SEE MANY
UPPER 30S IN THE FAVORED COOL INTERIOR VALLEYS. ESPECIALLY IN THE
NORTH BAY AND ALSO INTERIOR MONTEREY COUNTY.

&&

.AVIATION...AS OF 4:45 AM PDT SATURDAY...A PRE-FRONTAL BOUNDARY
CONTINUES TO PUSH INLAND THIS MORNING WITH LIGHT RAIN IMPACTING
THE MONTEREY BAY AREA TERMINALS. FURTHER NORTH...RAIN SHOWERS ARE
DEVELOPING ALONG THE COLD FRONT THAT WILL PUSH INLAND THROUGH THE
AFTERNOON. IN ADDITION...A FEW THUNDERSTORMS WILL BE POSSIBLE
OVER THE NORTH BAY TERMINALS THIS AFTERNOON AND EVENING. WINDS
WILL INCREASE SLIGHTLY THIS AFTERNOON AND SHIFT TO THE NORTHWEST
IN WAKE OF THE FRONTAL PASSAGE. PRECIPITATION CHANCES DIMINISH
THROUGH THE LATE EVENING.


VICINITY OF KSFO...VFR WITH BRIEF MVFR CONDITIONS THROUGH THE
AFTERNOON/EVENING BENEATH SHOWER ACTIVITY. WIND SPEEDS WILL LIKELY
INCREASE THIS AFTERNOON AND BECOME MORE WESTERLY THROUGH THE
EVENING. MODERATE CONFIDENCE.

KSFO BRIDGE APPROACH...SIMILAR TO KSFO.

MONTEREY BAY AREA TERMINALS...VFR WITH BRIEF MVFR CONDITIONS
THROUGH THE LATE MORNING BENEATH SHOWER ACTIVITY. VFR CONDITIONS
EXPECTED AFTER 21Z WITH A SLIGHT INCREASE IN WESTERLY WIND SPEEDS.
WINDS BECOME LIGHT OVERNIGHT WITH PATCHY STRATUS POSSIBLE...YET
WILL KEEP SCT CLOUDS AT THIS TIME. MODERATE CONFIDENCE.

&&

.MARINE...AS OF 09:10 AM PDT SATURDAY...A STRONG SURFACE LOW
PRESSURE CENTERED OFF THE OREGON COAST WILL CONTINUE TO LIFT
NORTHEASTWARD TODAY...RESULTING IN STRONG AND GUSTY SOUTHERLY
WINDS. WINDS WILL THEN DIMINISH AND SWITCH TO THE NORTHWEST
THROUGH THE AFTERNOON IN WAKE OF A FRONTAL PASSAGE. THIS SYSTEM
WILL BRING SHOWERS TO THE REGION TODAY WITH THE POSSIBILITY OF
THUNDERSTORMS OVER THE NORTHERN WATERS THIS AFTERNOON AND EVENING.
NORTHWEST FLOW WILL INCREASE EARLY NEXT WEEK AS HIGH PRESSURE
BUILDS OFF THE CALIFORNIA COAST.

&&

.MTR WATCHES/WARNINGS/ADVISORIES...
     .TDAY...WIND ADVISORY...NORTH BAY COAST AND MOUNTAINS
             WIND ADVISORY...SAN MATEO AND SANTA CRUZ COUNTY COASTS
             WIND ADVISORY...SANTA CRUZ MOUNTAINS
             SCA...SF BAY SOUTH OF THE BAY BRIDGE UNTIL 3 PM
             SCA...PT REYES TO PIGEON PT 0-10 NM UNTIL 3 PM
             SCA...PIGEON PT TO PT PINOS 0-10 NM UNTIL 3 PM
             SCA...PT PINOS TO PT PIEDRAS BLANCAS 0-10 NM UNTIL 3 PM
             SCA...PIGEON PT TO PT PINOS 10-60 NM UNTIL 3 PM
             SCA...PT PINOS TO PT PIEDRAS BLANCAS 10-60 NM UNTIL 3 PM
             SCA...PT ARENA TO PT REYES 0-10 NM FROM 2 PM
             SCA...PT ARENA TO PT REYES 10-60 NM FROM 2 PM
             SCA...PT REYES TO PIGEON PT 10-60 NM FROM 2 PM
             GLW...PT ARENA TO PT REYES 0-10 NM UNTIL 2 PM
             GLW...PT ARENA TO PT REYES 10-60 NM UNTIL 2 PM
             GLW...PT REYES TO PIGEON PT 10-60 NM UNTIL 2 PM
             SCA...ROUGH BAR ADVISORY FOR SF BAR
             SCA...SF BAY NORTH OF THE BAY BRIDGE


&&

$$

PUBLIC FORECAST: KBB
AVIATION/MARINE: RGASS

VISIT US AT WEATHER.GOV/SANFRANCISCO

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







000
FXUS66 KMTR 251753
AFDMTR

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SAN FRANCISCO BAY AREA
1053 AM PDT SAT OCT 25 2014

.SYNOPSIS...A PACIFIC STORM WILL CONTINUE TO IMPACT THE AREA TODAY
BEFORE LIFTING QUICKLY NORTHEAST OUT OF THE AREA BY SUNDAY MORNING.
A COLD FRONT WILL MOVE EAST OF THE AREA THIS AFTERNOON. GUSTY
SOUTHERLY WINDS ALONG THE COAST AND OVER THE MOUNTAINS SHOULD
GRADUALLY DECREASE THIS AFTERNOON AND EVENING. BEHIND THE COLD FRONT
AND ASSOCIATED RAIN BANDS... COOLER UNSTABLE AIR WILL BRING
SCATTERED SHOWERS TO MUCH OF THE AREA THIS AFTERNOON AND EVENING. A
FEW THUNDERSTORMS MAY DEVELOP AS WELL...ESPECIALLY FROM THE SANTA
CRUZ MOUNTAINS NORTHWARD. DRIER AND COOLER WEATHER IS EXPECTED
SUNDAY WITH A WARMING TREND BEGINNING MONDAY AS HIGH PRESSURE
REBUILDS ALONG THE COAST.

&&

.DISCUSSION...AS OF 08:35 AM PDT SATURDAY...FINE TUNING DETAILS IN
THE FORECAST FOR TODAY AND THIS EVENING. FRONTAL BAND IS
PROGRESSING EASTWARD AND HAS MARCHED INTO EAST BAY AND EXTENDS
SOUTH INTO MONTEREY COUNTY. GOOD BREAK IN PRECIPITATION BEHIND THE
FRONT WITH SF BAY LOOKING FOR A PERIOD OF DRY WEATHER BEFORE
COOLER MORE UNSTABLE AIR MASS MOVES ONSHORE. BACKED OFF
PRECIPITATION AND CLOUD COVER SOMEWHAT THIS MORNING CENTRAL AND
NORTH BAY.

BROAD BRUSHED MUCH OF AREA WITH SCATTERED SHOWERS AND EVEN
NUMEROUS SHOWERS NORTH BAY THIS AFTERNOON AS BREAKS IN CLOUDS AND
SOLAR HEATING WORK ON THE MOIST DESTABILIZING AIR MASS. ISOLATED
THUNDERSTORMS IN THE CARDS AS WELL FROM ABOUT SANTA CRUZ MOUNTAINS
NORTHWARD THIS AFTERNOON. BEST CHANCE OF ANY THREAT OF THUNDER
INTO THE BAY AREA WOULD BE MID AFTERNOON THRU EARLY EVENING. NORTH BAY
COULD EASILY SEE THUNDER ANYTIME THIS AFTERNOON. WOULD NOT RULE
OUT SMALL HAIL WITH SOME OF THE STORMS GIVEN RELATIVELY HIGH CAPE
VALUES. NAM FORECAST SOUNDING FOR STS THIS AFTERNOON SHOWS CAPES
OVER 500J WHICH IS PRETTY IMPRESSIVE FOR THIS AREA...BUT HELICITY
IS MUCH LOWER THAN WAS FORECAST YESTERDAY. WIND SHEAR STILL PRETTY
STRONG...BUT DIRECTIONAL SHEAR BREAKS DOWN ABOUT THE TIME
CONVECTION GETS GOING.

WIND ADVISORY IS MARGINAL GIVEN CURRENT WIND SPEEDS AND TREND IN
WIND WILL BE DOWNWARD THIS AFTERNOON. GIVEN POTENTIAL IMPACTS WITH
DROUGHT STRESSED TREES AND LACK OF SIGNIFICANT WINDS FOR SOME TIME
NOW...WILL LEAVE THE ADVISORY RIDE FOR NOW WITH GUSTS OVER 35 MPH
STILL LIKELY IN ELEVATED TERRAIN.

&&

.PREV DISCUSSION...AS OF 02:28 AM PDT SATURDAY...THE FORECAST
FOCUS TODAY IS ON RAIN CHANCES AND PROBABILITY OF THUNDERSTORMS
AND ANY SEVERE WEATHER POTENTIAL.

AS OF 09Z...A LOW PRESSURE CENTERED NEAR 40N/130W IS WELL EVIDENT
ON IR SATELLITE IMAGERY. THIS LOW IS EXPECTED TO LIFT
NORTHEASTWARD TODAY...AND INTO SOUTHWEST WASHINGTON BY 00Z SUN.
CURRENT RADAR SHOWS AN INITIAL BAND OF RAIN SHOWERS MOVING INTO
THE COASTAL NORTH BAY PRESENTLY. MODEL CONSENSUS CONTINUES TO BE
FOR LIGHT RAIN TO PUSH QUICKLY THROUGH THE AREA THIS MORNING.
TIMING IS FAIRLY CONSISTENT FROM PREVIOUS RUNS WHICH INDICATES
THAT SHOWERS WILL MOVE INTO THE IMMEDIATE SAN FRANCISCO BAY AREA
BY 12Z AND THE MONTEREY BAY AREA AROUND 15Z. HRRR INDICATES JUST A
QUICK SHOT...ABOUT 3-5 HOURS...OF LIGHT RAIN WITH RAPID MOVING
FRONTAL BANDS. AFTER THESE BANDS CLEAR THERE WILL BE A FEW HOURS
OF DRY WEATHER AS THE ATMOSPHERE DESTABILIZES WITH COLD ADVECTION
NOTED. THIS WILL PROVIDE THE BASIC INGREDIENTS NEEDED FOR
SCATTERED SHOWERS AND THUNDERSTORMS THIS AFTERNOON ESPECIALLY OVER
THE NORTH BAY. AN ANALYSIS OF FORECAST SOUNDINGS SHOWED A
MODERATELY UNSTABLE AIR MASS WITH SOME SURFACE BASED INSTABILITY.
THE PROFILE REMAINS MOIST ENOUGH TO SUPPORT CONVECTION AS WELL.
THERE WILL BE A VIGOROUS WIND FIELD WITH 0-6KM SHEAR IN EXCESS OF
30KTS AND NOTED LOW LEVEL SHEAR AS WELL. IN ADDITION...A JET
STREAK WILL PASS THROUGH NORTHERN CALIFORNIA AND LEAVE THE NORTH
BAY IN THE FAVORABLE RIGHT ENTRANCE REGION THIS AFTERNOON. THE
SURFACE BASED INSTABILITY WILL BE SOMEWHAT LIMITED HOWEVER NOTING
500 MB HEIGHT FALLS ASSOCIATED WITH A SHORTWAVE AT THAT LEVEL.
THIS WILL BE SUFFICIENT LIFT AND INSTABILITY TO SUPPORT SCATTERED
STORMS THIS AFTERNOON AND EVENING IN THE NORTH BAY
ESPECIALLY...WITH ISOLATED STORMS POSSIBLE EVEN AS FAR SOUTH AS
THE SANTA CRUZ MOUNTAINS. AGREE WITH SPC DAY 1 OUTLOOK OF MARGINAL
SEVERE THREAT IN THE NORTH BAY...AND THEIR FORECAST OF POTENTIAL
LOW TOPPED SUPERCELL STRUCTURE IS REASONABLE GIVEN LOW FREEZING
HEIGHTS AND AMPLE SHEAR. NOTED FAVORABLE HODOGRAPH AS WELL TO
SUPPORT THIS FORECAST. LOW FREEZING HEIGHT WILL SUPPORT SMALL HAIL
POTENTIAL. SHEAR BECOMES MORE UNIDIRECTIONAL AFTER 21Z...AND NOTED
STORM MOTION WILL BE QUICK FROM THE SOUTHWEST. 0-6KM MEAN WIND OF
35-40KTS BY 21Z TO ALSO INDICATE POTENTIAL FOR GUSTY WINDS IN
STORMS.

OTHER FACTOR OF NOTE TODAY IS WIND ADVISORY WHICH HAS BEEN
EXTENDED A FEW HOURS IN THE ELEVATED TERRAIN. MARGINAL EVENT WILL
HAVE POTENTIAL TO PRODUCE GREATER IMPACT GIVEN THAT IT IS THE FIRST
WIND OF THE SEASON...AND DROUGHT CONDITIONS HAVE PRODUCED MORE DEAD
OR DYING TREES AND VEGETATION THIS YEAR. MODELS CONTINUE TO SUGGEST
GUSTS NEAR 50 MPH OR HIGHER IN THE HIGH TERRAIN AND COAST. CURRENT
GUSTS ALREADY NEAR 50 MPH IN SOME AREAS SO THIS LOOKS REASONABLE.

HEIGHTS WILL BEGIN TO RISE OVERNIGHT AS THE LOW EXITS THE AREA.
SHOWERS WILL TAPER OFF OVERNIGHT AND DRYING CONDITIONS ARE
EXPECTED. RIDGING WILL GRADUALLY BUILD BACK INTO THE AREA AND
PRODUCE WARMING TEMPERATURES. BUT COOL NIGHTTIME LOWS EXPECTED IN
THE AREA SUNDAY NIGHT BEFORE THE WARMING TREND. LIKELY TO SEE MANY
UPPER 30S IN THE FAVORED COOL INTERIOR VALLEYS. ESPECIALLY IN THE
NORTH BAY AND ALSO INTERIOR MONTEREY COUNTY.

&&

.AVIATION...AS OF 4:45 AM PDT SATURDAY...A PRE-FRONTAL BOUNDARY
CONTINUES TO PUSH INLAND THIS MORNING WITH LIGHT RAIN IMPACTING
THE MONTEREY BAY AREA TERMINALS. FURTHER NORTH...RAIN SHOWERS ARE
DEVELOPING ALONG THE COLD FRONT THAT WILL PUSH INLAND THROUGH THE
AFTERNOON. IN ADDITION...A FEW THUNDERSTORMS WILL BE POSSIBLE
OVER THE NORTH BAY TERMINALS THIS AFTERNOON AND EVENING. WINDS
WILL INCREASE SLIGHTLY THIS AFTERNOON AND SHIFT TO THE NORTHWEST
IN WAKE OF THE FRONTAL PASSAGE. PRECIPITATION CHANCES DIMINISH
THROUGH THE LATE EVENING.


VICINITY OF KSFO...VFR WITH BRIEF MVFR CONDITIONS THROUGH THE
AFTERNOON/EVENING BENEATH SHOWER ACTIVITY. WIND SPEEDS WILL LIKELY
INCREASE THIS AFTERNOON AND BECOME MORE WESTERLY THROUGH THE
EVENING. MODERATE CONFIDENCE.

KSFO BRIDGE APPROACH...SIMILAR TO KSFO.

MONTEREY BAY AREA TERMINALS...VFR WITH BRIEF MVFR CONDITIONS
THROUGH THE LATE MORNING BENEATH SHOWER ACTIVITY. VFR CONDITIONS
EXPECTED AFTER 21Z WITH A SLIGHT INCREASE IN WESTERLY WIND SPEEDS.
WINDS BECOME LIGHT OVERNIGHT WITH PATCHY STRATUS POSSIBLE...YET
WILL KEEP SCT CLOUDS AT THIS TIME. MODERATE CONFIDENCE.

&&

.MARINE...AS OF 09:10 AM PDT SATURDAY...A STRONG SURFACE LOW
PRESSURE CENTERED OFF THE OREGON COAST WILL CONTINUE TO LIFT
NORTHEASTWARD TODAY...RESULTING IN STRONG AND GUSTY SOUTHERLY
WINDS. WINDS WILL THEN DIMINISH AND SWITCH TO THE NORTHWEST
THROUGH THE AFTERNOON IN WAKE OF A FRONTAL PASSAGE. THIS SYSTEM
WILL BRING SHOWERS TO THE REGION TODAY WITH THE POSSIBILITY OF
THUNDERSTORMS OVER THE NORTHERN WATERS THIS AFTERNOON AND EVENING.
NORTHWEST FLOW WILL INCREASE EARLY NEXT WEEK AS HIGH PRESSURE
BUILDS OFF THE CALIFORNIA COAST.

&&

.MTR WATCHES/WARNINGS/ADVISORIES...
     .TDAY...WIND ADVISORY...NORTH BAY COAST AND MOUNTAINS
             WIND ADVISORY...SAN MATEO AND SANTA CRUZ COUNTY COASTS
             WIND ADVISORY...SANTA CRUZ MOUNTAINS
             SCA...SF BAY SOUTH OF THE BAY BRIDGE UNTIL 3 PM
             SCA...PT REYES TO PIGEON PT 0-10 NM UNTIL 3 PM
             SCA...PIGEON PT TO PT PINOS 0-10 NM UNTIL 3 PM
             SCA...PT PINOS TO PT PIEDRAS BLANCAS 0-10 NM UNTIL 3 PM
             SCA...PIGEON PT TO PT PINOS 10-60 NM UNTIL 3 PM
             SCA...PT PINOS TO PT PIEDRAS BLANCAS 10-60 NM UNTIL 3 PM
             SCA...PT ARENA TO PT REYES 0-10 NM FROM 2 PM
             SCA...PT ARENA TO PT REYES 10-60 NM FROM 2 PM
             SCA...PT REYES TO PIGEON PT 10-60 NM FROM 2 PM
             GLW...PT ARENA TO PT REYES 0-10 NM UNTIL 2 PM
             GLW...PT ARENA TO PT REYES 10-60 NM UNTIL 2 PM
             GLW...PT REYES TO PIGEON PT 10-60 NM UNTIL 2 PM
             SCA...ROUGH BAR ADVISORY FOR SF BAR
             SCA...SF BAY NORTH OF THE BAY BRIDGE


&&

$$

PUBLIC FORECAST: KBB
AVIATION/MARINE: RGASS

VISIT US AT WEATHER.GOV/SANFRANCISCO

FOLLOW US ON FACEBOOK, TWITTER, AND YOUTUBE AT:
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WWW.TWITTER.COM/NWSBAYAREA
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000
FXUS66 KMTR 251620
AFDMTR

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SAN FRANCISCO BAY AREA
920 AM PDT SAT OCT 25 2014

.SYNOPSIS...A PACIFIC STORM WILL CONTINUE TO IMPACT THE AREA TODAY
BEFORE LIFTING QUICKLY NORTHEAST OUT OF THE AREA BY SUNDAY MORNING.
A COLD FRONT WILL MOVE EAST OF THE AREA THIS AFTERNOON. GUSTY
SOUTHERLY WINDS ALONG THE COAST AND OVER THE MOUNTAINS SHOULD
GRADUALLY DECREASE THIS AFTERNOON AND EVENING. BEHIND THE COLD FRONT
AND ASSOCIATED RAIN BANDS... COOLER UNSTABLE AIR WILL BRING
SCATTERED SHOWERS TO MUCH OF THE AREA THIS AFTERNOON AND EVENING. A
FEW THUNDERSTORMS MAY DEVELOP AS WELL...ESPECIALLY FROM THE SANTA
CRUZ MOUNTAINS NORTHWARD. DRIER AND COOLER WEATHER IS EXPECTED
SUNDAY WITH A WARMING TREND BEGINNING MONDAY AS HIGH PRESSURE
REBUILDS ALONG THE COAST.

&&

.DISCUSSION...AS OF 08:35 AM PDT SATURDAY...FINE TUNING DETAILS IN
THE FORECAST FOR TODAY AND THIS EVENING. FRONTAL BAND IS
PROGRESSING EASTWARD AND HAS MARCHED INTO EAST BAY AND EXTENDS
SOUTH INTO MONTEREY COUNTY. GOOD BREAK IN PRECIPITATION BEHIND THE
FRONT WITH SF BAY LOOKING FOR A PERIOD OF DRY WEATHER BEFORE
COOLER MORE UNSTABLE AIRMASS MOVES ONSHORE. BACKED OFF
PRECIPITATION AND CLOUD COVER SOMEWHAT THIS MORNING CENTRAL AND
NORTH BAY.

BROAD BRUSHED MUCH OF AREA WITH SCATTERED SHOWERS AND EVEN
NUMEROUS SHOWERS NORTH BAY THIS AFTERNOON AS BREAKS IN CLOUDS AND
SOLAR HEATING WORK ON THE MOIST DESTABILIZING AIRMASS. ISOLATED
THUNDERSTORMS IN THE CARDS AS WELL FROM ABOUT SANTA CRUZ MOUNTAINS
NORTHWARD THIS AFTERNOON. BEST CHANCE OF ANY THREAT OF THUNDER
INTO THE BAY AREA WOULD BE MID AFTERNOON THRU EARLY EVENING. NORTH BAY
COULD EASILY SEE THUNDER ANYTIME THIS AFTERNOON. WOULD NOT RULE
OUT SMALL HAIL WITH SOME OF THE STORMS GIVEN RELATIVELY HIGH CAPE
VALUES. NAM FORECAST SOUNDING FOR STS THIS AFTERNOON SHOWS CAPES
OVER 500J WHICH IS PRETTY IMPRESSIVE FOR THIS AREA...BUT HELICITY
IS MUCH LOWER THAN WAS FORECAST YESTERDAY. WIND SHEAR STILL PRETTY
STRONG...BUT DIRECTIONAL SHEAR BREAKS DOWN ABOUT THE TIME
CONVECTION GETS GOING.

WIND ADVISORY IS MARGINAL GIVEN CURRENT WIND SPEEDS AND TREND IN
WIND WILL BE DOWNWARD THIS AFTERNOON. GIVEN POTENTIAL IMPACTS WITH
DROUGHT STRESSED TREES AND LACK OF SIGNIFICANT WINDS FOR SOME TIME
NOW...WILL LEAVE THE ADVISORY RIDE FOR NOW WITH GUSTS OVER 35 MPH
STILL LIKELY IN ELEVATED TERRAIN.


&&

.PREV DISCUSSION...AS OF 02:28 AM PDT SATURDAY...
THE FORECAST FOCUS TODAY IS ON RAIN CHANCES AND PROBABILITY OF
THUNDERSTORMS AND ANY SEVERE WEATHER POTENTIAL.

AS OF 09Z...A LOW PRESSURE CENTERED NEAR 40N/130W IS WELL EVIDENT
ON IR SATELLITE IMAGERY. THIS LOW IS EXPECTED TO LIFT
NORTHEASTWARD TODAY...AND INTO SOUTHWEST WASHINGTON BY 00Z SUN.
CURRENT RADAR SHOWS AN INITIAL BAND OF RAIN SHOWERS MOVING INTO
THE COASTAL NORTH BAY PRESENTLY. MODEL CONSENSUS CONTINUES TO BE
FOR LIGHT RAIN TO PUSH QUICKLY THROUGH THE AREA THIS MORNING.
TIMING IS FAIRLY CONSISTENT FROM PREVIOUS RUNS WHICH INDICATES
THAT SHOWERS WILL MOVE INTO THE IMMEDIATE SAN FRANCISCO BAY AREA
BY 12Z AND THE MONTEREY BAY AREA AROUND 15Z. HRRR INDICATES JUST A
QUICK SHOT...ABOUT 3-5 HOURS...OF LIGHT RAIN WITH RAPID MOVING
FRONTAL BANDS. AFTER THESE BANDS CLEAR THERE WILL BE A FEW HOURS
OF DRY WEATHER AS THE ATMOSPHERE DESTABILIZES WITH COLD ADVECTION
NOTED. THIS WILL PROVIDE THE BASIC INGREDIENTS NEEDED FOR
SCATTERED SHOWERS AND THUNDERSTORMS THIS AFTERNOON ESPECIALLY OVER
THE NORTH BAY. AN ANALYSIS OF FORECAST SOUNDINGS SHOWED A
MODERATELY UNSTABLE AIRMASS WITH SOME SURFACE BASED INSTABILITY.
THE PROFILE REMAINS MOIST ENOUGH TO SUPPORT CONVECTION AS WELL.
THERE WILL BE A VIGOROUS WIND FIELD WITH 0-6KM SHEAR IN EXCESS OF
30KTS AND NOTED LOW LEVEL SHEAR AS WELL. IN ADDITION...A JET
STREAK WILL PASS THROUGH NORTHERN CALIFORNIA AND LEAVE THE NORTH
BAY IN THE FAVORABLE RIGHT ENTRANCE REGION THIS AFTERNOON. THE
SURFACE BASED INSTABILITY WILL BE SOMEWHAT LIMITED HOWEVER NOTING
500 MB HEIGHT FALLS ASSOCIATED WITH A SHORTWAVE AT THAT LEVEL.
THIS WILL BE SUFFICIENT LIFT AND INSTABILITY TO SUPPORT SCATTERED
STORMS THIS AFTERNOON AND EVENING IN THE NORTH BAY
ESPECIALLY...WITH ISOLATED STORMS POSSIBLE EVEN AS FAR SOUTH AS
THE SANTA CRUZ MOUNTAINS. AGREE WITH SPC DAY 1 OUTLOOK OF MARGINAL
SEVERE THREAT IN THE NORTH BAY...AND THEIR FORECAST OF POTENTIAL
LOW TOPPED SUPERCELL STRUCTURE IS REASONABLE GIVEN LOW FREEZING
HEIGHTS AND AMPLE SHEAR. NOTED FAVORABLE HODOGRAPH AS WELL TO
SUPPORT THIS FORECAST. LOW FREEZING HEIGHT WILL SUPPORT SMALL HAIL
POTENTIAL. SHEAR BECOMES MORE UNIDIRECTIONAL AFTER 21Z...AND NOTED
STORM MOTION WILL BE QUICK FROM THE SOUTHWEST. 0-6KM MEAN WIND OF
35-40KTS BY 21Z TO ALSO INDICATE POTENTIAL FOR GUSTY WINDS IN
STORMS.

OTHER FACTOR OF NOTE TODAY IS WIND ADVISORY WHICH HAS BEEN
EXTENDED A FEW HOURS IN THE ELEVATED TERRAIN. MARGINAL EVENT WILL
HAVE POTENTIAL TO PRODUCE GREATER IMPACT GIVEN THAT IT IS THE FIRST
WIND OF THE SEASON...AND DROUGHT CONDITIONS HAVE PRODUCED MORE DEAD
OR DYING TREES AND VEGETATION THIS YEAR. MODELS CONTINUE TO SUGGEST
GUSTS NEAR 50 MPH OR HIGHER IN THE HIGH TERRAIN AND COAST. CURRENT
GUSTS ALREADY NEAR 50 MPH IN SOME AREAS SO THIS LOOKS REASONABLE.

HEIGHTS WILL BEGIN TO RISE OVERNIGHT AS THE LOW EXITS THE AREA.
SHOWERS WILL TAPER OFF OVERNIGHT AND DRYING CONDITIONS ARE
EXPECTED. RIDGING WILL GRADUALLY BUILD BACK INTO THE AREA AND
PRODUCE WARMING TEMPERATURES. BUT COOL NIGHTTIME LOWS EXPECTED IN
THE AREA SUNDAY NIGHT BEFORE THE WARMING TREND. LIKELY TO SEE MANY
UPPER 30S IN THE FAVORED COOL INTERIOR VALLEYS. ESPECIALLY IN THE
NORTH BAY AND ALSO INTERIOR MONTEREY COUNTY.

&&

.AVIATION...AS OF 4:45 AM PDT SATURDAY...RAIN AND MVFR CIGS MOVING
INTO THE AREA WITH STRONG SOUTHEAST WINDS BLOWING AHEAD OF THE
FRONT. FRONTAL PASSAGE EXPECTED IN THE SFO BAY AREA AROUND 16Z
WITH A WIND SHIFT TO THE SOUTH TO SOUTHWEST. LOW PRESSURE OFF THE
NORTHERN CALIFORNIA COAST WILL KEEP A THREAT OF SHOWERS THROUGH
THE AFTERNOON. THERE IS A CHANCE OF THUNDERSTORMS IN STS. WINDS
WILL SWITCH TO THE WEST AFTER 02Z IN MOST AREAS.

VICINITY OF KSFO...MVFR THROUGH 21Z. LIGHT RAIN TURNING TO SHOWERS
AFTER 16Z. CIGS RISING INTO VFR RANGE AFTER 21Z. SHOWERS ENDING
WITH A WIND SHIFT TO THE WEST AFTER 02Z.

KSFO BRIDGE APPROACH...SIMILAR TO KSFO.

MONTEREY BAY AREA TERMINALS...CIGS COULD LOWER TO MVFR RANGE AFTER
14Z AS RAIN SHOWERS MOVE INTO THE MRY BAY AREA. STRONGEST
SOUTHEAST WINDS WILL BE IN THE SALINAS VALLEYS WITH WINDS TO 20
KT. WINDS EXPECTED TO SWITCH TO SOUTHWESTERLY SATURDAY AFTERNOON.

&&

.MARINE...AS OF 09:10 AM PDT SATURDAY...A STRONG SURFACE LOW
PRESSURE CENTERED OFF THE OREGON COAST WILL CONTINUE TO LIFT
NORTHEASTWARD TODAY...RESULTING IN STRONG AND GUSTY SOUTHERLY
WINDS. WINDS WILL THEN DIMINISH AND SWITCH TO THE NORTHWEST
THROUGH THE AFTERNOON IN WAKE OF A FRONTAL PASSAGE. THIS SYSTEM
WILL BRING SHOWERS TO THE REGION TODAY WITH THE POSSIBILITY OF
THUNDERSTORMS OVER THE NORTHERN WATERS THIS AFTERNOON AND EVENING.
NORTHWEST FLOW WILL INCREASE EARLY NEXT WEEK AS HIGH PRESSURE
BUILDS OFF THE CALIFORNIA COAST.

&&

.MTR WATCHES/WARNINGS/ADVISORIES...
     .TDAY...WIND ADVISORY...NORTH BAY COAST AND MOUNTAINS
             WIND ADVISORY...SAN MATEO AND SANTA CRUZ COUNTY COASTS
             WIND ADVISORY...SANTA CRUZ MOUNTAINS
             SCA...SF BAY SOUTH OF THE BAY BRIDGE UNTIL 3 PM
             SCA...PT REYES TO PIGEON PT 0-10 NM UNTIL 3 PM
             SCA...PIGEON PT TO PT PINOS 0-10 NM UNTIL 3 PM
             SCA...PT PINOS TO PT PIEDRAS BLANCAS 0-10 NM UNTIL 3 PM
             SCA...PIGEON PT TO PT PINOS 10-60 NM UNTIL 3 PM
             SCA...PT PINOS TO PT PIEDRAS BLANCAS 10-60 NM UNTIL 3 PM
             SCA...PT ARENA TO PT REYES 0-10 NM FROM 2 PM
             SCA...PT ARENA TO PT REYES 10-60 NM FROM 2 PM
             SCA...PT REYES TO PIGEON PT 10-60 NM FROM 2 PM
             GLW...PT ARENA TO PT REYES 0-10 NM UNTIL 2 PM
             GLW...PT ARENA TO PT REYES 10-60 NM UNTIL 2 PM
             GLW...PT REYES TO PIGEON PT 10-60 NM UNTIL 2 PM
             SCA...ROUGH BAR ADVISORY FOR SF BAR
             SCA...SF BAY NORTH OF THE BAY BRIDGE

&&

$$

PUBLIC FORECAST: KBB
AVIATION/MARINE: RGASS

VISIT US AT WEATHER.GOV/SANFRANCISCO

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








000
FXUS66 KMTR 251142
AFDMTR

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SAN FRANCISCO BAY AREA
442 AM PDT SAT OCT 25 2014

.SYNOPSIS...A PACIFIC STORM WILL CONTINUE TO IMPACT THE AREA ON
SATURDAY BEFORE LIFTING QUICKLY NORTHEAST OUT OF THE AREA BY
SUNDAY MORNING. IT WILL PUSH A COLD FRONT TOWARDS THE AREA. SOUTHERLY
WINDS WILL INCREASE AHEAD OF THE FRONT AND BECOME LOCALLY STRONG
AND GUSTY NEAR THE COAST AND IN THE HILLS SATURDAY MORNING. AT THE SAME
TIME...RAIN WILL SPREAD ACROSS MUCH OF THE REGION. THE FRONT WILL
PASS THROUGH QUICKLY ON SATURDAY MORNING...BUT COOLER UNSTABLE AIR
WILL BRING SCATTERED SHOWERS TO MUCH OF THE AREA SATURDAY
AFTERNOON AND EVENING. A FEW THUNDERSTORMS MAY DEVELOP AS
WELL...ESPECIALLY FROM THE SANTA CRUZ MOUNTAINS NORTHWARD. DRIER
AND COOLER WEATHER IS EXPECTED SUNDAY WITH A WARMING TREND
BEGINNING MONDAY AS HIGH PRESSURE REBUILDS ALONG THE COAST.

&&

.DISCUSSION...AS OF 02:28 AM PDT SATURDAY...
THE FORECAST FOCUS TODAY IS ON RAIN CHANCES AND PROBABILITY OF
THUNDERSTORMS AND ANY SEVERE WEATHER POTENTIAL.

AS OF 09Z...A LOW PRESSURE CENTERED NEAR 40N/130W IS WELL EVIDENT
ON IR SATELLITE IMAGERY. THIS LOW IS EXPECTED TO LIFT
NORTHEASTWARD TODAY...AND INTO SOUTHWEST WASHINGTON BY 00Z SUN.
CURRENT RADAR SHOWS AN INITIAL BAND OF RAIN SHOWERS MOVING INTO
THE COASTAL NORTH BAY PRESENTLY. MODEL CONSENSUS CONTINUES TO BE
FOR LIGHT RAIN TO PUSH QUICKLY THROUGH THE AREA THIS MORNING.
TIMING IS FAIRLY CONSISTENT FROM PREVIOUS RUNS WHICH INDICATES
THAT SHOWERS WILL MOVE INTO THE IMMEDIATE SAN FRANCISCO BAY AREA
BY 12Z AND THE MONTEREY BAY AREA AROUND 15Z. HRRR INDICATES JUST A
QUICK SHOT...ABOUT 3-5 HOURS...OF LIGHT RAIN WITH RAPID MOVING
FRONTAL BANDS. AFTER THESE BANDS CLEAR THERE WILL BE A FEW HOURS
OF DRY WEATHER AS THE ATMOSPHERE DESTABILIZES WITH COLD ADVECTION
NOTED. THIS WILL PROVIDE THE BASIC INGREDIENTS NEEDED FOR
SCATTERED SHOWERS AND THUNDERSTORMS THIS AFTERNOON ESPECIALLY OVER
THE NORTH BAY. AN ANALYSIS OF FORECAST SOUNDINGS SHOWED A
MODERATELY UNSTABLE AIRMASS WITH SOME SURFACE BASED INSTABILITY.
THE PROFILE REMAINS MOIST ENOUGH TO SUPPORT CONVECTION AS WELL.
THERE WILL BE A VIGOROUS WIND FIELD WITH 0-6KM SHEAR IN EXCESS OF
30KTS AND NOTED LOW LEVEL SHEAR AS WELL. IN ADDITION...A JET
STREAK WILL PASS THROUGH NORTHERN CALIFORNIA AND LEAVE THE NORTH
BAY IN THE FAVORABLE RIGHT ENTRANCE REGION THIS AFTERNOON. THE
SURFACE BASED INSTABILITY WILL BE SOMEWHAT LIMITED HOWEVER NOTING
500 MB HEIGHT FALLS ASSOCIATED WITH A SHORTWAVE AT THAT LEVEL.
THIS WILL BE SUFFICIENT LIFT AND INSTABILITY TO SUPPORT SCATTERED
STORMS THIS AFTERNOON AND EVENING IN THE NORTH BAY
ESPECIALLY...WITH ISOLATED STORMS POSSIBLE EVEN AS FAR SOUTH AS
THE SANTA CRUZ MOUNTAINS. AGREE WITH SPC DAY 1 OUTLOOK OF MARGINAL
SEVERE THREAT IN THE NORTH BAY...AND THEIR FORECAST OF POTENTIAL
LOW TOPPED SUPERCELL STRUCTURE IS REASONABLE GIVEN LOW FREEZING
HEIGHTS AND AMPLE SHEAR. NOTED FAVORABLE HODOGRAPH AS WELL TO
SUPPORT THIS FORECAST. LOW FREEZING HEIGHT WILL SUPPORT SMALL HAIL
POTENTIAL. SHEAR BECOMES MORE UNIDIRECTIONAL AFTER 21Z...AND NOTED
STORM MOTION WILL BE QUICK FROM THE SOUTHWEST. 0-6KM MEAN WIND OF
35-40KTS BY 21Z TO ALSO INDICATE POTENTIAL FOR GUSTY WINDS IN
STORMS.

OTHER FACTOR OF NOTE TODAY IS WIND ADVISORY WHICH HAS BEEN
EXTENDED A FEW HOURS IN THE ELEVATED TERRAIN. MARGINAL EVENT WILL
HAVE POTENTIAL TO PRODUCE GREATER IMPACT GIVEN THAT IT IS THE FIRST
WIND OF THE SEASON...AND DROUGHT CONDITIONS HAVE PRODUCED MORE DEAD
OR DYING TREES AND VEGETATION THIS YEAR. MODELS CONTINUE TO SUGGEST
GUSTS NEAR 50 MPH OR HIGHER IN THE HIGH TERRAIN AND COAST. CURRENT
GUSTS ALREADY NEAR 50 MPH IN SOME AREAS SO THIS LOOKS REASONABLE.

HEIGHTS WILL BEGIN TO RISE OVERNIGHT AS THE LOW EXITS THE AREA.
SHOWERS WILL TAPER OFF OVERNIGHT AND DRYING CONDITIONS ARE
EXPECTED. RIDGING WILL GRADUALLY BUILD BACK INTO THE AREA AND
PRODUCE WARMING TEMPERATURES. BUT COOL NIGHTTIME LOWS EXPECTED IN
THE AREA SUNDAY NIGHT BEFORE THE WARMING TREND. LIKELY TO SEE MANY
UPPER 30S IN THE FAVORED COOL INTERIOR VALLEYS. ESPECIALLY IN THE
NORTH BAY AND ALSO INTERIOR MONTEREY COUNTY.

&&

.AVIATION...AS OF 4:45 AM PDT SATURDAY...RAIN AND MVFR CIGS MOVING
INTO THE AREA WITH STRONG SOUTHEAST WINDS BLOWING AHEAD OF THE
FRONT. FRONTAL PASSAGE EXPECTED IN THE SFO BAY AREA AROUND 16Z
WITH A WIND SHIFT TO THE SOUTH TO SOUTHWEST. LOW PRESSURE OFF THE
NORTHERN CALIFORNIA COAST WILL KEEP A THREAT OF SHOWERS THROUGH
THE AFTERNOON. THERE IS A CHANCE OF THUNDERSTORMS IN STS. WINDS
WILL SWITCH TO THE WEST AFTER 02Z IN MOST AREAS.

VICINITY OF KSFO...MVFR THROUGH 21Z. LIGHT RAIN TURNING TO SHOWERS
AFTER 16Z. CIGS RISING INTO VFR RANGE AFTER 21Z. SHOWERS ENDING
WITH A WIND SHIFT TO THE WEST AFTER 02Z.

KSFO BRIDGE APPROACH...SIMILAR TO KSFO.

MONTEREY BAY AREA TERMINALS...CIGS COULD LOWER TO MVFR RANGE AFTER
14Z AS RAIN SHOWERS MOVE INTO THE MRY BAY AREA. STRONGEST
SOUTHEAST WINDS WILL BE IN THE SALINAS VALLEYS WITH WINDS TO 20
KT. WINDS EXPECTED TO SWITCH TO SOUTHWESTERLY SATURDAY AFTERNOON.

&&

.MARINE...AS OF 02:28 AM PDT SATURDAY...LOW PRESSURE SITUATED WEST
OF CAPE MENDOCINO WILL CONTINUE TO DEEPEN TONIGHT RESULTING IN
STRONG SOUTHERLY WINDS ACROSS THE COASTAL WATERS. GALE FORCE WINDS
WILL DEVELOP OVERNIGHT ACROSS THE NORTHERN WATERS WITH STRONG
SMALL CRAFT WINDS DEVELOPING ELSEWHERE. A LINE OF RAIN AND SHOWERS
WILL MOVE THROUGH THE WATERS EARLY SATURDAY MORNING WITH
THUNDERSTORMS POSSIBLE NORTH OF THE GOLDEN GATE SATURDAY
AFTERNOON. WINDS WILL EASE AND SHOWERS WILL END BY SATURDAY NIGHT
WITH LIGHTER WINDS AND MODERATE SEAS SUNDAY INTO MONDAY.

&&

.MTR WATCHES/WARNINGS/ADVISORIES...
     .TDAY...WIND ADVISORY...NORTH BAY COAST AND MOUNTAINS
             WIND ADVISORY...SAN MATEO AND SANTA CRUZ COUNTY COASTS
             WIND ADVISORY...SANTA CRUZ MOUNTAINS
             SCA...SF BAY NORTH OF THE BAY BRIDGE UNTIL 3 PM
             SCA...SF BAY SOUTH OF THE BAY BRIDGE UNTIL 3 PM
             SCA...PT REYES TO PIGEON PT 0-10 NM UNTIL 3 PM
             SCA...PIGEON PT TO PT PINOS 0-10 NM UNTIL 3 PM
             SCA...PT PINOS TO PT PIEDRAS BLANCAS 0-10 NM UNTIL 3 PM
             SCA...PIGEON PT TO PT PINOS 10-60 NM UNTIL 3 PM
             SCA...PT PINOS TO PT PIEDRAS BLANCAS 10-60 NM UNTIL 3 PM
             SCA...PT ARENA TO PT REYES 10-60 NM FROM 2 PM
             GLW...PT ARENA TO PT REYES 0-10 NM UNTIL 2 PM
             GLW...PT ARENA TO PT REYES 10-60 NM UNTIL 2 PM
             GLW...PT REYES TO PIGEON PT 10-60 NM UNTIL 2 PM
             SCA...ROUGH BAR ADVISORY FOR SF BAR

&&

$$

PUBLIC FORECAST: JOHNSON
AVIATION/MARINE: W PI

VISIT US AT WEATHER.GOV/SANFRANCISCO

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







000
FXUS66 KMTR 251142
AFDMTR

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SAN FRANCISCO BAY AREA
442 AM PDT SAT OCT 25 2014

.SYNOPSIS...A PACIFIC STORM WILL CONTINUE TO IMPACT THE AREA ON
SATURDAY BEFORE LIFTING QUICKLY NORTHEAST OUT OF THE AREA BY
SUNDAY MORNING. IT WILL PUSH A COLD FRONT TOWARDS THE AREA. SOUTHERLY
WINDS WILL INCREASE AHEAD OF THE FRONT AND BECOME LOCALLY STRONG
AND GUSTY NEAR THE COAST AND IN THE HILLS SATURDAY MORNING. AT THE SAME
TIME...RAIN WILL SPREAD ACROSS MUCH OF THE REGION. THE FRONT WILL
PASS THROUGH QUICKLY ON SATURDAY MORNING...BUT COOLER UNSTABLE AIR
WILL BRING SCATTERED SHOWERS TO MUCH OF THE AREA SATURDAY
AFTERNOON AND EVENING. A FEW THUNDERSTORMS MAY DEVELOP AS
WELL...ESPECIALLY FROM THE SANTA CRUZ MOUNTAINS NORTHWARD. DRIER
AND COOLER WEATHER IS EXPECTED SUNDAY WITH A WARMING TREND
BEGINNING MONDAY AS HIGH PRESSURE REBUILDS ALONG THE COAST.

&&

.DISCUSSION...AS OF 02:28 AM PDT SATURDAY...
THE FORECAST FOCUS TODAY IS ON RAIN CHANCES AND PROBABILITY OF
THUNDERSTORMS AND ANY SEVERE WEATHER POTENTIAL.

AS OF 09Z...A LOW PRESSURE CENTERED NEAR 40N/130W IS WELL EVIDENT
ON IR SATELLITE IMAGERY. THIS LOW IS EXPECTED TO LIFT
NORTHEASTWARD TODAY...AND INTO SOUTHWEST WASHINGTON BY 00Z SUN.
CURRENT RADAR SHOWS AN INITIAL BAND OF RAIN SHOWERS MOVING INTO
THE COASTAL NORTH BAY PRESENTLY. MODEL CONSENSUS CONTINUES TO BE
FOR LIGHT RAIN TO PUSH QUICKLY THROUGH THE AREA THIS MORNING.
TIMING IS FAIRLY CONSISTENT FROM PREVIOUS RUNS WHICH INDICATES
THAT SHOWERS WILL MOVE INTO THE IMMEDIATE SAN FRANCISCO BAY AREA
BY 12Z AND THE MONTEREY BAY AREA AROUND 15Z. HRRR INDICATES JUST A
QUICK SHOT...ABOUT 3-5 HOURS...OF LIGHT RAIN WITH RAPID MOVING
FRONTAL BANDS. AFTER THESE BANDS CLEAR THERE WILL BE A FEW HOURS
OF DRY WEATHER AS THE ATMOSPHERE DESTABILIZES WITH COLD ADVECTION
NOTED. THIS WILL PROVIDE THE BASIC INGREDIENTS NEEDED FOR
SCATTERED SHOWERS AND THUNDERSTORMS THIS AFTERNOON ESPECIALLY OVER
THE NORTH BAY. AN ANALYSIS OF FORECAST SOUNDINGS SHOWED A
MODERATELY UNSTABLE AIRMASS WITH SOME SURFACE BASED INSTABILITY.
THE PROFILE REMAINS MOIST ENOUGH TO SUPPORT CONVECTION AS WELL.
THERE WILL BE A VIGOROUS WIND FIELD WITH 0-6KM SHEAR IN EXCESS OF
30KTS AND NOTED LOW LEVEL SHEAR AS WELL. IN ADDITION...A JET
STREAK WILL PASS THROUGH NORTHERN CALIFORNIA AND LEAVE THE NORTH
BAY IN THE FAVORABLE RIGHT ENTRANCE REGION THIS AFTERNOON. THE
SURFACE BASED INSTABILITY WILL BE SOMEWHAT LIMITED HOWEVER NOTING
500 MB HEIGHT FALLS ASSOCIATED WITH A SHORTWAVE AT THAT LEVEL.
THIS WILL BE SUFFICIENT LIFT AND INSTABILITY TO SUPPORT SCATTERED
STORMS THIS AFTERNOON AND EVENING IN THE NORTH BAY
ESPECIALLY...WITH ISOLATED STORMS POSSIBLE EVEN AS FAR SOUTH AS
THE SANTA CRUZ MOUNTAINS. AGREE WITH SPC DAY 1 OUTLOOK OF MARGINAL
SEVERE THREAT IN THE NORTH BAY...AND THEIR FORECAST OF POTENTIAL
LOW TOPPED SUPERCELL STRUCTURE IS REASONABLE GIVEN LOW FREEZING
HEIGHTS AND AMPLE SHEAR. NOTED FAVORABLE HODOGRAPH AS WELL TO
SUPPORT THIS FORECAST. LOW FREEZING HEIGHT WILL SUPPORT SMALL HAIL
POTENTIAL. SHEAR BECOMES MORE UNIDIRECTIONAL AFTER 21Z...AND NOTED
STORM MOTION WILL BE QUICK FROM THE SOUTHWEST. 0-6KM MEAN WIND OF
35-40KTS BY 21Z TO ALSO INDICATE POTENTIAL FOR GUSTY WINDS IN
STORMS.

OTHER FACTOR OF NOTE TODAY IS WIND ADVISORY WHICH HAS BEEN
EXTENDED A FEW HOURS IN THE ELEVATED TERRAIN. MARGINAL EVENT WILL
HAVE POTENTIAL TO PRODUCE GREATER IMPACT GIVEN THAT IT IS THE FIRST
WIND OF THE SEASON...AND DROUGHT CONDITIONS HAVE PRODUCED MORE DEAD
OR DYING TREES AND VEGETATION THIS YEAR. MODELS CONTINUE TO SUGGEST
GUSTS NEAR 50 MPH OR HIGHER IN THE HIGH TERRAIN AND COAST. CURRENT
GUSTS ALREADY NEAR 50 MPH IN SOME AREAS SO THIS LOOKS REASONABLE.

HEIGHTS WILL BEGIN TO RISE OVERNIGHT AS THE LOW EXITS THE AREA.
SHOWERS WILL TAPER OFF OVERNIGHT AND DRYING CONDITIONS ARE
EXPECTED. RIDGING WILL GRADUALLY BUILD BACK INTO THE AREA AND
PRODUCE WARMING TEMPERATURES. BUT COOL NIGHTTIME LOWS EXPECTED IN
THE AREA SUNDAY NIGHT BEFORE THE WARMING TREND. LIKELY TO SEE MANY
UPPER 30S IN THE FAVORED COOL INTERIOR VALLEYS. ESPECIALLY IN THE
NORTH BAY AND ALSO INTERIOR MONTEREY COUNTY.

&&

.AVIATION...AS OF 4:45 AM PDT SATURDAY...RAIN AND MVFR CIGS MOVING
INTO THE AREA WITH STRONG SOUTHEAST WINDS BLOWING AHEAD OF THE
FRONT. FRONTAL PASSAGE EXPECTED IN THE SFO BAY AREA AROUND 16Z
WITH A WIND SHIFT TO THE SOUTH TO SOUTHWEST. LOW PRESSURE OFF THE
NORTHERN CALIFORNIA COAST WILL KEEP A THREAT OF SHOWERS THROUGH
THE AFTERNOON. THERE IS A CHANCE OF THUNDERSTORMS IN STS. WINDS
WILL SWITCH TO THE WEST AFTER 02Z IN MOST AREAS.

VICINITY OF KSFO...MVFR THROUGH 21Z. LIGHT RAIN TURNING TO SHOWERS
AFTER 16Z. CIGS RISING INTO VFR RANGE AFTER 21Z. SHOWERS ENDING
WITH A WIND SHIFT TO THE WEST AFTER 02Z.

KSFO BRIDGE APPROACH...SIMILAR TO KSFO.

MONTEREY BAY AREA TERMINALS...CIGS COULD LOWER TO MVFR RANGE AFTER
14Z AS RAIN SHOWERS MOVE INTO THE MRY BAY AREA. STRONGEST
SOUTHEAST WINDS WILL BE IN THE SALINAS VALLEYS WITH WINDS TO 20
KT. WINDS EXPECTED TO SWITCH TO SOUTHWESTERLY SATURDAY AFTERNOON.

&&

.MARINE...AS OF 02:28 AM PDT SATURDAY...LOW PRESSURE SITUATED WEST
OF CAPE MENDOCINO WILL CONTINUE TO DEEPEN TONIGHT RESULTING IN
STRONG SOUTHERLY WINDS ACROSS THE COASTAL WATERS. GALE FORCE WINDS
WILL DEVELOP OVERNIGHT ACROSS THE NORTHERN WATERS WITH STRONG
SMALL CRAFT WINDS DEVELOPING ELSEWHERE. A LINE OF RAIN AND SHOWERS
WILL MOVE THROUGH THE WATERS EARLY SATURDAY MORNING WITH
THUNDERSTORMS POSSIBLE NORTH OF THE GOLDEN GATE SATURDAY
AFTERNOON. WINDS WILL EASE AND SHOWERS WILL END BY SATURDAY NIGHT
WITH LIGHTER WINDS AND MODERATE SEAS SUNDAY INTO MONDAY.

&&

.MTR WATCHES/WARNINGS/ADVISORIES...
     .TDAY...WIND ADVISORY...NORTH BAY COAST AND MOUNTAINS
             WIND ADVISORY...SAN MATEO AND SANTA CRUZ COUNTY COASTS
             WIND ADVISORY...SANTA CRUZ MOUNTAINS
             SCA...SF BAY NORTH OF THE BAY BRIDGE UNTIL 3 PM
             SCA...SF BAY SOUTH OF THE BAY BRIDGE UNTIL 3 PM
             SCA...PT REYES TO PIGEON PT 0-10 NM UNTIL 3 PM
             SCA...PIGEON PT TO PT PINOS 0-10 NM UNTIL 3 PM
             SCA...PT PINOS TO PT PIEDRAS BLANCAS 0-10 NM UNTIL 3 PM
             SCA...PIGEON PT TO PT PINOS 10-60 NM UNTIL 3 PM
             SCA...PT PINOS TO PT PIEDRAS BLANCAS 10-60 NM UNTIL 3 PM
             SCA...PT ARENA TO PT REYES 10-60 NM FROM 2 PM
             GLW...PT ARENA TO PT REYES 0-10 NM UNTIL 2 PM
             GLW...PT ARENA TO PT REYES 10-60 NM UNTIL 2 PM
             GLW...PT REYES TO PIGEON PT 10-60 NM UNTIL 2 PM
             SCA...ROUGH BAR ADVISORY FOR SF BAR

&&

$$

PUBLIC FORECAST: JOHNSON
AVIATION/MARINE: W PI

VISIT US AT WEATHER.GOV/SANFRANCISCO

FOLLOW US ON FACEBOOK, TWITTER, AND YOUTUBE AT:
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000
FXUS66 KMTR 250956
AFDMTR

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SAN FRANCISCO BAY AREA
256 AM PDT SAT OCT 25 2014

.SYNOPSIS...A PACIFIC STORM WILL CONTINUE TO IMPACT THE AREA ON
SATURDAY BEFORE LIFTING QUICKLY NORTHEAST OUT OF THE AREA BY
SUNDAY MORNING. IT WILL PUSH A COLD FRONT TOWARDS THE AREA. SOUTHERLY
WINDS WILL INCREASE AHEAD OF THE FRONT AND BECOME LOCALLY STRONG
AND GUSTY NEAR THE COAST AND IN THE HILLS SATURDAY MORNING. AT THE SAME
TIME...RAIN WILL SPREAD ACROSS MUCH OF THE REGION. THE FRONT WILL
PASS THROUGH QUICKLY ON SATURDAY MORNING...BUT COOLER UNSTABLE AIR
WILL BRING SCATTERED SHOWERS TO MUCH OF THE AREA SATURDAY
AFTERNOON AND EVENING. A FEW THUNDERSTORMS MAY DEVELOP AS
WELL...ESPECIALLY FROM THE SANTA CRUZ MOUNTAINS NORTHWARD. DRIER
AND COOLER WEATHER IS EXPECTED SUNDAY WITH A WARMING TREND
BEGINNING MONDAY AS HIGH PRESSURE REBUILDS ALONG THE COAST.

&&

.DISCUSSION...AS OF 02:28 AM PDT SATURDAY...
THE FORECAST FOCUS TODAY IS ON RAIN CHANCES AND PROBABILITY OF
THUNDERSTORMS AND ANY SEVERE WEATHER POTENTIAL.

AS OF 09Z...A LOW PRESSURE CENTERED NEAR 40N/130W IS WELL EVIDENT
ON IR SATELLITE IMAGERY. THIS LOW IS EXPECTED TO LIFT
NORTHEASTWARD TODAY...AND INTO SOUTHWEST WASHINGTON BY 00Z SUN.
CURRENT RADAR SHOWS AN INITIAL BAND OF RAIN SHOWERS MOVING INTO
THE COASTAL NORTH BAY PRESENTLY. MODEL CONSENSUS CONTINUES TO BE
FOR LIGHT RAIN TO PUSH QUICKLY THROUGH THE AREA THIS MORNING.
TIMING IS FAIRLY CONSISTENT FROM PREVIOUS RUNS WHICH INDICATES
THAT SHOWERS WILL MOVE INTO THE IMMEDIATE SAN FRANCISCO BAY AREA
BY 12Z AND THE MONTEREY BAY AREA AROUND 15Z. HRRR INDICATES JUST A
QUICK SHOT...ABOUT 3-5 HOURS...OF LIGHT RAIN WITH RAPID MOVING
FRONTAL BANDS. AFTER THESE BANDS CLEAR THERE WILL BE A FEW HOURS
OF DRY WEATHER AS THE ATMOSPHERE DESTABILIZES WITH COLD ADVECTION
NOTED. THIS WILL PROVIDE THE BASIC INGREDIENTS NEEDED FOR
SCATTERED SHOWERS AND THUNDERSTORMS THIS AFTERNOON ESPECIALLY OVER
THE NORTH BAY. AN ANALYSIS OF FORECAST SOUNDINGS SHOWED A
MODERATELY UNSTABLE AIRMASS WITH SOME SURFACE BASED INSTABILITY.
THE PROFILE REMAINS MOIST ENOUGH TO SUPPORT CONVECTION AS WELL.
THERE WILL BE A VIGOROUS WIND FIELD WITH 0-6KM SHEAR IN EXCESS OF
30KTS AND NOTED LOW LEVEL SHEAR AS WELL. IN ADDITION...A JET
STREAK WILL PASS THROUGH NORTHERN CALIFORNIA AND LEAVE THE NORTH
BAY IN THE FAVORABLE RIGHT ENTRANCE REGION THIS AFTERNOON. THE
SURFACE BASED INSTABILITY WILL BE SOMEWHAT LIMITED HOWEVER NOTING
500 MB HEIGHT FALLS ASSOCIATED WITH A SHORTWAVE AT THAT LEVEL.
THIS WILL BE SUFFICIENT LIFT AND INSTABILITY TO SUPPORT SCATTERED
STORMS THIS AFTERNOON AND EVENING IN THE NORTH BAY
ESPECIALLY...WITH ISOLATED STORMS POSSIBLE EVEN AS FAR SOUTH AS
THE SANTA CRUZ MOUNTAINS. AGREE WITH SPC DAY 1 OUTLOOK OF MARGINAL
SEVERE THREAT IN THE NORTH BAY...AND THEIR FORECAST OF POTENTIAL
LOW TOPPED SUPERCELL STRUCTURE IS REASONABLE GIVEN LOW FREEZING
HEIGHTS AND AMPLE SHEAR. NOTED FAVORABLE HODOGRAPH AS WELL TO
SUPPORT THIS FORECAST. LOW FREEZING HEIGHT WILL SUPPORT SMALL HAIL
POTENTIAL. SHEAR BECOMES MORE UNIDIRECTIONAL AFTER 21Z...AND NOTED
STORM MOTION WILL BE QUICK FROM THE SOUTHWEST. 0-6KM MEAN WIND OF
35-40KTS BY 21Z TO ALSO INDICATE POTENTIAL FOR GUSTY WINDS IN
STORMS.

OTHER FACTOR OF NOTE TODAY IS WIND ADVISORY WHICH HAS BEEN
EXTENDED A FEW HOURS IN THE ELEVATED TERRAIN. MARGINAL EVENT WILL
HAVE POTENTIAL TO PRODUCE GREATER IMPACT GIVEN THAT IT IS THE FIRST
WIND OF THE SEASON...AND DROUGHT CONDITIONS HAVE PRODUCED MORE DEAD
OR DYING TREES AND VEGETATION THIS YEAR. MODELS CONTINUE TO SUGGEST
GUSTS NEAR 50 MPH OR HIGHER IN THE HIGH TERRAIN AND COAST. CURRENT
GUSTS ALREADY NEAR 50 MPH IN SOME AREAS SO THIS LOOKS REASONABLE.

HEIGHTS WILL BEGIN TO RISE OVERNIGHT AS THE LOW EXITS THE AREA.
SHOWERS WILL TAPER OFF OVERNIGHT AND DRYING CONDITIONS ARE
EXPECTED. RIDGING WILL GRADUALLY BUILD BACK INTO THE AREA AND
PRODUCE WARMING TEMPERATURES. BUT COOL NIGHTTIME LOWS EXPECTED IN
THE AREA SUNDAY NIGHT BEFORE THE WARMING TREND. LIKELY TO SEE MANY
UPPER 30S IN THE FAVORED COOL INTERIOR VALLEYS. ESPECIALLY IN THE
NORTH BAY AND ALSO INTERIOR MONTEREY COUNTY.

&&

.AVIATION...AS OF 10:51 PM PDT FRIDAY...FOR 06Z TAFS. AN
APPROACHING LOW PRESSURE SYSTEM AND ASSOCIATED COLD FRONT
SITUATED OFF THE NORTHERN CALIFORNIA COAST WILL BRING  INCREASING
SOUTHEASTERLY WINDS OVERNIGHT AND WET RUNWAYS BY MORNING. T-STORMS
REMAIN A CONCERT FOR SATURDAY AFTERNOON.

VICINITY OF KSFO...VFR CONDITIONS EXPECTED THROUGH LATE TONIGHT. LIGHT
SOUTH WINDS WILL TURN SOUTHEASTERLY AND STRENGTHEN OVERNIGHT. -RA
EXPECTED AROUND 11Z TONIGHT. BY SATURDAY MORNING MODERATE AND
GUSTY SOUTHEAST WINDS AND WET RUNWAYS WILL IMPACT THE MORNING
TRAFFIC. WINDS EXPECTED TO VEER SOUTHWESTERLY SATURDAY AFTERNOON.

KSFO BRIDGE APPROACH...SIMILAR TO KSFO.

MONTEREY BAY AREA TERMINALS...VFR CONDITIONS EXPECTED THROUGH
LATE TONIGHT. LIGHT WINDS WILL TURN SOUTHEASTERLY OVERNIGHT.
-SHRA EXPECTED TO DEVELOP AROUND 12Z-15Z SATURDAY. BY SATURDAY
MORNING SOUTHEAST WINDS AND WET RUNWAYS WILL IMPACT AREA
TERMINALS. WINDS EXPECTED TO VEER SOUTHWESTERLY SATURDAY
AFTERNOON.

&&

.MARINE...AS OF 02:28 AM PDT SATURDAY...LOW PRESSURE SITUATED WEST
OF CAPE MENDOCINO WILL CONTINUE TO DEEPEN TONIGHT RESULTING IN
STRONG SOUTHERLY WINDS ACROSS THE COASTAL WATERS. GALE FORCE WINDS
WILL DEVELOP OVERNIGHT ACROSS THE NORTHERN WATERS WITH STRONG
SMALL CRAFT WINDS DEVELOPING ELSEWHERE. A LINE OF RAIN AND SHOWERS
WILL MOVE THROUGH THE WATERS EARLY SATURDAY MORNING WITH
THUNDERSTORMS POSSIBLE NORTH OF THE GOLDEN GATE SATURDAY
AFTERNOON. WINDS WILL EASE AND SHOWERS WILL END BY SATURDAY NIGHT
WITH LIGHTER WINDS AND MODERATE SEAS SUNDAY INTO MONDAY.

&&

.MTR WATCHES/WARNINGS/ADVISORIES...
     .TDAY...WIND ADVISORY...NORTH BAY COAST AND MOUNTAINS
             WIND ADVISORY...SAN MATEO AND SANTA CRUZ COUNTY COASTS
             WIND ADVISORY...SANTA CRUZ MOUNTAINS
             SCA...SF BAY NORTH OF THE BAY BRIDGE UNTIL 3 PM
             SCA...SF BAY SOUTH OF THE BAY BRIDGE UNTIL 3 PM
             SCA...PIGEON PT TO PT PINOS 0-10 NM UNTIL 3 PM
             SCA...PT PINOS TO PT PIEDRAS BLANCAS 0-10 NM UNTIL 3 PM
             SCA...PT PINOS TO PT PIEDRAS BLANCAS 10-60 NM UNTIL 3 PM
             SCA...PT ARENA TO PT REYES 10-60 NM FROM 2 PM
             GLW...PT ARENA TO PT REYES 0-10 NM UNTIL 2 PM
             GLW...PT ARENA TO PT REYES 10-60 NM UNTIL 2 PM
             GLW...PT REYES TO PIGEON PT 10-60 NM UNTIL 2 PM
             SCA...PT REYES TO PIGEON PT 0-10 NM UNTIL 3 PM
             SCA...PIGEON PT TO PT PINOS 10-60 NM UNTIL 3 PM
             SCA...ROUGH BAR ADVISORY FOR SF BAR

&&

$$

PUBLIC FORECAST: JOHNSON
AVIATION/MARINE: W PI

VISIT US AT WEATHER.GOV/SANFRANCISCO

FOLLOW US ON FACEBOOK, TWITTER, AND YOUTUBE AT:
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000
FXUS66 KMTR 250552
AFDMTR

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SAN FRANCISCO BAY AREA
1052 PM PDT FRI OCT 24 2014

.SYNOPSIS...A COLD FRONT WILL APPROACH THE COAST LATE ON FRIDAY
NIGHT. SOUTHERLY WINDS WILL INCREASE AHEAD OF THE FRONT AND BECOME
LOCALLY STRONG AND GUSTY NEAR THE COAST AND IN THE HILLS LATE
FRIDAY NIGHT AND SATURDAY MORNING. AT THE SAME TIME...RAIN WILL
SPREAD ACROSS MUCH OF THE REGION. THE FRONT WILL PASS THROUGH
QUICKLY ON SATURDAY MORNING...BUT COOLER UNSTABLE AIR WILL BRING
SCATTERED SHOWERS TO MUCH OF THE AREA SATURDAY AFTERNOON AND
EVENING. A FEW THUNDERSTORMS MAY DEVELOP AS WELL...ESPECIALLY FROM
THE SANTA CRUZ MOUNTAINS NORTHWARD. DRIER AND COOLER WEATHER IS
EXPECTED SUNDAY WITH A WARMING TREND BEGINNING MONDAY AS HIGH
PRESSURE REBUILDS ALONG THE COAST.

&&

.DISCUSSION...AS OF 8:55 PM PDT FRIDAY...A STORM SYSTEM OVER THE
EASTERN PACIFIC CONTINUES TO ADVANCE TOWARDS THE WEST COAST AT A
MODERATE PACE. SATELLITE SHOWS A WELL-DEFINED COLD FRONT MOVING
JUST INSIDE 130W AND A POOL OF COLD UNSTABLE AIR BEHIND THE FRONT.

SOUTHERLY WINDS HAVE ALREADY DEVELOPED AHEAD OF THE FRONT AND HAVE
BEGUN TO INCREASE OVER OUR COASTAL WATERS. WIND SPEEDS WILL
GRADUALLY RAMP UP OVERNIGHT AS THE FRONT DRAWS CLOSER. WINDS WILL
BECOME LOCALLY STRONG AND GUSTY NEAR THE OCEAN AND IN THE HILLS BY
LATE TONIGHT. BASED ON THE LATEST NAM...THE COLD FRONT SHOULD PASS
THROUGH THE NORTH BAY BY ABOUT SUNRISE SATURDAY MORNING AND THEN
THROUGH THE REST OF THE SF BAY AREA BY MID MORNING. WINDS ARE
FORECAST TO VEER MORE TO THE SOUTHWEST AFTER FRONTAL PASSAGE...BUT
REMAIN QUITE STRONG AND GUSTY THROUGH MIDDAY SATURDAY. THIS LOOKS
LIKE A MARGINAL WIND ADVISORY SITUATION...WITH THE MOST
SIGNIFICANT PRESSURE GRADIENTS AND WINDS FORECAST TO REMAIN TO OUR
NORTH. WIND GUSTS UP IN THE 40-50 MPH RANGE WILL PROBABLY ONLY
OCCUR IN SOME OF OUR WINDIEST COASTAL AND RIDGETOP LOCATIONS LATE
TONIGHT AND SATURDAY MORNING. HOWEVER...DROUGHT-STRESSED TREES
HAVE NOT BEEN SUBJECTED TO WINDS OF ANY SIGNIFICANCE FOR QUITE
SOME TIME AND MANY ARE PRONE TO TOPPLING WITH THIS FIRST BLUSTERY
STORM SYSTEM OF THE SEASON. POWER OUTAGES OR PROPERTY DAMAGE ARE
POSSIBLE DUE TO FALLEN TREES OR TREE LIMBS. THEREFORE...WILL
CONTINUE WITH A WIND ADVISORY FOR THE NORTH BAY COAST AND
MOUNTAINS...THE SAN MATEO AND SANTA CRUZ COUNTY COASTS...AND THE
SANTA CRUZ MOUNTAINS FROM 3 AM TO NOON PDT ON SATURDAY.

THE COLD FRONT WILL SPREAD RAIN ACROSS MOST OF OUR REGION LATE
TONIGHT AND SATURDAY MORNING. THERE MAY BE A BIT OF A BREAK IN THE
PRECIP ACTION LATE SATURDAY MORNING AFTER FRONTAL PASSAGE...BUT
THEN BANDS OF SHOWERS ARE EXPECTED TO ROTATE THROUGH OUR REGION AS
THE COLD AND UNSTABLE AIRMASS ASSOCIATED WITH THE UPPER TROUGH
ARRIVES. THE 00Z NAM HAS BACKED OFF ON THE AMOUNT OF INSTABILITY
FORECAST ACROSS THE SF BAY AREA ON SATURDAY AFTERNOON AND SO
THUNDERSTORM CHANCES APPEAR TO BE DWINDLING. HOWEVER...AS POINTED
OUT IN THE PREVIOUS DISCUSSION...CONTINUED MUCH WARMER THAN NORMAL
SEA SURFACE TEMPERATURES ALONG OUR COAST MAY PROVIDE THE NECESSARY
INGREDIENT FOR GREATER INSTABILITY AND ISOLATED THUNDERSTORMS.

SHOWERS ARE EXPECTED TO TAPER OF SATURDAY EVENING AND END BY
DAYBREAK SUNDAY. SUNDAY WILL BE A RELATIVELY COOL DAY WITH
NORTHWEST BREEZES UNDER PARTLY CLOUDY SKIES.

A WARMING TREND IS FORECAST FOR THE FIRST HALF OF THE WORK WEEK AS
A LOW AMPLITUDE UPPER RIDGE BUILDS OVER CA. THE PATTERN WILL
REMAIN ACTIVE OVER THE NORTHEAST PACIFIC...WITH STORM SYSTEMS
FORECAST TO RIDE OVER THE RIDGE AND INTO THE PAC NW. IT CURRENTLY
APPEARS VERY UNLIKELY THAT ANY OF THIS PRECIP WILL MAKE IT INTO
OUR AREA...AND WE MAY WANT TO CONSIDER REMOVING POPS FROM THE
NORTH BAY AROUND THE MIDDLE OF NEXT WEEK.

CONFIDENCE IN THE FORECAST FALLS OFF CONSIDERABLY LATE IN THE
EXTENDED. THE MEDIUM RANGE MODELS AGREE THAT THE UPPER RIDGE WILL
MOVE EAST BY THE END OF NEXT WEEK...ALLOWING THE TROUGH OFFSHORE TO
APPROACH THE WEST COAST. BUT THE FORECAST OF PRECIP ONSET IN OUR AREA
VARIES CONSIDERABLY...FROM AS EARLY AS THURSDAY NIGHT (GEM) TO AS
LATE AS SUNDAY NIGHT (ECMWF).

&&

.AVIATION...AS OF 10:51 PM PDT FRIDAY...FOR 06Z TAFS. AN
APPROACHING LOW PRESSURE SYSTEM AND ASSOCIATED COLD FRONT
SITUATED OFF THE NORTHERN CALIFORNIA COAST WILL BRING  INCREASING
SOUTHEASTERLY WINDS OVERNIGHT AND WET RUNWAYS BY MORNING. T-STORMS
REMAIN A CONCERT FOR SATURDAY AFTERNOON.

VICINITY OF KSFO...VFR CONDITIONS EXPECTED THROUGH LATE TONIGHT. LIGHT
SOUTH WINDS WILL TURN SOUTHEASTERLY AND STRENGTHEN OVERNIGHT. -RA
EXPECTED AROUND 11Z TONIGHT. BY SATURDAY MORNING MODERATE AND
GUSTY SOUTHEAST WINDS AND WET RUNWAYS WILL IMPACT THE MORNING
TRAFFIC. WINDS EXPECTED TO VEER SOUTHWESTERLY SATURDAY AFTERNOON.

KSFO BRIDGE APPROACH...SIMILAR TO KSFO.

MONTEREY BAY AREA TERMINALS...VFR CONDITIONS EXPECTED THROUGH
LATE TONIGHT. LIGHT WINDS WILL TURN SOUTHEASTERLY OVERNIGHT.
-SHRA EXPECTED TO DEVELOP AROUND 12Z-15Z SATURDAY. BY SATURDAY
MORNING SOUTHEAST WINDS AND WET RUNWAYS WILL IMPACT AREA
TERMINALS. WINDS EXPECTED TO VEER SOUTHWESTERLY SATURDAY
AFTERNOON.

&&

.MARINE...AS OF 8:57 PM PDT FRIDAY...LOW PRESSURE SITUATED WEST
OF CAPE MENDOCINO WILL CONTINUE TO DEEPEN TONIGHT RESULTING IN
STRONG SOUTHERLY WINDS ACROSS THE COASTAL WATERS. GALE FORCE WINDS
WILL DEVELOP OVERNIGHT ACROSS THE NORTHERN WATERS WITH STRONG
SMALL CRAFT WINDS DEVELOPING ELSEWHERE. A LINE OF RAIN AND SHOWERS
WILL MOVE THROUGH THE WATERS EARLY SATURDAY MORNING WITH
THUNDERSTORMS POSSIBLE NORTH OF THE GOLDEN GATE SATURDAY
AFTERNOON. WINDS WILL EASE AND SHOWERS WILL END BY SATURDAY NIGHT
WITH LIGHTER WINDS AND MODERATE SEAS SUNDAY INTO MONDAY.

&&

.MTR WATCHES/WARNINGS/ADVISORIES...
     .TNGT...WIND ADVISORY...NORTH BAY COAST AND MOUNTAINS
             WIND ADVISORY...SAN MATEO AND SANTA CRUZ COUNTY COASTS
             WIND ADVISORY...SANTA CRUZ MOUNTAINS
             SCA...SF BAY NORTH OF THE BAY BRIDGE FROM 3 AM
             SCA...SF BAY SOUTH OF THE BAY BRIDGE FROM 3 AM
             SCA...PIGEON PT TO PT PINOS 0-10 NM FROM 3 AM
             SCA...PT PINOS TO PT PIEDRAS BLANCAS 0-10 NM FROM 3 AM
             SCA...PT PINOS TO PT PIEDRAS BLANCAS 10-60 NM FROM 3 AM
             GLW...PT ARENA TO PT REYES 10-60 NM
             SCA...PT REYES TO PIGEON PT 10-60 NM UNTIL MIDNIGHT
             GLW...PT REYES TO PIGEON PT 10-60 NM FROM MIDNIGHT
             SCA...PT REYES TO PIGEON PT 0-10 NM FROM 9 PM
             SCA...PIGEON PT TO PT PINOS 10-60 NM FROM 9 PM
             SCA...PT ARENA TO PT REYES 0-10 NM UNTIL 1 AM
             GLW...PT ARENA TO PT REYES 0-10 NM FROM 1 AM
             SCA...ROUGH BAR ADVISORY FOR SF BAR FROM 5 AM

&&

$$

PUBLIC FORECAST: DYKEMA
AVIATION/MARINE: CW

VISIT US AT WEATHER.GOV/SANFRANCISCO

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000
FXUS66 KMTR 250355
AFDMTR

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SAN FRANCISCO BAY AREA
855 PM PDT FRI OCT 24 2014

.SYNOPSIS...A COLD FRONT WILL APPROACH THE COAST LATE ON FRIDAY
NIGHT. SOUTHERLY WINDS WILL INCREASE AHEAD OF THE FRONT AND BECOME
LOCALLY STRONG AND GUSTY NEAR THE COAST AND IN THE HILLS LATE
FRIDAY NIGHT AND SATURDAY MORNING. AT THE SAME TIME...RAIN WILL
SPREAD ACROSS MUCH OF THE REGION. THE FRONT WILL PASS THROUGH
QUICKLY ON SATURDAY MORNING...BUT COOLER UNSTABLE AIR WILL BRING
SCATTERED SHOWERS TO MUCH OF THE AREA SATURDAY AFTERNOON AND
EVENING. A FEW THUNDERSTORMS MAY DEVELOP AS WELL...ESPECIALLY FROM
THE SANTA CRUZ MOUNTAINS NORTHWARD. DRIER AND COOLER WEATHER IS
EXPECTED SUNDAY WITH A WARMING TREND BEGINNING MONDAY AS HIGH
PRESSURE REBUILDS ALONG THE COAST.

&&

.DISCUSSION...AS OF 8:55 PM PDT FRIDAY...A STORM SYSTEM OVER THE
EASTERN PACIFIC CONTINUES TO ADVANCE TOWARDS THE WEST COAST AT A
MODERATE PACE. SATELLITE SHOWS A WELL-DEFINED COLD FRONT MOVING
JUST INSIDE 130W AND A POOL OF COLD UNSTABLE AIR BEHIND THE FRONT.

SOUTHERLY WINDS HAVE ALREADY DEVELOPED AHEAD OF THE FRONT AND HAVE
BEGUN TO INCREASE OVER OUR COASTAL WATERS. WIND SPEEDS WILL
GRADUALLY RAMP UP OVERNIGHT AS THE FRONT DRAWS CLOSER. WINDS WILL
BECOME LOCALLY STRONG AND GUSTY NEAR THE OCEAN AND IN THE HILLS BY
LATE TONIGHT. BASED ON THE LATEST NAM...THE COLD FRONT SHOULD PASS
THROUGH THE NORTH BAY BY ABOUT SUNRISE SATURDAY MORNING AND THEN
THROUGH THE REST OF THE SF BAY AREA BY MID MORNING. WINDS ARE
FORECAST TO VEER MORE TO THE SOUTHWEST AFTER FRONTAL PASSAGE...BUT
REMAIN QUITE STRONG AND GUSTY THROUGH MIDDAY SATURDAY. THIS LOOKS
LIKE A MARGINAL WIND ADVISORY SITUATION...WITH THE MOST
SIGNIFICANT PRESSURE GRADIENTS AND WINDS FORECAST TO REMAIN TO OUR
NORTH. WIND GUSTS UP IN THE 40-50 MPH RANGE WILL PROBABLY ONLY
OCCUR IN SOME OF OUR WINDIEST COASTAL AND RIDGETOP LOCATIONS LATE
TONIGHT AND SATURDAY MORNING. HOWEVER...DROUGHT-STRESSED TREES
HAVE NOT BEEN SUBJECTED TO WINDS OF ANY SIGNIFICANCE FOR QUITE
SOME TIME AND MANY ARE PRONE TO TOPPLING WITH THIS FIRST BLUSTERY
STORM SYSTEM OF THE SEASON. POWER OUTAGES OR PROPERTY DAMAGE ARE
POSSIBLE DUE TO FALLEN TREES OR TREE LIMBS. THEREFORE...WILL
CONTINUE WITH A WIND ADVISORY FOR THE NORTH BAY COAST AND
MOUNTAINS...THE SAN MATEO AND SANTA CRUZ COUNTY COASTS...AND THE
SANTA CRUZ MOUNTAINS FROM 3 AM TO NOON PDT ON SATURDAY.

THE COLD FRONT WILL SPREAD RAIN ACROSS MOST OF OUR REGION LATE
TONIGHT AND SATURDAY MORNING. THERE MAY BE A BIT OF A BREAK IN THE
PRECIP ACTION LATE SATURDAY MORNING AFTER FRONTAL PASSAGE...BUT
THEN BANDS OF SHOWERS ARE EXPECTED TO ROTATE THROUGH OUR REGION AS
THE COLD AND UNSTABLE AIRMASS ASSOCIATED WITH THE UPPER TROUGH
ARRIVES. THE 00Z NAM HAS BACKED OFF ON THE AMOUNT OF INSTABILITY
FORECAST ACROSS THE SF BAY AREA ON SATURDAY AFTERNOON AND SO
THUNDERSTORM CHANCES APPEAR TO BE DWINDLING. HOWEVER...AS POINTED
OUT IN THE PREVIOUS DISCUSSION...CONTINUED MUCH WARMER THAN NORMAL
SEA SURFACE TEMPERATURES ALONG OUR COAST MAY PROVIDE THE NECESSARY
INGREDIENT FOR GREATER INSTABILITY AND ISOLATED THUNDERSTORMS.

SHOWERS ARE EXPECTED TO TAPER OF SATURDAY EVENING AND END BY
DAYBREAK SUNDAY. SUNDAY WILL BE A RELATIVELY COOL DAY WITH
NORTHWEST BREEZES UNDER PARTLY CLOUDY SKIES.

A WARMING TREND IS FORECAST FOR THE FIRST HALF OF THE WORK WEEK AS
A LOW AMPLITUDE UPPER RIDGE BUILDS OVER CA. THE PATTERN WILL
REMAIN ACTIVE OVER THE NORTHEAST PACIFIC...WITH STORM SYSTEMS
FORECAST TO RIDE OVER THE RIDGE AND INTO THE PAC NW. IT CURRENTLY
APPEARS VERY UNLIKELY THAT ANY OF THIS PRECIP WILL MAKE IT INTO
OUR AREA...AND WE MAY WANT TO CONSIDER REMOVING POPS FROM THE
NORTH BAY AROUND THE MIDDLE OF NEXT WEEK.

CONFIDENCE IN THE FORECAST FALLS OFF CONSIDERABLY LATE IN THE
EXTENDED. THE MEDIUM RANGE MODELS AGREE THAT THE UPPER RIDGE WILL
MOVE EAST BY THE END OF NEXT WEEK...ALLOWING THE TROUGH OFFSHORE TO
APPROACH THE WEST COAST. BUT THE FORECAST OF PRECIP ONSET IN OUR AREA
VARIES CONSIDERABLY...FROM AS EARLY AS THURSDAY NIGHT (GEM) TO AS
LATE AS SUNDAY NIGHT (ECMWF).

&&

.AVIATION...AS OF 4:59 PM PDT FRIDAY...FOR 00Z TAFS. A WELL
DEFINED LOW PRESSURE SYSTEM SPINNING APPROXIMATELY 500 NM OFF THE
NORTHERN CALIFORNIA COAST WILL APPROACH THE REGION TONIGHT INTO
SATURDAY BRINGING STRONGER SOUTHEASTERLY WINDS AND WET RUNWAYS.
T-STORMS REMAIN A CONCERT FOR SATURDAY AFTERNOON BUT KEEP OUT OF
THE TAF AT THIS TIME.

VICINITY OF KSFO...VFR CONDITIONS EXPECTED THROUGH THIS EVENING. LIGHT
SOUTHWEST WILL TURN SOUTHEASTERLY AND STRENGTHEN OVERNIGHT. -RA
EXPECTED AROUND 11Z TONIGHT. BY SATURDAY MORNING MODERATE AND
GUSTY SOUTHEAST WINDS AND WET RUNWAYS WILL IMPACT THE MORNING
TRAFFIC. WINDS EXPECTED TO VEER SOUTHWESTERLY SATURDAY AFTERNOON.

KSFO BRIDGE APPROACH...SIMILAR TO KSFO.

MONTEREY BAY AREA TERMINALS...VFR CONDITIONS EXPECTED THROUGH
THIS EVENING. LIGHT SOUTHWEST WILL TURN SOUTHEASTERLY OVERNIGHT.
-SHRA EXPECTED TO DEVELOP AROUND 12Z-15Z SATURDAY. BY SATURDAY
MORNING SOUTHEAST WINDS AND WET RUNWAYS WILL IMPACT AREA
TERMINALS. WINDS EXPECTED TO VEER SOUTHWESTERLY SATURDAY
AFTERNOON.

&&

.MARINE...AS OF 3:00 PM PDT FRIDAY...A 992 MB LOW WILL DEEPEN
WEST OF CAPE MENDOCINO THIS EVENING WITH INCREASING SOUTHERLY
WINDS. GALE FORCE WINDS WILL DEVELOP OVERNIGHT ACROSS THE NORTHERN
WATERS WITH STRONG SMALL CRAFT WINDS DEVELOPING ELSEWHERE. A LINE
OF RAIN AND SHOWERS WILL MOVE THROUGH THE WATERS EARLY SATURDAY
MORNING WITH THUNDERSTORMS POSSIBLE NORTH OF THE GOLDEN GATE
SATURDAY AFTERNOON. WINDS WILL EASE AND SHOWERS WILL END BY
SATURDAY NIGHT WITH LIGHTER WINDS AND MODERATE SEAS SUNDAY INTO
MONDAY.

&&

.MTR WATCHES/WARNINGS/ADVISORIES...
     .TNGT...WIND ADVISORY...NORTH BAY COAST AND MOUNTAINS
             WIND ADVISORY...SAN MATEO AND SANTA CRUZ COUNTY COASTS
             WIND ADVISORY...SANTA CRUZ MOUNTAINS
             SCA...SF BAY NORTH OF THE BAY BRIDGE FROM 3 AM
             SCA...SF BAY SOUTH OF THE BAY BRIDGE FROM 3 AM
             SCA...PIGEON PT TO PT PINOS 0-10 NM FROM 3 AM
             SCA...PT PINOS TO PT PIEDRAS BLANCAS 0-10 NM FROM 3 AM
             SCA...PT PINOS TO PT PIEDRAS BLANCAS 10-60 NM FROM 3 AM
             GLW...PT ARENA TO PT REYES 10-60 NM
             SCA...PT REYES TO PIGEON PT 10-60 NM UNTIL MIDNIGHT
             GLW...PT REYES TO PIGEON PT 10-60 NM FROM MIDNIGHT
             SCA...PT REYES TO PIGEON PT 0-10 NM FROM 9 PM
             SCA...PIGEON PT TO PT PINOS 10-60 NM FROM 9 PM
             SCA...PT ARENA TO PT REYES 0-10 NM UNTIL 1 AM
             GLW...PT ARENA TO PT REYES 0-10 NM FROM 1 AM
             SCA...ROUGH BAR ADVISORY FOR SF BAR FROM 5 AM

&&

$$

PUBLIC FORECAST: DYKEMA
AVIATION: CW
MARINE: RWW

VISIT US AT WEATHER.GOV/SANFRANCISCO

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000
FXUS66 KMTR 250355
AFDMTR

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SAN FRANCISCO BAY AREA
855 PM PDT FRI OCT 24 2014

.SYNOPSIS...A COLD FRONT WILL APPROACH THE COAST LATE ON FRIDAY
NIGHT. SOUTHERLY WINDS WILL INCREASE AHEAD OF THE FRONT AND BECOME
LOCALLY STRONG AND GUSTY NEAR THE COAST AND IN THE HILLS LATE
FRIDAY NIGHT AND SATURDAY MORNING. AT THE SAME TIME...RAIN WILL
SPREAD ACROSS MUCH OF THE REGION. THE FRONT WILL PASS THROUGH
QUICKLY ON SATURDAY MORNING...BUT COOLER UNSTABLE AIR WILL BRING
SCATTERED SHOWERS TO MUCH OF THE AREA SATURDAY AFTERNOON AND
EVENING. A FEW THUNDERSTORMS MAY DEVELOP AS WELL...ESPECIALLY FROM
THE SANTA CRUZ MOUNTAINS NORTHWARD. DRIER AND COOLER WEATHER IS
EXPECTED SUNDAY WITH A WARMING TREND BEGINNING MONDAY AS HIGH
PRESSURE REBUILDS ALONG THE COAST.

&&

.DISCUSSION...AS OF 8:55 PM PDT FRIDAY...A STORM SYSTEM OVER THE
EASTERN PACIFIC CONTINUES TO ADVANCE TOWARDS THE WEST COAST AT A
MODERATE PACE. SATELLITE SHOWS A WELL-DEFINED COLD FRONT MOVING
JUST INSIDE 130W AND A POOL OF COLD UNSTABLE AIR BEHIND THE FRONT.

SOUTHERLY WINDS HAVE ALREADY DEVELOPED AHEAD OF THE FRONT AND HAVE
BEGUN TO INCREASE OVER OUR COASTAL WATERS. WIND SPEEDS WILL
GRADUALLY RAMP UP OVERNIGHT AS THE FRONT DRAWS CLOSER. WINDS WILL
BECOME LOCALLY STRONG AND GUSTY NEAR THE OCEAN AND IN THE HILLS BY
LATE TONIGHT. BASED ON THE LATEST NAM...THE COLD FRONT SHOULD PASS
THROUGH THE NORTH BAY BY ABOUT SUNRISE SATURDAY MORNING AND THEN
THROUGH THE REST OF THE SF BAY AREA BY MID MORNING. WINDS ARE
FORECAST TO VEER MORE TO THE SOUTHWEST AFTER FRONTAL PASSAGE...BUT
REMAIN QUITE STRONG AND GUSTY THROUGH MIDDAY SATURDAY. THIS LOOKS
LIKE A MARGINAL WIND ADVISORY SITUATION...WITH THE MOST
SIGNIFICANT PRESSURE GRADIENTS AND WINDS FORECAST TO REMAIN TO OUR
NORTH. WIND GUSTS UP IN THE 40-50 MPH RANGE WILL PROBABLY ONLY
OCCUR IN SOME OF OUR WINDIEST COASTAL AND RIDGETOP LOCATIONS LATE
TONIGHT AND SATURDAY MORNING. HOWEVER...DROUGHT-STRESSED TREES
HAVE NOT BEEN SUBJECTED TO WINDS OF ANY SIGNIFICANCE FOR QUITE
SOME TIME AND MANY ARE PRONE TO TOPPLING WITH THIS FIRST BLUSTERY
STORM SYSTEM OF THE SEASON. POWER OUTAGES OR PROPERTY DAMAGE ARE
POSSIBLE DUE TO FALLEN TREES OR TREE LIMBS. THEREFORE...WILL
CONTINUE WITH A WIND ADVISORY FOR THE NORTH BAY COAST AND
MOUNTAINS...THE SAN MATEO AND SANTA CRUZ COUNTY COASTS...AND THE
SANTA CRUZ MOUNTAINS FROM 3 AM TO NOON PDT ON SATURDAY.

THE COLD FRONT WILL SPREAD RAIN ACROSS MOST OF OUR REGION LATE
TONIGHT AND SATURDAY MORNING. THERE MAY BE A BIT OF A BREAK IN THE
PRECIP ACTION LATE SATURDAY MORNING AFTER FRONTAL PASSAGE...BUT
THEN BANDS OF SHOWERS ARE EXPECTED TO ROTATE THROUGH OUR REGION AS
THE COLD AND UNSTABLE AIRMASS ASSOCIATED WITH THE UPPER TROUGH
ARRIVES. THE 00Z NAM HAS BACKED OFF ON THE AMOUNT OF INSTABILITY
FORECAST ACROSS THE SF BAY AREA ON SATURDAY AFTERNOON AND SO
THUNDERSTORM CHANCES APPEAR TO BE DWINDLING. HOWEVER...AS POINTED
OUT IN THE PREVIOUS DISCUSSION...CONTINUED MUCH WARMER THAN NORMAL
SEA SURFACE TEMPERATURES ALONG OUR COAST MAY PROVIDE THE NECESSARY
INGREDIENT FOR GREATER INSTABILITY AND ISOLATED THUNDERSTORMS.

SHOWERS ARE EXPECTED TO TAPER OF SATURDAY EVENING AND END BY
DAYBREAK SUNDAY. SUNDAY WILL BE A RELATIVELY COOL DAY WITH
NORTHWEST BREEZES UNDER PARTLY CLOUDY SKIES.

A WARMING TREND IS FORECAST FOR THE FIRST HALF OF THE WORK WEEK AS
A LOW AMPLITUDE UPPER RIDGE BUILDS OVER CA. THE PATTERN WILL
REMAIN ACTIVE OVER THE NORTHEAST PACIFIC...WITH STORM SYSTEMS
FORECAST TO RIDE OVER THE RIDGE AND INTO THE PAC NW. IT CURRENTLY
APPEARS VERY UNLIKELY THAT ANY OF THIS PRECIP WILL MAKE IT INTO
OUR AREA...AND WE MAY WANT TO CONSIDER REMOVING POPS FROM THE
NORTH BAY AROUND THE MIDDLE OF NEXT WEEK.

CONFIDENCE IN THE FORECAST FALLS OFF CONSIDERABLY LATE IN THE
EXTENDED. THE MEDIUM RANGE MODELS AGREE THAT THE UPPER RIDGE WILL
MOVE EAST BY THE END OF NEXT WEEK...ALLOWING THE TROUGH OFFSHORE TO
APPROACH THE WEST COAST. BUT THE FORECAST OF PRECIP ONSET IN OUR AREA
VARIES CONSIDERABLY...FROM AS EARLY AS THURSDAY NIGHT (GEM) TO AS
LATE AS SUNDAY NIGHT (ECMWF).

&&

.AVIATION...AS OF 4:59 PM PDT FRIDAY...FOR 00Z TAFS. A WELL
DEFINED LOW PRESSURE SYSTEM SPINNING APPROXIMATELY 500 NM OFF THE
NORTHERN CALIFORNIA COAST WILL APPROACH THE REGION TONIGHT INTO
SATURDAY BRINGING STRONGER SOUTHEASTERLY WINDS AND WET RUNWAYS.
T-STORMS REMAIN A CONCERT FOR SATURDAY AFTERNOON BUT KEEP OUT OF
THE TAF AT THIS TIME.

VICINITY OF KSFO...VFR CONDITIONS EXPECTED THROUGH THIS EVENING. LIGHT
SOUTHWEST WILL TURN SOUTHEASTERLY AND STRENGTHEN OVERNIGHT. -RA
EXPECTED AROUND 11Z TONIGHT. BY SATURDAY MORNING MODERATE AND
GUSTY SOUTHEAST WINDS AND WET RUNWAYS WILL IMPACT THE MORNING
TRAFFIC. WINDS EXPECTED TO VEER SOUTHWESTERLY SATURDAY AFTERNOON.

KSFO BRIDGE APPROACH...SIMILAR TO KSFO.

MONTEREY BAY AREA TERMINALS...VFR CONDITIONS EXPECTED THROUGH
THIS EVENING. LIGHT SOUTHWEST WILL TURN SOUTHEASTERLY OVERNIGHT.
-SHRA EXPECTED TO DEVELOP AROUND 12Z-15Z SATURDAY. BY SATURDAY
MORNING SOUTHEAST WINDS AND WET RUNWAYS WILL IMPACT AREA
TERMINALS. WINDS EXPECTED TO VEER SOUTHWESTERLY SATURDAY
AFTERNOON.

&&

.MARINE...AS OF 3:00 PM PDT FRIDAY...A 992 MB LOW WILL DEEPEN
WEST OF CAPE MENDOCINO THIS EVENING WITH INCREASING SOUTHERLY
WINDS. GALE FORCE WINDS WILL DEVELOP OVERNIGHT ACROSS THE NORTHERN
WATERS WITH STRONG SMALL CRAFT WINDS DEVELOPING ELSEWHERE. A LINE
OF RAIN AND SHOWERS WILL MOVE THROUGH THE WATERS EARLY SATURDAY
MORNING WITH THUNDERSTORMS POSSIBLE NORTH OF THE GOLDEN GATE
SATURDAY AFTERNOON. WINDS WILL EASE AND SHOWERS WILL END BY
SATURDAY NIGHT WITH LIGHTER WINDS AND MODERATE SEAS SUNDAY INTO
MONDAY.

&&

.MTR WATCHES/WARNINGS/ADVISORIES...
     .TNGT...WIND ADVISORY...NORTH BAY COAST AND MOUNTAINS
             WIND ADVISORY...SAN MATEO AND SANTA CRUZ COUNTY COASTS
             WIND ADVISORY...SANTA CRUZ MOUNTAINS
             SCA...SF BAY NORTH OF THE BAY BRIDGE FROM 3 AM
             SCA...SF BAY SOUTH OF THE BAY BRIDGE FROM 3 AM
             SCA...PIGEON PT TO PT PINOS 0-10 NM FROM 3 AM
             SCA...PT PINOS TO PT PIEDRAS BLANCAS 0-10 NM FROM 3 AM
             SCA...PT PINOS TO PT PIEDRAS BLANCAS 10-60 NM FROM 3 AM
             GLW...PT ARENA TO PT REYES 10-60 NM
             SCA...PT REYES TO PIGEON PT 10-60 NM UNTIL MIDNIGHT
             GLW...PT REYES TO PIGEON PT 10-60 NM FROM MIDNIGHT
             SCA...PT REYES TO PIGEON PT 0-10 NM FROM 9 PM
             SCA...PIGEON PT TO PT PINOS 10-60 NM FROM 9 PM
             SCA...PT ARENA TO PT REYES 0-10 NM UNTIL 1 AM
             GLW...PT ARENA TO PT REYES 0-10 NM FROM 1 AM
             SCA...ROUGH BAR ADVISORY FOR SF BAR FROM 5 AM

&&

$$

PUBLIC FORECAST: DYKEMA
AVIATION: CW
MARINE: RWW

VISIT US AT WEATHER.GOV/SANFRANCISCO

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000
FXUS66 KMTR 242359
AFDMTR

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SAN FRANCISCO BAY AREA
459 PM PDT FRI OCT 24 2014

.SYNOPSIS...A COLD FRONT WILL APPROACH THE COAST LATER TONIGHT
INCREASING SOUTH WINDS AND RAIN CHANCES. THE FRONT WILL PASS
THROUGH QUICKLY IN THE MORNING...BUT COOLER UNSTABLE AIR WILL BRING
SHOWERS TO MUCH OF THE AREA SATURDAY AFTERNOON AND EVENING. A FEW
THUNDERSTORMS MAY DEVELOP ESPECIALLY SANTA CRUZ MOUNTAINS
NORTHWARD. DRIER AND COOLER WEATHER IS EXPECTED SUNDAY WITH A
WARMING TREND BEGINNING MONDAY AS HIGH PRESSURE REBUILDS ALONG THE
COAST.

&&

.DISCUSSION...AS OF 01:29 PM PDT FRIDAY...OFFSHORE WINDS HAVE
TURNED TO SOUTHERLY AS A FORERUNNER TO THE APPROACHING COLD FRONT
AND MARINE LAYER DEEPENING AND STARTING TO MIX OUT. COLD CORE
TROF LOCATED AROUND 135W WITH VORT CENTER AROUND 35N AND HAS
BOTTOMED OUT. FEATURE WILL PROGRESS EASTWARD AND SHEAR TO THE
NORTHEAST AS IT MOVES ONSHORE SATURDAY. GIVEN EXTENT OF COLD FRONT
TO THE SOUTH...BELIEVE THIS SYSTEM WILL PRODUCE RAINFALL ACROSS
MOST OF THE AREA WITH THE HEAVIEST PRECIPITATION IN THE NORTH BAY
AND SANTA CRUZ MOUNTAINS NORTHWARD. AMOUNTS WILL VARY CONSIDERABLY
WITH LESS THAN A TENTH OF AN INCH MOST OF MONTEREY COUNTY TO AS
MUCH AS THREE QUARTERS INCH NORTH BAY MOUNTAINS.

MAIN METEOROLOGICAL CONCERNS WILL BE SIGNIFICANT PRE FRONTAL SOUTH
WINDS ALONG THE COAST AND HIGHER ELEVATIONS OF COASTAL MOUNTAINS.
PLANNING ON ISSUING WIND ADVISORY FOR THESE AREAS LATE TONIGHT AND
SATURDAY MORNING. HIGHER RESOLUTION NAM AND WRF MODELS INDICATE
QUICK FRONTAL PASSAGE INTO THE BAY AREA EARLY IN THE MORNING AND
THROUGH THE REST OF THE DISTRICT BY EARLY AFTERNOON. COOL UNSTABLE
AIRMASS IN THE WAKE OF THE COLD FRONT WILL TRIGGER CONVECTION WITH
POSSIBLE THUNDERSTORMS SANTA CRUZ MOUNTAINS NORTHWARD. SHOULD SEE
A BRIEF LULL IN PRECIP AFTER THE COLD FRONT...THEN SATURDAY
AFTERNOON AND EVENING SHOULD BE ACTIVE WITH CONVECTION.

BELIEVE THE NAM IS A LITTLE OVERDONE WITH HIGH CAPE AND HELICITY
VALUES...BUT GFS IS LIKELY UNDERDONE WITH LOWER MODEL RESOLUTION
ISSUES. INTERESTING TO NOTE THAT UNUSUALLY WARM SEA SURFACE
TEMPERATURES COULD ASSIST CONVECTIVE DEVELOPMENT SATURDAY
AFTERNOON AS THE COOLER AIRMASS MOVES OVERHEAD. CONFIDENCE IN
CONVECTIVE STRENGTH IS LOW...BUT CONFIDENCE IS MODERATE FOR A
THUNDERSTORM OR TWO AT LEAST NORTH BAY.

DYNAMICS WITH THIS SYSTEM ARE NOT PARTICULARLY IMPRESSIVE
WITH AN APPARENT STABLE LAYER ABOVE 700 MB THAT SHOULD CAP ANY
SIGNIFICANT CONVECTION. HOWEVER...IF DEW POINTS STAY HIGH
ENOUGH...WOULD BE ABLE TO BREAK THROUGH THIS STABLE LAYER ALOFT.

THE COOLEST DAY SHOULD BE SUNDAY WITH NORTHWEST FLOW AND THE
AIRMASS WILL BEGIN TO DRY OUT. MODEL TRENDS ARE LEANING TOWARD
STRONGER HIGH PRESSURE NEXT WEEK KEEPING THE JET STREAM WELL TO
OUR NORTH. LOOK FOR DRIER AND WARMER CONDITIONS THROUGH MIDWEEK.
COULD BE A FEW SHOWERS EXTREME NORTH BAY AS WEAK SYSTEMS PUSH THRU
THE PACIFIC NW. LOTS OF DIFFERENCES IN THE MEDIUM RANGE GUIDANCE
LATE NEXT WEEK WITH A TREND TOWARD SLOWER APPROACH OF NEXT TROF
AND DELAYING NEXT SIGNIFICANT THREAT FOR RAIN UNTIL AT LEAST NEXT
WEEKEND.

&&

.AVIATION...AS OF 4:59 PM PDT FRIDAY...FOR 00Z TAFS. A WELL
DEFINED LOW PRESSURE SYSTEM SPINNING APPROXIMATELY 500 NM OFF THE
NORTHERN CALIFORNIA COAST WILL APPROACH THE REGION TONIGHT INTO
SATURDAY BRINGING STRONGER SOUTHEASTERLY WINDS AND WET RUNWAYS.
T-STORMS REMAIN A CONCERT FOR SATURDAY AFTERNOON BUT KEEP OUT OF
THE TAF AT THIS TIME.

VICINITY OF KSFO...VFR CONDITIONS EXPECTED THROUGH THIS EVENING. LIGHT
SOUTHWEST WILL TURN SOUTHEASTERLY AND STRENGTHEN OVERNIGHT. -RA
EXPECTED AROUND 11Z TONIGHT. BY SATURDAY MORNING MODERATE AND
GUSTY SOUTHEAST WINDS AND WET RUNWAYS WILL IMPACT THE MORNING
TRAFFIC. WINDS EXPECTED TO VEER SOUTHWESTERLY SATURDAY AFTERNOON.

KSFO BRIDGE APPROACH...SIMILAR TO KSFO.

MONTEREY BAY AREA TERMINALS...VFR CONDITIONS EXPECTED THROUGH
THIS EVENING. LIGHT SOUTHWEST WILL TURN SOUTHEASTERLY OVERNIGHT.
-SHRA EXPECTED TO DEVELOP AROUND 12Z-15Z SATURDAY. BY SATURDAY
MORNING SOUTHEAST WINDS AND WET RUNWAYS WILL IMPACT AREA
TERMINALS. WINDS EXPECTED TO VEER SOUTHWESTERLY SATURDAY
AFTERNOON.

&&

.MARINE...AS OF 3:00 PM PDT FRIDAY...A 992 MB LOW WILL DEEPEN
WEST OF CAPE MENDOCINO THIS EVENING WITH INCREASING SOUTHERLY
WINDS. GALE FORCE WINDS WILL DEVELOP OVERNIGHT ACROSS THE NORTHERN
WATERS WITH STRONG SMALL CRAFT WINDS DEVELOPING ELSEWHERE. A LINE
OF RAIN AND SHOWERS WILL MOVE THROUGH THE WATERS EARLY SATURDAY
MORNING WITH THUNDERSTORMS POSSIBLE NORTH OF THE GOLDEN GATE
SATURDAY AFTERNOON. WINDS WILL EASE AND SHOWERS WILL END BY
SATURDAY NIGHT WITH LIGHTER WINDS AND MODERATE SEAS SUNDAY INTO
MONDAY.

&&

.MTR WATCHES/WARNINGS/ADVISORIES...
             WIND ADVISORY...CAZ505-507-509-512-529 FROM 3 AM UNTIL
                             NOON SATURDAY
             SCA...SF BAY NORTH OF THE BAY BRIDGE FROM 3 AM
             SCA...SF BAY SOUTH OF THE BAY BRIDGE FROM 3 AM
             SCA...PIGEON PT TO PT PINOS 0-10 NM FROM 3 AM
             SCA...PT PINOS TO PT PIEDRAS BLANCAS 0-10 NM FROM 3 AM
             SCA...PT PINOS TO PT PIEDRAS BLANCAS 10-60 NM FROM 3 AM
             SCA...PT ARENA TO PT REYES 0-10 NM FROM 9 PM
             SCA...PT REYES TO PIGEON PT 0-10 NM FROM 9 PM
             SCA...PT ARENA TO PT REYES 10-60 NM FROM 9 PM
             SCA...PT REYES TO PIGEON PT 10-60 NM FROM 9 PM
             SCA...PIGEON PT TO PT PINOS 10-60 NM FROM 9 PM
             SCA...ROUGH BAR ADVISORY FOR SF BAR FROM 5 AM

&&

$$

PUBLIC FORECAST: KBB
AVIATION: CW
MARINE: RWW

VISIT US AT WEATHER.GOV/SANFRANCISCO

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000
FXUS66 KMTR 242118
AFDMTR

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SAN FRANCISCO BAY AREA
218 PM PDT FRI OCT 24 2014

.SYNOPSIS...A COLD FRONT WILL APPROACH THE COAST LATER TONIGHT
INCREASING SOUTH WINDS AND RAIN CHANCES. THE FRONT WILL PASS
THROUGH QUICKLY IN THE MORNING...BUT COOLER UNSTABLE AIR WILL BRING
SHOWERS TO MUCH OF THE AREA SATURDAY AFTERNOON AND EVENING. A FEW
THUNDERSTORMS MAY DEVELOP ESPECIALLY SANTA CRUZ MOUNTAINS
NORTHWARD. DRIER AND COOLER WEATHER IS EXPECTED SUNDAY WITH A
WARMING TREND BEGINNING MONDAY AS HIGH PRESSURE REBUILDS ALONG THE
COAST.

&&

.DISCUSSION...AS OF 01:29 PM PDT FRIDAY...OFFSHORE WINDS HAVE
TURNED TO SOUTHERLY AS A FORERUNNER TO THE APPROACHING COLD FRONT
AND MARINE LAYER DEEPENING AND STARTING TO MIX OUT. COLD CORE
TROF LOCATED AROUND 135W WITH VORT CENTER AROUND 35N AND HAS
BOTTOMED OUT. FEATURE WILL PROGRESS EASTWARD AND SHEAR TO THE
NORTHEAST AS IT MOVES ONSHORE SATURDAY. GIVEN EXTENT OF COLD FRONT
TO THE SOUTH...BELIEVE THIS SYSTEM WILL PRODUCE RAINFALL ACROSS
MOST OF THE AREA WITH THE HEAVIEST PRECIPITATION IN THE NORTH BAY
AND SANTA CRUZ MOUNTAINS NORTHWARD. AMOUNTS WILL VARY CONSIDERABLY
WITH LESS THAN A TENTH OF AN INCH MOST OF MONTEREY COUNTY TO AS
MUCH AS THREE QUARTERS INCH NORTH BAY MOUNTAINS.

MAIN METEOROLOGICAL CONCERNS WILL BE SIGNIFICANT PRE FRONTAL SOUTH
WINDS ALONG THE COAST AND HIGHER ELEVATIONS OF COASTAL MOUNTAINS.
PLANNING ON ISSUING WIND ADVISORY FOR THESE AREAS LATE TONIGHT AND
SATURDAY MORNING. HIGHER RESOLUTION NAM AND WRF MODELS INDICATE
QUICK FRONTAL PASSAGE INTO THE BAY AREA EARLY IN THE MORNING AND
THROUGH THE REST OF THE DISTRICT BY EARLY AFTERNOON. COOL UNSTABLE
AIRMASS IN THE WAKE OF THE COLD FRONT WILL TRIGGER CONVECTION WITH
POSSIBLE THUNDERSTORMS SANTA CRUZ MOUNTAINS NORTHWARD. SHOULD SEE
A BRIEF LULL IN PRECIP AFTER THE COLD FRONT...THEN SATURDAY
AFTERNOON AND EVENING SHOULD BE ACTIVE WITH CONVECTION.

BELIEVE THE NAM IS A LITTLE OVERDONE WITH HIGH CAPE AND HELICITY
VALUES...BUT GFS IS LIKELY UNDERDONE WITH LOWER MODEL RESOLUTION
ISSUES. INTERESTING TO NOTE THAT UNUSUALLY WARM SEA SURFACE
TEMPERATURES COULD ASSIST CONVECTIVE DEVELOPMENT SATURDAY
AFTERNOON AS THE COOLER AIRMASS MOVES OVERHEAD. CONFIDENCE IN
CONVECTIVE STRENGTH IS LOW...BUT CONFIDENCE IS MODERATE FOR A
THUNDERSTORM OR TWO AT LEAST NORTH BAY.

DYNAMICS WITH THIS SYSTEM ARE NOT PARTICULARLY IMPRESSIVE
WITH AN APPARENT STABLE LAYER ABOVE 700 MB THAT SHOULD CAP ANY
SIGNIFICANT CONVECTION. HOWEVER...IF DEW POINTS STAY HIGH
ENOUGH...WOULD BE ABLE TO BREAK THROUGH THIS STABLE LAYER ALOFT.

THE COOLEST DAY SHOULD BE SUNDAY WITH NORTHWEST FLOW AND THE
AIRMASS WILL BEGIN TO DRY OUT. MODEL TRENDS ARE LEANING TOWARD
STRONGER HIGH PRESSURE NEXT WEEK KEEPING THE JET STREAM WELL TO
OUR NORTH. LOOK FOR DRIER AND WARMER CONDITIONS THROUGH MIDWEEK.
COULD BE A FEW SHOWERS EXTREME NORTH BAY AS WEAK SYSTEMS PUSH THRU
THE PACIFIC NW. LOTS OF DIFFERENCES IN THE MEDIUM RANGE GUIDANCE
LATE NEXT WEEK WITH A TREND TOWARD SLOWER APPROACH OF NEXT TROF
AND DELAYING NEXT SIGNIFICANT THREAT FOR RAIN UNTIL AT LEAST NEXT
WEEKEND.

&&

.AVIATION...AS OF 10:52 AM PDT FRIDAY...FOR 18Z TAFS. NO CONCERNS
FOR THIS AFTERNOON WITH MAINLY CLEAR SKIES AND SOME LIGHT
SOUTHERLY WINDS DEVELOPING BUT THEY SHOULD TREND SOUTHWEST THIS
AFTERNOON. FAIRLY IMPRESSIVE LOW WILL DEEPEN OFF THE COAST LATER
THIS AFTERNOON AND EVENING WITH INCREASING SOUTHEAST FLOW
DEVELOPING LATER THIS EVENING AND OVERNIGHT. PRETTY HIGH
CONFIDENCE FOR STRONG SOUTHEAST WINDS AND WET RUNWAYS FOR SATURDAY
MORNING. T-STORMS EVEN POSSIBLE SATURDAY AFTERNOON BUT WONT SHOW
THAT IN TAF AT THIS TIME.

VICINITY OF KSFO...VFR SKIES THIS AFTERNOON AND EVENING. LIGHT
SOUTHEAST WINDS THROUGH EARLY AFTERNOON SHOULD TREND SOUTHWEST AND
NOT IMPACT OPERATIONS. INCREASING SOUTHEAST WINDS OVERNIGHT WILL
LIKELY CAUSE ISSUES FOR SATURDAY MORNING PLANNING.

KSFO BRIDGE APPROACH...SIMILAR TO KSFO.

MONTEREY BAY AREA TERMINALS...CLEAR FOR KSNS THIS AFTERNOON WITH
CLOUD BANK CURRENTLY HOVERING OVER KMRY. EXPECT PARTIAL CLEARING
AT THE COAST. SOUTHERLY WINDS SHOULD DEVELOP OVERNIGHT WITH SOME
-SHRA BY AROUND 12-15Z SATURDAY.

&&

.MARINE...AS OF 10:52 AM PDT FRIDAY...HIGH PRESSURE OFF THE
SOUTHERN CALIFORNIA COAST WILL WEAKEN AS A DEEPENING LOW PRESSURE
SYSTEM APPROACHES FROM THE WEST.  THE LOW WILL LIFT NORTHEAST ON
SATURDAY MOVING INLAND OVER THE PACIFIC NORTHWEST SATURDAY NIGHT.
SOUTH WINDS WILL INCREASE TODAY THROUGH SATURDAY THEN SWITCH TO
NORTHWEST SATURDAY NIGHT AND SUNDAY. THE LOW WILL BRING A SLIGHT
CHANCE OF THUNDERSTORMS TO THE NORTHERN WATERS SATURDAY.

&&

.MTR WATCHES/WARNINGS/ADVISORIES...
             WIND ADVISORY...CAZ505-507-509-512-529 FROM 3 AM UNTIL
                             NOON SATURDAY
             SCA...SF BAY NORTH OF THE BAY BRIDGE FROM 3 AM
             SCA...SF BAY SOUTH OF THE BAY BRIDGE FROM 3 AM
             SCA...PIGEON PT TO PT PINOS 0-10 NM FROM 3 AM
             SCA...PT PINOS TO PT PIEDRAS BLANCAS 0-10 NM FROM 3 AM
             SCA...PT PINOS TO PT PIEDRAS BLANCAS 10-60 NM FROM 3 AM
             SCA...PT ARENA TO PT REYES 0-10 NM FROM 9 PM
             SCA...PT REYES TO PIGEON PT 0-10 NM FROM 9 PM
             SCA...PT ARENA TO PT REYES 10-60 NM FROM 9 PM
             SCA...PT REYES TO PIGEON PT 10-60 NM FROM 9 PM
             SCA...PIGEON PT TO PT PINOS 10-60 NM FROM 9 PM
             SCA...ROUGH BAR ADVISORY FOR SF BAR FROM 5 AM

&&

$$

PUBLIC FORECAST: KBB
AVIATION/MARINE: RWW

VISIT US AT WEATHER.GOV/SANFRANCISCO

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000
FXUS66 KMTR 241752
AFDMTR

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SAN FRANCISCO BAY AREA
1052 AM PDT FRI OCT 24 2014

.SYNOPSIS...MOSTLY SUNNY CONDITIONS ARE EXPECTED TODAY...ASIDE
FROM SOME MORNING FOG AND LOW CLOUDINESS NEAR THE COAST AND IN THE
NORTH BAY VALLEYS. HOWEVER...INCREASING RAIN CHANCES WILL THEN
RAPIDLY SPREAD IN FROM THE NORTHWEST LATER TONIGHT AND SATURDAY
MORNING AS A STRONGER AND WETTER PACIFIC WEATHER SYSTEM MOVES
INTO NORTHERN AND CENTRAL CALIFORNIA. RESIDUAL SHOWERS ARE
EXPECTED TO TAPER OFF SATURDAY EVENING...WITH DRY WEATHER RETURNING
DISTRICTWIDE SUNDAY AND CONTINUING INTO AT LEAST THE FIRST HALF OF
NEXT WEEK.

&&

.DISCUSSION...AS OF 9:06 AM PDT FRIDAY...STRATUS AND PATCHY FOG
EXTENDS ALONG THE COAST FROM SAN MATEO COUNTY SOUTHWARD. PATCHY
DENSE FOG ALSO EVIDENT IN NORTH BAY VALLEYS AND PARTS OF THE SOUTH
BAY. WITH THE SHORTER DAYS FOG AND CLOUDS WILL BE SLOW TO CLEAR
THIS MORNING AND SHOULD PERSIST ALONG THE COAST ALL DAY. OTHERWISE
MOST AREAS WILL BY MOSTLY SUNNY TODAY. WOULD EXPECT STRATUS TO
SPREAD INLAND THIS EVENING AND MIX OUT QUICKLY WITH THE APPROACH
OF THE COLD FRONT AND INCREASING SOUTH WINDS.

DETAILS ARE STARTING TO EMERGE FROM THE LATEST NAM RUN REGARDING
TIMING OF RAINFALL AND CONVECTIVE POTENTIAL. GFS NOT AS ROBUST AS
NAM WITH CONVECTION BEHIND FRONTAL BOUNDARY SATURDAY
AFTERNOON...BUT IMPRESSIVE CAPE FROM NAM RAISES POTENTIAL FOR
THUNDERSTORMS EVEN INTO BAY AREA AND SANTA CRUZ MOUNTAINS BY
SATURDAY AFTERNOON. EXTENDED SLIGHT CHANCE OF THUNDERSTORMS
FURTHER SOUTH IN THE GRID FORECASTS FOR SATURDAY AFTERNOON.

WILL ALSO EVALUATE POTENTIAL FOR WIND ADVISORY ALONG THE COAST AND
IN THE MOUNTAINS FROM SANTA CRUZ MOUNTAINS AND SAN MATEO COAST
NORTHWARD LATE TONIGHT AND AT LEAST INTO SATURDAY MORNING. WINDS
COULD BE GUSTY ENOUGH TO KNOCK DOWN SOME LARGER TREE LIMBS GIVEN
THE WEAKENED STATE OF TREES WITH THE DROUGHT.

EXPECTING WINDS TO INCREASE RAPIDLY AFTER MIDNIGHT WITH A QUICK
MOVING FRONTAL BAND AND MOSTLY LIGHT RAIN LATE TONIGHT AND EARLY
SATURDAY SPREADING SOUTHEAST ACROSS THE AREA. COLD POCKET
ASSOCIATED WITH OFFSHORE TROF MOVES THROUGH THE AREA SATURDAY
AFTERNOON AND SHOULD TRIGGER PLENTY OF SHOWERS AND POSSIBLE
THUNDERSTORMS ESPECIALLY NORTH BAY DOWN TO BAY AREA.

&&

.PREV DISCUSSION...ASIDE FROM THE AFOREMENTIONED MORNING LOW
CLOUDINESS AND FOG...MOSTLY SUNNY CONDITIONS ARE EXPECTED TODAY
WITH AFTERNOON HIGHS AROUND THE BAYS GENERALLY IN THE LOWER 70S.

TONIGHT AND SATURDAY...RAIN CHANCES WILL RAPIDLY DEVELOP FROM THE
NORTHWEST DURING THE OVERNIGHT HOURS AS A COLD FRONTAL RAIN BAND
AHEAD OF THE NEXT AND STRONGER PACIFIC LOW PRESSURE SYSTEM APPROACHES.
GENERAL TREND OF RECENT MODEL RUNS HAS BEEN TO SPEED THINGS UP A
BIT. CONSENSUS TIMING OF LATEST OUTPUT FROM THE NAM...GFS AND
ECMWF DETERMINISTIC SOLUTIONS HAS RAIN BEGINNING IN SANTA ROSA
AROUND A COUPLE OF HOURS BEFORE SUNRISE ON SATURDAY...SAN
FRANCISCO DURING THE FIRST PART OF THE MONTEREY...AND WITH A GOOD
CHANCE SOUTH TO NEAR MONTEREY BY MID-TO-LATE MORNING. AND THEN
AFTER A SHORT BREAK...ANOTHER ROUND OF PRECIP...THIS TIME MORE
SHOWERY IN NATURE...IS LIKELY AS THE COOL UPPER LEVEL TROUGH AXIS
QUICKLY FOLLOWS THROUGH. RAINFALL AMOUNTS THROUGH SATURDAY EVENING
COULD POTENTIALLY BE AS MUCH AS 0.75 TO 1.0 INCHES IN WETTEST SPOTS OF
THE COASTAL NORTH BAY HILLS...BUT OTHERWISE GENERALLY 0.25 INCHES
OR LESS ASIDE PERHAPS FROM A BIT MORE AT SOME LOCATIONS IN THE
SANTA CRUZ MTNS. AND SHOULD NOTE THAT SOME PORTIONS OF INTERIOR
MONTEREY AND SAN BENITO COUNTIES MAY WELL NOT RECEIVE ANY RAIN AT
ALL.

AS THIS WILL BE THE FIRST SIGNIFICANT PRECIP EVENT IN SOME
TIME ACROSS MUCH OF THE AREA...ROADWAYS WILL BECOME ESPECIALLY
SLICK AS ACCUMULATED SURFACE OILS MIX IN ESPECIALLY DURING THE
FIRST HOUR OR SO OF PRECIP. ALSO...HAVE INCLUDED MENTION OF A
SLIGHT CHANCE OF THUNDERSTORMS OVER THE NORTH BAY ON
SATURDAY...GIVEN SUBSTANTIAL SURFACE-BASED CAPE VALUES EVIDENT IN
MODEL OUTPUT SOUNDINGS...ESPECIALLY THOSE FROM THE NAM. 500 MB
TEMPS REALLY DON`T GET ALL THAT COLD...ONLY DOWN INTO THE -18C TO
TO -20C RANGE EVEN WITH THE UPPER LEVEL TROUGH PASSAGE. BUT
SURFACE TEMPS AND ESPECIALLY DEW POINTS ARE PROJECTED TO BE HIGH
ENOUGH TO COUNTERBALANCE THAT...THE LATTER IN PARTICULAR
REFLECTING THE UNUSUALLY WARM SEA SURFACE TEMPS THAT CONTINUE IN
OUR COASTAL WATERS. THERE MAY BE A FEW RESIDUAL SHOWERS SATURDAY
EVENING...BUT DRY CONDITIONS ARE PROJECTED TO RETURN DISTRICTWIDE
BY THE LATE NIGHT HOURS.

SUNDAY THROUGH WEDNESDAY...DRY CONDITIONS ARE EXPECTED DISTRICTWIDE
ASIDE FROM JUST A SLIGHT CHANCE OF SOME LIGHT PRECIP IN THE NORTH
BAY AS MIDWEEK APPROACHES AND LONGER RANGE MODEL SOLUTIONS THEN
BEGIN TO DIVERGE A BIT AS TO WHETHER THE PRECIP BAND STARTS TO
SAG BACK DOWN TOWARDS OUR NORTHERN BOUNDARY.

IN THE EVEN LONGER TERM...HAVE NOTED THAT THE ECMWF IN PARTICULAR
HAS REMAINED CONSISTENT OVER ITS LAST SEVERAL RUNS IN PROJECTING
ANOTHER ROUND OF WET WEATHER FOR OUR AREA AROUND NEXT WEEKEND.

&&

.AVIATION...AS OF 10:52 AM PDT FRIDAY...FOR 18Z TAFS. NO CONCERNS
FOR THIS AFTERNOON WITH MAINLY CLEAR SKIES AND SOME LIGHT
SOUTHERLY WINDS DEVELOPING BUT THEY SHOULD TREND SOUTHWEST THIS
AFTERNOON. FAIRLY IMPRESSIVE LOW WILL DEEPEN OFF THE COAST LATER
THIS AFTERNOON AND EVENING WITH INCREASING SOUTHEAST FLOW
DEVELOPING LATER THIS EVENING AND OVERNIGHT. PRETTY HIGH
CONFIDENCE FOR STRONG SOUTHEAST WINDS AND WET RUNWAYS FOR SATURDAY
MORNING. T-STORMS EVEN POSSIBLE SATURDAY AFTERNOON BUT WONT SHOW
THAT IN TAF AT THIS TIME.

VICINITY OF KSFO...VFR SKIES THIS AFTERNOON AND EVENING. LIGHT
SOUTHEAST WINDS THROUGH EARLY AFTERNOON SHOULD TREND SOUTHWEST AND
NOT IMPACT OPERATIONS. INCREASING SOUTHEAST WINDS OVERNIGHT WILL
LIKELY CAUSE ISSUES FOR SATURDAY MORNING PLANNING.

KSFO BRIDGE APPROACH...SIMILAR TO KSFO.

MONTEREY BAY AREA TERMINALS...CLEAR FOR KSNS THIS AFTERNOON WITH
CLOUD BANK CURRENTLY HOVERING OVER KMRY. EXPECT PARTIAL CLEARING
AT THE COAST. SOUTHERLY WINDS SHOULD DEVELOP OVERNIGHT WITH SOME
-SHRA BY AROUND 12-15Z SATURDAY.

&&

.MARINE...AS OF 10:52 AM PDT FRIDAY...HIGH PRESSURE OFF THE
SOUTHERN CALIFORNIA COAST WILL WEAKEN AS A DEEPENING LOW PRESSURE
SYSTEM APPROACHES FROM THE WEST.  THE LOW WILL LIFT NORTHEAST ON
SATURDAY MOVING INLAND OVER THE PACIFIC NORTHWEST SATURDAY NIGHT.
SOUTH WINDS WILL INCREASE TODAY THROUGH SATURDAY THEN SWITCH TO
NORTHWEST SATURDAY NIGHT AND SUNDAY. THE LOW WILL BRING A SLIGHT
CHANCE OF THUNDERSTORMS TO THE NORTHERN WATERS SATURDAY.

&&

.MTR WATCHES/WARNINGS/ADVISORIES...
     .TDAY...NONE.

&&

$$

PUBLIC FORECAST: KBB
AVIATION/MARINE: RWW

VISIT US AT WEATHER.GOV/SANFRANCISCO

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000
FXUS66 KMTR 241624
AFDMTR

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SAN FRANCISCO BAY AREA
924 AM PDT FRI OCT 24 2014

.SYNOPSIS...MOSTLY SUNNY CONDITIONS ARE EXPECTED TODAY...ASIDE
FROM SOME MORNING FOG AND LOW CLOUDINESS NEAR THE COAST AND IN THE
NORTH BAY VALLEYS. HOWEVER...INCREASING RAIN CHANCES WILL THEN
RAPIDLY SPREAD IN FROM THE NORTHWEST LATER TONIGHT AND SATURDAY
MORNING AS A STRONGER AND WETTER PACIFIC WEATHER SYSTEM MOVES
INTO NORTHERN AND CENTRAL CALIFORNIA. RESIDUAL SHOWERS ARE
EXPECTED TO TAPER OFF SATURDAY EVENING...WITH DRY WEATHER RETURNING
DISTRICTWIDE SUNDAY AND CONTINUING INTO AT LEAST THE FIRST HALF OF
NEXT WEEK.

&&

.DISCUSSION...AS OF 09:06 AM PDT FRIDAY...STRATUS AND PATCHY FOG
EXTENDS ALONG THE COAST FROM SAN MATEO COUNTY SOUTHWARD. PATCHY
DENSE FOG ALSO EVIDENT IN NORTH BAY VALLEYS AND PARTS OF THE
SOUTH BAY. WITH THE SHORTER DAYS FOG AND CLOUDS WILL BE SLOW TO
CLEAR THIS MORNING AND SHOULD PERSIST ALONG THE COAST ALL DAY.
OTHERWISE MOST AREAS WILL BY MOSTLY SUNNY TODAY. WOULD EXPECT
STRATUS TO SPREAD INLAND THIS EVENING AND MIX OUT QUICKLY WITH THE
APPROACH OF THE COLD FRONT AND INCREASING SOUTH WINDS.

DETAILS ARE STARTING TO EMERGE FROM THE LATEST NAM RUN REGARDING
TIMING OF RAINFALL AND CONVECTIVE POTENTIAL. GFS NOT AS ROBUST AS
NAM WITH CONVECTION BEHIND FRONTAL BOUNDARY SATURDAY
AFTERNOON...BUT IMPRESSIVE CAPE FROM NAM RAISES POTENTIAL FOR
THUNDERSTORMS EVEN INTO BAY AREA AND SANTA CRUZ MOUNTAINS BY
SATURDAY AFTERNOON. EXTENDED SLIGHT CHANCE OF THUNDERSTORMS
FURTHER SOUTH IN THE GRID FORECASTS FOR SATURDAY AFTERNOON.

WILL ALSO EVALUATE POTENTIAL FOR WIND ADVISORY ALONG THE COAST AND
IN THE MOUNTAINS FROM SANTA CRUZ MOUNTAINS AND SAN MATEO COAST
NORTHWARD LATE TONIGHT AND AT LEAST INTO SATURDAY MORNING. WINDS
COULD BE GUSTY ENOUGH TO KNOCK DOWN SOME LARGER TREE LIMBS GIVEN
THE WEAKENED STATE OF TREES WITH THE DROUGHT.

EXPECTING WINDS TO INCREASE RAPIDLY AFTER MIDNIGHT WITH A QUICK
MOVING FRONTAL BAND AND MOSTLY LIGHT RAIN LATE TONIGHT AND EARLY
SATURDAY SPREADING SOUTHEAST ACROSS THE AREA. COLD POCKET
ASSOCIATED WITH OFFSHORE TROF MOVES THROUGH THE AREA SATURDAY
AFTERNOON AND SHOULD TRIGGER PLENTY OF SHOWERS AND POSSIBLE
THUNDERSTORMS ESPECIALLY NORTH BAY DOWN TO BAY AREA.


&&

.PREV DISCUSSION...ASIDE FROM THE AFOREMENTIONED MORNING LOW
CLOUDINESS AND FOG...MOSTLY SUNNY CONDITIONS ARE EXPECTED TODAY
WITH AFTERNOON HIGHS AROUND THE BAYS GENERALLY IN THE LOWER 70S.

TONIGHT AND SATURDAY...RAIN CHANCES WILL RAPIDLY DEVELOP FROM THE
NORTHWEST DURING THE OVERNIGHT HOURS AS A COLD FRONTAL RAIN BAND
AHEAD OF THE NEXT AND STRONGER PACIFIC LOW PRESSURE SYSTEM APPROACHES.
GENERAL TREND OF RECENT MODEL RUNS HAS BEEN TO SPEED THINGS UP A
BIT. CONSENSUS TIMING OF LATEST OUTPUT FROM THE NAM...GFS AND
ECMWF DETERMINISTIC SOLUTIONS HAS RAIN BEGINNING IN SANTA ROSA
AROUND A COUPLE OF HOURS BEFORE SUNRISE ON SATURDAY...SAN
FRANCISCO DURING THE FIRST PART OF THE MONTEREY...AND WITH A GOOD
CHANCE SOUTH TO NEAR MONTEREY BY MID-TO-LATE MORNING. AND THEN
AFTER A SHORT BREAK...ANOTHER ROUND OF PRECIP...THIS TIME MORE
SHOWERY IN NATURE...IS LIKELY AS THE COOL UPPER LEVEL TROUGH AXIS
QUICKLY FOLLOWS THROUGH. RAINFALL AMOUNTS THROUGH SATURDAY EVENING
COULD POTENTIALLY BE AS MUCH AS 0.75 TO 1.0 INCHES IN WETTEST SPOTS OF
THE COASTAL NORTH BAY HILLS...BUT OTHERWISE GENERALLY 0.25 INCHES
OR LESS ASIDE PERHAPS FROM A BIT MORE AT SOME LOCATIONS IN THE
SANTA CRUZ MTNS. AND SHOULD NOTE THAT SOME PORTIONS OF INTERIOR
MONTEREY AND SAN BENITO COUNTIES MAY WELL NOT RECEIVE ANY RAIN AT
ALL.

AS THIS WILL BE THE FIRST SIGNIFICANT PRECIP EVENT IN SOME
TIME ACROSS MUCH OF THE AREA...ROADWAYS WILL BECOME ESPECIALLY
SLICK AS ACCUMULATED SURFACE OILS MIX IN ESPECIALLY DURING THE
FIRST HOUR OR SO OF PRECIP. ALSO...HAVE INCLUDED MENTION OF A
SLIGHT CHANCE OF THUNDERSTORMS OVER THE NORTH BAY ON
SATURDAY...GIVEN SUBSTANTIAL SURFACE-BASED CAPE VALUES EVIDENT IN
MODEL OUTPUT SOUNDINGS...ESPECIALLY THOSE FROM THE NAM. 500 MB
TEMPS REALLY DON`T GET ALL THAT COLD...ONLY DOWN INTO THE -18C TO
TO -20C RANGE EVEN WITH THE UPPER LEVEL TROUGH PASSAGE. BUT
SURFACE TEMPS AND ESPECIALLY DEW POINTS ARE PROJECTED TO BE HIGH
ENOUGH TO COUNTERBALANCE THAT...THE LATTER IN PARTICULAR
REFLECTING THE UNUSUALLY WARM SEA SURFACE TEMPS THAT CONTINUE IN
OUR COASTAL WATERS. THERE MAY BE A FEW RESIDUAL SHOWERS SATURDAY
EVENING...BUT DRY CONDITIONS ARE PROJECTED TO RETURN DISTRICTWIDE
BY THE LATE NIGHT HOURS.

SUNDAY THROUGH WEDNESDAY...DRY CONDITIONS ARE EXPECTED DISTRICTWIDE
ASIDE FROM JUST A SLIGHT CHANCE OF SOME LIGHT PRECIP IN THE NORTH
BAY AS MIDWEEK APPROACHES AND LONGER RANGE MODEL SOULTIONS THEN
BEGIN TO DIVERGE A BIT AS TO WHETHER THE PRECIP BAND STARTS TO
SAG BACK DOWN TOWARDS OUR NORTHERN BOUNDARY.

IN THE EVEN LONGER TERM...HAVE NOTED THAT THE ECMWF IN PARTICULAR
HAS REMAINED CONSISTENT OVER ITS LAST SEVERAL RUNS IN PROJECTING
ANOTHER ROUND OF WET WEATHER FOR OUR AREA AROUND NEXT WEEKEND.

&&

.AVIATION...AS OF 4:30 AM PDT FRIDAY...STRATUS ALONG THE COAST
REMAINS DISORGANIZED WITH ONLY PATCHES GETTING IN TO THE SFO BAY
AREA. THE LACK OF AN INVERSION LAYER SHOULD KEEP STRATUS PATCHY IN
NATURE. THEREFORE ANY CIGS AFFECTING THE SFO APPROACH WILL CLEAR
OUT BY 16Z.

VICINITY OF KSFO...PATCHY MVFR CIGS THROUGH 16Z.
SOUTH WINDS 5-10 KT SWITCHING TO SOUTHWEST-WEST AFTER 20Z.

KSFO BRIDGE APPROACH...SIMILAR TO KSFO.

MONTEREY BAY AREA TERMINALS...SATTELITE IMAGE SHOWS STRATUS OVER
MRY BAY MAKING LITTLE INLAND PROGRESS. STILL BELIEVE IFR CIGS WILL
REACH SNS AND LINGER THROUGH 17Z. IFR CIGS THROUGH 18Z AT MRY.

&&

.MARINE...AS OF 3:11 AM PDT FRIDAY...HIGH PRESSURE OFF THE
SOUTHERN CALIFORNIA COAST WILL WEAKEN AS A DEEPENING LOW PRESSURE
SYSTEM APPROACHES FROM THE WEST. THE LOW WILL LIFT NORTHEAST ON
SATURDAY MOVING INLAND OVER THE PACIFIC NORTHWEST SATURDAY NIGHT.
SOUTH WINDS WILL INCREASE TODAY THROUGH SATURDAY THEN SWITCH TO
NORTHWEST SATURDAY NIGHT AND SUNDAY. THE LOW WILL BRING A SLIGHT
CHANCE OF THUNDERSTORMS TO THE NORTHERN WATERS SATURDAY.

&&

.MTR WATCHES/WARNINGS/ADVISORIES...
     .TDAY...NONE.

&&

$$

PUBLIC FORECAST: KBB
AVIATION/MARINE: W PI

VISIT US AT WEATHER.GOV/SANFRANCISCO

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000
FXUS66 KMTR 241134
AFDMTR

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SAN FRANCISCO BAY AREA
434 AM PDT FRI OCT 24 2014

.SYNOPSIS...MOSTLY SUNNY CONDITIONS ARE EXPECTED TODAY...ASIDE
FROM SOME MORNING FOG AND LOW CLOUDINESS NEAR THE COAST AND IN THE
NORTH BAY VALLEYS. HOWEVER...INCREASING RAIN CHANCES WILL THEN
RAPIDLY SPREAD IN FROM THE NORTHWEST LATER TONIGHT AND SATURDAY
MORNING AS A STRONGER AND WETTER PACIFIC WEATHER SYSTEM MOVES
INTO NORTHERN AND CENTRAL CALIFORNIA. RESIDUAL SHOWERS ARE
EXPECTED TO TAPER OFF SATURDAY EVENING...WITH DRY WEATHER RETURNING
DISTRICTWIDE SUNDAY AND CONTINUING INTO AT LEAST THE FIRST HALF OF
NEXT WEEK.

&&

.DISCUSSION...AS OF 3:35 AM PDT FRIDAY...THE WEAK FRONTAL BOUNDARY
THAT DRAPED DOWN TO NEAR THE NORTHERN BORDER OF OUR DISTRICT IS
NOW LIFTING NORTHWARD AS THE NEXT AND SOMEWHAT STRONGER AND
WETTER PACIFIC WEATHER SYSTEM BEGINS TO APPROACH. EVEN WITH A LOT
OF SEARCHING...LARGEST RAINFALL TOTAL FOUND FOR THURSDAY WAS 0.04
INCHES AT A MESONET SITE AT SEA RANCH...ON THE NORTHERN SONOMA
COUNTY COAST. NO MEASURABLE PRECIP WAS REPORTED AT ANY OF OUR ASOS
OR RAWS SITES.

FOR TODAY...LATEST FOG PRODUCT SATELLITE IMAGERY SHOWS LOW
CLOUDINESS ALONG VIRTUALLY ALL OF OUR COAST AND LOCALLY IN THE
NORTH BAY VALLEYS...AND BEGINNING TO EXTEND THROUGH THE SAN BRUNO
GAP...BUT OTHERWISE SKIES ARE MOSTLY CLEAR. HAVE NOTED THAT JUST
WITHIN THE LAST HOUR THE VISIBILITY REPORTED BY THE HALF MOON BAY
AWOS HAS DROPPED TO UNDER 1/4 MILE AND WILL MONITOR TO SEE IF
PERSISTS AND SPREADS TO THE POINT THAT A SHORT TERM FORECAST OR
DENSE FOG ADVISORY IS NEEDED AS DAWN APPROACHES. ASIDE FROM THE
AFOREMENTIONED MORNING LOW CLOUDINESS AND FOG...MOSTLY SUNNY
CONDITIONS ARE EXPECTED TODAY WITH AFTERNOON HIGHS AROUND THE BAYS
GENERALLY IN THE LOWER 70S.

TONIGHT AND SATURDAY...RAIN CHANCES WILL RAPIDLY DEVELOP FROM THE
NORTHWEST DURING THE OVERNIGHT HOURS AS A COLD FRONTAL RAIN BAND
AHEAD OF THE NEXT AND STRONGER PACIFIC LOW PRESSURE SYSTEM APPROACHES.
GENERAL TREND OF RECENT MODEL RUNS HAS BEEN TO SPEED THINGS UP A
BIT. CONSENSUS TIMING OF LATEST OUTPUT FROM THE NAM...GFS AND
ECMWF DETERMINISTIC SOLUTIONS HAS RAIN BEGINNING IN SANTA ROSA
AROUND A COUPLE OF HOURS BEFORE SUNRISE ON SATURDAY...SAN
FRANCISCO DURING THE FIRST PART OF THE MONTEREY...AND WITH A GOOD
CHANCE SOUTH TO NEAR MONTEREY BY MID-TO-LATE MORNING. AND THEN
AFTER A SHORT BREAK...ANOTHER ROUND OF PRECIP...THIS TIME MORE
SHOWERY IN NATURE...IS LIKELY AS THE COOL UPPER LEVEL TROUGH AXIS
QUICKLY FOLLOWS THROUGH. RAINFALL AMOUNTS THROUGH SATURDAY EVENING
COULD POTENTIALLY BE AS MUCH AS 0.75 TO 1.0 INCHES IN WETTEST SPOTS OF
THE COASTAL NORTH BAY HILLS...BUT OTHERWISE GENERALLY 0.25 INCHES
OR LESS ASIDE PERHAPS FROM A BIT MORE AT SOME LOCATIONS IN THE
SANTA CRUZ MTNS. AND SHOULD NOTE THAT SOME PORTIONS OF INTERIOR
MONTEREY AND SAN BENITO COUNTIES MAY WELL NOT RECEIVE ANY RAIN AT
ALL.

AS THIS WILL BE THE FIRST SIGNIFICANT PRECIP EVENT IN SOME
TIME ACROSS MUCH OF THE AREA...ROADWAYS WILL BECOME ESPECIALLY
SLICK AS ACCUMULATED SURFACE OILS MIX IN ESPECIALLY DURING THE
FIRST HOUR OR SO OF PRECIP. ALSO...HAVE INCLUDED MENTION OF A
SLIGHT CHANCE OF THUNDERSTORMS OVER THE NORTH BAY ON
SATURDAY...GIVEN SUBSTANTIAL SURFACE-BASED CAPE VALUES EVIDENT IN
MODEL OUTPUT SOUNDINGS...ESPECIALLY THOSE FROM THE NAM. 500 MB
TEMPS REALLY DON`T GET ALL THAT COLD...ONLY DOWN INTO THE -18C TO
TO -20C RANGE EVEN WITH THE UPPER LEVEL TROUGH PASSAGE. BUT
SURFACE TEMPS AND ESPECIALLY DEW POINTS ARE PROJECTED TO BE HIGH
ENOUGH TO COUNTERBALANCE THAT...THE LATTER IN PARTICULAR
REFLECTING THE UNUSUALLY WARM SEA SURFACE TEMPS THAT CONTINUE IN
OUR COASTAL WATERS. THERE MAY BE A FEW RESIDUAL SHOWERS SATURDAY
EVENING...BUT DRY CONDITIONS ARE PROJECTED TO RETURN DISTRICTWIDE
BY THE LATE NIGHT HOURS.

SUNDAY THROUGH WEDNESDAY...DRY CONDITIONS ARE EXPECTED DISTRICTWIDE
ASIDE FROM JUST A SLIGHT CHANCE OF SOME LIGHT PRECIP IN THE NORTH
BAY AS MIDWEEK APPROACHES AND LONGER RANGE MODEL SOULTIONS THEN
BEGIN TO DIVERGE A BIT AS TO WHETHER THE PRECIP BAND STARTS TO
SAG BACK DOWN TOWARDS OUR NORTHERN BOUNDARY.

IN THE EVEN LONGER TERM...HAVE NOTED THAT THE ECMWF IN PARTICULAR
HAS REMAINED CONSISTENT OVER ITS LAST SEVERAL RUNS IN PROJECTING
ANOTHER ROUND OF WET WEATHER FOR OUR AREA AROUND NEXT WEEKEND.

&&

.AVIATION...AS OF 4:30 AM PDT FRIDAY...STRATUS ALONG THE COAST
REMAINS DISORGANIZED WITH ONLY PATCHES GETTING IN TO THE SFO BAY
AREA. THE LACK OF AN INVERSION LAYER SHOULD KEEP STRATUS PATCHY IN
NATURE. THEREFORE ANY CIGS AFFECTING THE SFO APPROACH WILL CLEAR
OUT BY 16Z.

VICINITY OF KSFO...PATCHY MVFR CIGS THROUGH 16Z.
SOUTH WINDS 5-10 KT SWITCHING TO SOUTHWEST-WEST AFTER 20Z.

KSFO BRIDGE APPROACH...SIMILAR TO KSFO.

MONTEREY BAY AREA TERMINALS...SATTELITE IMAGE SHOWS STRATUS OVER
MRY BAY MAKING LITTLE INLAND PROGRESS. STILL BELIEVE IFR CIGS WILL
REACH SNS AND LINGER THROUGH 17Z. IFR CIGS THROUGH 18Z AT MRY.


&&

.MARINE...AS OF 3:11 AM PDT FRIDAY...HIGH PRESSURE OFF THE
SOUTHERN CALIFORNIA COAST WILL WEAKEN AS A DEEPENING LOW PRESSURE
SYSTEM APPROACHES FROM THE WEST. THE LOW WILL LIFT NORTHEAST ON
SATURDAY MOVING INLAND OVER THE PACIFIC NORTHWEST SATURDAY NIGHT.
SOUTH WINDS WILL INCREASE TODAY THROUGH SATURDAY THEN SWITCH TO
NORTHWEST SATURDAY NIGHT AND SUNDAY. THE LOW WILL BRING A SLIGHT
CHANCE OF THUNDERSTORMS TO THE NORTHERN WATERS SATURDAY.

&&

.MTR WATCHES/WARNINGS/ADVISORIES...
     .TDAY...NONE.

&&

$$

PUBLIC FORECAST: BLIER
AVIATION/MARINE: W PI

VISIT US AT WEATHER.GOV/SANFRANCISCO

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







000
FXUS66 KMTR 241055 CCA
AFDMTR

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SAN FRANCISCO BAY AREA
353 AM PDT FRI OCT 24 2014

.SYNOPSIS...MOSTLY SUNNY CONDITIONS ARE EXPECTED TODAY...ASIDE
FROM SOME MORNING FOG AND LOW CLOUDINESS NEAR THE COAST AND IN THE
NORTH BAY VALLEYS. HOWEVER...INCREASING RAIN CHANCES WILL THEN
RAPIDLY SPREAD IN FROM THE NORTHWEST LATER TONIGHT AND SATURDAY
MORNING AS A STRONGER AND WETTER PACIFIC WEATHER SYSTEM MOVES
INTO NORTHERN AND CENTRAL CALIFORNIA. RESIDUAL SHOWERS ARE
EXPECTED TO TAPER OFF SATURDAY EVENING...WITH DRY WEATHER RETURNING
DISTRICTWIDE SUNDAY AND CONTINUING INTO AT LEAST THE FIRST HALF OF
NEXT WEEK.

&&

.DISCUSSION...AS OF 3:35 AM PDT FRIDAY...THE WEAK FRONTAL BOUNDARY
THAT DRAPED DOWN TO NEAR THE NORTHERN BORDER OF OUR DISTRICT IS
NOW LIFTING NORTHWARD AS THE NEXT AND SOMEWHAT STRONGER AND
WETTER PACIFIC WEATHER SYSTEM BEGINS TO APPROACH. EVEN WITH A LOT
OF SEARCHING...LARGEST RAINFALL TOTAL FOUND FOR THURSDAY WAS 0.04
INCHES AT A MESONET SITE AT SEA RANCH...ON THE NORTHERN SONOMA
COUNTY COAST. NO MEASURABLE PRECIP WAS REPORTED AT ANY OF OUR ASOS
OR RAWS SITES.

FOR TODAY...LATEST FOG PRODUCT SATELLITE IMAGERY SHOWS LOW
CLOUDINESS ALONG VIRTUALLY ALL OF OUR COAST AND LOCALLY IN THE
NORTH BAY VALLEYS...AND BEGINNING TO EXTEND THROUGH THE SAN BRUNO
GAP...BUT OTHERWISE SKIES ARE MOSTLY CLEAR. HAVE NOTED THAT JUST
WITHIN THE LAST HOUR THE VISIBILITY REPORTED BY THE HALF MOON BAY
AWOS HAS DROPPED TO UNDER 1/4 MILE AND WILL MONITOR TO SEE IF
PERSISTS AND SPREADS TO THE POINT THAT A SHORT TERM FORECAST OR
DENSE FOG ADVISORY IS NEEDED AS DAWN APPROACHES. ASIDE FROM THE
AFOREMENTIONED MORNING LOW CLOUDINESS AND FOG...MOSTLY SUNNY
CONDITIONS ARE EXPECTED TODAY WITH AFTERNOON HIGHS AROUND THE BAYS
GENERALLY IN THE LOWER 70S.

TONIGHT AND SATURDAY...RAIN CHANCES WILL RAPIDLY DEVELOP FROM THE
NORTHWEST DURING THE OVERNIGHT HOURS AS A COLD FRONTAL RAIN BAND
AHEAD OF THE NEXT AND STRONGER PACIFIC LOW PRESSURE SYSTEM APPROACHES.
GENERAL TREND OF RECENT MODEL RUNS HAS BEEN TO SPEED THINGS UP A
BIT. CONSENSUS TIMING OF LATEST OUTPUT FROM THE NAM...GFS AND
ECMWF DETERMINISTIC SOLUTIONS HAS RAIN BEGINNING IN SANTA ROSA
AROUND A COUPLE OF HOURS BEFORE SUNRISE ON SATURDAY...SAN
FRANCISCO DURING THE FIRST PART OF THE MONTEREY...AND WITH A GOOD
CHANCE SOUTH TO NEAR MONTEREY BY MID-TO-LATE MORNING. AND THEN
AFTER A SHORT BREAK...ANOTHER ROUND OF PRECIP...THIS TIME MORE
SHOWERY IN NATURE...IS LIKELY AS THE COOL UPPER LEVEL TROUGH AXIS
QUICKLY FOLLOWS THROUGH. RAINFALL AMOUNTS THROUGH SATURDAY EVENING
COULD POTENTIALLY BE AS MUCH AS 0.75 TO 1.0 INCHES IN WETTEST SPOTS OF
THE COASTAL NORTH BAY HILLS...BUT OTHERWISE GENERALLY 0.25 INCHES
OR LESS ASIDE PERHAPS FROM A BIT MORE AT SOME LOCATIONS IN THE
SANTA CRUZ MTNS. AND SHOULD NOTE THAT SOME PORTIONS OF INTERIOR
MONTEREY AND SAN BENITO COUNTIES MAY WELL NOT RECEIVE ANY RAIN AT
ALL.

AS THIS WILL BE THE FIRST SIGNIFICANT PRECIP EVENT IN SOME
TIME ACROSS MUCH OF THE AREA...ROADWAYS WILL BECOME ESPECIALLY
SLICK AS ACCUMULATED SURFACE OILS MIX IN ESPECIALLY DURING THE
FIRST HOUR OR SO OF PRECIP. ALSO...HAVE INCLUDED MENTION OF A
SLIGHT CHANCE OF THUNDERSTORMS OVER THE NORTH BAY ON
SATURDAY...GIVEN SUBSTANTIAL SURFACE-BASED CAPE VALUES EVIDENT IN
MODEL OUTPUT SOUNDINGS...ESPECIALLY THOSE FROM THE NAM. 500 MB
TEMPS REALLY DON`T GET ALL THAT COLD...ONLY DOWN INTO THE -18C TO
TO -20C RANGE EVEN WITH THE UPPER LEVEL TROUGH PASSAGE. BUT
SURFACE TEMPS AND ESPECIALLY DEW POINTS ARE PROJECTED TO BE HIGH
ENOUGH TO COUNTERBALANCE THAT...THE LATTER IN PARTICULAR
REFLECTING THE UNUSUALLY WARM SEA SURFACE TEMPS THAT CONTINUE IN
OUR COASTAL WATERS. THERE MAY BE A FEW RESIDUAL SHOWERS SATURDAY
EVENING...BUT DRY CONDITIONS ARE PROJECTED TO RETURN DISTRICTWIDE
BY THE LATE NIGHT HOURS.

SUNDAY THROUGH WEDNESDAY...DRY CONDITIONS ARE EXPECTED DISTRICTWIDE
ASIDE FROM JUST A SLIGHT CHANCE OF SOME LIGHT PRECIP IN THE NORTH
BAY AS MIDWEEK APPROACHES AND LONGER RANGE MODEL SOULTIONS THEN
BEGIN TO DIVERGE A BIT AS TO WHETHER THE PRECIP BAND STARTS TO
SAG BACK DOWN TOWARDS OUR NORTHERN BOUNDARY.

IN THE EVEN LONGER TERM...HAVE NOTED THAT THE ECMWF IN PARTICULAR
HAS REMAINED CONSISTENT OVER ITS LAST SEVERAL RUNS IN PROJECTING
ANOTHER ROUND OF WET WEATHER FOR OUR AREA AROUND NEXT WEEKEND.

&&

.AVIATION...AS OF 10:47 PM PDT THURSDAY...STALLED COLD FRONT AND
ASSOCIATED RAINFALL ACROSS NORTHERN CALIFORNIA EXPECTED TO REMAIN
JUST NORTH OF ALL TERMINALS TONIGHT AND THEN LIFT FARTHER TO THE
NORTH ON FRIDAY. MVFR TO IFR CIGS EXPECTED OVERNIGHT ACROSS ALL
TERMINALS AS LOW CLOUDS ADVECT INLAND OR DEVELOP OVER TERMINALS.
CLEARING IS EXPECTED IN MOST AREAS BY 18Z FRIDAY. WINDS WILL BE
LIGHT TONIGHT...TURNING LIGHT SOUTHERLY BY OVERNIGHT...THEN VEERING
TO THE SOUTHWEST AND INCREASING SOMEWHAT ON FRIDAY.

VICINITY OF KSFO...VFR CONDITIONS EXPECTED THROUGH LATE TONIGHT
WITH MVFR CIGS LIKELY BY 07-08Z...CONTINUING UNTIL ABOUT 18Z
FRIDAY. LIGHT WINDS THROUGH LATE TONIGHT...TURNING LIGHT
SOUTHERLY OVERNIGHT AND THEN TO THE SOUTHWEST ON FRIDAY AFTERNOON.
MODERATE CONFIDENCE.

KSFO BRIDGE APPROACH...SIMILAR TO KSFO.

MONTEREY BAY AREA TERMINALS...VFR CONDITIONS EXPECTED THROUGH
LATE TONIGHT WITH IFR CIGS LIKELY BETWEEN 10-12Z...CONTINUING UNTIL
ABOUT 18Z FRIDAY. LIGHT WINDS WILL CONTINUE THROUGH LATE
TONIGHT...TURNING LIGHT SOUTHEASTERLY OVERNIGHT AND THEN TO THE
WEST SOUTHWEST ON FRIDAY AFTERNOON. MODERATE CONFIDENCE.

&&

.MARINE...AS OF 3:11 AM PDT FRIDAY...HIGH PRESSURE OFF THE
SOUTHERN CALIFORNIA COAST WILL WEAKEN AS A DEEPENING LOW PRESSURE
SYSTEM APPROACHES FROM THE WEST. THE LOW WILL LIFT NORTHEAST ON
SATURDAY MOVING INLAND OVER THE PACIFIC NORTHWEST SATURDAY NIGHT.
SOUTH WINDS WILL INCREASE TODAY THROUGH SATURDAY THEN SWITCH TO
NORTHWEST SATURDAY NIGHT AND SUNDAY. THE LOW WILL BRING A SLIGHT
CHANCE OF THUNDERSTORMS TO THE NORTHERN WATERS SATURDAY.

&&

.MTR WATCHES/WARNINGS/ADVISORIES...
     .TDAY...NONE.

&&

$$

PUBLIC FORECAST: BLIER
AVIATION: CW
MARINE: W PI

VISIT US AT WEATHER.GOV/SANFRANCISCO

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










000
FXUS66 KMTR 241055 CCA
AFDMTR

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SAN FRANCISCO BAY AREA
353 AM PDT FRI OCT 24 2014

.SYNOPSIS...MOSTLY SUNNY CONDITIONS ARE EXPECTED TODAY...ASIDE
FROM SOME MORNING FOG AND LOW CLOUDINESS NEAR THE COAST AND IN THE
NORTH BAY VALLEYS. HOWEVER...INCREASING RAIN CHANCES WILL THEN
RAPIDLY SPREAD IN FROM THE NORTHWEST LATER TONIGHT AND SATURDAY
MORNING AS A STRONGER AND WETTER PACIFIC WEATHER SYSTEM MOVES
INTO NORTHERN AND CENTRAL CALIFORNIA. RESIDUAL SHOWERS ARE
EXPECTED TO TAPER OFF SATURDAY EVENING...WITH DRY WEATHER RETURNING
DISTRICTWIDE SUNDAY AND CONTINUING INTO AT LEAST THE FIRST HALF OF
NEXT WEEK.

&&

.DISCUSSION...AS OF 3:35 AM PDT FRIDAY...THE WEAK FRONTAL BOUNDARY
THAT DRAPED DOWN TO NEAR THE NORTHERN BORDER OF OUR DISTRICT IS
NOW LIFTING NORTHWARD AS THE NEXT AND SOMEWHAT STRONGER AND
WETTER PACIFIC WEATHER SYSTEM BEGINS TO APPROACH. EVEN WITH A LOT
OF SEARCHING...LARGEST RAINFALL TOTAL FOUND FOR THURSDAY WAS 0.04
INCHES AT A MESONET SITE AT SEA RANCH...ON THE NORTHERN SONOMA
COUNTY COAST. NO MEASURABLE PRECIP WAS REPORTED AT ANY OF OUR ASOS
OR RAWS SITES.

FOR TODAY...LATEST FOG PRODUCT SATELLITE IMAGERY SHOWS LOW
CLOUDINESS ALONG VIRTUALLY ALL OF OUR COAST AND LOCALLY IN THE
NORTH BAY VALLEYS...AND BEGINNING TO EXTEND THROUGH THE SAN BRUNO
GAP...BUT OTHERWISE SKIES ARE MOSTLY CLEAR. HAVE NOTED THAT JUST
WITHIN THE LAST HOUR THE VISIBILITY REPORTED BY THE HALF MOON BAY
AWOS HAS DROPPED TO UNDER 1/4 MILE AND WILL MONITOR TO SEE IF
PERSISTS AND SPREADS TO THE POINT THAT A SHORT TERM FORECAST OR
DENSE FOG ADVISORY IS NEEDED AS DAWN APPROACHES. ASIDE FROM THE
AFOREMENTIONED MORNING LOW CLOUDINESS AND FOG...MOSTLY SUNNY
CONDITIONS ARE EXPECTED TODAY WITH AFTERNOON HIGHS AROUND THE BAYS
GENERALLY IN THE LOWER 70S.

TONIGHT AND SATURDAY...RAIN CHANCES WILL RAPIDLY DEVELOP FROM THE
NORTHWEST DURING THE OVERNIGHT HOURS AS A COLD FRONTAL RAIN BAND
AHEAD OF THE NEXT AND STRONGER PACIFIC LOW PRESSURE SYSTEM APPROACHES.
GENERAL TREND OF RECENT MODEL RUNS HAS BEEN TO SPEED THINGS UP A
BIT. CONSENSUS TIMING OF LATEST OUTPUT FROM THE NAM...GFS AND
ECMWF DETERMINISTIC SOLUTIONS HAS RAIN BEGINNING IN SANTA ROSA
AROUND A COUPLE OF HOURS BEFORE SUNRISE ON SATURDAY...SAN
FRANCISCO DURING THE FIRST PART OF THE MONTEREY...AND WITH A GOOD
CHANCE SOUTH TO NEAR MONTEREY BY MID-TO-LATE MORNING. AND THEN
AFTER A SHORT BREAK...ANOTHER ROUND OF PRECIP...THIS TIME MORE
SHOWERY IN NATURE...IS LIKELY AS THE COOL UPPER LEVEL TROUGH AXIS
QUICKLY FOLLOWS THROUGH. RAINFALL AMOUNTS THROUGH SATURDAY EVENING
COULD POTENTIALLY BE AS MUCH AS 0.75 TO 1.0 INCHES IN WETTEST SPOTS OF
THE COASTAL NORTH BAY HILLS...BUT OTHERWISE GENERALLY 0.25 INCHES
OR LESS ASIDE PERHAPS FROM A BIT MORE AT SOME LOCATIONS IN THE
SANTA CRUZ MTNS. AND SHOULD NOTE THAT SOME PORTIONS OF INTERIOR
MONTEREY AND SAN BENITO COUNTIES MAY WELL NOT RECEIVE ANY RAIN AT
ALL.

AS THIS WILL BE THE FIRST SIGNIFICANT PRECIP EVENT IN SOME
TIME ACROSS MUCH OF THE AREA...ROADWAYS WILL BECOME ESPECIALLY
SLICK AS ACCUMULATED SURFACE OILS MIX IN ESPECIALLY DURING THE
FIRST HOUR OR SO OF PRECIP. ALSO...HAVE INCLUDED MENTION OF A
SLIGHT CHANCE OF THUNDERSTORMS OVER THE NORTH BAY ON
SATURDAY...GIVEN SUBSTANTIAL SURFACE-BASED CAPE VALUES EVIDENT IN
MODEL OUTPUT SOUNDINGS...ESPECIALLY THOSE FROM THE NAM. 500 MB
TEMPS REALLY DON`T GET ALL THAT COLD...ONLY DOWN INTO THE -18C TO
TO -20C RANGE EVEN WITH THE UPPER LEVEL TROUGH PASSAGE. BUT
SURFACE TEMPS AND ESPECIALLY DEW POINTS ARE PROJECTED TO BE HIGH
ENOUGH TO COUNTERBALANCE THAT...THE LATTER IN PARTICULAR
REFLECTING THE UNUSUALLY WARM SEA SURFACE TEMPS THAT CONTINUE IN
OUR COASTAL WATERS. THERE MAY BE A FEW RESIDUAL SHOWERS SATURDAY
EVENING...BUT DRY CONDITIONS ARE PROJECTED TO RETURN DISTRICTWIDE
BY THE LATE NIGHT HOURS.

SUNDAY THROUGH WEDNESDAY...DRY CONDITIONS ARE EXPECTED DISTRICTWIDE
ASIDE FROM JUST A SLIGHT CHANCE OF SOME LIGHT PRECIP IN THE NORTH
BAY AS MIDWEEK APPROACHES AND LONGER RANGE MODEL SOULTIONS THEN
BEGIN TO DIVERGE A BIT AS TO WHETHER THE PRECIP BAND STARTS TO
SAG BACK DOWN TOWARDS OUR NORTHERN BOUNDARY.

IN THE EVEN LONGER TERM...HAVE NOTED THAT THE ECMWF IN PARTICULAR
HAS REMAINED CONSISTENT OVER ITS LAST SEVERAL RUNS IN PROJECTING
ANOTHER ROUND OF WET WEATHER FOR OUR AREA AROUND NEXT WEEKEND.

&&

.AVIATION...AS OF 10:47 PM PDT THURSDAY...STALLED COLD FRONT AND
ASSOCIATED RAINFALL ACROSS NORTHERN CALIFORNIA EXPECTED TO REMAIN
JUST NORTH OF ALL TERMINALS TONIGHT AND THEN LIFT FARTHER TO THE
NORTH ON FRIDAY. MVFR TO IFR CIGS EXPECTED OVERNIGHT ACROSS ALL
TERMINALS AS LOW CLOUDS ADVECT INLAND OR DEVELOP OVER TERMINALS.
CLEARING IS EXPECTED IN MOST AREAS BY 18Z FRIDAY. WINDS WILL BE
LIGHT TONIGHT...TURNING LIGHT SOUTHERLY BY OVERNIGHT...THEN VEERING
TO THE SOUTHWEST AND INCREASING SOMEWHAT ON FRIDAY.

VICINITY OF KSFO...VFR CONDITIONS EXPECTED THROUGH LATE TONIGHT
WITH MVFR CIGS LIKELY BY 07-08Z...CONTINUING UNTIL ABOUT 18Z
FRIDAY. LIGHT WINDS THROUGH LATE TONIGHT...TURNING LIGHT
SOUTHERLY OVERNIGHT AND THEN TO THE SOUTHWEST ON FRIDAY AFTERNOON.
MODERATE CONFIDENCE.

KSFO BRIDGE APPROACH...SIMILAR TO KSFO.

MONTEREY BAY AREA TERMINALS...VFR CONDITIONS EXPECTED THROUGH
LATE TONIGHT WITH IFR CIGS LIKELY BETWEEN 10-12Z...CONTINUING UNTIL
ABOUT 18Z FRIDAY. LIGHT WINDS WILL CONTINUE THROUGH LATE
TONIGHT...TURNING LIGHT SOUTHEASTERLY OVERNIGHT AND THEN TO THE
WEST SOUTHWEST ON FRIDAY AFTERNOON. MODERATE CONFIDENCE.

&&

.MARINE...AS OF 3:11 AM PDT FRIDAY...HIGH PRESSURE OFF THE
SOUTHERN CALIFORNIA COAST WILL WEAKEN AS A DEEPENING LOW PRESSURE
SYSTEM APPROACHES FROM THE WEST. THE LOW WILL LIFT NORTHEAST ON
SATURDAY MOVING INLAND OVER THE PACIFIC NORTHWEST SATURDAY NIGHT.
SOUTH WINDS WILL INCREASE TODAY THROUGH SATURDAY THEN SWITCH TO
NORTHWEST SATURDAY NIGHT AND SUNDAY. THE LOW WILL BRING A SLIGHT
CHANCE OF THUNDERSTORMS TO THE NORTHERN WATERS SATURDAY.

&&

.MTR WATCHES/WARNINGS/ADVISORIES...
     .TDAY...NONE.

&&

$$

PUBLIC FORECAST: BLIER
AVIATION: CW
MARINE: W PI

VISIT US AT WEATHER.GOV/SANFRANCISCO

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










000
FXUS66 KMTR 241053
AFDMTR

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SAN FRANCISCO BAY AREA
353 AM PDT FRI OCT 24 2014

.SYNOPSIS...MOSTLY SUNNY CONDITIONS ARE EXPECTED TODAY...ASIDE
FROM SOME MORNING FOG AND LOW CLOUDINESS NEAR THE COAST AND IN THE
NORTH BAY VALLEYS. HOWEVER...INCREASING RAIN CHANCES WILL THEN
RAPIDLY SPREAD IN FROM THE NORTHWEST LATER TONIGHT AND SATURDAY
MORNING AS A STRONGER AND WETTER PACIFIC WEATHER SYSTEM MOVES
INTO NORTHERN AND CENTRAL CALIFORNIA. RESIDUAL SHOWERS ARE
EXPECTED TO TAPER OFF SATURDAY EVENING...WITH DRY WEATHER RETURNING
DISTRICTWIDE SUNDAY AND CONTINUING INTO AT LEAST THE FIRST HALF OF
NEXT WEEK.

&&

.DISCUSSION...AS OF 3:35 AM PDT FRIDAY...THE WEAK FRONTAL BOUNDARY
THAT DRAPED DOWN TO NEAR THE NORTHERN BORDER OF OUR DISTRICT IS
NOW LIFTING NORTHWARD AS THE NEXT AND SOMEWHAT STRONGER AND
WETTER PACIFIC WEATHER SYSTEM BEGINS TO APPROACH. EVEN WITH A LOT
OF SEARCHING...LARGEST RAINFALL TOTAL FOUND FOR THURSDAY WAS 0.04
INCHES AT A MESONET SITE AT SEA RANCH...ON THE NORTHERN SONOMA
COUNTY COAST. NO MEASURABLE PRECIP WAS REPORTED AT ANY OF OUR ASOS
OR RAWS SITES.

FOR TODAY...LATEST FOG PRODUCT SATELLITE IMAGERY SHOWS LOW
CLOUDINESS ALONG VIRTUALLY ALL OF OUR COAST AND LOCALLY IN THE
NORTH BAY VALLEYS...AND BEGINNING TO EXTEND THROUGH THE SAN BRUNO
GAP...BUT OTHERWISE SKIES ARE MOSTLY CLEAR. HAVE NOTED THAT JUST
WITHIN THE LAST HOUR THE VISIBILITY REPORTED BY THE HALF MOON BAY
AWOS HAS DROPPED TO UNDER 1/4 MILE AND WILL MONITOR TO SEE IF
PERSISTS AND SPREADS TO THE POINT THAT A SHORT TERM FORECAST OR
DENSE FOG ADVISORY IS NEEDED AS DAWN APPROACHES. ASIDE FROM THE
AFOREMENTIONED MORNING LOW CLOUDINESS AND FOG...MOSTLY SUNNY
CONDITIONS ARE EXPECTED TODAY WITH AFTERNOON HIGHS AROUND THE BAYS
GENERALLY IN THE LOWER 70S.

TONIGHT AND SATURDAY...RAIN CHANCES WILL RAPIDLY DEVELOP FROM THE
NORTHWEST DURING THE OVERNIGHT HOURS AS A COLD FRONTAL RAIN BAND
AHEAD OF THE NEXT AND STRONGER PACIFIC LOW PRESSURE SYSTEM APPROACHES.
GENERAL TREND OF RECENT MODEL RUNS HAS BEEN TO SPEED THINGS UP A
BIT. CONSENSUS TIMING OF LATEST OUTPUT FROM THE NAM...GFS AND
ECMWF DETERMINISTIC SOLUTIONS HAS RAIN BEGINNING IN SANTA ROSA
AROUND A COUPLE OF HOURS BEFORE SUNRISE ON SATURDAY...SAN
FRANCISCO DURING THE FIRST PART OF THE MONTEREY...AND WITH A GOOD
CHANCE SOUTH TO NEAR MONTEREY BY MID-TO-LATE MORNING. AND THEN
AFTER A SHORT BREAK...ANOTHER ROUND OF PRECIP...THIS TIME MORE
SHOWERY IN NATURE...IS LIKELY AS THE COOL UPPER LEVEL TROUGH AXIS
QUICKLY FOLLOWS THROUGH. RAINFALL AMOUNTS THROUGH SATURDAY EVENING
COULD POTENTIALLY BE AS MUCH AS 0.75 TO 1.0 INCHES IN WETTEST SPOTS OF
THE COASTAL NORTH BAY HILLS...BUT OTHERWISE GENERALLY 0.25 INCHES
OR LESS ASIDE PERHAPS FROM A BIT MORE AT SOME LOCATIONS IN THE
SANTA CRUZ MTNS. AND SHOULD NOTE THAT SOME PORTIONS OF INTERIOR
MONTEREY AND SAN BENITO COUNTIES MAY WELL NOT RECEIVE ANY RAIN AT
ALL.

AS THIS WILL BE THE FIRST SIGNIFICANT PRECIP EVENT IN SOME
TIME ACROSS MUCH OF THE AREA...ROADWAYS WILL BECOME ESPECIALLY
SLICK AS ACCUMULATED SURFACE OILS MIX IN ESPECIALLY DURING THE
FIRST HOUR OR SO OF PRECIP. ALSO...HAVE INCLUDED MENTION OF A
SLIGHT CHANCE OF THUNDERSTORMS OVER THE NORTH BAY ON
SATURDAY...GIVEN SUBSTANTIAL SURFACE-BASED CAPE VALUES EVIDENT IN
MODEL OUTPUT SOUNDINGS...ESPECIALLY THOSE FROM THE NAM. 500 MB
TEMPS REALLY DON`T GET ALL THAT COLD...ONLY DOWN INTO THE -18C TO
TO -20C RANGE EVEN WITH THE UPPER LEVEL TROUGH PASSAGE. BUT
SURFACE TEMPS AND ESPECIALLY DEW POINTS ARE PROJECTED TO BE HIGH
ENOUGH TO COUNTERBALANCE THAT...THE LATTER IN PARTICULAR
REFLECTING THE UNUSUALLY WARM SEA SURFACE TEMPS THAT CONTINUE IN
OUR COASTAL WATERS. THERE MAY BE A FEW RESIDUAL SHOWERS SATURDAY
EVENING...BUT DRY CONDITIONS ARE PROJECTED TO RETURN DISTRICTWIDE
BY THE LATE NIGHT HOURS.

SUNDAY THROUGH WEDNESDAY...DRY CONDITIONS ARE EXPECTED DISTRICTWIDE
ASIDE FROM JUST A SLIGHT CHANCE OF SOME LIGHT PRECIP IN THE NORTH
BAY AS MIDWEEK APPROACHES AND LONGER RANGE MODEL SOULTIONS THEN
BEGIN TO DIVERGE A BIT AS TO WHETHER THE PRECIP BAND STARTS TO
SAG BACK DOWN TOWARDS OUR NORTHERN BOUNDARY.

IN THE EVEN LONGER TERM...HAVE NOTED THAT THE ECMWF IN PARTICULAR
HAS REMAINED CONSISTENT OVER ITS LAST SEVERAL RUNS IN PROJECTING
ANOTHER ROUND OF WET WEATHER FOR OUR AREA AROUND NEXT WEEKEND.

&&

.AVIATION...AS OF 10:47 PM PDT THURSDAY...STALLED COLD FRONT AND
ASSOCIATED RAINFALL ACROSS NORTHERN CALIFORNIA EXPECTED TO REMAIN
JUST NORTH OF ALL TERMINALS TONIGHT AND THEN LIFT FARTHER TO THE
NORTH ON FRIDAY. MVFR TO IFR CIGS EXPECTED OVERNIGHT ACROSS ALL
TERMINALS AS LOW CLOUDS ADVECT INLAND OR DEVELOP OVER TERMINALS.
CLEARING IS EXPECTED IN MOST AREAS BY 18Z FRIDAY. WINDS WILL BE
LIGHT TONIGHT...TURNING LIGHT SOUTHERLY BY OVERNIGHT...THEN VEERING
TO THE SOUTHWEST AND INCREASING SOMEWHAT ON FRIDAY.

VICINITY OF KSFO...VFR CONDITIONS EXPECTED THROUGH LATE TONIGHT
WITH MVFR CIGS LIKELY BY 07-08Z...CONTINUING UNTIL ABOUT 18Z
FRIDAY. LIGHT WINDS THROUGH LATE TONIGHT...TURNING LIGHT
SOUTHERLY OVERNIGHT AND THEN TO THE SOUTHWEST ON FRIDAY AFTERNOON.
MODERATE CONFIDENCE.

KSFO BRIDGE APPROACH...SIMILAR TO KSFO.

MONTEREY BAY AREA TERMINALS...VFR CONDITIONS EXPECTED THROUGH
LATE TONIGHT WITH IFR CIGS LIKELY BETWEEN 10-12Z...CONTINUING UNTIL
ABOUT 18Z FRIDAY. LIGHT WINDS WILL CONTINUE THROUGH LATE
TONIGHT...TURNING LIGHT SOUTHEASTERLY OVERNIGHT AND THEN TO THE
WEST SOUTHWEST ON FRIDAY AFTERNOON. MODERATE CONFIDENCE.

&&

.MARINE...AS OF 3:11 AM PDT FRIDAY...HIGH PRESSURE OFF THE
SOUTHERN CALIFORNIA COAST WILL WEAKEN AS A DEEPENING LOW PRESSURE
SYSTEM APPROACHES FROM THE WEST. THE LOW WILL LIFT NORTHEAST ON
SATURDAY MOVING INLAND OVER THE PACIFIC NORTHWEST SATURDAY NIGHT.
SOUTH WINDS WILL INCREASE TODAY THROUGH SATURDAY THEN SWITCH TO
NORTHWEST SATURDAY NIGHT AND SUNDAY. THE LOW WILL BRING A SLIGHT
CHANCE OF THUNDERSTORMS TO THE NORTHERN WATERS SATURDAY.

&&

.MTR WATCHES/WARNINGS/ADVISORIES...
     .TDAY...SCA...PT ARENA TO PT REYES 0-10 NM FROM 3 PM
             SCA...PT ARENA TO PT REYES 10-60 NM FROM 3 PM
             SCA...PT REYES TO PIGEON PT 10-60 NM FROM 3 PM

&&

$$

PUBLIC FORECAST: BLIER
AVIATION: CW
MARINE: W PI

VISIT US AT WEATHER.GOV/SANFRANCISCO

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







000
FXUS66 KMTR 241053
AFDMTR

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SAN FRANCISCO BAY AREA
353 AM PDT FRI OCT 24 2014

.SYNOPSIS...MOSTLY SUNNY CONDITIONS ARE EXPECTED TODAY...ASIDE
FROM SOME MORNING FOG AND LOW CLOUDINESS NEAR THE COAST AND IN THE
NORTH BAY VALLEYS. HOWEVER...INCREASING RAIN CHANCES WILL THEN
RAPIDLY SPREAD IN FROM THE NORTHWEST LATER TONIGHT AND SATURDAY
MORNING AS A STRONGER AND WETTER PACIFIC WEATHER SYSTEM MOVES
INTO NORTHERN AND CENTRAL CALIFORNIA. RESIDUAL SHOWERS ARE
EXPECTED TO TAPER OFF SATURDAY EVENING...WITH DRY WEATHER RETURNING
DISTRICTWIDE SUNDAY AND CONTINUING INTO AT LEAST THE FIRST HALF OF
NEXT WEEK.

&&

.DISCUSSION...AS OF 3:35 AM PDT FRIDAY...THE WEAK FRONTAL BOUNDARY
THAT DRAPED DOWN TO NEAR THE NORTHERN BORDER OF OUR DISTRICT IS
NOW LIFTING NORTHWARD AS THE NEXT AND SOMEWHAT STRONGER AND
WETTER PACIFIC WEATHER SYSTEM BEGINS TO APPROACH. EVEN WITH A LOT
OF SEARCHING...LARGEST RAINFALL TOTAL FOUND FOR THURSDAY WAS 0.04
INCHES AT A MESONET SITE AT SEA RANCH...ON THE NORTHERN SONOMA
COUNTY COAST. NO MEASURABLE PRECIP WAS REPORTED AT ANY OF OUR ASOS
OR RAWS SITES.

FOR TODAY...LATEST FOG PRODUCT SATELLITE IMAGERY SHOWS LOW
CLOUDINESS ALONG VIRTUALLY ALL OF OUR COAST AND LOCALLY IN THE
NORTH BAY VALLEYS...AND BEGINNING TO EXTEND THROUGH THE SAN BRUNO
GAP...BUT OTHERWISE SKIES ARE MOSTLY CLEAR. HAVE NOTED THAT JUST
WITHIN THE LAST HOUR THE VISIBILITY REPORTED BY THE HALF MOON BAY
AWOS HAS DROPPED TO UNDER 1/4 MILE AND WILL MONITOR TO SEE IF
PERSISTS AND SPREADS TO THE POINT THAT A SHORT TERM FORECAST OR
DENSE FOG ADVISORY IS NEEDED AS DAWN APPROACHES. ASIDE FROM THE
AFOREMENTIONED MORNING LOW CLOUDINESS AND FOG...MOSTLY SUNNY
CONDITIONS ARE EXPECTED TODAY WITH AFTERNOON HIGHS AROUND THE BAYS
GENERALLY IN THE LOWER 70S.

TONIGHT AND SATURDAY...RAIN CHANCES WILL RAPIDLY DEVELOP FROM THE
NORTHWEST DURING THE OVERNIGHT HOURS AS A COLD FRONTAL RAIN BAND
AHEAD OF THE NEXT AND STRONGER PACIFIC LOW PRESSURE SYSTEM APPROACHES.
GENERAL TREND OF RECENT MODEL RUNS HAS BEEN TO SPEED THINGS UP A
BIT. CONSENSUS TIMING OF LATEST OUTPUT FROM THE NAM...GFS AND
ECMWF DETERMINISTIC SOLUTIONS HAS RAIN BEGINNING IN SANTA ROSA
AROUND A COUPLE OF HOURS BEFORE SUNRISE ON SATURDAY...SAN
FRANCISCO DURING THE FIRST PART OF THE MONTEREY...AND WITH A GOOD
CHANCE SOUTH TO NEAR MONTEREY BY MID-TO-LATE MORNING. AND THEN
AFTER A SHORT BREAK...ANOTHER ROUND OF PRECIP...THIS TIME MORE
SHOWERY IN NATURE...IS LIKELY AS THE COOL UPPER LEVEL TROUGH AXIS
QUICKLY FOLLOWS THROUGH. RAINFALL AMOUNTS THROUGH SATURDAY EVENING
COULD POTENTIALLY BE AS MUCH AS 0.75 TO 1.0 INCHES IN WETTEST SPOTS OF
THE COASTAL NORTH BAY HILLS...BUT OTHERWISE GENERALLY 0.25 INCHES
OR LESS ASIDE PERHAPS FROM A BIT MORE AT SOME LOCATIONS IN THE
SANTA CRUZ MTNS. AND SHOULD NOTE THAT SOME PORTIONS OF INTERIOR
MONTEREY AND SAN BENITO COUNTIES MAY WELL NOT RECEIVE ANY RAIN AT
ALL.

AS THIS WILL BE THE FIRST SIGNIFICANT PRECIP EVENT IN SOME
TIME ACROSS MUCH OF THE AREA...ROADWAYS WILL BECOME ESPECIALLY
SLICK AS ACCUMULATED SURFACE OILS MIX IN ESPECIALLY DURING THE
FIRST HOUR OR SO OF PRECIP. ALSO...HAVE INCLUDED MENTION OF A
SLIGHT CHANCE OF THUNDERSTORMS OVER THE NORTH BAY ON
SATURDAY...GIVEN SUBSTANTIAL SURFACE-BASED CAPE VALUES EVIDENT IN
MODEL OUTPUT SOUNDINGS...ESPECIALLY THOSE FROM THE NAM. 500 MB
TEMPS REALLY DON`T GET ALL THAT COLD...ONLY DOWN INTO THE -18C TO
TO -20C RANGE EVEN WITH THE UPPER LEVEL TROUGH PASSAGE. BUT
SURFACE TEMPS AND ESPECIALLY DEW POINTS ARE PROJECTED TO BE HIGH
ENOUGH TO COUNTERBALANCE THAT...THE LATTER IN PARTICULAR
REFLECTING THE UNUSUALLY WARM SEA SURFACE TEMPS THAT CONTINUE IN
OUR COASTAL WATERS. THERE MAY BE A FEW RESIDUAL SHOWERS SATURDAY
EVENING...BUT DRY CONDITIONS ARE PROJECTED TO RETURN DISTRICTWIDE
BY THE LATE NIGHT HOURS.

SUNDAY THROUGH WEDNESDAY...DRY CONDITIONS ARE EXPECTED DISTRICTWIDE
ASIDE FROM JUST A SLIGHT CHANCE OF SOME LIGHT PRECIP IN THE NORTH
BAY AS MIDWEEK APPROACHES AND LONGER RANGE MODEL SOULTIONS THEN
BEGIN TO DIVERGE A BIT AS TO WHETHER THE PRECIP BAND STARTS TO
SAG BACK DOWN TOWARDS OUR NORTHERN BOUNDARY.

IN THE EVEN LONGER TERM...HAVE NOTED THAT THE ECMWF IN PARTICULAR
HAS REMAINED CONSISTENT OVER ITS LAST SEVERAL RUNS IN PROJECTING
ANOTHER ROUND OF WET WEATHER FOR OUR AREA AROUND NEXT WEEKEND.

&&

.AVIATION...AS OF 10:47 PM PDT THURSDAY...STALLED COLD FRONT AND
ASSOCIATED RAINFALL ACROSS NORTHERN CALIFORNIA EXPECTED TO REMAIN
JUST NORTH OF ALL TERMINALS TONIGHT AND THEN LIFT FARTHER TO THE
NORTH ON FRIDAY. MVFR TO IFR CIGS EXPECTED OVERNIGHT ACROSS ALL
TERMINALS AS LOW CLOUDS ADVECT INLAND OR DEVELOP OVER TERMINALS.
CLEARING IS EXPECTED IN MOST AREAS BY 18Z FRIDAY. WINDS WILL BE
LIGHT TONIGHT...TURNING LIGHT SOUTHERLY BY OVERNIGHT...THEN VEERING
TO THE SOUTHWEST AND INCREASING SOMEWHAT ON FRIDAY.

VICINITY OF KSFO...VFR CONDITIONS EXPECTED THROUGH LATE TONIGHT
WITH MVFR CIGS LIKELY BY 07-08Z...CONTINUING UNTIL ABOUT 18Z
FRIDAY. LIGHT WINDS THROUGH LATE TONIGHT...TURNING LIGHT
SOUTHERLY OVERNIGHT AND THEN TO THE SOUTHWEST ON FRIDAY AFTERNOON.
MODERATE CONFIDENCE.

KSFO BRIDGE APPROACH...SIMILAR TO KSFO.

MONTEREY BAY AREA TERMINALS...VFR CONDITIONS EXPECTED THROUGH
LATE TONIGHT WITH IFR CIGS LIKELY BETWEEN 10-12Z...CONTINUING UNTIL
ABOUT 18Z FRIDAY. LIGHT WINDS WILL CONTINUE THROUGH LATE
TONIGHT...TURNING LIGHT SOUTHEASTERLY OVERNIGHT AND THEN TO THE
WEST SOUTHWEST ON FRIDAY AFTERNOON. MODERATE CONFIDENCE.

&&

.MARINE...AS OF 3:11 AM PDT FRIDAY...HIGH PRESSURE OFF THE
SOUTHERN CALIFORNIA COAST WILL WEAKEN AS A DEEPENING LOW PRESSURE
SYSTEM APPROACHES FROM THE WEST. THE LOW WILL LIFT NORTHEAST ON
SATURDAY MOVING INLAND OVER THE PACIFIC NORTHWEST SATURDAY NIGHT.
SOUTH WINDS WILL INCREASE TODAY THROUGH SATURDAY THEN SWITCH TO
NORTHWEST SATURDAY NIGHT AND SUNDAY. THE LOW WILL BRING A SLIGHT
CHANCE OF THUNDERSTORMS TO THE NORTHERN WATERS SATURDAY.

&&

.MTR WATCHES/WARNINGS/ADVISORIES...
     .TDAY...SCA...PT ARENA TO PT REYES 0-10 NM FROM 3 PM
             SCA...PT ARENA TO PT REYES 10-60 NM FROM 3 PM
             SCA...PT REYES TO PIGEON PT 10-60 NM FROM 3 PM

&&

$$

PUBLIC FORECAST: BLIER
AVIATION: CW
MARINE: W PI

VISIT US AT WEATHER.GOV/SANFRANCISCO

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







000
FXUS66 KMTR 240547
AFDMTR

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SAN FRANCISCO BAY AREA
1047 PM PDT THU OCT 23 2014

.SYNOPSIS...A FRONTAL BOUNDARY DRAPED ACROSS NORTHERN CALIFORNIA
WILL LIFT TO THE NORTH TONIGHT AND FRIDAY...THEREBY KEEPING ALL
RAIN NORTH OF OUR FORECAST AREA. RAIN CHANCES WILL DEVELOP REGION-WIDE
FRIDAY NIGHT THROUGH SATURDAY MORNING AS A STRONGER SYSTEM PUSHES
A COLD FRONT INTO NORTHERN AND CENTRAL CALIFORNIA. DRY WEATHER
WILL RETURN BY SUNDAY.

&&

.DISCUSSION...AS OF 8:50 PM PDT THURSDAY...A STATIONARY FRONTAL
BOUNDARY REMAINS DRAPED ACROSS NORTHERN CALIFORNIA THIS EVENING.
ACCORDING TO LATEST RADAR AND RAIN GAGE DATA...ALL PRECIP WITH THIS
BOUNDARY IS TO THE NORTH OF OUR FORECAST AREA. AND...BASED ON THE
00Z NAM AND OTHER MODEL DATA...THE FRONTAL BOUNDARY ACROSS
NORTHERN CA IS EXPECTED TO BEGIN LIFTING NORTHWARD OVERNIGHT AS
THE TROUGH OFFSHORE DEEPENS. THIS WILL FURTHER DIMINISH RAIN
CHANCES IN THE N BAY. A FORECAST UPDATE WAS RECENTLY COMPLETED TO
REDUCE NORTH BAY RAIN CHANCES TONIGHT...ESSENTIALLY LIMITING
SLIGHT CHANCE POPS TO AREAS NORTH OF SANTA ROSA. ANOTHER CHANGE
MADE TO THE SHORT-TERM FORECAST WAS TO ADD PATCHY FOG TO COASTAL
AREAS TONIGHT AS THERE HAS ALREADY BEEN REPORTS OF FOG AT HALF
MOON BAY. FOG WAS ALSO ADDED TO THE NORTH BAY VALLEYS LATER
TONIGHT THROUGH EARLY TOMORROW MORNING. THERE HAS BEEN ENOUGH
CLEARING TO RESULT IN RADIATIONAL FOG IN THE TYPICAL FOGGY N BAY
VALLEY LOCATIONS. FINALLY...CLOUD COVER WAS REDUCED IN THE
FORECAST FOR THIS EVENING AND FOR SOME INLAND AREAS ON FRIDAY
MORNING.

FRIDAY IS SHAPING UP TO BE A MOSTLY SUNNY DAY...AFTER PATCHY
MORNING FOG AND LOW CLOUDS CLEAR...ALONG WITH SLIGHTLY ABOVE
NORMAL TEMPS.

ATTENTION THEN TURNS TO ROBUST PACIFIC WEATHER SYSTEM CURRENTLY
DEEPENING OFFSHORE ALONG 140W. THE 00Z NAM IS CONSISTENT WITH
PREVIOUS MODEL RUNS IN SPREADING A COLD-FRONTAL RAIN BAND ACROSS
MOST OF THE FORECAST AREA LATE FRIDAY NIGHT INTO SATURDAY
MORNING. BANDS OF SHOWERS ARE THEN FORECAST TO FOLLOW THE FRONT
THROUGH THE REMAINDER OF SATURDAY. THERE IS ALSO EXPECTED TO BE
ENOUGH INSTABILITY IN THE NORTH BAY TO JUSTIFY AT LEAST A SLIGHT
CHANCE OF THUNDERSTORMS SATURDAY AFTERNOON AS THE COLD UPPER
TROUGH PRESSES INLAND. IN FACT...BASED ON THE 00Z NAM...AN
ARGUMENT COULD BE MADE TO ADD SLIGHT THUNDERSTORM CHANCES FOR
SATURDAY AFTERNOON AS FAR SOUTH AS THE SF PENINSULA AND EAST BAY.
SHOWERS WILL THEN TAPER OFF ON SATURDAY EVENING...WITH PRECIP
EXPECTED TO END BY SUNDAY. RAINFALL AMOUNTS THROUGH SATURDAY
EVENING ARE PROJECTED TO RANGE FROM 0.25 TO 0.75 IN THE NORTH BAY.
LOCATIONS SOUTH OF THE GOLDEN GATE ARE EXPECTED TO SEE LESS THAN A
QUARTER OF AN INCH EXCEPT PERHAPS LOCALLY UP TO A HALF INCH IN THE
SANTA CRUZ MOUNTAINS. SOME PORTIONS OF INTERIOR MONTEREY AND SAN
BENITO COUNTIES MAY NOT SEE ANY RAIN FROM THE SATURDAY SYSTEM.

SUNDAY SHOULD BE A PARTLY CLOUDY AND DRY DAY WITH COOL
NORTHWESTERLY WINDS. THE WEATHER PATTERN IS LOOKING DRY FROM
MONDAY THROUGH FRIDAY OF NEXT WEEK AS AN UPPER RIDGE OVER
CALIFORNIA DIVERTS ALL PACIFIC STORMS/PRECIP TO OUR NORTH.

&&

.AVIATION...AS OF 10:47 PM PDT THURSDAY...STALLED COLD FRONT AND
ASSOCIATED RAINFALL ACROSS NORTHERN CALIFORNIA EXPECTED TO REMAIN
JUST NORTH OF ALL TERMINALS TONIGHT AND THEN LIFT FARTHER TO THE
NORTH ON FRIDAY. MVFR TO IFR CIGS EXPECTED OVERNIGHT ACROSS ALL
TERMINALS AS LOW CLOUDS ADVECT INLAND OR DEVELOP OVER TERMINALS.
CLEARING IS EXPECTED IN MOST AREAS BY 18Z FRIDAY. WINDS WILL BE
LIGHT TONIGHT...TURNING LIGHT SOUTHERLY BY OVERNIGHT...THEN VEERING
TO THE SOUTHWEST AND INCREASING SOMEWHAT ON FRIDAY.

VICINITY OF KSFO...VFR CONDITIONS EXPECTED THROUGH LATE TONIGHT
WITH MVFR CIGS LIKELY BY 07-08Z...CONTINUING UNTIL ABOUT 18Z
FRIDAY. LIGHT WINDS THROUGH LATE TONIGHT...TURNING LIGHT
SOUTHERLY OVERNIGHT AND THEN TO THE SOUTHWEST ON FRIDAY AFTERNOON.
MODERATE CONFIDENCE.

KSFO BRIDGE APPROACH...SIMILAR TO KSFO.

MONTEREY BAY AREA TERMINALS...VFR CONDITIONS EXPECTED THROUGH
LATE TONIGHT WITH IFR CIGS LIKELY BETWEEN 10-12Z...CONTINUING UNTIL
ABOUT 18Z FRIDAY. LIGHT WINDS WILL CONTINUE THROUGH LATE
TONIGHT...TURNING LIGHT SOUTHEASTERLY OVERNIGHT AND THEN TO THE
WEST SOUTHWEST ON FRIDAY AFTERNOON. MODERATE CONFIDENCE.

&&

.MARINE...AS OF 10:36 PM PDT THURSDAY...A WEAK RIDGE OF HIGH
PRESSURE CONTINUES OVER SOUTHERN CALIFORNIA COAST WHILE LOW
PRESSURE WILL STRENGTHEN TO OUR WEST OVER THE NEXT FEW DAYS. THIS
IS BRINGING LIGHT WINDS TO THE AREA TODAY WHICH WILL BECOME
SOUTHERLY AND INCREASE FRIDAY AND SATURDAY AS THE LOW PRESSURE
SYSTEM STRENGTHENS OFF THE OREGON COAST. HIGH PRESSURE WILL BUILD
OFF THE CALIFORNIA COAST SUNDAY AND MONDAY AFTER THE LOW MOVES
INLAND.

&&

.MTR WATCHES/WARNINGS/ADVISORIES...
     .TNGT...NONE.

&&

$$

PUBLIC FORECAST: DYKEMA
AVIATION/MARINE: CW

VISIT US AT WEATHER.GOV/SANFRANCISCO

FOLLOW US ON FACEBOOK, TWITTER, AND YOUTUBE AT:
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WWW.TWITTER.COM/NWSBAYAREA
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000
FXUS66 KMTR 240547
AFDMTR

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SAN FRANCISCO BAY AREA
1047 PM PDT THU OCT 23 2014

.SYNOPSIS...A FRONTAL BOUNDARY DRAPED ACROSS NORTHERN CALIFORNIA
WILL LIFT TO THE NORTH TONIGHT AND FRIDAY...THEREBY KEEPING ALL
RAIN NORTH OF OUR FORECAST AREA. RAIN CHANCES WILL DEVELOP REGION-WIDE
FRIDAY NIGHT THROUGH SATURDAY MORNING AS A STRONGER SYSTEM PUSHES
A COLD FRONT INTO NORTHERN AND CENTRAL CALIFORNIA. DRY WEATHER
WILL RETURN BY SUNDAY.

&&

.DISCUSSION...AS OF 8:50 PM PDT THURSDAY...A STATIONARY FRONTAL
BOUNDARY REMAINS DRAPED ACROSS NORTHERN CALIFORNIA THIS EVENING.
ACCORDING TO LATEST RADAR AND RAIN GAGE DATA...ALL PRECIP WITH THIS
BOUNDARY IS TO THE NORTH OF OUR FORECAST AREA. AND...BASED ON THE
00Z NAM AND OTHER MODEL DATA...THE FRONTAL BOUNDARY ACROSS
NORTHERN CA IS EXPECTED TO BEGIN LIFTING NORTHWARD OVERNIGHT AS
THE TROUGH OFFSHORE DEEPENS. THIS WILL FURTHER DIMINISH RAIN
CHANCES IN THE N BAY. A FORECAST UPDATE WAS RECENTLY COMPLETED TO
REDUCE NORTH BAY RAIN CHANCES TONIGHT...ESSENTIALLY LIMITING
SLIGHT CHANCE POPS TO AREAS NORTH OF SANTA ROSA. ANOTHER CHANGE
MADE TO THE SHORT-TERM FORECAST WAS TO ADD PATCHY FOG TO COASTAL
AREAS TONIGHT AS THERE HAS ALREADY BEEN REPORTS OF FOG AT HALF
MOON BAY. FOG WAS ALSO ADDED TO THE NORTH BAY VALLEYS LATER
TONIGHT THROUGH EARLY TOMORROW MORNING. THERE HAS BEEN ENOUGH
CLEARING TO RESULT IN RADIATIONAL FOG IN THE TYPICAL FOGGY N BAY
VALLEY LOCATIONS. FINALLY...CLOUD COVER WAS REDUCED IN THE
FORECAST FOR THIS EVENING AND FOR SOME INLAND AREAS ON FRIDAY
MORNING.

FRIDAY IS SHAPING UP TO BE A MOSTLY SUNNY DAY...AFTER PATCHY
MORNING FOG AND LOW CLOUDS CLEAR...ALONG WITH SLIGHTLY ABOVE
NORMAL TEMPS.

ATTENTION THEN TURNS TO ROBUST PACIFIC WEATHER SYSTEM CURRENTLY
DEEPENING OFFSHORE ALONG 140W. THE 00Z NAM IS CONSISTENT WITH
PREVIOUS MODEL RUNS IN SPREADING A COLD-FRONTAL RAIN BAND ACROSS
MOST OF THE FORECAST AREA LATE FRIDAY NIGHT INTO SATURDAY
MORNING. BANDS OF SHOWERS ARE THEN FORECAST TO FOLLOW THE FRONT
THROUGH THE REMAINDER OF SATURDAY. THERE IS ALSO EXPECTED TO BE
ENOUGH INSTABILITY IN THE NORTH BAY TO JUSTIFY AT LEAST A SLIGHT
CHANCE OF THUNDERSTORMS SATURDAY AFTERNOON AS THE COLD UPPER
TROUGH PRESSES INLAND. IN FACT...BASED ON THE 00Z NAM...AN
ARGUMENT COULD BE MADE TO ADD SLIGHT THUNDERSTORM CHANCES FOR
SATURDAY AFTERNOON AS FAR SOUTH AS THE SF PENINSULA AND EAST BAY.
SHOWERS WILL THEN TAPER OFF ON SATURDAY EVENING...WITH PRECIP
EXPECTED TO END BY SUNDAY. RAINFALL AMOUNTS THROUGH SATURDAY
EVENING ARE PROJECTED TO RANGE FROM 0.25 TO 0.75 IN THE NORTH BAY.
LOCATIONS SOUTH OF THE GOLDEN GATE ARE EXPECTED TO SEE LESS THAN A
QUARTER OF AN INCH EXCEPT PERHAPS LOCALLY UP TO A HALF INCH IN THE
SANTA CRUZ MOUNTAINS. SOME PORTIONS OF INTERIOR MONTEREY AND SAN
BENITO COUNTIES MAY NOT SEE ANY RAIN FROM THE SATURDAY SYSTEM.

SUNDAY SHOULD BE A PARTLY CLOUDY AND DRY DAY WITH COOL
NORTHWESTERLY WINDS. THE WEATHER PATTERN IS LOOKING DRY FROM
MONDAY THROUGH FRIDAY OF NEXT WEEK AS AN UPPER RIDGE OVER
CALIFORNIA DIVERTS ALL PACIFIC STORMS/PRECIP TO OUR NORTH.

&&

.AVIATION...AS OF 10:47 PM PDT THURSDAY...STALLED COLD FRONT AND
ASSOCIATED RAINFALL ACROSS NORTHERN CALIFORNIA EXPECTED TO REMAIN
JUST NORTH OF ALL TERMINALS TONIGHT AND THEN LIFT FARTHER TO THE
NORTH ON FRIDAY. MVFR TO IFR CIGS EXPECTED OVERNIGHT ACROSS ALL
TERMINALS AS LOW CLOUDS ADVECT INLAND OR DEVELOP OVER TERMINALS.
CLEARING IS EXPECTED IN MOST AREAS BY 18Z FRIDAY. WINDS WILL BE
LIGHT TONIGHT...TURNING LIGHT SOUTHERLY BY OVERNIGHT...THEN VEERING
TO THE SOUTHWEST AND INCREASING SOMEWHAT ON FRIDAY.

VICINITY OF KSFO...VFR CONDITIONS EXPECTED THROUGH LATE TONIGHT
WITH MVFR CIGS LIKELY BY 07-08Z...CONTINUING UNTIL ABOUT 18Z
FRIDAY. LIGHT WINDS THROUGH LATE TONIGHT...TURNING LIGHT
SOUTHERLY OVERNIGHT AND THEN TO THE SOUTHWEST ON FRIDAY AFTERNOON.
MODERATE CONFIDENCE.

KSFO BRIDGE APPROACH...SIMILAR TO KSFO.

MONTEREY BAY AREA TERMINALS...VFR CONDITIONS EXPECTED THROUGH
LATE TONIGHT WITH IFR CIGS LIKELY BETWEEN 10-12Z...CONTINUING UNTIL
ABOUT 18Z FRIDAY. LIGHT WINDS WILL CONTINUE THROUGH LATE
TONIGHT...TURNING LIGHT SOUTHEASTERLY OVERNIGHT AND THEN TO THE
WEST SOUTHWEST ON FRIDAY AFTERNOON. MODERATE CONFIDENCE.

&&

.MARINE...AS OF 10:36 PM PDT THURSDAY...A WEAK RIDGE OF HIGH
PRESSURE CONTINUES OVER SOUTHERN CALIFORNIA COAST WHILE LOW
PRESSURE WILL STRENGTHEN TO OUR WEST OVER THE NEXT FEW DAYS. THIS
IS BRINGING LIGHT WINDS TO THE AREA TODAY WHICH WILL BECOME
SOUTHERLY AND INCREASE FRIDAY AND SATURDAY AS THE LOW PRESSURE
SYSTEM STRENGTHENS OFF THE OREGON COAST. HIGH PRESSURE WILL BUILD
OFF THE CALIFORNIA COAST SUNDAY AND MONDAY AFTER THE LOW MOVES
INLAND.

&&

.MTR WATCHES/WARNINGS/ADVISORIES...
     .TNGT...NONE.

&&

$$

PUBLIC FORECAST: DYKEMA
AVIATION/MARINE: CW

VISIT US AT WEATHER.GOV/SANFRANCISCO

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







000
FXUS66 KMTR 240350
AFDMTR

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SAN FRANCISCO BAY AREA
850 PM PDT THU OCT 23 2014

.SYNOPSIS...A FRONTAL BOUNDARY DRAPED ACROSS NORTHERN CALIFORNIA
WILL LIFT TO THE NORTH TONIGHT AND FRIDAY...THEREBY KEEPING ALL
RAIN NORTH OF OUR FORECAST AREA. RAIN CHANCES WILL DEVELOP REGION-WIDE
FRIDAY NIGHT THROUGH SATURDAY MORNING AS A STRONGER SYSTEM PUSHES
A COLD FRONT INTO NORTHERN AND CENTRAL CALIFORNIA. DRY WEATHER
WILL RETURN BY SUNDAY.

&&

.DISCUSSION...AS OF 8:50 PM PDT THURSDAY...A STATIONARY FRONTAL
BOUNDARY REMAINS DRAPED ACROSS NORTHERN CALIFORNIA THIS EVENING.
ACCORDING TO LATEST RADAR AND RAIN GAGE DATA...ALL PRECIP WITH THIS
BOUNDARY IS TO THE NORTH OF OUR FORECAST AREA. AND...BASED ON THE
00Z NAM AND OTHER MODEL DATA...THE FRONTAL BOUNDARY ACROSS
NORTHERN CA IS EXPECTED TO BEGIN LIFTING NORTHWARD OVERNIGHT AS
THE TROUGH OFFSHORE DEEPENS. THIS WILL FURTHER DIMINISH RAIN
CHANCES IN THE N BAY. A FORECAST UPDATE WAS RECENTLY COMPLETED TO
REDUCE NORTH BAY RAIN CHANCES TONIGHT...ESSENTIALLY LIMITING
SLIGHT CHANCE POPS TO AREAS NORTH OF SANTA ROSA. ANOTHER CHANGE
MADE TO THE SHORT-TERM FORECAST WAS TO ADD PATCHY FOG TO COASTAL
AREAS TONIGHT AS THERE HAS ALREADY BEEN REPORTS OF FOG AT HALF
MOON BAY. FOG WAS ALSO ADDED TO THE NORTH BAY VALLEYS LATER
TONIGHT THROUGH EARLY TOMORROW MORNING. THERE HAS BEEN ENOUGH
CLEARING TO RESULT IN RADIATIONAL FOG IN THE TYPICAL FOGGY N BAY
VALLEY LOCATIONS. FINALLY...CLOUD COVER WAS REDUCED IN THE
FORECAST FOR THIS EVENING AND FOR SOME INLAND AREAS ON FRIDAY
MORNING.

FRIDAY IS SHAPING UP TO BE A MOSTLY SUNNY DAY...AFTER PATCHY
MORNING FOG AND LOW CLOUDS CLEAR...ALONG WITH SLIGHTLY ABOVE
NORMAL TEMPS.

ATTENTION THEN TURNS TO ROBUST PACIFIC WEATHER SYSTEM CURRENTLY
DEEPENING OFFSHORE ALONG 140W. THE 00Z NAM IS CONSISTENT WITH
PREVIOUS MODEL RUNS IN SPREADING A COLD-FRONTAL RAIN BAND ACROSS
MOST OF THE FORECAST AREA LATE FRIDAY NIGHT INTO SATURDAY
MORNING. BANDS OF SHOWERS ARE THEN FORECAST TO FOLLOW THE FRONT
THROUGH THE REMAINDER OF SATURDAY. THERE IS ALSO EXPECTED TO BE
ENOUGH INSTABILITY IN THE NORTH BAY TO JUSTIFY AT LEAST A SLIGHT
CHANCE OF THUNDERSTORMS SATURDAY AFTERNOON AS THE COLD UPPER
TROUGH PRESSES INLAND. IN FACT...BASED ON THE 00Z NAM...AN
ARGUMENT COULD BE MADE TO ADD SLIGHT THUNDERSTORM CHANCES FOR
SATURDAY AFTERNOON AS FAR SOUTH AS THE SF PENINSULA AND EAST BAY.
SHOWERS WILL THEN TAPER OFF ON SATURDAY EVENING...WITH PRECIP
EXPECTED TO END BY SUNDAY. RAINFALL AMOUNTS THROUGH SATURDAY
EVENING ARE PROJECTED TO RANGE FROM 0.25 TO 0.75 IN THE NORTH BAY.
LOCATIONS SOUTH OF THE GOLDEN GATE ARE EXPECTED TO SEE LESS THAN A
QUARTER OF AN INCH EXCEPT PERHAPS LOCALLY UP TO A HALF INCH IN THE
SANTA CRUZ MOUNTAINS. SOME PORTIONS OF INTERIOR MONTEREY AND SAN
BENITO COUNTIES MAY NOT SEE ANY RAIN FROM THE SATURDAY SYSTEM.

SUNDAY SHOULD BE A PARTLY CLOUDY AND DRY DAY WITH COOL
NORTHWESTERLY WINDS. THE WEATHER PATTERN IS LOOKING DRY FROM
MONDAY THROUGH FRIDAY OF NEXT WEEK AS AN UPPER RIDGE OVER
CALIFORNIA DIVERTS ALL PACIFIC STORMS/PRECIP TO OUR NORTH.

&&

.AVIATION...AS OF 4:30 PM PDT THURSDAY...STALLED COLD FRONT AND
ASSOCIATED RAINFALL ACROSS NORTHERN CALIFORNIA EXPECTED TO REMAIN
JUST NORTH OF ALL TERMINALS TONIGHT AND THEN LIFT FARTHER TO THE
NORTH ON FRIDAY. CONSIDERABLE CLOUD COVER WILL PERSIST ACROSS THE
NORTH BAY WHERE MVFR CIGS WILL DEVELOP ON THURSDAY EVENING AND
THEN LOWERING TO IFR CONDITIONS OVERNIGHT. LOW CLOUDS ARE ALSO
FORECAST TO MOVE INTO SF BAY AND INLAND FROM MONTEREY BAY BY LATE
EVENING. CLEARING EXPECTED IN MOST AREAS BY 18Z FRIDAY. WINDS
WILL BE LIGHT WESTERLY THIS EVENING...TURNING LIGHT SOUTHERLY BY
LATE TONIGHT...THEN VEERING TO THE SOUTHWEST AND INCREASING
SOMEWHAT ON FRIDAY.

VICINITY OF KSFO...VFR CONDITIONS EXPECTED THROUGH THE EVENING
RUSH WITH MVFR CIGS LIKELY BY 07-08Z...CONTINUING UNTIL ABOUT 18Z
FRIDAY. CONFIDENCE MODERATE. WINDS LIGHT WESTERLY THIS
EVENING...TURNING LIGHT SOUTHERLY OVERNIGHT AND THEN TO THE
SOUTHWEST ON FRIDAY AFTERNOON.

KSFO BRIDGE APPROACH...SIMILAR TO KSFO.

MONTEREY BAY AREA TERMINALS...IFR CONDITIONS THROUGH EARLY
EVENING. MVFR CIGS LIKELY BY 06Z...LOWERING TO IFR BY 12Z.
CLEARING EXPECTED AROUND 18Z FRIDAY. LIGHT WINDS.

&&

.MARINE...AS OF 02:04 PM PDT THURSDAY...A WEAK RIDGE OF HIGH
PRESSURE CONTINUES OVER SOUTHERN CALIFORNIA COAST WHILE LOW
PRESSURE WILL STRENGTHEN TO OUR WEST OVER THE NEXT FEW DAYS. THIS
IS BRINGING LIGHT WINDS TO THE AREA TODAY WHICH WILL BECOME
SOUTHERLY AND INCREASE FRIDAY AND SATURDAY AS THE LOW PRESSURE
SYSTEM STRENGTHENS OFF THE OREGON COAST. HIGH PRESSURE WILL BUILD
OFF THE CALIFORNIA COAST SUNDAY AND MONDAY AFTER THE LOW MOVES
INLAND.

&&

.MTR WATCHES/WARNINGS/ADVISORIES...
     .TNGT...NONE.

&&

$$

PUBLIC FORECAST: DYKEMA
AVIATION: DYKEMA
MARINE: JOHNSON

VISIT US AT WEATHER.GOV/SANFRANCISCO

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







000
FXUS66 KMTR 240350
AFDMTR

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SAN FRANCISCO BAY AREA
850 PM PDT THU OCT 23 2014

.SYNOPSIS...A FRONTAL BOUNDARY DRAPED ACROSS NORTHERN CALIFORNIA
WILL LIFT TO THE NORTH TONIGHT AND FRIDAY...THEREBY KEEPING ALL
RAIN NORTH OF OUR FORECAST AREA. RAIN CHANCES WILL DEVELOP REGION-WIDE
FRIDAY NIGHT THROUGH SATURDAY MORNING AS A STRONGER SYSTEM PUSHES
A COLD FRONT INTO NORTHERN AND CENTRAL CALIFORNIA. DRY WEATHER
WILL RETURN BY SUNDAY.

&&

.DISCUSSION...AS OF 8:50 PM PDT THURSDAY...A STATIONARY FRONTAL
BOUNDARY REMAINS DRAPED ACROSS NORTHERN CALIFORNIA THIS EVENING.
ACCORDING TO LATEST RADAR AND RAIN GAGE DATA...ALL PRECIP WITH THIS
BOUNDARY IS TO THE NORTH OF OUR FORECAST AREA. AND...BASED ON THE
00Z NAM AND OTHER MODEL DATA...THE FRONTAL BOUNDARY ACROSS
NORTHERN CA IS EXPECTED TO BEGIN LIFTING NORTHWARD OVERNIGHT AS
THE TROUGH OFFSHORE DEEPENS. THIS WILL FURTHER DIMINISH RAIN
CHANCES IN THE N BAY. A FORECAST UPDATE WAS RECENTLY COMPLETED TO
REDUCE NORTH BAY RAIN CHANCES TONIGHT...ESSENTIALLY LIMITING
SLIGHT CHANCE POPS TO AREAS NORTH OF SANTA ROSA. ANOTHER CHANGE
MADE TO THE SHORT-TERM FORECAST WAS TO ADD PATCHY FOG TO COASTAL
AREAS TONIGHT AS THERE HAS ALREADY BEEN REPORTS OF FOG AT HALF
MOON BAY. FOG WAS ALSO ADDED TO THE NORTH BAY VALLEYS LATER
TONIGHT THROUGH EARLY TOMORROW MORNING. THERE HAS BEEN ENOUGH
CLEARING TO RESULT IN RADIATIONAL FOG IN THE TYPICAL FOGGY N BAY
VALLEY LOCATIONS. FINALLY...CLOUD COVER WAS REDUCED IN THE
FORECAST FOR THIS EVENING AND FOR SOME INLAND AREAS ON FRIDAY
MORNING.

FRIDAY IS SHAPING UP TO BE A MOSTLY SUNNY DAY...AFTER PATCHY
MORNING FOG AND LOW CLOUDS CLEAR...ALONG WITH SLIGHTLY ABOVE
NORMAL TEMPS.

ATTENTION THEN TURNS TO ROBUST PACIFIC WEATHER SYSTEM CURRENTLY
DEEPENING OFFSHORE ALONG 140W. THE 00Z NAM IS CONSISTENT WITH
PREVIOUS MODEL RUNS IN SPREADING A COLD-FRONTAL RAIN BAND ACROSS
MOST OF THE FORECAST AREA LATE FRIDAY NIGHT INTO SATURDAY
MORNING. BANDS OF SHOWERS ARE THEN FORECAST TO FOLLOW THE FRONT
THROUGH THE REMAINDER OF SATURDAY. THERE IS ALSO EXPECTED TO BE
ENOUGH INSTABILITY IN THE NORTH BAY TO JUSTIFY AT LEAST A SLIGHT
CHANCE OF THUNDERSTORMS SATURDAY AFTERNOON AS THE COLD UPPER
TROUGH PRESSES INLAND. IN FACT...BASED ON THE 00Z NAM...AN
ARGUMENT COULD BE MADE TO ADD SLIGHT THUNDERSTORM CHANCES FOR
SATURDAY AFTERNOON AS FAR SOUTH AS THE SF PENINSULA AND EAST BAY.
SHOWERS WILL THEN TAPER OFF ON SATURDAY EVENING...WITH PRECIP
EXPECTED TO END BY SUNDAY. RAINFALL AMOUNTS THROUGH SATURDAY
EVENING ARE PROJECTED TO RANGE FROM 0.25 TO 0.75 IN THE NORTH BAY.
LOCATIONS SOUTH OF THE GOLDEN GATE ARE EXPECTED TO SEE LESS THAN A
QUARTER OF AN INCH EXCEPT PERHAPS LOCALLY UP TO A HALF INCH IN THE
SANTA CRUZ MOUNTAINS. SOME PORTIONS OF INTERIOR MONTEREY AND SAN
BENITO COUNTIES MAY NOT SEE ANY RAIN FROM THE SATURDAY SYSTEM.

SUNDAY SHOULD BE A PARTLY CLOUDY AND DRY DAY WITH COOL
NORTHWESTERLY WINDS. THE WEATHER PATTERN IS LOOKING DRY FROM
MONDAY THROUGH FRIDAY OF NEXT WEEK AS AN UPPER RIDGE OVER
CALIFORNIA DIVERTS ALL PACIFIC STORMS/PRECIP TO OUR NORTH.

&&

.AVIATION...AS OF 4:30 PM PDT THURSDAY...STALLED COLD FRONT AND
ASSOCIATED RAINFALL ACROSS NORTHERN CALIFORNIA EXPECTED TO REMAIN
JUST NORTH OF ALL TERMINALS TONIGHT AND THEN LIFT FARTHER TO THE
NORTH ON FRIDAY. CONSIDERABLE CLOUD COVER WILL PERSIST ACROSS THE
NORTH BAY WHERE MVFR CIGS WILL DEVELOP ON THURSDAY EVENING AND
THEN LOWERING TO IFR CONDITIONS OVERNIGHT. LOW CLOUDS ARE ALSO
FORECAST TO MOVE INTO SF BAY AND INLAND FROM MONTEREY BAY BY LATE
EVENING. CLEARING EXPECTED IN MOST AREAS BY 18Z FRIDAY. WINDS
WILL BE LIGHT WESTERLY THIS EVENING...TURNING LIGHT SOUTHERLY BY
LATE TONIGHT...THEN VEERING TO THE SOUTHWEST AND INCREASING
SOMEWHAT ON FRIDAY.

VICINITY OF KSFO...VFR CONDITIONS EXPECTED THROUGH THE EVENING
RUSH WITH MVFR CIGS LIKELY BY 07-08Z...CONTINUING UNTIL ABOUT 18Z
FRIDAY. CONFIDENCE MODERATE. WINDS LIGHT WESTERLY THIS
EVENING...TURNING LIGHT SOUTHERLY OVERNIGHT AND THEN TO THE
SOUTHWEST ON FRIDAY AFTERNOON.

KSFO BRIDGE APPROACH...SIMILAR TO KSFO.

MONTEREY BAY AREA TERMINALS...IFR CONDITIONS THROUGH EARLY
EVENING. MVFR CIGS LIKELY BY 06Z...LOWERING TO IFR BY 12Z.
CLEARING EXPECTED AROUND 18Z FRIDAY. LIGHT WINDS.

&&

.MARINE...AS OF 02:04 PM PDT THURSDAY...A WEAK RIDGE OF HIGH
PRESSURE CONTINUES OVER SOUTHERN CALIFORNIA COAST WHILE LOW
PRESSURE WILL STRENGTHEN TO OUR WEST OVER THE NEXT FEW DAYS. THIS
IS BRINGING LIGHT WINDS TO THE AREA TODAY WHICH WILL BECOME
SOUTHERLY AND INCREASE FRIDAY AND SATURDAY AS THE LOW PRESSURE
SYSTEM STRENGTHENS OFF THE OREGON COAST. HIGH PRESSURE WILL BUILD
OFF THE CALIFORNIA COAST SUNDAY AND MONDAY AFTER THE LOW MOVES
INLAND.

&&

.MTR WATCHES/WARNINGS/ADVISORIES...
     .TNGT...NONE.

&&

$$

PUBLIC FORECAST: DYKEMA
AVIATION: DYKEMA
MARINE: JOHNSON

VISIT US AT WEATHER.GOV/SANFRANCISCO

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







000
FXUS66 KMTR 232334
AFDMTR

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SAN FRANCISCO BAY AREA
434 PM PDT THU OCT 23 2014

.SYNOPSIS...A STALLED OUT FRONTAL BOUNDARY JUST TO THE NORTH
SHOULD KEEP MOST PRECIPITATION OUT OF THE REGION THROUGH FRIDAY.
RAIN CHANCES INCREASE REGION-WIDE FRIDAY NIGHT THROUGH SATURDAY
MORNING AS A STRONGER SYSTEM PUSHES A COLD FRONT INTO CENTRAL
CALIFORNIA. CHANCES FOR PRECIPITATION WILL DIMINISH SUNDAY INTO
MONDAY WITH NEAR SEASONAL TEMPERATURES.

&&

.DISCUSSION...AS OF 02:04 PM PDT THURSDAY...A WEAK FRONTAL
BOUNDARY STALLED JUST NORTH OF SONOMA AND NAPA COUNTIES SHOULD
KEEP MOST PRECIPITATION NORTH OF THE REGION TONIGHT.
HOWEVER...WITH THE POSSIBILITY OF THIS DEEPER MOISTURE AND FRONTAL
BOUNDARY SAGGING SOUTHWARD...HAVE KEPT CHANCES FOR PRECIPITATION
OVER PORTIONS OF THE NORTH BAY. OVERALL...ANY RAINFALL AMOUNTS
SHOULD REMAIN LIGHT ACROSS THE NORTH BAY REGION OVERNIGHT. THIS
BOUNDARY IS FORECAST TO LIFT NORTHWARD ON FRIDAY AND WILL LIKELY
KEEP DRY WEATHER CONDITIONS AND MILD TEMPERATURES OVER THE ENTIRE
REGION. THE MAIN FORECAST CHALLENGE FOR FRIDAY MORNING WILL BE THE
DEVELOPMENT OF COASTAL STRATUS. HAVE INCREASED CLOUD COVER OVER
THE COASTAL WATERS AND ALONG THE COAST OVERNIGHT TONIGHT THROUGH
FRIDAY MORNING AS BOUNDARY LAYER MOISTURE IS EXPECTED TO RAPIDLY
RETURN. ALREADY SEEING SOME STRATUS OFFSHORE BELOW THE HIGH CLOUDS
ON VISIBLE SATELLITE.

THE NEXT MID/UPPER LEVEL TROUGH IS FORECAST DO DEEPEN OVER THE
EASTERN PACIFIC AND APPROACH THE PACIFIC NORTHWEST LATE FRIDAY
NIGHT. WITH THIS...RAIN CHANCES WILL INCREASE OVER THE COASTAL
WATERS AND NORTH BAY AS MOISTURE ADVECTS ACROSS THE REGION AHEAD OF
THE FRONTAL BOUNDARY. WITH INCREASED MID/UPPER LEVEL SUPPORT AS THE
FRONT MOVES INTO THE REGION...ISOLATED THUNDERSTORMS WILL BE
POSSIBLE SATURDAY MORNING/AFTERNOON ACROSS OUR NORTHERN COASTAL
WATERS INLAND INTO THE NORTH BAY. FURTHER SOUTH...SHOWERS WILL
INCREASE ALONG THE BOUNDARY AND BRING RAIN TO MUCH OF THE SAN
FRANCISCO BAY AREA DOWN ALONG THEN CENTRAL COAST. AT THIS TIME...THE
GREATEST RAINFALL AMOUNTS APPEAR TO OCCUR OVER THE NORTH BAY AND
ALONG THE WEST/SOUTHWEST FACING SLOPES DOWN THE COASTLINE. CANNOT
RULE OUT SOME LOCATIONS PICKING UP ONE-QUARTER TO NEARLY ONE INCH OF
RAINFALL FRIDAY NIGHT THROUGH SATURDAY. WITH INCREASED CLOUDS AND
PRECIPITATION CHANCES...TEMPERATURES WILL BE NOTICEABLY COOLER ON
SATURDAY.

WHILE LINGERING SHOWERS WILL BE POSSIBLE SATURDAY EVENING IN WAKE OF
THE FRONTAL PASSAGE...MOST LOCATIONS WILL BEGIN TO DRY OUT SATURDAY
NIGHT INTO SUNDAY. WITH A COOLER AND DRIER AIR MASS ALOFT...SURFACE
TEMPERATURES WILL REMAIN ON THE COOL SIDE OF NORMAL SUNDAY AND
MONDAY. EARLY NEXT WEEK...THE FORECAST MODELS DIFFER ON THE UPPER
LEVEL PATTERN ACROSS THE STATE. CANNOT RULE OUT LIGHT PRECIPITATION
RETURNING TO THE NORTH BAY TUESDAY AS ANOTHER PLUME OF MOISTURE
SPREADS INTO NORTHERN CALIFORNIA. HOWEVER...WILL KEEP MOST AREAS DRY
THROUGH EARLY NEXT WEEK UNTIL THE FORECAST MODELS DIVERGE ON A MORE
CONCISE SOLUTION.

&&

.AVIATION...AS OF 4:30 PM PDT THURSDAY...STALLED COLD FRONT AND
ASSOCIATED RAINFALL ACROSS NORTHERN CALIFORNIA EXPECTED TO REMAIN
JUST NORTH OF ALL TERMINALS TONIGHT AND THEN LIFT FARTHER TO THE
NORTH ON FRIDAY. CONSIDERABLE CLOUD COVER WILL PERSIST ACROSS THE
NORTH BAY WHERE MVFR CIGS WILL DEVELOP ON THURSDAY EVENING AND
THEN LOWERING TO IFR CONDITIONS OVERNIGHT. LOW CLOUDS ARE ALSO
FORECAST TO MOVE INTO SF BAY AND INLAND FROM MONTEREY BAY BY LATE
EVENING. CLEARING EXPECTED IN MOST AREAS BY 18Z FRIDAY. WINDS
WILL BE LIGHT WESTERLY THIS EVENING...TURNING LIGHT SOUTHERLY BY
LATE TONIGHT...THEN VEERING TO THE SOUTHWEST AND INCREASING
SOMEWHAT ON FRIDAY.

VICINITY OF KSFO...VFR CONDITIONS EXPECTED THROUGH THE EVENING
RUSH WITH MVFR CIGS LIKELY BY 07-08Z...CONTINUING UNTIL ABOUT 18Z
FRIDAY. CONFIDENCE MODERATE. WINDS LIGHT WESTERLY THIS
EVENING...TURNING LIGHT SOUTHERLY OVERNIGHT AND THEN TO THE
SOUTHWEST ON FRIDAY AFTERNOON.

KSFO BRIDGE APPROACH...SIMILAR TO KSFO.

MONTEREY BAY AREA TERMINALS...IFR CONDITIONS THROUGH EARLY
EVENING. MVFR CIGS LIKELY BY 06Z...LOWERING TO IFR BY 12Z.
CLEARING EXPECTED AROUND 18Z FRIDAY. LIGHT WINDS.

&&

.MARINE...AS OF 02:04 PM PDT THURSDAY...A WEAK RIDGE OF HIGH
PRESSURE CONTINUES OVER SOUTHERN CALIFORNIA COAST WHILE LOW
PRESSURE WILL STRENGTHEN TO OUR WEST OVER THE NEXT FEW DAYS. THIS
IS BRINGING LIGHT WINDS TO THE AREA TODAY WHICH WILL BECOME
SOUTHERLY AND INCREASE FRIDAY AND SATURDAY AS THE LOW PRESSURE
SYSTEM STRENGTHENS OFF THE OREGON COAST. HIGH PRESSURE WILL BUILD
OFF THE CALIFORNIA COAST SUNDAY AND MONDAY AFTER THE LOW MOVES
INLAND.

&&

.MTR WATCHES/WARNINGS/ADVISORIES...
     .TNGT...NONE.

&&

$$

PUBLIC FORECAST: RGASS
AVIATION: DYKEMA
MARINE: JOHNSON

VISIT US AT WEATHER.GOV/SANFRANCISCO

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000
FXUS66 KMTR 232107
AFDMTR

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SAN FRANCISCO BAY AREA
207 PM PDT THU OCT 23 2014

.SYNOPSIS...A STALLED OUT FRONTAL BOUNDARY JUST TO THE NORTH
SHOULD KEEP MOST PRECIPITATION OUT OF THE REGION THROUGH FRIDAY.
RAIN CHANCES INCREASE REGION-WIDE FRIDAY NIGHT THROUGH SATURDAY
MORNING AS A STRONGER SYSTEM PUSHES A COLD FRONT INTO CENTRAL
CALIFORNIA. CHANCES FOR PRECIPITATION WILL DIMINISH SUNDAY INTO
MONDAY WITH NEAR SEASONAL TEMPERATURES.

&&

.DISCUSSION...AS OF 02:04 PM PDT THURSDAY...A WEAK FRONTAL
BOUNDARY STALLED JUST NORTH OF SONOMA AND NAPA COUNTIES SHOULD
KEEP MOST PRECIPITATION NORTH OF THE REGION TONIGHT.
HOWEVER...WITH THE POSSIBILITY OF THIS DEEPER MOISTURE AND FRONTAL
BOUNDARY SAGGING SOUTHWARD...HAVE KEPT CHANCES FOR PRECIPITATION
OVER PORTIONS OF THE NORTH BAY. OVERALL...ANY RAINFALL AMOUNTS
SHOULD REMAIN LIGHT ACROSS THE NORTH BAY REGION OVERNIGHT. THIS
BOUNDARY IS FORECAST TO LIFT NORTHWARD ON FRIDAY AND WILL LIKELY
KEEP DRY WEATHER CONDITIONS AND MILD TEMPERATURES OVER THE ENTIRE
REGION. THE MAIN FORECAST CHALLENGE FOR FRIDAY MORNING WILL BE THE
DEVELOPMENT OF COASTAL STRATUS. HAVE INCREASED CLOUD COVER OVER
THE COASTAL WATERS AND ALONG THE COAST OVERNIGHT TONIGHT THROUGH
FRIDAY MORNING AS BOUNDARY LAYER MOISTURE IS EXPECTED TO RAPIDLY
RETURN. ALREADY SEEING SOME STRATUS OFFSHORE BELOW THE HIGH CLOUDS
ON VISIBLE SATELLITE.

THE NEXT MID/UPPER LEVEL TROUGH IS FORECAST DO DEEPEN OVER THE
EASTERN PACIFIC AND APPROACH THE PACIFIC NORTHWEST LATE FRIDAY
NIGHT. WITH THIS...RAIN CHANCES WILL INCREASE OVER THE COASTAL
WATERS AND NORTH BAY AS MOISTURE ADVECTS ACROSS THE REGION AHEAD OF
THE FRONTAL BOUNDARY. WITH INCREASED MID/UPPER LEVEL SUPPORT AS THE
FRONT MOVES INTO THE REGION...ISOLATED THUNDERSTORMS WILL BE
POSSIBLE SATURDAY MORNING/AFTERNOON ACROSS OUR NORTHERN COASTAL
WATERS INLAND INTO THE NORTH BAY. FURTHER SOUTH...SHOWERS WILL
INCREASE ALONG THE BOUNDARY AND BRING RAIN TO MUCH OF THE SAN
FRANCISCO BAY AREA DOWN ALONG THEN CENTRAL COAST. AT THIS TIME...THE
GREATEST RAINFALL AMOUNTS APPEAR TO OCCUR OVER THE NORTH BAY AND
ALONG THE WEST/SOUTHWEST FACING SLOPES DOWN THE COASTLINE. CANNOT
RULE OUT SOME LOCATIONS PICKING UP ONE-QUARTER TO NEARLY ONE INCH OF
RAINFALL FRIDAY NIGHT THROUGH SATURDAY. WITH INCREASED CLOUDS AND
PRECIPITATION CHANCES...TEMPERATURES WILL BE NOTICEABLY COOLER ON
SATURDAY.

WHILE LINGERING SHOWERS WILL BE POSSIBLE SATURDAY EVENING IN WAKE OF
THE FRONTAL PASSAGE...MOST LOCATIONS WILL BEGIN TO DRY OUT SATURDAY
NIGHT INTO SUNDAY. WITH A COOLER AND DRIER AIR MASS ALOFT...SURFACE
TEMPERATURES WILL REMAIN ON THE COOL SIDE OF NORMAL SUNDAY AND
MONDAY. EARLY NEXT WEEK...THE FORECAST MODELS DIFFER ON THE UPPER
LEVEL PATTERN ACROSS THE STATE. CANNOT RULE OUT LIGHT PRECIPITATION
RETURNING TO THE NORTH BAY TUESDAY AS ANOTHER PLUME OF MOISTURE
SPREADS INTO NORTHERN CALIFORNIA. HOWEVER...WILL KEEP MOST AREAS DRY
THROUGH EARLY NEXT WEEK UNTIL THE FORECAST MODELS DIVERGE ON A MORE
CONCISE SOLUTION.

&&

.AVIATION...AS OF 10:50 AM PDT THURSDAY...LARGE AREA OF MID AND
HIGH CLOUDS STREAMING ACROSS THE NORTHERN HALF OF THE BAY AREA AS
A LOW MOVES INTO THE PACIFIC NORTHWEST. CURRENT EXPECTATIONS ARE
THAT THE RAIN WILL NOT MAKE IT TO ANY TERMINALS SO HAVE NOT
MENTIONED ANY RAIN IN THE TAFS. LOWER CLOUDS WILL DEVELOP LATE
TONIGHT ESPECIALLY TOWARDS THE 12Z FRI TIME FRAME. THESE LOWER
CIGS WILL PERSIST THROUGH MOST OF THE REMAINING TAF PERIOD.

VICINITY OF KSFO...VFR CONDITIONS WITH JUST MID AND HIGH CLOUDS.
INCREASING LOW LEVEL MOISTURE WILL PRODUCE REDUCED CEILINGS AFTER
07Z. THIS WILL PERSIST THROUGH THE END OF THE TAF PERIOD. LOW-
MODERATE CONFIDENCE.

KSFO BRIDGE APPROACH...SIMILAR TO KSFO.

MONTEREY BAY AREA TERMINALS...VFR CONDITIONS EXPECTED ALL DAY WITH
JUST SOME MID LEVEL CLOUDS MOVING IN. MVFR-IFR CONDITIONS DEVELOP
AFTER 06Z AND WORSEN AROUND 13Z FRI AND PERSIST THROUGH END OF TAF
PERIOD.

&&

.MARINE...AS OF 02:04 PM PDT THURSDAY...A WEAK RIDGE OF HIGH
PRESSURE CONTINUES OVER SOUTHERN CALIFORNIA COAST WHILE LOW
PRESSURE WILL STRENGTHEN TO OUR WEST OVER THE NEXT FEW DAYS. THIS
IS BRINGING LIGHT WINDS TO THE AREA TODAY WHICH WILL BECOME
SOUTHERLY AND INCREASE FRIDAY AND SATURDAY AS THE LOW PRESSURE
SYSTEM STRENGTHENS OFF THE OREGON COAST. HIGH PRESSURE WILL BUILD
OFF THE CALIFORNIA COAST SUNDAY AND MONDAY AFTER THE LOW MOVES
INLAND.

&&

.MTR WATCHES/WARNINGS/ADVISORIES...
     .TNGT...NONE.

&&

$$

PUBLIC FORECAST: RGASS
AVIATION/MARINE: JOHNSON

VISIT US AT WEATHER.GOV/SANFRANCISCO

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000
FXUS66 KMTR 231801
AFDMTR

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SAN FRANCISCO BAY AREA
1101 AM PDT THU OCT 23 2014

.SYNOPSIS...THE WEAK TAIL END OF AN APPROACHING PACIFIC WEATHER
SYSTEM WILL LIKELY BRING SOME LIGHT RAINFALL TO THE NORTHERNMOST
PORTIONS OF OUR DISTRICT TODAY...OTHERWISE MILD CONDITIONS ARE
EXPECTED. FRIDAY LOOKS TO BE MOSTLY SUNNY AND MILD...BUT THEN A
SOMEWHAT WETTER SYSTEM WILL MOVE IN ON SATURDAY AND SPREAD RAIN
CHANCES ACROSS MUCH OF OUR AREA. AFTER A FEW RESIDUAL SHOWERS ON
SUNDAY...DRY CONDITIONS AND SEASONAL TEMPERATURES ARE PROJECTED
INTO THE FIRST PART OF NEXT WEEK.

&&

.DISCUSSION...AS OF 09:21 AM PDT THURSDAY...A DEEP MOISTURE PLUME
CONTINUES TO IMPACT NORTHERN CALIFORNIA THIS MORNING WITH JUST
ABOUT ALL OF THE PRECIPITATION OCCURRING NORTH OF THE REGION.
LOOKING AT THE LATEST HRRR AND OTHER MODEL OUTPUT...HAVE BACKED
OFF ON PRECIPITATION ACROSS THE NORTH BAY AND KEPT ONLY A CHANCE TO
SLIGHT CHANCE OF RAIN NORTH OF THE GOLDEN GATE. FURTHER SOUTH...WE
CAN EXPECT WARMER TEMPERATURES THIS AFTERNOON WITH PLENTY OF HIGH
CLOUDS STREAMING OVER OUR NORTHERN AREAS. OTHERWISE...THE FORECAST
REMAINS ON TRACK FOR THE REMAINDER OF THE DAY.

&&

.PREV DISCUSSION...AS OF 3:09 AM PDT THURSDAY...MAINLY HIGH
CLOUDS ARE STREAMING ACROSS THE NORTHERN TWO THIRDS OF THE CWA AT
THIS TIME...AS THE SOUTHERN EDGE OF A SYSTEM NOW AFFECTING THE
PACIFIC NORTHWEST MOVES THROUGH. LATEST RADAR IMAGERY SHOWS ECHOES
ARE MAINLY REMAINING NORTH OF SONOMA AND NAPA COUNTIES AT THIS
TIME AND NO APPRECIABLE RAINFALL HAS YET BEEN PICKED UP BY
AUTOMATED GAUGES. EXPECT THE RAIN LINE TO SAG INTO THE NORTH BAY
TODAY BUT NOT MUCH RAINFALL IS EXPECTED WITH THIS WEAK SYSTEM.

AFTER THIS WEAK SYSTEM MOVES TO THE EAST...A STRONGER SYSTEM IS
PROGGED TO AFFECT MORE OF THE DISTRICT LATE FRIDAY NIGHT AND
SATURDAY WITH RAIN CHANCES EXTENDING AS FAR SOUTH AS WELL INTO
MONTEREY COUNTY BY MIDDAY SATURDAY. RAINFALL AMOUNTS OF UP TO ONE
INCH ARE POSSIBLE ACROSS PORTIONS OF THE NORTH BAY...WITH MUCH
LESS FROM THE BAY AREA SOUTH. AS THE UPPER LOW CENTER MOVES
ACROSS...ENOUGH INSTABILITY AND COLDER AIR ALOFT FOR A SLIGHT
CHANCE OF THUNDERSTORMS ACROSS PORTIONS OF THE NORTH BAY SATURDAY
AFTERNOON. SHOWERS TO TAPER OFF ON SUNDAY THEN DRIER CONDITIONS
ARE EXPECTED INTO THE EARLY PART OF NEXT WEEK. THERE CONTINUES TO
BE LARGE DIFFERENCES AMONGST THE MEDIUM RANGE MODELS REGARDING
RAIN CHANCES NEXT WEEK. THUS HAVE LEFT SOME SLIGHT CHANCE POPS
ACROSS THE NORTH FOR TUESDAY AND WEDNESDAY BUT DRY ELSEWHERE. LOW
CONFIDENCE.

&&

.AVIATION...AS OF 10:50 AM PDT THURSDAY...LARGE AREA OF MID AND
HIGH CLOUDS STREAMING ACROSS THE NORTHERN HALF OF THE BAY AREA AS
A LOW MOVES INTO THE PACIFIC NORTHWEST. CURRENT EXPECTATIONS ARE
THAT THE RAIN WILL NOT MAKE IT TO ANY TERMINALS SO HAVE NOT
MENTIONED ANY RAIN IN THE TAFS. LOWER CLOUDS WILL DEVELOP LATE
TONIGHT ESPECIALLY TOWARDS THE 12Z FRI TIME FRAME. THESE LOWER
CIGS WILL PERSIST THROUGH MOST OF THE REMAINING TAF PERIOD.

VICINITY OF KSFO...VFR CONDITIONS WITH JUST MID AND HIGH CLOUDS.
INCREASING LOW LEVEL MOISTURE WILL PRODUCE REDUCED CEILINGS AFTER
07Z. THIS WILL PERSIST THROUGH THE END OF THE TAF PERIOD. LOW-
MODERATE CONFIDENCE.

KSFO BRIDGE APPROACH...SIMILAR TO KSFO.

MONTEREY BAY AREA TERMINALS...VFR CONDITIONS EXPECTED ALL DAY WITH
JUST SOME MID LEVEL CLOUDS MOVING IN. MVFR-IFR CONDITIONS DEVELOP
AFTER 06Z AND WORSEN AROUND 13Z FRI AND PERIST THROUGH END OF TAF
PERIOD.

&&

.MARINE...AS OF 10:51 AM PDT THURSDAY...HIGH PRESSURE CONTINUES
OFF THE SOUTHERN CALIFORNIA COAST WHILE LOW PRESSURE IS OFF
VANCOUVER ISLAND. THIS IS BRINGING LIGHT WINDS TO THE AREA WITH
STRONGER WINDS IN THE SOUTHERN WATERS. SOUTHERLY WINDS WILL
INCREASE FRIDAY NIGHT AND SATURDAY AS A LOW PRESSURE SYSTEM
DEEPENS OFF THE OREGON COAST. HIGH PRESSURE WILL BUILD OFF THE
CALIFORNIA COAST SUNDAY AND MONDAY AFTER THE LOW MOVES INLAND.

&&

.MTR WATCHES/WARNINGS/ADVISORIES...
     .TDAY...NONE.

$$

PUBLIC FORECAST: RGASS
AVIATION/MARINE: JOHNSON

VISIT US AT WEATHER.GOV/SANFRANCISCO

FOLLOW US ON FACEBOOK, TWITTER, AND YOUTUBE AT:
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000
FXUS66 KMTR 231801
AFDMTR

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SAN FRANCISCO BAY AREA
1101 AM PDT THU OCT 23 2014

.SYNOPSIS...THE WEAK TAIL END OF AN APPROACHING PACIFIC WEATHER
SYSTEM WILL LIKELY BRING SOME LIGHT RAINFALL TO THE NORTHERNMOST
PORTIONS OF OUR DISTRICT TODAY...OTHERWISE MILD CONDITIONS ARE
EXPECTED. FRIDAY LOOKS TO BE MOSTLY SUNNY AND MILD...BUT THEN A
SOMEWHAT WETTER SYSTEM WILL MOVE IN ON SATURDAY AND SPREAD RAIN
CHANCES ACROSS MUCH OF OUR AREA. AFTER A FEW RESIDUAL SHOWERS ON
SUNDAY...DRY CONDITIONS AND SEASONAL TEMPERATURES ARE PROJECTED
INTO THE FIRST PART OF NEXT WEEK.

&&

.DISCUSSION...AS OF 09:21 AM PDT THURSDAY...A DEEP MOISTURE PLUME
CONTINUES TO IMPACT NORTHERN CALIFORNIA THIS MORNING WITH JUST
ABOUT ALL OF THE PRECIPITATION OCCURRING NORTH OF THE REGION.
LOOKING AT THE LATEST HRRR AND OTHER MODEL OUTPUT...HAVE BACKED
OFF ON PRECIPITATION ACROSS THE NORTH BAY AND KEPT ONLY A CHANCE TO
SLIGHT CHANCE OF RAIN NORTH OF THE GOLDEN GATE. FURTHER SOUTH...WE
CAN EXPECT WARMER TEMPERATURES THIS AFTERNOON WITH PLENTY OF HIGH
CLOUDS STREAMING OVER OUR NORTHERN AREAS. OTHERWISE...THE FORECAST
REMAINS ON TRACK FOR THE REMAINDER OF THE DAY.

&&

.PREV DISCUSSION...AS OF 3:09 AM PDT THURSDAY...MAINLY HIGH
CLOUDS ARE STREAMING ACROSS THE NORTHERN TWO THIRDS OF THE CWA AT
THIS TIME...AS THE SOUTHERN EDGE OF A SYSTEM NOW AFFECTING THE
PACIFIC NORTHWEST MOVES THROUGH. LATEST RADAR IMAGERY SHOWS ECHOES
ARE MAINLY REMAINING NORTH OF SONOMA AND NAPA COUNTIES AT THIS
TIME AND NO APPRECIABLE RAINFALL HAS YET BEEN PICKED UP BY
AUTOMATED GAUGES. EXPECT THE RAIN LINE TO SAG INTO THE NORTH BAY
TODAY BUT NOT MUCH RAINFALL IS EXPECTED WITH THIS WEAK SYSTEM.

AFTER THIS WEAK SYSTEM MOVES TO THE EAST...A STRONGER SYSTEM IS
PROGGED TO AFFECT MORE OF THE DISTRICT LATE FRIDAY NIGHT AND
SATURDAY WITH RAIN CHANCES EXTENDING AS FAR SOUTH AS WELL INTO
MONTEREY COUNTY BY MIDDAY SATURDAY. RAINFALL AMOUNTS OF UP TO ONE
INCH ARE POSSIBLE ACROSS PORTIONS OF THE NORTH BAY...WITH MUCH
LESS FROM THE BAY AREA SOUTH. AS THE UPPER LOW CENTER MOVES
ACROSS...ENOUGH INSTABILITY AND COLDER AIR ALOFT FOR A SLIGHT
CHANCE OF THUNDERSTORMS ACROSS PORTIONS OF THE NORTH BAY SATURDAY
AFTERNOON. SHOWERS TO TAPER OFF ON SUNDAY THEN DRIER CONDITIONS
ARE EXPECTED INTO THE EARLY PART OF NEXT WEEK. THERE CONTINUES TO
BE LARGE DIFFERENCES AMONGST THE MEDIUM RANGE MODELS REGARDING
RAIN CHANCES NEXT WEEK. THUS HAVE LEFT SOME SLIGHT CHANCE POPS
ACROSS THE NORTH FOR TUESDAY AND WEDNESDAY BUT DRY ELSEWHERE. LOW
CONFIDENCE.

&&

.AVIATION...AS OF 10:50 AM PDT THURSDAY...LARGE AREA OF MID AND
HIGH CLOUDS STREAMING ACROSS THE NORTHERN HALF OF THE BAY AREA AS
A LOW MOVES INTO THE PACIFIC NORTHWEST. CURRENT EXPECTATIONS ARE
THAT THE RAIN WILL NOT MAKE IT TO ANY TERMINALS SO HAVE NOT
MENTIONED ANY RAIN IN THE TAFS. LOWER CLOUDS WILL DEVELOP LATE
TONIGHT ESPECIALLY TOWARDS THE 12Z FRI TIME FRAME. THESE LOWER
CIGS WILL PERSIST THROUGH MOST OF THE REMAINING TAF PERIOD.

VICINITY OF KSFO...VFR CONDITIONS WITH JUST MID AND HIGH CLOUDS.
INCREASING LOW LEVEL MOISTURE WILL PRODUCE REDUCED CEILINGS AFTER
07Z. THIS WILL PERSIST THROUGH THE END OF THE TAF PERIOD. LOW-
MODERATE CONFIDENCE.

KSFO BRIDGE APPROACH...SIMILAR TO KSFO.

MONTEREY BAY AREA TERMINALS...VFR CONDITIONS EXPECTED ALL DAY WITH
JUST SOME MID LEVEL CLOUDS MOVING IN. MVFR-IFR CONDITIONS DEVELOP
AFTER 06Z AND WORSEN AROUND 13Z FRI AND PERIST THROUGH END OF TAF
PERIOD.

&&

.MARINE...AS OF 10:51 AM PDT THURSDAY...HIGH PRESSURE CONTINUES
OFF THE SOUTHERN CALIFORNIA COAST WHILE LOW PRESSURE IS OFF
VANCOUVER ISLAND. THIS IS BRINGING LIGHT WINDS TO THE AREA WITH
STRONGER WINDS IN THE SOUTHERN WATERS. SOUTHERLY WINDS WILL
INCREASE FRIDAY NIGHT AND SATURDAY AS A LOW PRESSURE SYSTEM
DEEPENS OFF THE OREGON COAST. HIGH PRESSURE WILL BUILD OFF THE
CALIFORNIA COAST SUNDAY AND MONDAY AFTER THE LOW MOVES INLAND.

&&

.MTR WATCHES/WARNINGS/ADVISORIES...
     .TDAY...NONE.

$$

PUBLIC FORECAST: RGASS
AVIATION/MARINE: JOHNSON

VISIT US AT WEATHER.GOV/SANFRANCISCO

FOLLOW US ON FACEBOOK, TWITTER, AND YOUTUBE AT:
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000
FXUS66 KMTR 231631
AFDMTR

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SAN FRANCISCO BAY AREA
931 AM PDT THU OCT 23 2014

.SYNOPSIS...THE WEAK TAIL END OF AN APPROACHING PACIFIC WEATHER
SYSTEM WILL LIKELY BRING SOME LIGHT RAINFALL TO THE NORTHERNMOST
PORTIONS OF OUR DISTRICT TODAY...OTHERWISE MILD CONDITIONS ARE
EXPECTED. FRIDAY LOOKS TO BE MOSTLY SUNNY AND MILD...BUT THEN A
SOMEWHAT WETTER SYSTEM WILL MOVE IN ON SATURDAY AND SPREAD RAIN
CHANCES ACROSS MUCH OF OUR AREA. AFTER A FEW RESIDUAL SHOWERS ON
SUNDAY...DRY CONDITIONS AND SEASONAL TEMPERATURES ARE PROJECTED
INTO THE FIRST PART OF NEXT WEEK.

&&

.DISCUSSION...AS OF 09:21 AM PDT THURSDAY...A DEEP MOISTURE PLUME
CONTINUES TO IMPACT NORTHERN CALIFORNIA THIS MORNING WITH JUST
ABOUT ALL OF THE PRECIPITATION OCCURRING NORTH OF THE REGION.
LOOKING AT THE LATEST HRRR AND OTHER MODEL OUTPUT...HAVE BACKED
OFF ON PRECIPITATION ACROSS THE NORTH BAY AND KEPT ONLY A CHANCE TO
SLIGHT CHANCE OF RAIN NORTH OF THE GOLDEN GATE. FURTHER SOUTH...WE
CAN EXPECT WARMER TEMPERATURES THIS AFTERNOON WITH PLENTY OF HIGH
CLOUDS STREAMING OVER OUR NORTHERN AREAS. OTHERWISE...THE FORECAST
REMAINS ON TRACK FOR THE REMAINDER OF THE DAY.

&&

.PREV DISCUSSION...AS OF 3:09 AM PDT THURSDAY...MAINLY HIGH
CLOUDS ARE STREAMING ACROSS THE NORTHERN TWO THIRDS OF THE CWA AT
THIS TIME...AS THE SOUTHERN EDGE OF A SYSTEM NOW AFFECTING THE
PACIFIC NORTHWEST MOVES THROUGH. LATEST RADAR IMAGERY SHOWS ECHOES
ARE MAINLY REMAINING NORTH OF SONOMA AND NAPA COUNTIES AT THIS
TIME AND NO APPRECIABLE RAINFALL HAS YET BEEN PICKED UP BY
AUTOMATED GAUGES. EXPECT THE RAIN LINE TO SAG INTO THE NORTH BAY
TODAY BUT NOT MUCH RAINFALL IS EXPECTED WITH THIS WEAK SYSTEM.

AFTER THIS WEAK SYSTEM MOVES TO THE EAST...A STRONGER SYSTEM IS
PROGGED TO AFFECT MORE OF THE DISTRICT LATE FRIDAY NIGHT AND
SATURDAY WITH RAIN CHANCES EXTENDING AS FAR SOUTH AS WELL INTO
MONTEREY COUNTY BY MIDDAY SATURDAY. RAINFALL AMOUNTS OF UP TO ONE
INCH ARE POSSIBLE ACROSS PORTIONS OF THE NORTH BAY...WITH MUCH
LESS FROM THE BAY AREA SOUTH. AS THE UPPER LOW CENTER MOVES
ACROSS...ENOUGH INSTABILITY AND COLDER AIR ALOFT FOR A SLIGHT
CHANCE OF THUNDERSTORMS ACROSS PORTIONS OF THE NORTH BAY SATURDAY
AFTERNOON. SHOWERS TO TAPER OFF ON SUNDAY THEN DRIER CONDITIONS
ARE EXPECTED INTO THE EARLY PART OF NEXT WEEK. THERE CONTINUES TO
BE LARGE DIFFERENCES AMONGST THE MEDIUM RANGE MODELS REGARDING
RAIN CHANCES NEXT WEEK. THUS HAVE LEFT SOME SLIGHT CHANCE POPS
ACROSS THE NORTH FOR TUESDAY AND WEDNESDAY BUT DRY ELSEWHERE. LOW
CONFIDENCE.

&&

.AVIATION...AS OF 4:30 AM PDT THURSDAY...SATELLITE IMAGE SUGGESTS
AREAS OF STRATUS ALONG THE COASTAL HILLS OF THE SFO EXTENDING INTO
SFO AND OAK AS WELL AS THE NORTH BAY VALLEYS. THE HIGH CLOUDS WILL
ALLOW FOR SLOWER CLEARING OF THE STRATUS AND THEREFORE BURN-OFF
TIME IS NOT UNTIL 18-19Z DESPITE THE PATCHY NATURE OF THE STRATUS.

VICINITY OF KSFO...MVFR CONDITIONS THROUGH 18Z.

KSFO BRIDGE APPROACH...SIMILAR TO KSFO.

MONTEREY BAY AREA TERMINALS...NO STRATUS REPORTED IN THE MRY BAY
AREA THIS MORNING. BELIEVE THERE MAY BE AN OFFSHORE DRAINAGE WIND
THAT IS KEEPING THE COASTAL STRATUS OUT OF THE BAY. FT ORD
PROFILER SUPPORTS THIS. THEREFORE FORECAST HAS BEEN CHANGED TO VFR
CONDITIONS FOR THE DAY.

&&

.MARINE...AS OF 3:05 AM PDT THURSDAY...HIGH PRESSURE CONTINUES
OFF THE SOUTHERN CALIFORNIA COAST WHILE LOW PRESSURE IS OFF
VANCOUVER ISLAND. THIS IS BRINGING LIGHT WINDS TO THE AREA WITH
STRONGER WINDS IN THE SOUTHERN WATERS. SOUTHERLY WINDS WILL
INCREASE FRIDAY NIGHT AND SATURDAY AS A LOW PRESSURE SYSTEM
DEEPENS OFF THE OREGON COAST. HIGH PRESSURE WILL BUILD OFF THE
CALIFORNIA COAST SUNDAY AND MONDAY AFTER THE LOW MOVES INLAND.

&&

.MTR WATCHES/WARNINGS/ADVISORIES...
     .TDAY...NONE.

$$

PUBLIC FORECAST: RGASS
AVIATION/MARINE: W PI

VISIT US AT WEATHER.GOV/SANFRANCISCO

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000
FXUS66 KMTR 231138
AFDMTR

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SAN FRANCISCO BAY AREA
438 AM PDT THU OCT 23 2014

.SYNOPSIS...THE WEAK TAIL END OF AN APPROACHING PACIFIC WEATHER
SYSTEM WILL LIKELY BRING SOME LIGHT RAINFALL TO THE NORTHERNMOST
PORTIONS OF OUR DISTRICT TODAY...OTHERWISE MILD CONDITIONS ARE
EXPECTED. FRIDAY LOOKS TO BE MOSTLY SUNNY AND MILD...BUT THEN A
SOMEWHAT WETTER SYSTEM WILL MOVE IN ON SATURDAY AND SPREAD RAIN
CHANCES ACROSS MUCH OF OUR AREA. AFTER A FEW RESIDUAL SHOWERS ON
SUNDAY...DRY CONDITIONS AND SEASONAL TEMPERATURES ARE PROJECTED
INTO THE FIRST PART OF NEXT WEEK.

&&

.DISCUSSION...AS OF 3:09 AM PDT THURSDAY...MAINLY HIGH CLOUDS ARE
STREAMING ACROSS THE NORTHERN TWO THIRDS OF THE CWA AT THIS
TIME...AS THE SOUTHERN EDGE OF A SYSTEM NOW AFFECTING THE PACIFIC
NORTHWEST MOVES THROUGH. LATEST RADAR IMAGERY SHOWS ECHOES ARE MAINLY
REMAINING NORTH OF SONOMA AND NAPA COUNTIES AT THIS TIME AND NO
APPRECIABLE RAINFALL HAS YET BEEN PICKED UP BY AUTOMATED GAUGES.
EXPECT THE RAIN LINE TO SAG INTO THE NORTH BAY TODAY BUT NOT MUCH
RAINFALL IS EXPECTED WITH THIS WEAK SYSTEM.

AFTER THIS WEAK SYSTEM MOVES TO THE EAST...A STRONGER SYSTEM IS
PROGGED TO AFFECT MORE OF THE DISTRICT LATE FRIDAY NIGHT AND
SATURDAY WITH RAIN CHANCES EXTENDING AS FAR SOUTH AS WELL INTO
MONTEREY COUNTY BY MIDDAY SATURDAY. RAINFALL AMOUNTS OF UP TO ONE
INCH ARE POSSIBLE ACROSS PORTIONS OF THE NORTH BAY...WITH MUCH
LESS FROM THE BAY AREA SOUTH. AS THE UPPER LOW CENTER MOVES
ACROSS...ENOUGH INSTABILITY AND COLDER AIR ALOFT FOR A SLIGHT
CHANCE OF THUNDERSTORMS ACROSS PORTIONS OF THE NORTH BAY SATURDAY
AFTERNOON. SHOWERS TO TAPER OFF ON SUNDAY THEN DRIER CONDITIONS
ARE EXPECTED INTO THE EARLY PART OF NEXT WEEK. THERE CONTINUES TO
BE LARGE DIFFERENCES AMONGST THE MEDIUM RANGE MODELS REGARDING
RAIN CHANCES NEXT WEEK. THUS HAVE LEFT SOME SLIGHT CHANCE POPS
ACROSS THE NORTH FOR TUESDAY AND WEDNESDAY BUT DRY ELSEWHERE. LOW
CONFIDENCE.

&&

.AVIATION...AS OF 4:30 AM PDT THURSDAY...SATELLITE IMAGE SUGGESTS
AREAS OF STRATUS ALONG THE COASTAL HILLS OF THE SFO EXTENDING INTO
SFO AND OAK AS WELL AS THE NORTH BAY VALLEYS. THE HIGH CLOUDS WILL
ALLOW FOR SLOWER CLEARING OF THE STRATUS AND THEREFORE BURNOFF
TIME IS NOT UNTIL 18-19Z DESPITE THE PATCHY NATURE OF THE STRATUS.

VICINITY OF KSFO...MVFR CONDITIONS THROUGH 18Z.

KSFO BRIDGE APPROACH...SIMILAR TO KSFO.

MONTEREY BAY AREA TERMINALS...NO STRATUS REPORTED IN THE MRY BAY
AREA THIS MORNING. BELIEVE THERE MAY BE AN OFFSHORE DRAINAGE WIND
THAT IS KEEPING THE COASTAL STRATUS OUT OF THE BAY. FT ORD
PROFILER SUPPORTS THIS. THEREFORE FORECAST HAS BEEN CHANGED TO VFR
CONDITIONS FOR THE DAY.

&&

.MARINE...AS OF 3:05 AM PDT THURSDAY...HIGH PRESSURE CONTINUES
OFF THE SOUTHERN CALIFORNIA COAST WHILE LOW PRESSURE IS OFF
VANCOUVER ISLAND. THIS IS BRINGING LIGHT WINDS TO THE AREA WITH
STRONGER WINDS IN THE SOUTHERN WATERS. SOUTHERLY WINDS WILL
INCREASE FRIDAY NIGHT AND SATURDAY AS A LOW PRESSURE SYSTEM
DEEPENS OFF THE OREGON COAST. HIGH PRESSURE WILL BUILD OFF THE
CALIFORNIA COAST SUNDAY AND MONDAY AFTER THE LOW MOVES INLAND.

&&

.MTR WATCHES/WARNINGS/ADVISORIES...
     .TDAY...NONE.

$$

PUBLIC FORECAST: SIMS
AVIATION/MARINE: W PI

VISIT US AT WEATHER.GOV/SANFRANCISCO

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000
FXUS66 KMTR 231009
AFDMTR

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SAN FRANCISCO BAY AREA
309 AM PDT THU OCT 23 2014

.SYNOPSIS...THE WEAK TAIL END OF AN APPROACHING PACIFIC WEATHER
SYSTEM WILL LIKELY BRING SOME LIGHT RAINFALL TO THE NORTHERNMOST
PORTIONS OF OUR DISTRICT TODAY...OTHERWISE MILD CONDITIONS ARE
EXPECTED. FRIDAY LOOKS TO BE MOSTLY SUNNY AND MILD...BUT THEN A
SOMEWHAT WETTER SYSTEM WILL MOVE IN ON SATURDAY AND SPREAD RAIN
CHANCES ACROSS MUCH OF OUR AREA. AFTER A FEW RESIDUAL SHOWERS ON
SUNDAY...DRY CONDITIONS AND SEASONAL TEMPERATURES ARE PROJECTED
INTO THE FIRST PART OF NEXT WEEK.

&&

.DISCUSSION...AS OF 3:09 AM PDT THURSDAY...MAINLY HIGH CLOUDS ARE
STREAMING ACROSS THE NORTHERN TWO THIRDS OF THE CWA AT THIS
TIME...AS THE SOUTHERN EDGE OF A SYSTEM NOW AFFECTING THE PACIFIC
NORTHWEST MOVES THROUGH. LATEST RADAR IMAGERY SHOWS ECHOES ARE MAINLY
REMAINING NORTH OF SONOMA AND NAPA COUNTIES AT THIS TIME AND NO
APPRECIABLE RAINFALL HAS YET BEEN PICKED UP BY AUTOMATED GAUGES.
EXPECT THE RAIN LINE TO SAG INTO THE NORTH BAY TODAY BUT NOT MUCH
RAINFALL IS EXPECTED WITH THIS WEAK SYSTEM.

AFTER THIS WEAK SYSTEM MOVES TO THE EAST...A STRONGER SYSTEM IS
PROGGED TO AFFECT MORE OF THE DISTRICT LATE FRIDAY NIGHT AND
SATURDAY WITH RAIN CHANCES EXTENDING AS FAR SOUTH AS WELL INTO
MONTEREY COUNTY BY MIDDAY SATURDAY. RAINFALL AMOUNTS OF UP TO ONE
INCH ARE POSSIBLE ACROSS PORTIONS OF THE NORTH BAY...WITH MUCH
LESS FROM THE BAY AREA SOUTH. AS THE UPPER LOW CENTER MOVES
ACROSS...ENOUGH INSTABILITY AND COLDER AIR ALOFT FOR A SLIGHT
CHANCE OF THUNDERSTORMS ACROSS PORTIONS OF THE NORTH BAY SATURDAY
AFTERNOON. SHOWERS TO TAPER OFF ON SUNDAY THEN DRIER CONDITIONS
ARE EXPECTED INTO THE EARLY PART OF NEXT WEEK. THERE CONTINUES TO
BE LARGE DIFFERENCES AMONGST THE MEDIUM RANGE MODELS REGARDING
RAIN CHANCES NEXT WEEK. THUS HAVE LEFT SOME SLIGHT CHANCE POPS
ACROSS THE NORTH FOR TUESDAY AND WEDNESDAY BUT DRY ELSEWHERE. LOW
CONFIDENCE.

&&

.AVIATION...AS OF 10:30 PM PDT WEDNESDAY...VFR CONDITIONS WILL
PERSIST THROUGH LATE TONIGHT WITH HIGH CLOUDS CONTINUE TO
STREAMING ACROSS THE REGION. A FRONTAL BOUNDARY IS FORECAST TO
APPROACH THE NORTH BAY TONIGHT AND SHOULD HELP INCREASE THE
AMOUNT OF LOW LEVEL CLOUD COVER...ESPECIALLY OVER THE SAN
FRANCISCO BAY AREA NORTHWARD. LIGHT RAIN OR DRIZZLE WILL BE
POSSIBLE OVER KSTS...YET CONFIDENCE REMAINS LOW AND HAVE LEFT
PRECIPITATION OUT OF THE TAF FOR NOW. LOW CLOUDS THAT DO DEVELOP
OVER THE REGION WILL BE SLOW TO BURN-OFF THURSDAY MORNING.
FURTHER SOUTH...CONFIDENCE IS LOWER ON THE RETURN OF STRATUS OVER
THE TERMINALS AS BOUNDARY LAYER MOISTURE WILL BE SLOWER TO RETURN.

VICINITY OF KSFO...VFR CONDITIONS WILL CONTINUE THROUGH LATE
TONIGHT WITH  LOW CLOUDS EXPECTED TO RETURN AFTER 09Z.
LIGHT WEST WINDS WILL CONTINUE THROUGH TONIGHT. MODERATE
CONFIDENCE.

KSFO BRIDGE APPROACH...SIMILAR TO KSFO.

MONTEREY BAY AREA TERMINALS...VFR CONDITIONS WILL CONTINUE
THROUGH LATE TONIGHT WITH LOW CLOUDS EXPECTED TO RETURN AFTER 09Z.
LIGHT WEST WINDS WILL PERSIST BECOMING LIGHT AND VARIABLE
OVERNIGHT. MODERATE CONFIDENCE.

&&

.MARINE...AS OF 3:05 AM PDT THURSDAY...HIGH PRESSURE CONTINUES
OFF THE SOUTHERN CALIFORNIA COAST WHILE LOW PRESSURE IS OFF
VANCOUVER ISLAND. THIS IS BRINGING LIGHT WINDS TO THE AREA WITH
STRONGER WINDS IN THE SOUTHERN WATERS. SOUTHERLY WINDS WILL
INCREASE FRIDAY NIGHT AND SATURDAY AS A LOW PRESSURE SYSTEM
DEEPENS OFF THE OREGON COAST. HIGH PRESSURE WILL BUILD OFF THE
CALIFORNIA COAST SUNDAY AND MONDAY AFTER THE LOW MOVES INLAND.

&&

.MTR WATCHES/WARNINGS/ADVISORIES...
     .TDAY...SCA...PT PINOS TO PT PIEDRAS BLANCAS 0-10 NM

&&

$$

PUBLIC FORECAST: SIMS
AVIATION: CW
MARINE: W PI

VISIT US AT WEATHER.GOV/SANFRANCISCO

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000
FXUS66 KMTR 231009
AFDMTR

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SAN FRANCISCO BAY AREA
309 AM PDT THU OCT 23 2014

.SYNOPSIS...THE WEAK TAIL END OF AN APPROACHING PACIFIC WEATHER
SYSTEM WILL LIKELY BRING SOME LIGHT RAINFALL TO THE NORTHERNMOST
PORTIONS OF OUR DISTRICT TODAY...OTHERWISE MILD CONDITIONS ARE
EXPECTED. FRIDAY LOOKS TO BE MOSTLY SUNNY AND MILD...BUT THEN A
SOMEWHAT WETTER SYSTEM WILL MOVE IN ON SATURDAY AND SPREAD RAIN
CHANCES ACROSS MUCH OF OUR AREA. AFTER A FEW RESIDUAL SHOWERS ON
SUNDAY...DRY CONDITIONS AND SEASONAL TEMPERATURES ARE PROJECTED
INTO THE FIRST PART OF NEXT WEEK.

&&

.DISCUSSION...AS OF 3:09 AM PDT THURSDAY...MAINLY HIGH CLOUDS ARE
STREAMING ACROSS THE NORTHERN TWO THIRDS OF THE CWA AT THIS
TIME...AS THE SOUTHERN EDGE OF A SYSTEM NOW AFFECTING THE PACIFIC
NORTHWEST MOVES THROUGH. LATEST RADAR IMAGERY SHOWS ECHOES ARE MAINLY
REMAINING NORTH OF SONOMA AND NAPA COUNTIES AT THIS TIME AND NO
APPRECIABLE RAINFALL HAS YET BEEN PICKED UP BY AUTOMATED GAUGES.
EXPECT THE RAIN LINE TO SAG INTO THE NORTH BAY TODAY BUT NOT MUCH
RAINFALL IS EXPECTED WITH THIS WEAK SYSTEM.

AFTER THIS WEAK SYSTEM MOVES TO THE EAST...A STRONGER SYSTEM IS
PROGGED TO AFFECT MORE OF THE DISTRICT LATE FRIDAY NIGHT AND
SATURDAY WITH RAIN CHANCES EXTENDING AS FAR SOUTH AS WELL INTO
MONTEREY COUNTY BY MIDDAY SATURDAY. RAINFALL AMOUNTS OF UP TO ONE
INCH ARE POSSIBLE ACROSS PORTIONS OF THE NORTH BAY...WITH MUCH
LESS FROM THE BAY AREA SOUTH. AS THE UPPER LOW CENTER MOVES
ACROSS...ENOUGH INSTABILITY AND COLDER AIR ALOFT FOR A SLIGHT
CHANCE OF THUNDERSTORMS ACROSS PORTIONS OF THE NORTH BAY SATURDAY
AFTERNOON. SHOWERS TO TAPER OFF ON SUNDAY THEN DRIER CONDITIONS
ARE EXPECTED INTO THE EARLY PART OF NEXT WEEK. THERE CONTINUES TO
BE LARGE DIFFERENCES AMONGST THE MEDIUM RANGE MODELS REGARDING
RAIN CHANCES NEXT WEEK. THUS HAVE LEFT SOME SLIGHT CHANCE POPS
ACROSS THE NORTH FOR TUESDAY AND WEDNESDAY BUT DRY ELSEWHERE. LOW
CONFIDENCE.

&&

.AVIATION...AS OF 10:30 PM PDT WEDNESDAY...VFR CONDITIONS WILL
PERSIST THROUGH LATE TONIGHT WITH HIGH CLOUDS CONTINUE TO
STREAMING ACROSS THE REGION. A FRONTAL BOUNDARY IS FORECAST TO
APPROACH THE NORTH BAY TONIGHT AND SHOULD HELP INCREASE THE
AMOUNT OF LOW LEVEL CLOUD COVER...ESPECIALLY OVER THE SAN
FRANCISCO BAY AREA NORTHWARD. LIGHT RAIN OR DRIZZLE WILL BE
POSSIBLE OVER KSTS...YET CONFIDENCE REMAINS LOW AND HAVE LEFT
PRECIPITATION OUT OF THE TAF FOR NOW. LOW CLOUDS THAT DO DEVELOP
OVER THE REGION WILL BE SLOW TO BURN-OFF THURSDAY MORNING.
FURTHER SOUTH...CONFIDENCE IS LOWER ON THE RETURN OF STRATUS OVER
THE TERMINALS AS BOUNDARY LAYER MOISTURE WILL BE SLOWER TO RETURN.

VICINITY OF KSFO...VFR CONDITIONS WILL CONTINUE THROUGH LATE
TONIGHT WITH  LOW CLOUDS EXPECTED TO RETURN AFTER 09Z.
LIGHT WEST WINDS WILL CONTINUE THROUGH TONIGHT. MODERATE
CONFIDENCE.

KSFO BRIDGE APPROACH...SIMILAR TO KSFO.

MONTEREY BAY AREA TERMINALS...VFR CONDITIONS WILL CONTINUE
THROUGH LATE TONIGHT WITH LOW CLOUDS EXPECTED TO RETURN AFTER 09Z.
LIGHT WEST WINDS WILL PERSIST BECOMING LIGHT AND VARIABLE
OVERNIGHT. MODERATE CONFIDENCE.

&&

.MARINE...AS OF 3:05 AM PDT THURSDAY...HIGH PRESSURE CONTINUES
OFF THE SOUTHERN CALIFORNIA COAST WHILE LOW PRESSURE IS OFF
VANCOUVER ISLAND. THIS IS BRINGING LIGHT WINDS TO THE AREA WITH
STRONGER WINDS IN THE SOUTHERN WATERS. SOUTHERLY WINDS WILL
INCREASE FRIDAY NIGHT AND SATURDAY AS A LOW PRESSURE SYSTEM
DEEPENS OFF THE OREGON COAST. HIGH PRESSURE WILL BUILD OFF THE
CALIFORNIA COAST SUNDAY AND MONDAY AFTER THE LOW MOVES INLAND.

&&

.MTR WATCHES/WARNINGS/ADVISORIES...
     .TDAY...SCA...PT PINOS TO PT PIEDRAS BLANCAS 0-10 NM

&&

$$

PUBLIC FORECAST: SIMS
AVIATION: CW
MARINE: W PI

VISIT US AT WEATHER.GOV/SANFRANCISCO

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000
FXUS66 KMTR 230533
AFDMTR

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SAN FRANCISCO BAY AREA
1033 PM PDT WED OCT 22 2014

.SYNOPSIS...DRY WEATHER CONDITIONS AND PARTLY CLOUDY SKIES ARE
EXPECTED TONIGHT...BUT THEN ON THURSDAY THE WEAK TAIL END OF AN
APPROACHING PACIFIC WEATHER SYSTEM WILL LIKELY BRING SOME LIGHT
RAINFALL TO NORTHERNMOST PORTIONS OF OUR DISTRICT. FRIDAY LOOKS TO
BE MOSTLY SUNNY AND MILD...BUT THEN A SOMEWHAT WETTER SYSTEM
WILL MOVE IN ON SATURDAY AND SPREAD RAIN CHANCES ACROSS MUCH OF
OUR AREA. DRY CONDITIONS AND SEASONAL TEMPERATURES ARE PROJECTED
FOR SUNDAY INTO THE FIRST PART OF NEXT WEEK.

&&

.DISCUSSION...AS OF 8:45 PM PDT WEDNESDAY...TEMPERATURES WERE FOR
THE MOST PART A LITTLE MILDER AND A FEW DEGREES ABOVE NORMAL ACROSS
THE AREA TODAY. THE ONLY EXCEPTION TO THIS WAS OVER THE SOUTH BAY
WHERE AVERAGE TEMPERATURES WERE 1 TO 4 DEGREES FAHRENHEIT BELOW NORMAL
TODAY. HIGHS RANGED FROM THE MID 60S COAST TO THE 70S INLAND.

MID TO HIGH CLOUDS ARE DRIFTING IN OVER THE BAY AREA FROM THE
NORTHWEST. WINDS ARE MOSTLY LIGHT THIS EVENING AND THE RAIN IS
STILL SITUATED WELL TO THE NORTH OF THE BAY AREA. BELIEVE IT OR
NOT SHORTWAVE RIDGING IS STILL IN PLACE THIS EVENING OVER THE
FORECAST AREA WITH 500 MB HEIGHTS OVER THE SOUTH BAY STILL
HOVERING UP NEAR 580 DECAMETERS. 500 MB HEIGHTS WILL BRIEFLY
SUBSIDE A LITTLE AROUND 5 AM THURSDAY MORNING THEN BUMP UPWARDS
AGAIN TO WHERE THEY ARE NOW BY THURSDAY AFTERNOON. THE INCOMING
FRONTAL SYSTEM WILL BE ON THE WEAK SIDE WITH ONLY VERY LIGHT
AMOUNTS OF RAIN EXPECTED...MOSTLY OVER THE NORTHERN SONOMA COUNTY
COAST WHERE UP TO 1/3" TOTAL OF RAIN COULD FALL LATE TONIGHT AND
THURSDAY MORNING. THE NEWEST 00Z NAM MODEL DOES NOT PREDICT ANY
MEASURABLE RAINFALL ANYWHERE ELSE OVER THE AREA TONIGHT OR
THURSDAY. DEWPOINT TEMPERATURES ARE SOLIDLY HIGHER THIS EVENING
AREA-WIDE SO PERIODIC LIGHT DRIZZLE OR LIGHT RAIN IS STILL
POSSIBLE TO THE SOUTH OF SONOMA COUNTY AS THE WEAKENING SHORTWAVE
TROUGH SQUEEZES OUT A LITTLE BIT OF MOISTURE AS IT MOVES OVER THE
AREA. A FEW AREAS MAY SEE A TINY AMOUNT OF MEASURABLE RAINFALL
OVERNIGHT...UP TO A COUPLE HUNDREDTHS POSSIBLY. THE NEAR TERM FITS
PERFECTLY AS A LOW POP LOW QPF FORECAST. NOT PLANNING ON MAKING
ANY ADJUSTMENTS TO FIRST OR SECOND PERIOD POP FORECASTS.

ONCE THE WEAK TROUGH RIPPLES EAST AWAY FROM THE BAY AREA THURSDAY
ANOTHER (MORE AMPLIFIED AND STRENGTHENING) LOW PRESSURE SYSTEM NEAR
39N/134W FRIDAY EVENING MOVES NORTHEAST WITH THE MAIN MID-UPPER
LEVEL LOW PRESSURE AREA REACHING THE PAC NW EARLY SATURDAY
EVENING. THE LOW PRESSURE SYSTEM WILL BE TRAILING A COLD FRONT
EASTWARD WHICH WILL REACH NORTHERNMOST CA BY EARLY SAT MORNING AND
THEN THE BAY AREA DURING THE DAY SATURDAY. AS MUCH AS 1" RAINFALL
IS POSSIBLE OVER SONOMA...ABOUT 1/2"-3/4" NAPA AND MARIN COUNTIES
AND 2/10" OR LESS OVER THE REMAINDER OF THE BAY AREA AND NORTH
CENTRAL COAST. BY THE TIME THE LOW PRESSURE AREA GETS TO CA THE
STRONGEST JET STREAM DYNAMICS WILL HAVE ALREADY POSITIONED ITSELF
FORWARD OF THE TROUGH AXIS SUGGESTING AN ACCELERATION OF THE LOW
AS WELL AS THE HEAVIEST RAINFALL TO THE NORTH OF THE BAY AREA. IF
ONE IS TRAVELLING TO THE PACIFIC NW FOR THE WEEKEND EXPECT HEAVIER
STEADIER RAINS. MID LEVEL TEMPERATURES REACH ABOUT -18C OVER THE
NORTH BAY BY LATE SATURDAY MORNING...NOT AN EXCEPTIONALLY COLD SYSTEM.
THE 00Z NAM PREDICTS A SMALL POCKET...ALBEIT JUST BELOW 35...OF MODIFIED
TOTAL TOTALS MID LEVEL INSTABILITY BY 21Z SATURDAY OVER NORTHERN
SONOMA COUNTY. OFTEN TIMES LOW PRESSURE AREAS SWING OVER THE AREA A
LITTLE FASTER THAN MODELS PREDICT. IT IS QUITE POSSIBLE THAT THE MID
LEVEL INSTABILITY ARRIVES IN THE NORTH BAY AREA AS EARLY AS VERY
EARLY SATURDAY MORNING. THE NAM DEPICTS THE MID LEVEL INSTABILITY
QUICKLY JUMPING OVER TO NAPA COUNTY THEN MOVING EAST TO THE NORTHERN
SACRAMENTO VALLEY SATURDAY. SLIGHT CHANCE OF T-STORMS WAS ADDED IN
EARLIER TODAY AND SEE NO REASON TO MAKE ANY CHANGES EXCEPT THERE`S A
SMALL POSSIBILITY THE T-STORM ACTIVITY MAY ARRIVE A LITTLE EARLIER
THAN PRESENTLY INDICATED.

THERE`S MUCH LESS CONFIDENCE REGARDING NEXT WEEK`S WEATHER AS THE MODELS
DIVERGE ON SOLUTIONS. FOR INSTANCE THE ECWMF AND GFS MODELS WANT TO
BRING RAIN TO THE AREA BY HALLOWEEN BUT THE GEM MODEL IS DRY. WAY TOO
EARLY TO SAY WITH ANY CONFIDENCE IF IT`LL BE WET OR DRY FOR TRICK OR
TREATERS.

&&

.PREVIOUS DISCUSSION...AS OF 3:05 PM PDT WEDNESDAY...SKIES ARE
CLEAR TO PARTLY CLOUDY WITH MID AFTERNOON TEMPERATURES AROUND THE
BAYS GENERALLY RUNNING IN THE UPPER 60S TO MID 70S...A COUPLE OF
DEGS WARMER THAN AT THE SAME TIME YESTERDAY. TONIGHT...THE WEAK
TAIL END OF A PACIFIC WEATHER SYSTEM NOW MOVING INTO THE PACIFIC
NORTHWEST WILL SPREAD IN INCREASING MID AND HIGH CLOUDINESS OVER
MORE NORTHERN PORTIONS OF OUR AREA. THEN ON THURSDAY...MODEL
SOLUTIONS INDICATE A LIKELIHOOD OF SOME RAIN SOUTH TO NEAR BODEGA
BAY...WITH A SLIGHT CHANCE AS FAR SOUTH AS ABOUT SAN FRANCISCO.
RAINFALL TOTALS LOOK TO BE QUITE LIGHT...EXCEPT IN THE FAR
NORTHERN COASTAL HILLS OF SONOMA COUNTY WHERE LOCAL AMOUNTS UP TO
THE 1/3 TO 1/2 INCH RANGE ARE POSSIBLE.

ANY RESIDUAL NORTH BAY SHOWERS SHOULD TAPER OFF AND END THURSDAY
NIGHT WITH DRY CONDITIONS THEN EXPECTED DISTRICT-WIDE ON FRIDAY
AS A SHORT WAVE UPPER LEVEL RIDGE TEMPORARILY BUILDS IN WESTWARD FROM
THE INTERIOR. BY LATE FRIDAY NIGHT HOWEVER...THE NEXT PACIFIC
WEATHER SYSTEM IS EXPECTED TO RAPIDLY APPROACH FROM THE NORTHWEST.
LATEST MODEL OUTPUT CONTINUES TO INDICATE IT WILL BE BOTH A BIT
STRONGER AND WETTER THAN THE ONE ON THURSDAY...WITH A LIKELIHOOD
OF AT LEAST SOME LIGHT PRECIP SPREADING AS FAR SOUTH AS THE
MONTEREY BAY REGION BY SATURDAY AFTERNOON. SHOULD ALSO NOTE THAT
BOTH LATEST NAM DETERMINISTIC MODEL OUTPUT SOUNDINGS AND SURFACE BASED
CAPE VALUES...AND SREF MUCAPE PLUMES...INDICATE A SUFFICIENT
POSSIBILITY OF CONVECTION SATURDAY AFTERNOON OVER THE NORTH BAY TO
WARRANT INCLUSION IN THE FORECAST OF MENTION OF A SLIGHT CHANCE OF
THUNDERSTORMS.

HERE AGAIN POST FRONTAL SHOWERS LOOK TO TAPER OFF AND END PRETTY
QUICKLY...WITH DRY WEATHER CONDITIONS RETURNING ACROSS ALL BUT
POSSIBLY THE EASTERNMOST MARGIN OF OUR AREA BY SUNDAY MORNING. DRY
CONDITIONS AND SEASONAL TEMPERATURES ARE EXPECTED ACROSS THE
DISTRICT THROUGH AT LEAST MONDAY NIGHT. THEREAFTER LONGER RANGE
MODEL SOLUTIONS BEGIN TO DIVERGE...WITH FOR EXAMPLE THE 12Z GFS
BRINGING IN ANOTHER WEAK SYSTEM AND LIGHT PRECIP TO THE NORTH BAY
ON TUESDAY WHILE THE ECMWF CONFINES ASSOCIATED RAINFALL TO AREAS
NORTH OF OUR CWA.

&&

.AVIATION...AS OF 10:30 PM PDT WEDNESDAY...VFR CONDITIONS WILL
PERSIST THROUGH LATE TONIGHT WITH HIGH CLOUDS CONTINUE TO
STREAMING ACROSS THE REGION. A FRONTAL BOUNDARY IS FORECAST TO
APPROACH THE NORTH BAY TONIGHT AND SHOULD HELP INCREASE THE
AMOUNT OF LOW LEVEL CLOUD COVER...ESPECIALLY OVER THE SAN
FRANCISCO BAY AREA NORTHWARD. LIGHT RAIN OR DRIZZLE WILL BE
POSSIBLE OVER KSTS...YET CONFIDENCE REMAINS LOW AND HAVE LEFT
PRECIPITATION OUT OF THE TAF FOR NOW. LOW CLOUDS THAT DO DEVELOP
OVER THE REGION WILL BE SLOW TO BURN-OFF THURSDAY MORNING.
FURTHER SOUTH...CONFIDENCE IS LOWER ON THE RETURN OF STRATUS OVER
THE TERMINALS AS BOUNDARY LAYER MOISTURE WILL BE SLOWER TO RETURN.

VICINITY OF KSFO...VFR CONDITIONS WILL CONTINUE THROUGH LATE
TONIGHT WITH  LOW CLOUDS EXPECTED TO RETURN AFTER 09Z.
LIGHT WEST WINDS WILL CONTINUE THROUGH TONIGHT. MODERATE
CONFIDENCE.

KSFO BRIDGE APPROACH...SIMILAR TO KSFO.

MONTEREY BAY AREA TERMINALS...VFR CONDITIONS WILL CONTINUE
THROUGH LATE TONIGHT WITH LOW CLOUDS EXPECTED TO RETURN AFTER 09Z.
LIGHT WEST WINDS WILL PERSIST BECOMING LIGHT AND VARIABLE
OVERNIGHT. MODERATE CONFIDENCE.

&&

.MARINE...AS OF 8:51 PM PDT WEDNESDAY...GENERALLY LIGHT NORTHWEST
WINDS WILL PERSIST ACROSS THE COASTAL WATERS THROUGH FRIDAY...WITH
EXCEPTION TO THE COASTAL JET SOUTH OF POINT SUR WHERE MODERATE
WINDS WILL PERSIST THROUGH THURSDAY NIGHT. WIND SPEEDS WILL THEN
INCREASE AND BECOME SOUTHERLY FRIDAY NIGHT INTO SATURDAY AHEAD OF
AN APPROACHING COLD FRONT THAT WILL ALSO BRING CHANCES OF RAIN TO
THE REGION. NORTHWEST SWELL WILL SLOWLY DIMINISH THROUGH FRIDAY
THEN INCREASE OVER THE WEEKEND.

&&

.MTR WATCHES/WARNINGS/ADVISORIES...
     .TNGT...SCA...PT PINOS TO PT PIEDRAS BLANCAS 0-10 NM

&&

$$

PUBLIC FORECAST: CW
AVIATION/MARINE: CW

VISIT US AT WEATHER.GOV/SANFRANCISCO

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000
FXUS66 KMTR 230413 CCA
AFDMTR

AREA FORECAST DISCUSSION...CORRECTED
NATIONAL WEATHER SERVICE SAN FRANCISCO BAY AREA
858 PM PDT WED OCT 22 2014

.SYNOPSIS...DRY WEATHER CONDITIONS AND PARTLY CLOUDY SKIES ARE
EXPECTED TONIGHT...BUT THEN ON THURSDAY THE WEAK TAIL END OF AN
APPROACHING PACIFIC WEATHER SYSTEM WILL LIKELY BRING SOME LIGHT
RAINFALL TO NORTHERNMOST PORTIONS OF OUR DISTRICT. FRIDAY LOOKS TO
BE MOSTLY SUNNY AND MILD...BUT THEN A SOMEWHAT WETTER SYSTEM
WILL MOVE IN ON SATURDAY AND SPREAD RAIN CHANCES ACROSS MUCH OF
OUR AREA. DRY CONDITIONS AND SEASONAL TEMPERATURES ARE PROJECTED
FOR SUNDAY INTO THE FIRST PART OF NEXT WEEK.

&&

.DISCUSSION...AS OF 8:45 PM PDT WEDNESDAY...TEMPERATURES WERE FOR
THE MOST PART A LITTLE MILDER AND A FEW DEGREES ABOVE NORMAL ACROSS
THE AREA TODAY. THE ONLY EXCEPTION TO THIS WAS OVER THE SOUTH BAY
WHERE AVERAGE TEMPERATURES WERE 1 TO 4 DEGREES FAHRENHEIT BELOW NORMAL
TODAY. HIGHS RANGED FROM THE MID 60S COAST TO THE 70S INLAND.

MID TO HIGH CLOUDS ARE DRIFTING IN OVER THE BAY AREA FROM THE
NORTHWEST. WINDS ARE MOSTLY LIGHT THIS EVENING AND THE RAIN IS
STILL SITUATED WELL TO THE NORTH OF THE BAY AREA. BELIEVE IT OR
NOT SHORTWAVE RIDGING IS STILL IN PLACE THIS EVENING OVER THE
FORECAST AREA WITH 500 MB HEIGHTS OVER THE SOUTH BAY STILL
HOVERING UP NEAR 580 DECAMETERS. 500 MB HEIGHTS WILL BRIEFLY
SUBSIDE A LITTLE AROUND 5 AM THURSDAY MORNING THEN BUMP UPWARDS
AGAIN TO WHERE THEY ARE NOW BY THURSDAY AFTERNOON. THE INCOMING
FRONTAL SYSTEM WILL BE ON THE WEAK SIDE WITH ONLY VERY LIGHT
AMOUNTS OF RAIN EXPECTED...MOSTLY OVER THE NORTHERN SONOMA COUNTY
COAST WHERE UP TO 1/3" TOTAL OF RAIN COULD FALL LATE TONIGHT AND
THURSDAY MORNING. THE NEWEST 00Z NAM MODEL DOES NOT PREDICT ANY
MEASURABLE RAINFALL ANYWHERE ELSE OVER THE AREA TONIGHT OR
THURSDAY. DEWPOINT TEMPERATURES ARE SOLIDLY HIGHER THIS EVENING
AREA-WIDE SO PERIODIC LIGHT DRIZZLE OR LIGHT RAIN IS STILL
POSSIBLE TO THE SOUTH OF SONOMA COUNTY AS THE WEAKENING SHORTWAVE
TROUGH SQUEEZES OUT A LITTLE BIT OF MOISTURE AS IT MOVES OVER THE
AREA. A FEW AREAS MAY SEE A TINY AMOUNT OF MEASURABLE RAINFALL
OVERNIGHT...UP TO A COUPLE HUNDREDTHS POSSIBLY. THE NEAR TERM FITS
PERFECTLY AS A LOW POP LOW QPF FORECAST. NOT PLANNING ON MAKING
ANY ADJUSTMENTS TO FIRST OR SECOND PERIOD POP FORECASTS.

ONCE THE WEAK TROUGH RIPPLES EAST AWAY FROM THE BAY AREA THURSDAY
ANOTHER (MORE AMPLIFIED AND STRENGTHENING) LOW PRESSURE SYSTEM NEAR
39N/134W FRIDAY EVENING MOVES NORTHEAST WITH THE MAIN MID-UPPER
LEVEL LOW PRESSURE AREA REACHING THE PAC NW EARLY SATURDAY
EVENING. THE LOW PRESSURE SYSTEM WILL BE TRAILING A COLD FRONT
EASTWARD WHICH WILL REACH NORTHERNMOST CA BY EARLY SAT MORNING AND
THEN THE BAY AREA DURING THE DAY SATURDAY. AS MUCH AS 1" RAINFALL
IS POSSIBLE OVER SONOMA...ABOUT 1/2"-3/4" NAPA AND MARIN COUNTIES
AND 2/10" OR LESS OVER THE REMAINDER OF THE BAY AREA AND NORTH
CENTRAL COAST. BY THE TIME THE LOW PRESSURE AREA GETS TO CA THE
STRONGEST JET STREAM DYNAMICS WILL HAVE ALREADY POSITIONED ITSELF
FORWARD OF THE TROUGH AXIS SUGGESTING AN ACCELERATION OF THE LOW
AS WELL AS THE HEAVIEST RAINFALL TO THE NORTH OF THE BAY AREA. IF
ONE IS TRAVELLING TO THE PACIFIC NW FOR THE WEEKEND EXPECT HEAVIER
STEADIER RAINS. MID LEVEL TEMPERATURES REACH ABOUT -18C OVER THE
NORTH BAY BY LATE SATURDAY MORNING...NOT AN EXCEPTIONALLY COLD SYSTEM.
THE 00Z NAM PREDICTS A SMALL POCKET...ALBEIT JUST BELOW 35...OF MODIFIED
TOTAL TOTALS MID LEVEL INSTABILITY BY 21Z SATURDAY OVER NORTHERN
SONOMA COUNTY. OFTEN TIMES LOW PRESSURE AREAS SWING OVER THE AREA A
LITTLE FASTER THAN MODELS PREDICT. IT IS QUITE POSSIBLE THAT THE MID
LEVEL INSTABILITY ARRIVES IN THE NORTH BAY AREA AS EARLY AS VERY
EARLY SATURDAY MORNING. THE NAM DEPICTS THE MID LEVEL INSTABILITY
QUICKLY JUMPING OVER TO NAPA COUNTY THEN MOVING EAST TO THE NORTHERN
SACRAMENTO VALLEY SATURDAY. SLIGHT CHANCE OF T-STORMS WAS ADDED IN
EARLIER TODAY AND SEE NO REASON TO MAKE ANY CHANGES EXCEPT THERE`S A
SMALL POSSIBILITY THE T-STORM ACTIVITY MAY ARRIVE A LITTLE EARLIER
THAN PRESENTLY INDICATED.

THERE`S MUCH LESS CONFIDENCE REGARDING NEXT WEEK`S WEATHER AS THE MODELS
DIVERGE ON SOLUTIONS. FOR INSTANCE THE ECWMF AND GFS MODELS WANT TO
BRING RAIN TO THE AREA BY HALLOWEEN BUT THE GEM MODEL IS DRY. WAY TOO
EARLY TO SAY WITH ANY CONFIDENCE IF IT`LL BE WET OR DRY FOR TRICK OR
TREATERS.

&&

.PREVIOUS DISCUSSION...AS OF 3:05 PM PDT WEDNESDAY...SKIES ARE
CLEAR TO PARTLY CLOUDY WITH MID AFTERNOON TEMPERATURES AROUND THE
BAYS GENERALLY RUNNING IN THE UPPER 60S TO MID 70S...A COUPLE OF
DEGS WARMER THAN AT THE SAME TIME YESTERDAY. TONIGHT...THE WEAK
TAIL END OF A PACIFIC WEATHER SYSTEM NOW MOVING INTO THE PACIFIC
NORTHWEST WILL SPREAD IN INCREASING MID AND HIGH CLOUDINESS OVER
MORE NORTHERN PORTIONS OF OUR AREA. THEN ON THURSDAY...MODEL
SOLUTIONS INDICATE A LIKELIHOOD OF SOME RAIN SOUTH TO NEAR BODEGA
BAY...WITH A SLIGHT CHANCE AS FAR SOUTH AS ABOUT SAN FRANCISCO.
RAINFALL TOTALS LOOK TO BE QUITE LIGHT...EXCEPT IN THE FAR
NORTHERN COASTAL HILLS OF SONOMA COUNTY WHERE LOCAL AMOUNTS UP TO
THE 1/3 TO 1/2 INCH RANGE ARE POSSIBLE.

ANY RESIDUAL NORTH BAY SHOWERS SHOULD TAPER OFF AND END THURSDAY
NIGHT WITH DRY CONDITIONS THEN EXPECTED DISTRICT-WIDE ON FRIDAY
AS A SHORT WAVE UPPER LEVEL RIDGE TEMPORARILY BUILDS IN WESTWARD FROM
THE INTERIOR. BY LATE FRIDAY NIGHT HOWEVER...THE NEXT PACIFIC
WEATHER SYSTEM IS EXPECTED TO RAPIDLY APPROACH FROM THE NORTHWEST.
LATEST MODEL OUTPUT CONTINUES TO INDICATE IT WILL BE BOTH A BIT
STRONGER AND WETTER THAN THE ONE ON THURSDAY...WITH A LIKELIHOOD
OF AT LEAST SOME LIGHT PRECIP SPREADING AS FAR SOUTH AS THE
MONTEREY BAY REGION BY SATURDAY AFTERNOON. SHOULD ALSO NOTE THAT
BOTH LATEST NAM DETERMINISTIC MODEL OUTPUT SOUNDINGS AND SURFACE BASED
CAPE VALUES...AND SREF MUCAPE PLUMES...INDICATE A SUFFICIENT
POSSIBILITY OF CONVECTION SATURDAY AFTERNOON OVER THE NORTH BAY TO
WARRANT INCLUSION IN THE FORECAST OF MENTION OF A SLIGHT CHANCE OF
THUNDERSTORMS.

HERE AGAIN POST FRONTAL SHOWERS LOOK TO TAPER OFF AND END PRETTY
QUICKLY...WITH DRY WEATHER CONDITIONS RETURNING ACROSS ALL BUT
POSSIBLY THE EASTERNMOST MARGIN OF OUR AREA BY SUNDAY MORNING. DRY
CONDITIONS AND SEASONAL TEMPERATURES ARE EXPECTED ACROSS THE
DISTRICT THROUGH AT LEAST MONDAY NIGHT. THEREAFTER LONGER RANGE
MODEL SOLUTIONS BEGIN TO DIVERGE...WITH FOR EXAMPLE THE 12Z GFS
BRINGING IN ANOTHER WEAK SYSTEM AND LIGHT PRECIP TO THE NORTH BAY
ON TUESDAY WHILE THE ECMWF CONFINES ASSOCIATED RAINFALL TO AREAS
NORTH OF OUR CWA.

&&

.AVIATION...AS OF 5:00 PM PDT WEDNESDAY...VFR CONDITIONS WILL
PERSIST THROUGH LATE TONIGHT WITH HIGH CLOUDS STREAMING
ACROSS THE REGION. A FRONTAL BOUNDARY IS FORECAST TO APPROACH THE
NORTH BAY TONIGHT AND SHOULD HELP INCREASE THE AMOUNT OF LOW LEVEL
CLOUD COVER...ESPECIALLY OVER THE SAN FRANCISCO BAY AREA
NORTHWARD. LIGHT RAIN OR DRIZZLE WILL BE POSSIBLE OVER KSTS...YET
CONFIDENCE REMAINS LOW AND HAVE LEFT PRECIPITATION OUT OF THE TAF
FOR NOW. LOW CLOUDS THAT DO DEVELOP OVER THE REGION WILL BE SLOW
TO BURN-OFF THURSDAY MORNING. FURTHER SOUTH...CONFIDENCE IS LOWER
ON THE RETURN OF STRATUS OVER THE TERMINALS AS BOUNDARY LAYER
MOISTURE WILL BE SLOWER TO RETURN.

VICINITY OF KSFO...VFR CONDITIONS WILL CONTINUE THROUGH THIS
EVENING. LOW CLOUDS EXPECTED TO RETURN LATE TONIGHT. MODERATE
WINDS WILL EASE OVERNIGHT. MODERATE CONFIDENCE.

KSFO BRIDGE APPROACH...SIMILAR TO KSFO.

MONTEREY BAY AREA TERMINALS...VFR CONDITIONS WILL CONTINUE
THROUGH THIS EVENING. LOW CLOUDS EXPECTED TO RETURN AFTER MIDNIGHT.
MODERATE WINDS WILL EASE OVERNIGHT. MODERATE CONFIDENCE.

&&

.MARINE...AS OF 2:41 PM PDT WEDNESDAY...GENERALLY LIGHT NORTHWEST WINDS
WILL PERSIST ACROSS THE COASTAL WATERS THROUGH FRIDAY...WITH
MODERATE WIND SPEEDS OFF THE BIG SUR COAST. WIND SPEEDS WILL THEN
INCREASE AND BECOME SOUTHERLY FRIDAY NIGHT INTO SATURDAY AHEAD OF
AN APPROACHING COLD FRONT THAT WILL ALSO BRING CHANCES OF RAIN TO
THE REGION. NORTHWEST SWELL WILL SLOWLY DIMINISH THROUGH FRIDAY
THEN INCREASE OVER THE WEEKEND.

&&

.MTR WATCHES/WARNINGS/ADVISORIES...
     .TNGT...SCA...PT PINOS TO PT PIEDRAS BLANCAS 0-10 NM

&&

$$

PUBLIC FORECAST: CANEPA/BLIER
AVIATION: CW
MARINE: RGASS/DRP

VISIT US AT WEATHER.GOV/SANFRANCISCO

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










000
FXUS66 KMTR 230413 CCA
AFDMTR

AREA FORECAST DISCUSSION...CORRECTED
NATIONAL WEATHER SERVICE SAN FRANCISCO BAY AREA
858 PM PDT WED OCT 22 2014

.SYNOPSIS...DRY WEATHER CONDITIONS AND PARTLY CLOUDY SKIES ARE
EXPECTED TONIGHT...BUT THEN ON THURSDAY THE WEAK TAIL END OF AN
APPROACHING PACIFIC WEATHER SYSTEM WILL LIKELY BRING SOME LIGHT
RAINFALL TO NORTHERNMOST PORTIONS OF OUR DISTRICT. FRIDAY LOOKS TO
BE MOSTLY SUNNY AND MILD...BUT THEN A SOMEWHAT WETTER SYSTEM
WILL MOVE IN ON SATURDAY AND SPREAD RAIN CHANCES ACROSS MUCH OF
OUR AREA. DRY CONDITIONS AND SEASONAL TEMPERATURES ARE PROJECTED
FOR SUNDAY INTO THE FIRST PART OF NEXT WEEK.

&&

.DISCUSSION...AS OF 8:45 PM PDT WEDNESDAY...TEMPERATURES WERE FOR
THE MOST PART A LITTLE MILDER AND A FEW DEGREES ABOVE NORMAL ACROSS
THE AREA TODAY. THE ONLY EXCEPTION TO THIS WAS OVER THE SOUTH BAY
WHERE AVERAGE TEMPERATURES WERE 1 TO 4 DEGREES FAHRENHEIT BELOW NORMAL
TODAY. HIGHS RANGED FROM THE MID 60S COAST TO THE 70S INLAND.

MID TO HIGH CLOUDS ARE DRIFTING IN OVER THE BAY AREA FROM THE
NORTHWEST. WINDS ARE MOSTLY LIGHT THIS EVENING AND THE RAIN IS
STILL SITUATED WELL TO THE NORTH OF THE BAY AREA. BELIEVE IT OR
NOT SHORTWAVE RIDGING IS STILL IN PLACE THIS EVENING OVER THE
FORECAST AREA WITH 500 MB HEIGHTS OVER THE SOUTH BAY STILL
HOVERING UP NEAR 580 DECAMETERS. 500 MB HEIGHTS WILL BRIEFLY
SUBSIDE A LITTLE AROUND 5 AM THURSDAY MORNING THEN BUMP UPWARDS
AGAIN TO WHERE THEY ARE NOW BY THURSDAY AFTERNOON. THE INCOMING
FRONTAL SYSTEM WILL BE ON THE WEAK SIDE WITH ONLY VERY LIGHT
AMOUNTS OF RAIN EXPECTED...MOSTLY OVER THE NORTHERN SONOMA COUNTY
COAST WHERE UP TO 1/3" TOTAL OF RAIN COULD FALL LATE TONIGHT AND
THURSDAY MORNING. THE NEWEST 00Z NAM MODEL DOES NOT PREDICT ANY
MEASURABLE RAINFALL ANYWHERE ELSE OVER THE AREA TONIGHT OR
THURSDAY. DEWPOINT TEMPERATURES ARE SOLIDLY HIGHER THIS EVENING
AREA-WIDE SO PERIODIC LIGHT DRIZZLE OR LIGHT RAIN IS STILL
POSSIBLE TO THE SOUTH OF SONOMA COUNTY AS THE WEAKENING SHORTWAVE
TROUGH SQUEEZES OUT A LITTLE BIT OF MOISTURE AS IT MOVES OVER THE
AREA. A FEW AREAS MAY SEE A TINY AMOUNT OF MEASURABLE RAINFALL
OVERNIGHT...UP TO A COUPLE HUNDREDTHS POSSIBLY. THE NEAR TERM FITS
PERFECTLY AS A LOW POP LOW QPF FORECAST. NOT PLANNING ON MAKING
ANY ADJUSTMENTS TO FIRST OR SECOND PERIOD POP FORECASTS.

ONCE THE WEAK TROUGH RIPPLES EAST AWAY FROM THE BAY AREA THURSDAY
ANOTHER (MORE AMPLIFIED AND STRENGTHENING) LOW PRESSURE SYSTEM NEAR
39N/134W FRIDAY EVENING MOVES NORTHEAST WITH THE MAIN MID-UPPER
LEVEL LOW PRESSURE AREA REACHING THE PAC NW EARLY SATURDAY
EVENING. THE LOW PRESSURE SYSTEM WILL BE TRAILING A COLD FRONT
EASTWARD WHICH WILL REACH NORTHERNMOST CA BY EARLY SAT MORNING AND
THEN THE BAY AREA DURING THE DAY SATURDAY. AS MUCH AS 1" RAINFALL
IS POSSIBLE OVER SONOMA...ABOUT 1/2"-3/4" NAPA AND MARIN COUNTIES
AND 2/10" OR LESS OVER THE REMAINDER OF THE BAY AREA AND NORTH
CENTRAL COAST. BY THE TIME THE LOW PRESSURE AREA GETS TO CA THE
STRONGEST JET STREAM DYNAMICS WILL HAVE ALREADY POSITIONED ITSELF
FORWARD OF THE TROUGH AXIS SUGGESTING AN ACCELERATION OF THE LOW
AS WELL AS THE HEAVIEST RAINFALL TO THE NORTH OF THE BAY AREA. IF
ONE IS TRAVELLING TO THE PACIFIC NW FOR THE WEEKEND EXPECT HEAVIER
STEADIER RAINS. MID LEVEL TEMPERATURES REACH ABOUT -18C OVER THE
NORTH BAY BY LATE SATURDAY MORNING...NOT AN EXCEPTIONALLY COLD SYSTEM.
THE 00Z NAM PREDICTS A SMALL POCKET...ALBEIT JUST BELOW 35...OF MODIFIED
TOTAL TOTALS MID LEVEL INSTABILITY BY 21Z SATURDAY OVER NORTHERN
SONOMA COUNTY. OFTEN TIMES LOW PRESSURE AREAS SWING OVER THE AREA A
LITTLE FASTER THAN MODELS PREDICT. IT IS QUITE POSSIBLE THAT THE MID
LEVEL INSTABILITY ARRIVES IN THE NORTH BAY AREA AS EARLY AS VERY
EARLY SATURDAY MORNING. THE NAM DEPICTS THE MID LEVEL INSTABILITY
QUICKLY JUMPING OVER TO NAPA COUNTY THEN MOVING EAST TO THE NORTHERN
SACRAMENTO VALLEY SATURDAY. SLIGHT CHANCE OF T-STORMS WAS ADDED IN
EARLIER TODAY AND SEE NO REASON TO MAKE ANY CHANGES EXCEPT THERE`S A
SMALL POSSIBILITY THE T-STORM ACTIVITY MAY ARRIVE A LITTLE EARLIER
THAN PRESENTLY INDICATED.

THERE`S MUCH LESS CONFIDENCE REGARDING NEXT WEEK`S WEATHER AS THE MODELS
DIVERGE ON SOLUTIONS. FOR INSTANCE THE ECWMF AND GFS MODELS WANT TO
BRING RAIN TO THE AREA BY HALLOWEEN BUT THE GEM MODEL IS DRY. WAY TOO
EARLY TO SAY WITH ANY CONFIDENCE IF IT`LL BE WET OR DRY FOR TRICK OR
TREATERS.

&&

.PREVIOUS DISCUSSION...AS OF 3:05 PM PDT WEDNESDAY...SKIES ARE
CLEAR TO PARTLY CLOUDY WITH MID AFTERNOON TEMPERATURES AROUND THE
BAYS GENERALLY RUNNING IN THE UPPER 60S TO MID 70S...A COUPLE OF
DEGS WARMER THAN AT THE SAME TIME YESTERDAY. TONIGHT...THE WEAK
TAIL END OF A PACIFIC WEATHER SYSTEM NOW MOVING INTO THE PACIFIC
NORTHWEST WILL SPREAD IN INCREASING MID AND HIGH CLOUDINESS OVER
MORE NORTHERN PORTIONS OF OUR AREA. THEN ON THURSDAY...MODEL
SOLUTIONS INDICATE A LIKELIHOOD OF SOME RAIN SOUTH TO NEAR BODEGA
BAY...WITH A SLIGHT CHANCE AS FAR SOUTH AS ABOUT SAN FRANCISCO.
RAINFALL TOTALS LOOK TO BE QUITE LIGHT...EXCEPT IN THE FAR
NORTHERN COASTAL HILLS OF SONOMA COUNTY WHERE LOCAL AMOUNTS UP TO
THE 1/3 TO 1/2 INCH RANGE ARE POSSIBLE.

ANY RESIDUAL NORTH BAY SHOWERS SHOULD TAPER OFF AND END THURSDAY
NIGHT WITH DRY CONDITIONS THEN EXPECTED DISTRICT-WIDE ON FRIDAY
AS A SHORT WAVE UPPER LEVEL RIDGE TEMPORARILY BUILDS IN WESTWARD FROM
THE INTERIOR. BY LATE FRIDAY NIGHT HOWEVER...THE NEXT PACIFIC
WEATHER SYSTEM IS EXPECTED TO RAPIDLY APPROACH FROM THE NORTHWEST.
LATEST MODEL OUTPUT CONTINUES TO INDICATE IT WILL BE BOTH A BIT
STRONGER AND WETTER THAN THE ONE ON THURSDAY...WITH A LIKELIHOOD
OF AT LEAST SOME LIGHT PRECIP SPREADING AS FAR SOUTH AS THE
MONTEREY BAY REGION BY SATURDAY AFTERNOON. SHOULD ALSO NOTE THAT
BOTH LATEST NAM DETERMINISTIC MODEL OUTPUT SOUNDINGS AND SURFACE BASED
CAPE VALUES...AND SREF MUCAPE PLUMES...INDICATE A SUFFICIENT
POSSIBILITY OF CONVECTION SATURDAY AFTERNOON OVER THE NORTH BAY TO
WARRANT INCLUSION IN THE FORECAST OF MENTION OF A SLIGHT CHANCE OF
THUNDERSTORMS.

HERE AGAIN POST FRONTAL SHOWERS LOOK TO TAPER OFF AND END PRETTY
QUICKLY...WITH DRY WEATHER CONDITIONS RETURNING ACROSS ALL BUT
POSSIBLY THE EASTERNMOST MARGIN OF OUR AREA BY SUNDAY MORNING. DRY
CONDITIONS AND SEASONAL TEMPERATURES ARE EXPECTED ACROSS THE
DISTRICT THROUGH AT LEAST MONDAY NIGHT. THEREAFTER LONGER RANGE
MODEL SOLUTIONS BEGIN TO DIVERGE...WITH FOR EXAMPLE THE 12Z GFS
BRINGING IN ANOTHER WEAK SYSTEM AND LIGHT PRECIP TO THE NORTH BAY
ON TUESDAY WHILE THE ECMWF CONFINES ASSOCIATED RAINFALL TO AREAS
NORTH OF OUR CWA.

&&

.AVIATION...AS OF 5:00 PM PDT WEDNESDAY...VFR CONDITIONS WILL
PERSIST THROUGH LATE TONIGHT WITH HIGH CLOUDS STREAMING
ACROSS THE REGION. A FRONTAL BOUNDARY IS FORECAST TO APPROACH THE
NORTH BAY TONIGHT AND SHOULD HELP INCREASE THE AMOUNT OF LOW LEVEL
CLOUD COVER...ESPECIALLY OVER THE SAN FRANCISCO BAY AREA
NORTHWARD. LIGHT RAIN OR DRIZZLE WILL BE POSSIBLE OVER KSTS...YET
CONFIDENCE REMAINS LOW AND HAVE LEFT PRECIPITATION OUT OF THE TAF
FOR NOW. LOW CLOUDS THAT DO DEVELOP OVER THE REGION WILL BE SLOW
TO BURN-OFF THURSDAY MORNING. FURTHER SOUTH...CONFIDENCE IS LOWER
ON THE RETURN OF STRATUS OVER THE TERMINALS AS BOUNDARY LAYER
MOISTURE WILL BE SLOWER TO RETURN.

VICINITY OF KSFO...VFR CONDITIONS WILL CONTINUE THROUGH THIS
EVENING. LOW CLOUDS EXPECTED TO RETURN LATE TONIGHT. MODERATE
WINDS WILL EASE OVERNIGHT. MODERATE CONFIDENCE.

KSFO BRIDGE APPROACH...SIMILAR TO KSFO.

MONTEREY BAY AREA TERMINALS...VFR CONDITIONS WILL CONTINUE
THROUGH THIS EVENING. LOW CLOUDS EXPECTED TO RETURN AFTER MIDNIGHT.
MODERATE WINDS WILL EASE OVERNIGHT. MODERATE CONFIDENCE.

&&

.MARINE...AS OF 2:41 PM PDT WEDNESDAY...GENERALLY LIGHT NORTHWEST WINDS
WILL PERSIST ACROSS THE COASTAL WATERS THROUGH FRIDAY...WITH
MODERATE WIND SPEEDS OFF THE BIG SUR COAST. WIND SPEEDS WILL THEN
INCREASE AND BECOME SOUTHERLY FRIDAY NIGHT INTO SATURDAY AHEAD OF
AN APPROACHING COLD FRONT THAT WILL ALSO BRING CHANCES OF RAIN TO
THE REGION. NORTHWEST SWELL WILL SLOWLY DIMINISH THROUGH FRIDAY
THEN INCREASE OVER THE WEEKEND.

&&

.MTR WATCHES/WARNINGS/ADVISORIES...
     .TNGT...SCA...PT PINOS TO PT PIEDRAS BLANCAS 0-10 NM

&&

$$

PUBLIC FORECAST: CANEPA/BLIER
AVIATION: CW
MARINE: RGASS/DRP

VISIT US AT WEATHER.GOV/SANFRANCISCO

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










000
FXUS66 KMTR 230358
AFDMTR

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SAN FRANCISCO BAY AREA
858 PM PDT WED OCT 22 2014

.SYNOPSIS...DRY WEATHER CONDITIONS AND PARTLY CLOUDY SKIES ARE
EXPECTED TONIGHT...BUT THEN ON THURSDAY THE WEAK TAIL END OF AN
APPROACHING PACIFIC WEATHER SYSTEM WILL LIKELY BRING SOME LIGHT
RAINFALL TO NORTHERNMOST PORTIONS OF OUR DISTRICT. FRIDAY LOOKS TO
BE MOSTLY SUNNY AND MILD...BUT THEN A SOMEWHAT WETTER SYSTEM
WILL MOVE IN ON SATURDAY AND SPREAD RAIN CHANCES ACROSS MUCH OF
OUR AREA. DRY CONDITIONS AND SEASONAL TEMPERATURES ARE PROJECTED
FOR SUNDAY INTO THE FIRST PART OF NEXT WEEK.

&&

.DISCUSSION...AS OF 8:45 PM PDT WEDNESDAY...TEMPERATURES WERE FOR
THE MOST PART A LITTLE MILDER AND A FEW DEGREES ABOVE NORMAL ACROSS
THE AREA TODAY. THE ONLY EXCEPTION TO THIS WAS OVER THE SOUTH BAY
WHERE AVERAGE TEMPERATURES WERE 1 TO 4 DEGREES FAHRENHEIT BELOW NORMAL
TODAY. HIGHS RANGED FROM THE MID 60S COAST TO THE 70S INLAND.

MID TO HIGH CLOUDS ARE DRIFTING IN OVER THE BAY AREA FROM THE
NORTHWEST. WINDS ARE MOSTLY LIGHT THIS EVENING AND THE RAIN IS
STILL SITUATED WELL TO THE NORTH OF THE BAY AREA. BELIEVE IT OR
NOT SHORTWAVE RIDGING IS STILL IN PLACE THIS EVENING OVER THE
FORECAST AREA WITH 500 MB HEIGHTS OVER THE SOUTH BAY STILL
HOVERING UP NEAR 580 DECAMETERS. 500 MB HEIGHTS WILL BRIEFLY
SUBSIDE A LITTLE AROUND 5 AM THURSDAY MORNING THEN BUMP UPWARDS
AGAIN TO WHERE THEY ARE NOW BY THURSDAY AFTERNOON. THE INCOMING
FRONTAL SYSTEM WILL BE ON THE WEAK SIDE WITH ONLY VERY LIGHT
AMOUNTS OF RAIN EXPECTED...MOSTLY OVER THE NORTHERN SONOMA COUNTY
COAST WHERE UP TO 1/3" TOTAL OF RAIN COULD FALL LATE TONIGHT AND
THURSDAY MORNING. THE NEWEST 00Z NAM MODEL DOES NOT PREDICT ANY
MEASURABLE RAINFALL ANYWHERE ELSE OVER THE AREA TONIGHT OR
THURSDAY. DEWPOINT TEMPERATURES ARE SOLIDLY HIGHER THIS EVENING
AREA-WIDE SO PERIODIC LIGHT DRIZZLE OR LIGHT RAIN IS STILL
POSSIBLE TO THE SOUTH OF SONOMA COUNTY AS THE WEAKENING SHORTWAVE
TROUGH SQUEEZES OUT A LITTLE BIT OF MOISTURE AS IT MOVES OVER THE
AREA. A FEW AREAS MAY SEE A TINY AMOUNT OF MEASURABLE RAINFALL
OVERNIGHT...UP TO A COUPLE HUNDREDTHS POSSIBLY. THE NEAR TERM FITS
PERFECTLY AS A LOW POP LOW QPF FORECAST. NOT PLANNING ON MAKING
ANY ADJUSTMENTS TO FIRST OR SECOND PERIOD POP FORECASTS.

ONCE THE WEAK TROUGH RIPPLES EAST AWAY FROM THE BAY AREA THURSDAY
ANOTHER (MORE AMPLIFIED AND STRENGTHENING) LOW PRESSURE SYSTEM NEAR
39N/134W FRIDAY EVENING MOVES NORTHEAST WITH THE MAIN MID-UPPER
LEVEL LOW PRESSURE AREA REACHING THE PAC NW EARLY SATURDAY
EVENING. THE LOW PRESSURE SYSTEM WILL BE TRAILING A COLD FRONT
EASTWARD WHICH WILL REACH NORTHERNMOST CA BY EARLY SAT MORNING AND
THEN THE BAY AREA DURING THE DAY SATURDAY. AS MUCH AS 1" RAINFALL
IS POSSIBLE OVER SONOMA...ABOUT 1/2"-3/4" NAPA AND MARIN COUNTIES
AND 2/10" OR LESS OVER THE REMAINDER OF THE BAY AREA AND NORTH
CENTRAL COAST. BY THE TIME THE LOW PRESSURE AREA GETS TO CA THE
STRONGEST JET STREAM DYNAMICS WILL HAVE ALREADY POSITIONED ITSELF
FORWARD OF THE TROUGH AXIS SUGGESTING AN ACCELERATION OF THE LOW
AS WELL AS THE HEAVIEST RAINFALL TO THE NORTH OF THE BAY AREA. IF
ONE IS TRAVELLING TO THE PACIFIC NW FOR THE WEEKEND EXPECT HEAVIER
STEADIER RAINS. MID LEVEL TEMPERATURES REACH ABOUT -18C OVER THE
NORTH BAY BY LATE SATURDAY MORNING...NOT AN EXCEPTIONALLY COLD SYSTEM.
THE 00Z NAM PREDICTS A SMALL POCKET...ALBEIT JUST BELOW 35...OF MODIFIED
TOTAL TOTALS MID LEVEL INSTABILITY BY 21Z SATURDAY OVER NORTHERN
SONOMA COUNTY. OFTEN TIMES LOW PRESSURE AREAS SWING OVER THE AREA
A LITTLE FASTER THAN MODELS PREDICT EVEN UP TO A COUPLE DAYS AHEAD
OF TIME...SO IT IS QUITE POSSIBLE THAT THE MID LEVEL INSTABILITY
ARRIVES IN THE NORTH BAY AREA AS EARLY AS VERY EARLY SATURDAY MORNING.
THE NAM DEPICTS THE MID LEVEL INSTABILITY QUICKLY JUMPING OVER TO
NAPA COUNTY THEN MOVING EAST TO THE NORTHERN SACRAMENTO VALLEY
SATURDAY. SLIGHT CHANCE OF T-STORMS WAS ADDED IN EARLIER TODAY AND
SEE NO REASON TO MAKE ANY CHANGES EXCEPT THERE`S A SMALL POSSIBILITY
THE T-STORM ACTIVITY MAY ARRIVE A LITTLE EARLIER THAN PRESENTLY
INDICATED.

THERE`S MUCH LESS CONFIDENCE REGARDING NEXT WEEK`S WEATHER AS THE MODELS
DIVERGE ON SOLUTIONS. FOR INSTANCE THE ECWMF AND GFS MODELS WANT TO
BRING RAIN TO THE AREA BY HALLOWEEN BUT THE GEM MODEL IS DRY. WAY TOO
EARLY TO SAY WITH ANY CONFIDENCE IF IT`LL BE WET OR DRY FOR TRICK OR
TREATERS.

&&

.PREVIOUS DISCUSSION...AS OF 3:05 PM PDT WEDNESDAY...SKIES ARE
CLEAR TO PARTLY CLOUDY WITH MID AFTERNOON TEMPERATURES AROUND THE
BAYS GENERALLY RUNNING IN THE UPPER 60S TO MID 70S...A COUPLE OF
DEGS WARMER THAN AT THE SAME TIME YESTERDAY. TONIGHT...THE WEAK
TAIL END OF A PACIFIC WEATHER SYSTEM NOW MOVING INTO THE PACIFIC
NORTHWEST WILL SPREAD IN INCREASING MID AND HIGH CLOUDINESS OVER
MORE NORTHERN PORTIONS OF OUR AREA. THEN ON THURSDAY...MODEL
SOLUTIONS INDICATE A LIKELIHOOD OF SOME RAIN SOUTH TO NEAR BODEGA
BAY...WITH A SLIGHT CHANCE AS FAR SOUTH AS ABOUT SAN FRANCISCO.
RAINFALL TOTALS LOOK TO BE QUITE LIGHT...EXCEPT IN THE FAR
NORTHERN COASTAL HILLS OF SONOMA COUNTY WHERE LOCAL AMOUNTS UP TO
THE 1/3 TO 1/2 INCH RANGE ARE POSSIBLE.

ANY RESIDUAL NORTH BAY SHOWERS SHOULD TAPER OFF AND END THURSDAY
NIGHT WITH DRY CONDITIONS THEN EXPECTED DISTRICT-WIDE ON FRIDAY
AS A SHORT WAVE UPPER LEVEL RIDGE TEMPORARILY BUILDS IN WESTWARD FROM
THE INTERIOR. BY LATE FRIDAY NIGHT HOWEVER...THE NEXT PACIFIC
WEATHER SYSTEM IS EXPECTED TO RAPIDLY APPROACH FROM THE NORTHWEST.
LATEST MODEL OUTPUT CONTINUES TO INDICATE IT WILL BE BOTH A BIT
STRONGER AND WETTER THAN THE ONE ON THURSDAY...WITH A LIKELIHOOD
OF AT LEAST SOME LIGHT PRECIP SPREADING AS FAR SOUTH AS THE
MONTEREY BAY REGION BY SATURDAY AFTERNOON. SHOULD ALSO NOTE THAT
BOTH LATEST NAM DETERMINISTIC MODEL OUTPUT SOUNDINGS AND SURFACE BASED
CAPE VALUES...AND SREF MUCAPE PLUMES...INDICATE A SUFFICIENT
POSSIBILITY OF CONVECTION SATURDAY AFTERNOON OVER THE NORTH BAY TO
WARRANT INCLUSION IN THE FORECAST OF MENTION OF A SLIGHT CHANCE OF
THUNDERSTORMS.

HERE AGAIN POST FRONTAL SHOWERS LOOK TO TAPER OFF AND END PRETTY
QUICKLY...WITH DRY WEATHER CONDITIONS RETURNING ACROSS ALL BUT
POSSIBLY THE EASTERNMOST MARGIN OF OUR AREA BY SUNDAY MORNING. DRY
CONDITIONS AND SEASONAL TEMPERATURES ARE EXPECTED ACROSS THE
DISTRICT THROUGH AT LEAST MONDAY NIGHT. THEREAFTER LONGER RANGE
MODEL SOLUTIONS BEGIN TO DIVERGE...WITH FOR EXAMPLE THE 12Z GFS
BRINGING IN ANOTHER WEAK SYSTEM AND LIGHT PRECIP TO THE NORTH BAY
ON TUESDAY WHILE THE ECMWF CONFINES ASSOCIATED RAINFALL TO AREAS
NORTH OF OUR CWA.

&&

.AVIATION...AS OF 5:00 PM PDT WEDNESDAY...VFR CONDITIONS WILL
PERSIST THROUGH LATE TONIGHT WITH HIGH CLOUDS STREAMING
ACROSS THE REGION. A FRONTAL BOUNDARY IS FORECAST TO APPROACH THE
NORTH BAY TONIGHT AND SHOULD HELP INCREASE THE AMOUNT OF LOW LEVEL
CLOUD COVER...ESPECIALLY OVER THE SAN FRANCISCO BAY AREA
NORTHWARD. LIGHT RAIN OR DRIZZLE WILL BE POSSIBLE OVER KSTS...YET
CONFIDENCE REMAINS LOW AND HAVE LEFT PRECIPITATION OUT OF THE TAF
FOR NOW. LOW CLOUDS THAT DO DEVELOP OVER THE REGION WILL BE SLOW
TO BURN-OFF THURSDAY MORNING. FURTHER SOUTH...CONFIDENCE IS LOWER
ON THE RETURN OF STRATUS OVER THE TERMINALS AS BOUNDARY LAYER
MOISTURE WILL BE SLOWER TO RETURN.

VICINITY OF KSFO...VFR CONDITIONS WILL CONTINUE THROUGH THIS
EVENING. LOW CLOUDS EXPECTED TO RETURN LATE TONIGHT. MODERATE
WINDS WILL EASE OVERNIGHT. MODERATE CONFIDENCE.

KSFO BRIDGE APPROACH...SIMILAR TO KSFO.

MONTEREY BAY AREA TERMINALS...VFR CONDITIONS WILL CONTINUE
THROUGH THIS EVENING. LOW CLOUDS EXPECTED TO RETURN AFTER MIDNIGHT.
MODERATE WINDS WILL EASE OVERNIGHT. MODERATE CONFIDENCE.

&&

.MARINE...AS OF 2:41 PM PDT WEDNESDAY...GENERALLY LIGHT NORTHWEST WINDS
WILL PERSIST ACROSS THE COASTAL WATERS THROUGH FRIDAY...WITH
MODERATE WIND SPEEDS OFF THE BIG SUR COAST. WIND SPEEDS WILL THEN
INCREASE AND BECOME SOUTHERLY FRIDAY NIGHT INTO SATURDAY AHEAD OF
AN APPROACHING COLD FRONT THAT WILL ALSO BRING CHANCES OF RAIN TO
THE REGION. NORTHWEST SWELL WILL SLOWLY DIMINISH THROUGH FRIDAY
THEN INCREASE OVER THE WEEKEND.

&&

.MTR WATCHES/WARNINGS/ADVISORIES...
     .TNGT...SCA...PT PINOS TO PT PIEDRAS BLANCAS 0-10 NM

&&

$$

PUBLIC FORECAST: CANEPA/BLIER
AVIATION: CW
MARINE: RGASS/DRP

VISIT US AT WEATHER.GOV/SANFRANCISCO

FOLLOW US ON FACEBOOK, TWITTER, AND YOUTUBE AT:
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000
FXUS66 KMTR 230358
AFDMTR

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SAN FRANCISCO BAY AREA
858 PM PDT WED OCT 22 2014

.SYNOPSIS...DRY WEATHER CONDITIONS AND PARTLY CLOUDY SKIES ARE
EXPECTED TONIGHT...BUT THEN ON THURSDAY THE WEAK TAIL END OF AN
APPROACHING PACIFIC WEATHER SYSTEM WILL LIKELY BRING SOME LIGHT
RAINFALL TO NORTHERNMOST PORTIONS OF OUR DISTRICT. FRIDAY LOOKS TO
BE MOSTLY SUNNY AND MILD...BUT THEN A SOMEWHAT WETTER SYSTEM
WILL MOVE IN ON SATURDAY AND SPREAD RAIN CHANCES ACROSS MUCH OF
OUR AREA. DRY CONDITIONS AND SEASONAL TEMPERATURES ARE PROJECTED
FOR SUNDAY INTO THE FIRST PART OF NEXT WEEK.

&&

.DISCUSSION...AS OF 8:45 PM PDT WEDNESDAY...TEMPERATURES WERE FOR
THE MOST PART A LITTLE MILDER AND A FEW DEGREES ABOVE NORMAL ACROSS
THE AREA TODAY. THE ONLY EXCEPTION TO THIS WAS OVER THE SOUTH BAY
WHERE AVERAGE TEMPERATURES WERE 1 TO 4 DEGREES FAHRENHEIT BELOW NORMAL
TODAY. HIGHS RANGED FROM THE MID 60S COAST TO THE 70S INLAND.

MID TO HIGH CLOUDS ARE DRIFTING IN OVER THE BAY AREA FROM THE
NORTHWEST. WINDS ARE MOSTLY LIGHT THIS EVENING AND THE RAIN IS
STILL SITUATED WELL TO THE NORTH OF THE BAY AREA. BELIEVE IT OR
NOT SHORTWAVE RIDGING IS STILL IN PLACE THIS EVENING OVER THE
FORECAST AREA WITH 500 MB HEIGHTS OVER THE SOUTH BAY STILL
HOVERING UP NEAR 580 DECAMETERS. 500 MB HEIGHTS WILL BRIEFLY
SUBSIDE A LITTLE AROUND 5 AM THURSDAY MORNING THEN BUMP UPWARDS
AGAIN TO WHERE THEY ARE NOW BY THURSDAY AFTERNOON. THE INCOMING
FRONTAL SYSTEM WILL BE ON THE WEAK SIDE WITH ONLY VERY LIGHT
AMOUNTS OF RAIN EXPECTED...MOSTLY OVER THE NORTHERN SONOMA COUNTY
COAST WHERE UP TO 1/3" TOTAL OF RAIN COULD FALL LATE TONIGHT AND
THURSDAY MORNING. THE NEWEST 00Z NAM MODEL DOES NOT PREDICT ANY
MEASURABLE RAINFALL ANYWHERE ELSE OVER THE AREA TONIGHT OR
THURSDAY. DEWPOINT TEMPERATURES ARE SOLIDLY HIGHER THIS EVENING
AREA-WIDE SO PERIODIC LIGHT DRIZZLE OR LIGHT RAIN IS STILL
POSSIBLE TO THE SOUTH OF SONOMA COUNTY AS THE WEAKENING SHORTWAVE
TROUGH SQUEEZES OUT A LITTLE BIT OF MOISTURE AS IT MOVES OVER THE
AREA. A FEW AREAS MAY SEE A TINY AMOUNT OF MEASURABLE RAINFALL
OVERNIGHT...UP TO A COUPLE HUNDREDTHS POSSIBLY. THE NEAR TERM FITS
PERFECTLY AS A LOW POP LOW QPF FORECAST. NOT PLANNING ON MAKING
ANY ADJUSTMENTS TO FIRST OR SECOND PERIOD POP FORECASTS.

ONCE THE WEAK TROUGH RIPPLES EAST AWAY FROM THE BAY AREA THURSDAY
ANOTHER (MORE AMPLIFIED AND STRENGTHENING) LOW PRESSURE SYSTEM NEAR
39N/134W FRIDAY EVENING MOVES NORTHEAST WITH THE MAIN MID-UPPER
LEVEL LOW PRESSURE AREA REACHING THE PAC NW EARLY SATURDAY
EVENING. THE LOW PRESSURE SYSTEM WILL BE TRAILING A COLD FRONT
EASTWARD WHICH WILL REACH NORTHERNMOST CA BY EARLY SAT MORNING AND
THEN THE BAY AREA DURING THE DAY SATURDAY. AS MUCH AS 1" RAINFALL
IS POSSIBLE OVER SONOMA...ABOUT 1/2"-3/4" NAPA AND MARIN COUNTIES
AND 2/10" OR LESS OVER THE REMAINDER OF THE BAY AREA AND NORTH
CENTRAL COAST. BY THE TIME THE LOW PRESSURE AREA GETS TO CA THE
STRONGEST JET STREAM DYNAMICS WILL HAVE ALREADY POSITIONED ITSELF
FORWARD OF THE TROUGH AXIS SUGGESTING AN ACCELERATION OF THE LOW
AS WELL AS THE HEAVIEST RAINFALL TO THE NORTH OF THE BAY AREA. IF
ONE IS TRAVELLING TO THE PACIFIC NW FOR THE WEEKEND EXPECT HEAVIER
STEADIER RAINS. MID LEVEL TEMPERATURES REACH ABOUT -18C OVER THE
NORTH BAY BY LATE SATURDAY MORNING...NOT AN EXCEPTIONALLY COLD SYSTEM.
THE 00Z NAM PREDICTS A SMALL POCKET...ALBEIT JUST BELOW 35...OF MODIFIED
TOTAL TOTALS MID LEVEL INSTABILITY BY 21Z SATURDAY OVER NORTHERN
SONOMA COUNTY. OFTEN TIMES LOW PRESSURE AREAS SWING OVER THE AREA
A LITTLE FASTER THAN MODELS PREDICT EVEN UP TO A COUPLE DAYS AHEAD
OF TIME...SO IT IS QUITE POSSIBLE THAT THE MID LEVEL INSTABILITY
ARRIVES IN THE NORTH BAY AREA AS EARLY AS VERY EARLY SATURDAY MORNING.
THE NAM DEPICTS THE MID LEVEL INSTABILITY QUICKLY JUMPING OVER TO
NAPA COUNTY THEN MOVING EAST TO THE NORTHERN SACRAMENTO VALLEY
SATURDAY. SLIGHT CHANCE OF T-STORMS WAS ADDED IN EARLIER TODAY AND
SEE NO REASON TO MAKE ANY CHANGES EXCEPT THERE`S A SMALL POSSIBILITY
THE T-STORM ACTIVITY MAY ARRIVE A LITTLE EARLIER THAN PRESENTLY
INDICATED.

THERE`S MUCH LESS CONFIDENCE REGARDING NEXT WEEK`S WEATHER AS THE MODELS
DIVERGE ON SOLUTIONS. FOR INSTANCE THE ECWMF AND GFS MODELS WANT TO
BRING RAIN TO THE AREA BY HALLOWEEN BUT THE GEM MODEL IS DRY. WAY TOO
EARLY TO SAY WITH ANY CONFIDENCE IF IT`LL BE WET OR DRY FOR TRICK OR
TREATERS.

&&

.PREVIOUS DISCUSSION...AS OF 3:05 PM PDT WEDNESDAY...SKIES ARE
CLEAR TO PARTLY CLOUDY WITH MID AFTERNOON TEMPERATURES AROUND THE
BAYS GENERALLY RUNNING IN THE UPPER 60S TO MID 70S...A COUPLE OF
DEGS WARMER THAN AT THE SAME TIME YESTERDAY. TONIGHT...THE WEAK
TAIL END OF A PACIFIC WEATHER SYSTEM NOW MOVING INTO THE PACIFIC
NORTHWEST WILL SPREAD IN INCREASING MID AND HIGH CLOUDINESS OVER
MORE NORTHERN PORTIONS OF OUR AREA. THEN ON THURSDAY...MODEL
SOLUTIONS INDICATE A LIKELIHOOD OF SOME RAIN SOUTH TO NEAR BODEGA
BAY...WITH A SLIGHT CHANCE AS FAR SOUTH AS ABOUT SAN FRANCISCO.
RAINFALL TOTALS LOOK TO BE QUITE LIGHT...EXCEPT IN THE FAR
NORTHERN COASTAL HILLS OF SONOMA COUNTY WHERE LOCAL AMOUNTS UP TO
THE 1/3 TO 1/2 INCH RANGE ARE POSSIBLE.

ANY RESIDUAL NORTH BAY SHOWERS SHOULD TAPER OFF AND END THURSDAY
NIGHT WITH DRY CONDITIONS THEN EXPECTED DISTRICT-WIDE ON FRIDAY
AS A SHORT WAVE UPPER LEVEL RIDGE TEMPORARILY BUILDS IN WESTWARD FROM
THE INTERIOR. BY LATE FRIDAY NIGHT HOWEVER...THE NEXT PACIFIC
WEATHER SYSTEM IS EXPECTED TO RAPIDLY APPROACH FROM THE NORTHWEST.
LATEST MODEL OUTPUT CONTINUES TO INDICATE IT WILL BE BOTH A BIT
STRONGER AND WETTER THAN THE ONE ON THURSDAY...WITH A LIKELIHOOD
OF AT LEAST SOME LIGHT PRECIP SPREADING AS FAR SOUTH AS THE
MONTEREY BAY REGION BY SATURDAY AFTERNOON. SHOULD ALSO NOTE THAT
BOTH LATEST NAM DETERMINISTIC MODEL OUTPUT SOUNDINGS AND SURFACE BASED
CAPE VALUES...AND SREF MUCAPE PLUMES...INDICATE A SUFFICIENT
POSSIBILITY OF CONVECTION SATURDAY AFTERNOON OVER THE NORTH BAY TO
WARRANT INCLUSION IN THE FORECAST OF MENTION OF A SLIGHT CHANCE OF
THUNDERSTORMS.

HERE AGAIN POST FRONTAL SHOWERS LOOK TO TAPER OFF AND END PRETTY
QUICKLY...WITH DRY WEATHER CONDITIONS RETURNING ACROSS ALL BUT
POSSIBLY THE EASTERNMOST MARGIN OF OUR AREA BY SUNDAY MORNING. DRY
CONDITIONS AND SEASONAL TEMPERATURES ARE EXPECTED ACROSS THE
DISTRICT THROUGH AT LEAST MONDAY NIGHT. THEREAFTER LONGER RANGE
MODEL SOLUTIONS BEGIN TO DIVERGE...WITH FOR EXAMPLE THE 12Z GFS
BRINGING IN ANOTHER WEAK SYSTEM AND LIGHT PRECIP TO THE NORTH BAY
ON TUESDAY WHILE THE ECMWF CONFINES ASSOCIATED RAINFALL TO AREAS
NORTH OF OUR CWA.

&&

.AVIATION...AS OF 5:00 PM PDT WEDNESDAY...VFR CONDITIONS WILL
PERSIST THROUGH LATE TONIGHT WITH HIGH CLOUDS STREAMING
ACROSS THE REGION. A FRONTAL BOUNDARY IS FORECAST TO APPROACH THE
NORTH BAY TONIGHT AND SHOULD HELP INCREASE THE AMOUNT OF LOW LEVEL
CLOUD COVER...ESPECIALLY OVER THE SAN FRANCISCO BAY AREA
NORTHWARD. LIGHT RAIN OR DRIZZLE WILL BE POSSIBLE OVER KSTS...YET
CONFIDENCE REMAINS LOW AND HAVE LEFT PRECIPITATION OUT OF THE TAF
FOR NOW. LOW CLOUDS THAT DO DEVELOP OVER THE REGION WILL BE SLOW
TO BURN-OFF THURSDAY MORNING. FURTHER SOUTH...CONFIDENCE IS LOWER
ON THE RETURN OF STRATUS OVER THE TERMINALS AS BOUNDARY LAYER
MOISTURE WILL BE SLOWER TO RETURN.

VICINITY OF KSFO...VFR CONDITIONS WILL CONTINUE THROUGH THIS
EVENING. LOW CLOUDS EXPECTED TO RETURN LATE TONIGHT. MODERATE
WINDS WILL EASE OVERNIGHT. MODERATE CONFIDENCE.

KSFO BRIDGE APPROACH...SIMILAR TO KSFO.

MONTEREY BAY AREA TERMINALS...VFR CONDITIONS WILL CONTINUE
THROUGH THIS EVENING. LOW CLOUDS EXPECTED TO RETURN AFTER MIDNIGHT.
MODERATE WINDS WILL EASE OVERNIGHT. MODERATE CONFIDENCE.

&&

.MARINE...AS OF 2:41 PM PDT WEDNESDAY...GENERALLY LIGHT NORTHWEST WINDS
WILL PERSIST ACROSS THE COASTAL WATERS THROUGH FRIDAY...WITH
MODERATE WIND SPEEDS OFF THE BIG SUR COAST. WIND SPEEDS WILL THEN
INCREASE AND BECOME SOUTHERLY FRIDAY NIGHT INTO SATURDAY AHEAD OF
AN APPROACHING COLD FRONT THAT WILL ALSO BRING CHANCES OF RAIN TO
THE REGION. NORTHWEST SWELL WILL SLOWLY DIMINISH THROUGH FRIDAY
THEN INCREASE OVER THE WEEKEND.

&&

.MTR WATCHES/WARNINGS/ADVISORIES...
     .TNGT...SCA...PT PINOS TO PT PIEDRAS BLANCAS 0-10 NM

&&

$$

PUBLIC FORECAST: CANEPA/BLIER
AVIATION: CW
MARINE: RGASS/DRP

VISIT US AT WEATHER.GOV/SANFRANCISCO

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







000
FXUS66 KMTR 230034
AFDMTR

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SAN FRANCISCO BAY AREA
534 PM PDT WED OCT 22 2014

.SYNOPSIS...DRY WEATHER CONDITIONS AND PARTLY CLOUDY SKIES ARE
EXPECTED TONIGHT...BUT THEN ON THURSDAY THE WEAK TAIL END OF AN
APPROACHING PACIFIC WEATHER SYSTEM WILL LIKELY BRING SOME LIGHT
RAINFALL TO NORTHERNMOST PORTIONS OF OUR DISTRICT. FRIDAY LOOKS TO
BE MOSTLY SUNNY AND MILD...BUT THEN A SOMEWHAT WETTER SYSTEM
WILL MOVE IN ON SATURDAY AND SPREAD RAIN CHANCES ACROSS MUCH OF
OUR AREA. DRY CONDITIONS AND SEASONAL TEMPERATURES ARE PROJECTED
FOR SUNDAY INTO THE FIRST PART OF NEXT WEEK.

&&

.DISCUSSION...AS OF 3:05 PM PDT WEDNESDAY...SKIES ARE CLEAR TO
PARTLY CLOUDY WITH MID AFTERNOON TEMPERATURES AROUND THE BAYS
GENERALLY RUNNING IN THE UPPER 60S TO MID 70S...A COUPLE OF DEGS
WARMER THAN AT THE SAME TIME YESTERDAY. TONIGHT...THE WEAK TAIL
END OF A PACIFIC WEATHER SYSTEM NOW MOVING INTO THE PACIFIC
NORTHWEST WILL SPREAD IN INCREASING MID AND HIGH CLOUDINESS OVER
MORE NORTHERN PORTIONS OF OUR AREA. THEN ON THURSDAY...MODEL SOLUTIONS
INDICATE A LIKELIHOOD OF SOME RAIN SOUTH TO NEAR BODEGA BAY...WITH
A SLIGHT CHANCE AS FAR SOUTH AS ABOUT SAN FRANCISCO. RAINFALL TOTALS
LOOK TO BE QUITE LIGHT...EXCEPT IN THE FAR NORTHERN COASTAL HILLS
OF SONOMA COUNTY WHERE LOCAL AMOUNTS UP TO THE 1/3 TO 1/2 INCH
RANGE ARE POSSIBLE.

ANY RESIDUAL NORTH BAY SHOWERS SHOULD TAPER OFF AND END THURSDAY
NIGHT WITH DRY CONDITIONS THEN EXPECTED DISTRICT-WIDE ON FRIDAY
AS A SHORT WAVE UPPER LEVEL RIDGE TEMPORARILY BUILDS IN WESTWARD FROM
THE INTERIOR. BY LATE FRIDAY NIGHT HOWEVER...THE NEXT PACIFIC
WEATHER SYSTEM IS EXPECTED TO RAPIDLY APPROACH FROM THE NORTHWEST.
LATEST MODEL OUTPUT CONTINUES TO INDICATE IT WILL BE BOTH A BIT
STRONGER AND WETTER THAN THE ONE ON THURSDAY...WITH A LIKELIHOOD
OF AT LEAST SOME LIGHT PRECIP SPREADING AS FAR SOUTH AS THE
MONTEREY BAY REGION BY SATURDAY AFTERNOON. SHOULD ALSO NOTE THAT
BOTH LATEST NAM DETERMINISTIC MODEL OUTPUT SOUNDINGS AND SURFACE BASED
CAPE VALUES...AND SREF MUCAPE PLUMES...INDICATE A SUFFICIENT
POSSIBILITY OF CONVECTION SATURDAY AFTERNOON OVER THE NORTH BAY TO
WARRANT INCLUSION IN THE FORECAST OF MENTION OF A SLIGHT CHANCE OF
THUNDERSTORMS.

HERE AGAIN POST FRONTAL SHOWERS LOOK TO TAPER OFF AND END PRETTY
QUICKLY...WITH DRY WEATHER CONDITIONS RETURNING ACROSS ALL BUT
POSSIBLY THE EASTERNMOST MARGIN OF OUR AREA BY SUNDAY MORNING. DRY
CONDITIONS AND SEASONAL TEMPERATURES ARE EXPECTED ACROSS THE
DISTRICT THROUGH AT LEAST MONDAY NIGHT. THEREAFTER LONGER RANGE
MODEL SOLUTIONS BEGIN TO DIVERGE...WITH FOR EXAMPLE THE 12Z GFS
BRINGING IN ANOTHER WEAK SYSTEM AND LIGHT PRECIP TO THE NORTH BAY
ON TUESDAY WHILE THE ECMWF CONFINES ASSOCIATED RAINFALL TO AREAS
NORTH OF OUR CWA.

&&

.AVIATION...AS OF 5:00 PM PDT WEDNESDAY...VFR CONDITIONS WILL
PERSIST THROUGH LATE TONIGHT WITH HIGH CLOUDS STREAMING
ACROSS THE REGION. A FRONTAL BOUNDARY IS FORECAST TO APPROACH THE
NORTH BAY TONIGHT AND SHOULD HELP INCREASE THE AMOUNT OF LOW LEVEL
CLOUD COVER...ESPECIALLY OVER THE SAN FRANCISCO BAY AREA
NORTHWARD. LIGHT RAIN OR DRIZZLE WILL BE POSSIBLE OVER KSTS...YET
CONFIDENCE REMAINS LOW AND HAVE LEFT PRECIPITATION OUT OF THE TAF
FOR NOW. LOW CLOUDS THAT DO DEVELOP OVER THE REGION WILL BE SLOW
TO BURN-OFF THURSDAY MORNING. FURTHER SOUTH...CONFIDENCE IS LOWER
ON THE RETURN OF STRATUS OVER THE TERMINALS AS BOUNDARY LAYER
MOISTURE WILL BE SLOWER TO RETURN.

VICINITY OF KSFO...VFR CONDITIONS WILL CONTINUE THROUGH THIS
EVENING. LOW CLOUDS EXPECTED TO RETURN LATE TONIGHT. MODERATE
WINDS WILL EASE OVERNIGHT. MODERATE CONFIDENCE.

KSFO BRIDGE APPROACH...SIMILAR TO KSFO.

MONTEREY BAY AREA TERMINALS...VFR CONDITIONS WILL CONTINUE
THROUGH THIS EVENING. LOW CLOUDS EXPECTED TO RETURN AFTER MIDNIGHT.
MODERATE WINDS WILL EASE OVERNIGHT. MODERATE CONFIDENCE.

&&

.MARINE...AS OF 2:41 PM PDT WEDNESDAY...GENERALLY LIGHT NORTHWEST WINDS
WILL PERSIST ACROSS THE COASTAL WATERS THROUGH FRIDAY...WITH
MODERATE WIND SPEEDS OFF THE BIG SUR COAST. WIND SPEEDS WILL THEN
INCREASE AND BECOME SOUTHERLY FRIDAY NIGHT INTO SATURDAY AHEAD OF
AN APPROACHING COLD FRONT THAT WILL ALSO BRING CHANCES OF RAIN TO
THE REGION. NORTHWEST SWELL WILL SLOWLY DIMINISH THROUGH FRIDAY
THEN INCREASE OVER THE WEEKEND.

&&

.MTR WATCHES/WARNINGS/ADVISORIES...
     .TNGT...SCA...PT PINOS TO PT PIEDRAS BLANCAS 0-10 NM

&&

$$

PUBLIC FORECAST: BLIER
AVIATION: CW
MARINE: RGASS/DRP

VISIT US AT WEATHER.GOV/SANFRANCISCO

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







000
FXUS66 KMTR 230034
AFDMTR

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SAN FRANCISCO BAY AREA
534 PM PDT WED OCT 22 2014

.SYNOPSIS...DRY WEATHER CONDITIONS AND PARTLY CLOUDY SKIES ARE
EXPECTED TONIGHT...BUT THEN ON THURSDAY THE WEAK TAIL END OF AN
APPROACHING PACIFIC WEATHER SYSTEM WILL LIKELY BRING SOME LIGHT
RAINFALL TO NORTHERNMOST PORTIONS OF OUR DISTRICT. FRIDAY LOOKS TO
BE MOSTLY SUNNY AND MILD...BUT THEN A SOMEWHAT WETTER SYSTEM
WILL MOVE IN ON SATURDAY AND SPREAD RAIN CHANCES ACROSS MUCH OF
OUR AREA. DRY CONDITIONS AND SEASONAL TEMPERATURES ARE PROJECTED
FOR SUNDAY INTO THE FIRST PART OF NEXT WEEK.

&&

.DISCUSSION...AS OF 3:05 PM PDT WEDNESDAY...SKIES ARE CLEAR TO
PARTLY CLOUDY WITH MID AFTERNOON TEMPERATURES AROUND THE BAYS
GENERALLY RUNNING IN THE UPPER 60S TO MID 70S...A COUPLE OF DEGS
WARMER THAN AT THE SAME TIME YESTERDAY. TONIGHT...THE WEAK TAIL
END OF A PACIFIC WEATHER SYSTEM NOW MOVING INTO THE PACIFIC
NORTHWEST WILL SPREAD IN INCREASING MID AND HIGH CLOUDINESS OVER
MORE NORTHERN PORTIONS OF OUR AREA. THEN ON THURSDAY...MODEL SOLUTIONS
INDICATE A LIKELIHOOD OF SOME RAIN SOUTH TO NEAR BODEGA BAY...WITH
A SLIGHT CHANCE AS FAR SOUTH AS ABOUT SAN FRANCISCO. RAINFALL TOTALS
LOOK TO BE QUITE LIGHT...EXCEPT IN THE FAR NORTHERN COASTAL HILLS
OF SONOMA COUNTY WHERE LOCAL AMOUNTS UP TO THE 1/3 TO 1/2 INCH
RANGE ARE POSSIBLE.

ANY RESIDUAL NORTH BAY SHOWERS SHOULD TAPER OFF AND END THURSDAY
NIGHT WITH DRY CONDITIONS THEN EXPECTED DISTRICT-WIDE ON FRIDAY
AS A SHORT WAVE UPPER LEVEL RIDGE TEMPORARILY BUILDS IN WESTWARD FROM
THE INTERIOR. BY LATE FRIDAY NIGHT HOWEVER...THE NEXT PACIFIC
WEATHER SYSTEM IS EXPECTED TO RAPIDLY APPROACH FROM THE NORTHWEST.
LATEST MODEL OUTPUT CONTINUES TO INDICATE IT WILL BE BOTH A BIT
STRONGER AND WETTER THAN THE ONE ON THURSDAY...WITH A LIKELIHOOD
OF AT LEAST SOME LIGHT PRECIP SPREADING AS FAR SOUTH AS THE
MONTEREY BAY REGION BY SATURDAY AFTERNOON. SHOULD ALSO NOTE THAT
BOTH LATEST NAM DETERMINISTIC MODEL OUTPUT SOUNDINGS AND SURFACE BASED
CAPE VALUES...AND SREF MUCAPE PLUMES...INDICATE A SUFFICIENT
POSSIBILITY OF CONVECTION SATURDAY AFTERNOON OVER THE NORTH BAY TO
WARRANT INCLUSION IN THE FORECAST OF MENTION OF A SLIGHT CHANCE OF
THUNDERSTORMS.

HERE AGAIN POST FRONTAL SHOWERS LOOK TO TAPER OFF AND END PRETTY
QUICKLY...WITH DRY WEATHER CONDITIONS RETURNING ACROSS ALL BUT
POSSIBLY THE EASTERNMOST MARGIN OF OUR AREA BY SUNDAY MORNING. DRY
CONDITIONS AND SEASONAL TEMPERATURES ARE EXPECTED ACROSS THE
DISTRICT THROUGH AT LEAST MONDAY NIGHT. THEREAFTER LONGER RANGE
MODEL SOLUTIONS BEGIN TO DIVERGE...WITH FOR EXAMPLE THE 12Z GFS
BRINGING IN ANOTHER WEAK SYSTEM AND LIGHT PRECIP TO THE NORTH BAY
ON TUESDAY WHILE THE ECMWF CONFINES ASSOCIATED RAINFALL TO AREAS
NORTH OF OUR CWA.

&&

.AVIATION...AS OF 5:00 PM PDT WEDNESDAY...VFR CONDITIONS WILL
PERSIST THROUGH LATE TONIGHT WITH HIGH CLOUDS STREAMING
ACROSS THE REGION. A FRONTAL BOUNDARY IS FORECAST TO APPROACH THE
NORTH BAY TONIGHT AND SHOULD HELP INCREASE THE AMOUNT OF LOW LEVEL
CLOUD COVER...ESPECIALLY OVER THE SAN FRANCISCO BAY AREA
NORTHWARD. LIGHT RAIN OR DRIZZLE WILL BE POSSIBLE OVER KSTS...YET
CONFIDENCE REMAINS LOW AND HAVE LEFT PRECIPITATION OUT OF THE TAF
FOR NOW. LOW CLOUDS THAT DO DEVELOP OVER THE REGION WILL BE SLOW
TO BURN-OFF THURSDAY MORNING. FURTHER SOUTH...CONFIDENCE IS LOWER
ON THE RETURN OF STRATUS OVER THE TERMINALS AS BOUNDARY LAYER
MOISTURE WILL BE SLOWER TO RETURN.

VICINITY OF KSFO...VFR CONDITIONS WILL CONTINUE THROUGH THIS
EVENING. LOW CLOUDS EXPECTED TO RETURN LATE TONIGHT. MODERATE
WINDS WILL EASE OVERNIGHT. MODERATE CONFIDENCE.

KSFO BRIDGE APPROACH...SIMILAR TO KSFO.

MONTEREY BAY AREA TERMINALS...VFR CONDITIONS WILL CONTINUE
THROUGH THIS EVENING. LOW CLOUDS EXPECTED TO RETURN AFTER MIDNIGHT.
MODERATE WINDS WILL EASE OVERNIGHT. MODERATE CONFIDENCE.

&&

.MARINE...AS OF 2:41 PM PDT WEDNESDAY...GENERALLY LIGHT NORTHWEST WINDS
WILL PERSIST ACROSS THE COASTAL WATERS THROUGH FRIDAY...WITH
MODERATE WIND SPEEDS OFF THE BIG SUR COAST. WIND SPEEDS WILL THEN
INCREASE AND BECOME SOUTHERLY FRIDAY NIGHT INTO SATURDAY AHEAD OF
AN APPROACHING COLD FRONT THAT WILL ALSO BRING CHANCES OF RAIN TO
THE REGION. NORTHWEST SWELL WILL SLOWLY DIMINISH THROUGH FRIDAY
THEN INCREASE OVER THE WEEKEND.

&&

.MTR WATCHES/WARNINGS/ADVISORIES...
     .TNGT...SCA...PT PINOS TO PT PIEDRAS BLANCAS 0-10 NM

&&

$$

PUBLIC FORECAST: BLIER
AVIATION: CW
MARINE: RGASS/DRP

VISIT US AT WEATHER.GOV/SANFRANCISCO

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







000
FXUS66 KMTR 222223
AFDMTR

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SAN FRANCISCO BAY AREA
323 PM PDT WED OCT 22 2014

.SYNOPSIS...DRY WEATHER CONDITIONS AND PARTLY CLOUDY SKIES ARE
EXPECTED TONIGHT...BUT THEN ON THURSDAY THE WEAK TAIL END OF AN
APPROACHING PACIFIC WEATHER SYSTEM WILL LIKELY BRING SOME LIGHT
RAINFALL TO NORTHERNMOST PORTIONS OF OUR DISTRICT. FRIDAY LOOKS TO
BE MOSTLY SUNNY AND MILD...BUT THEN A SOMEWHAT WETTER SYSTEM
WILL MOVE IN ON SATURDAY AND SPREAD RAIN CHANCES ACROSS MUCH OF
OUR AREA. DRY CONDITIONS AND SEASONAL TEMPERATURES ARE PROJECTED
FOR SUNDAY INTO THE FIRST PART OF NEXT WEEK.

&&

.DISCUSSION...AS OF 3:05 PM PDT WEDNESDAY...SKIES ARE CLEAR TO
PARTLY CLOUDY WITH MID AFTERNOON TEMPERATURES AROUND THE BAYS
GENERALLY RUNNING IN THE UPPER 60S TO MID 70S...A COUPLE OF DEGS
WARMER THAN AT THE SAME TIME YESTERDAY. TONIGHT...THE WEAK TAIL
END OF A PACIFIC WEATHER SYSTEM NOW MOVING INTO THE PACIFIC
NORTHWEST WILL SPREAD IN INCREASING MID AND HIGH CLOUDINESS OVER
MORE NORTHERN PORTIONS OF OUR AREA. THEN ON THURSDAY...MODEL SOLUTIONS
INDICATE A LIKELIHOOD OF SOME RAIN SOUTH TO NEAR BODEGA BAY...WITH
A SLIGHT CHANCE AS FAR SOUTH AS ABOUT SAN FRANCISCO. RAINFALL TOTALS
LOOK TO BE QUITE LIGHT...EXCEPT IN THE FAR NORTHERN COASTAL HILLS
OF SONOMA COUNTY WHERE LOCAL AMOUNTS UP TO THE 1/3 TO 1/2 INCH
RANGE ARE POSSIBLE.

ANY RESIDUAL NORTH BAY SHOWERS SHOULD TAPER OFF AND END THURSDAY
NIGHT WITH DRY CONDITIONS THEN EXPECTED DISTRICT-WIDE ON FRIDAY
AS A SHORT WAVE UPPER LEVEL RIDGE TEMPORARILY BUILDS IN WESTWARD FROM
THE INTERIOR. BY LATE FRIDAY NIGHT HOWEVER...THE NEXT PACIFIC
WEATHER SYSTEM IS EXPECTED TO RAPIDLY APPROACH FROM THE NORTHWEST.
LATEST MODEL OUTPUT CONTINUES TO INDICATE IT WILL BE BOTH A BIT
STRONGER AND WETTER THAN THE ONE ON THURSDAY...WITH A LIKELIHOOD
OF AT LEAST SOME LIGHT PRECIP SPREADING AS FAR SOUTH AS THE
MONTEREY BAY REGION BY SATURDAY AFTERNOON. SHOULD ALSO NOTE THAT
BOTH LATEST NAM DETERMINISTIC MODEL OUTPUT SOUNDINGS AND SURFACE BASED
CAPE VALUES...AND SREF MUCAPE PLUMES...INDICATE A SUFFICIENT
POSSIBILITY OF CONVECTION SATURDAY AFTERNOON OVER THE NORTH BAY TO
WARRANT INCLUSION IN THE FORECAST OF MENTION OF A SLIGHT CHANCE OF
THUNDERSTORMS.

HERE AGAIN POST FRONTAL SHOWERS LOOK TO TAPER OFF AND END PRETTY
QUICKLY...WITH DRY WEATHER CONDITIONS RETURNING ACROSS ALL BUT
POSSIBLY THE EASTERNMOST MARGIN OF OUR AREA BY SUNDAY MORNING. DRY
CONDITIONS AND SEASONAL TEMPERATURES ARE EXPECTED ACROSS THE
DISTRICT THROUGH AT LEAST MONDAY NIGHT. THEREAFTER LONGER RANGE
MODEL SOLUTIONS BEGIN TO DIVERGE...WITH FOR EXAMPLE THE 12Z GFS
BRINGING IN ANOTHER WEAK SYSTEM AND LIGHT PRECIP TO THE NORTH BAY
ON TUESDAY WHILE THE ECMWF CONFINES ASSOCIATED RAINFALL TO AREAS
NORTH OF OUR CWA.

&&

.AVIATION...AS OF 10:40 AM PDT WEDNESDAY...VFR CONDITIONS WILL
PERSIST THROUGH THE AFTERNOON/EVENING WITH HIGH CLOUDS STREAMING
ACROSS THE REGION. A FRONTAL BOUNDARY IS FORECAST TO APPROACH THE
NORTH BAY TONIGHT AND SHOULD HELP INCREASE THE AMOUNT OF LOW LEVEL
CLOUD COVER...ESPECIALLY OVER THE SAN FRANCISCO BAY AREA
NORTHWARD. LIGHT RAIN OR DRIZZLE WILL BE POSSIBLE OVER KSTS...YET
CONFIDENCE REMAINS LOW AND HAVE LEFT PRECIPITATION OUT OF THE TAF
FOR NOW. LOW CLOUDS THAT DO DEVELOP OVER THE REGION WILL BE SLOW
TO BURN-OFF THURSDAY MORNING. FURTHER SOUTH...CONFIDENCE IS LOWER
ON THE RETURN OF STRATUS OVER THE TERMINALS AS BOUNDARY LAYER
MOISTURE WILL BE SLOWER TO RETURN.

VICINITY OF KSFO...VFR. LIGHT WINDS INCREASE THIS AFTERNOON AS A
SEA-BREEZE DEVELOPS AND PUSHES INLAND. STRATUS POSSIBLE LATE
TONIGHT INTO THURSDAY MORNING. MODERATE CONFIDENCE BEYOND 06Z.

KSFO BRIDGE APPROACH...SIMILAR TO KSFO.

MONTEREY BAY AREA TERMINALS...VFR. LIGHT WINDS INCREASE SLIGHTLY
THIS AFTERNOON...YET WILL GENERALLY REMAIN BELOW 12 KT. STRATUS
POSSIBLE EARLY THURSDAY MORNING. LOW CONFIDENCE BEYOND 03Z.

&&

.MARINE...AS OF 2:41 PM PDT WEDNESDAY...GENERALLY LIGHT NORTHWEST WINDS
WILL PERSIST ACROSS THE COASTAL WATERS THROUGH FRIDAY...WITH
MODERATE WIND SPEEDS OFF THE BIG SUR COAST. WIND SPEEDS WILL THEN
INCREASE AND BECOME SOUTHERLY FRIDAY NIGHT INTO SATURDAY AHEAD OF
AN APPROACHING COLD FRONT THAT WILL ALSO BRING CHANCES OF RAIN TO
THE REGION. NORTHWEST SWELL WILL SLOWLY DIMINISH THROUGH FRIDAY
THEN INCREASE OVER THE WEEKEND.

&&

.MTR WATCHES/WARNINGS/ADVISORIES...
     .TNGT...SCA...PT PINOS TO PT PIEDRAS BLANCAS 0-10 NM

&&

$$

PUBLIC FORECAST: BLIER
AVIATION/MARINE: RGASS/DRP

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