Area Forecast Discussion
Issued by NWS San Francisco Bay Area, CA

Home | Current Version | Previous Version | Text Only | Print | Product List | Glossary On
Versions: 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50
000
FXUS66 KMTR 301742
AFDMTR

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SAN FRANCISCO BAY AREA
1042 AM PDT TUE SEP 30 2014

.SYNOPSIS...BUILDING HIGH PRESSURE OVER THE REGION WILL RESULT IN
A DRYING AND WARMING TREND THROUGH LATE WEEK. WITH THIS...DAYTIME
TEMPERATURES WILL BE AS MUCH AS 10 TO 15 DEGREES ABOVE SEASONAL
AVERAGES BY LATE WEEK.

&&

.DISCUSSION...AS OF 08:59 AM PDT TUESDAY...NO CHANGES NEEDED TO
THE ONGOING FORECAST THIS MORNING. LOW CLOUDS WILL BURN OFF
THROUGH LATE MORNING AND GIVE WAY TO MOSTLY SUNNY CONDITIONS.
PLEASE SEE PREVIOUS DISCUSSION FOR MORE DETAILS ON THE SHORT-TERM.
TODAY`S FOCUS WILL BE ON THE THURSDAY THROUGH SATURDAY TIME-FRAME
WITH TEMPERATURES POSSIBLY APPROACHING RECORD VALUES.

&&

.PREV DISCUSSION...AS OF 2:16 AM PDT TUESDAY...A POORLY DEFINED
1000 FOOT MARINE LAYER PERSISTS ALONG THE COAST THIS MORNING WITH
PATCHY MARINE CLOUDS DEVELOPING AROUND THE BAY AND VALLEYS ONCE
AGAIN THIS MORNING. ONSHORE GRADIENTS REMAIN AROUND 2 MB FROM SFO-
SAC WITH A VERY WEAK FRONT MOVING INTO FAR NORTHERN CALIFORNIA.
THIS BOUNDARY WILL WASH OUT BY MIDDAY AND IN ITS WAKE A STRONG
SURFACE PRESSURE GRADIENT WILL SET-UP ACROSS THE REGION. NORTH
WINDS WILL DEVELOP IN THE SAC VALLEY THIS EVENING AND THEN
OVERSPREAD THE NAPA HILLS BY LATER TONIGHT. NAM 925 MB WINDS ARE
FORECAST AROUND 25-35 MPH OVER THE RIDGES LATE TONIGHT THROUGH
EARLY WEDS MORNING. IN GENERAL THE WINDS ARE EXPECTED TO ONLY
IMPACT SOME OF THE HIGHER PEAKS ABOVE 2500 FEET...AS WE USUALLY
NEED A COLD ADVECTION PATTERN TO MIX THE AIR DOWN. THEREFORE WONT
ISSUE ANY WIND ADVISORIES AND JUST EXPECT THE USUAL WINDY SPOTS
LIKE MT DIABLO AND THE COUNTY LINE ALONG NAPA/YOLO AND NORTHERN
SONOMA TO SEE SOME OF THE STRONGER WINDS.

EXPECT TEMPERATURES TO WARM FROM 5-10 DEGREES ON WEDS UNDER THE
IDEAL ADIABATIC/DONWSLOPE WARMING PATTERN. RIDGE-TOP WINDS WILL EASE
BY MID-MORNING BUT THEN A MUCH DRIER AIRMASS WILL SETTLE OVER THE
REGION WHERE EVEN SUBTLE DOWNSLOPE WINDS WILL ALLOW VALLEYS TEMPS
TO QUICKLY SOAR INTO THE 80S AND LOWER 90S FOR MUCH OF THE BAY AREA.

BY THURSDAY HIGH PRESSURE WILL BE CENTERED OVER MUCH OF CALIFORNIA
WITH LIGHT BUT PERSISTENT OFFSHORE FLOW CONTINUING. 850 MB TEMPS
WILL WARM TO AROUND 20 CELSIUS BY THURSDAY AND THEN STAY BETWEEN
20-22 CELSIUS THROUGH THE WEEKEND. ALTHOUGH NOT EXCEEDINGLY WARM
ALOFT THE SURFACE AND LOW LEVEL PATTERN WILL PROMOTE WARM TO HOT
WEATHER ACROSS THE DISTRICT THURSDAY THROUGH SUNDAY. MOST OF THE
MOS GUIDANCE HINTS AT FRIDAY AS A POSSIBLY EXCEEDINGLY WARM DAY
WITH WIDESPREAD 90S AND SOME NEAR TRIPLE DIGIT HEAT.

HEAT IMPACTS WILL BE A CONCERN FOR SENSITIVE POPULATIONS (ELDERLY
AND YOUNG) AS WELL AS A PROLONGED PERIOD OF FIRE WEATHER CONCERNS.
WILL STILL HAVE TO MULL OVER POSSIBLE FIRE WEATHER HEADLINES BUT
LET DAY SHIFT COORDINATE THAT WITH LAND MANAGEMENT AGENCIES. ONE
SUBTLE MITIGATING FACTOR IS THE RAIN FROM LAST WEEK THAT HAS
RAISED SOME OF THE FUEL STICK READINGS. NONETHELESS IT WASN`T ENOUGH
RAIN TO HAVE LASTING IMPACTS GIVEN THE LONG TERM DROUGHT AND THE
FORECAST OF SEVERAL DAYS OF HOT WEATHER AND LOW HUMIDITY.

NO REAL CHANGE IN THE PATTERN UNTIL AT LEAST MONDAY WHEN SOME
ONSHORE WINDS RETURN TO THE COAST. LONG RANGE MODELS KEEP THE
RIDGE OVER THE WEST COAST AT LEAST THROUGH THE MIDDLE OF NEXT
WEEK.

&&

.AVIATION...AS OF 10:30 AM PDT TUESDAY...PATCHY LOW CLOUDS FILLED
IN ACROSS SF BAY SO BURN OFF TAKING A BIT LONGER THIS MORNING. NW
FLOW REINFORCING CLOUDS ACROSS MRY BAY THRU NOON. OTHERWISE VFR. LIGHT
SEA BREEZE THIS AFTERNOON. NORTHERLY GRADIENT SHOULD PREVENT LOW
CLOUD DEVELOPMENT TONIGHT EXCEPT SRN MRY BAY DURING THE EVENING
WHICH WOULD LIKELY CLEAR OUT LATER.

VICINITY OF KSFO...MVFR CIGS TO CLEAR SHORTLY. THEN VFR THROUGH
WEDNESDAY.

KSFO BRIDGE APPROACH...SIMILAR TO KSFO.

MONTEREY BAY AREA TERMINALS...NW FLOW BRINGING MORE STRATUS INTO
MRY BAY. SNS TO STAY VFR WITH MVFR POSSIBLE THRU AROUND NOON MRY.
CIGS LOOK TO COME BACK BRIEFLY TONIGHT BEFORE OFFSHORE FLOW AND
THE INCREASING NORTH GRADIENT CLEAR SKIES ONCE AGAIN.

&&

.CLIMATE...RECORD HIGH TEMPERATURES FOR WEDNESDAY THROUGH FRIDAY
(10/1 TO 10/3) ALONG WITH THE MOST RECENT DATE IT OCCURRED.

SF BAY AREA
.LOCATION.................10/1...........10/2............10/3...
 KENTFIELD................97/2012.......100/2012.........99/2012
 SAN RAFAEL..............104/1980.......106/1980........105/1980
 NAPA....................106/1980.......102/1980........103/1917
 SAN FRANCISCO............97/1980........96/1980.........97/1985
 SFO AIRPORT..............97/1980........96/1980.........94/1985
 OAKLAND (DOWNTOWN)......103/1980.......103/1980........100/1985
 OAKLAND AIRPORT..........94/1952........98/1980.........95/1985
 RICHMOND.................99/1980.......100/1980.........97/2012
 LIVERMORE...............102/1952.......106/1980........106/1980
 MOFFETT FIELD............93/1980........95/2012.........97/1985
 SAN JOSE.................97/1980........96/2012.........97/1985
 GILROY..................104/2001.......107/1980........106/1980

MONTEREY BAY AREA
.LOCATION.................10/1...........10/2............10/3...
 MONTEREY................103/1980.......101/1980.........96/1985
 SANTA CRUZ..............102/1965.......102/1980........102/1980
 SALINAS.................104/1980.......100/1980.........97/1985
 SALINAS AIRPORT.........105/1980.......103/1980.........99/1985
 KING CITY...............109/1980.......107/1980........102/1980

&&

.MARINE...AS OF 08:59 AM PDT TUESDAY...HIGH PRESSURE IS
STRENGTHENING OFF THE NORTHERN CALIFORNIA COAST. THIS WILL BRING
MODERATE NORTHWEST WINDS WITH STRONGEST WINDS OVER THE NORTHERN
OUTER WATERS. WINDS WILL DECREASE WEDNESDAY NIGHT AND THURSDAY AS
HIGH PRESSURE BUILDS OVER THE GREAT BASIN AND BRINGS OFFSHORE FLOW
TO THE AREA.

&&

.MTR WATCHES/WARNINGS/ADVISORIES...
     .TDAY...SCA...PT ARENA TO PT REYES 10-60 NM
             SCA...PT REYES TO PIGEON PT 10-60 NM
             SCA...PIGEON PT TO PT PINOS 10-60 NM
             SCA...PT PINOS TO PT PIEDRAS BLANCAS 10-60 NM
             SCA...PT ARENA TO PT REYES 0-10 NM
             SCA...PT PINOS TO PT PIEDRAS BLANCAS 0-10 NM

&&

$$

PUBLIC FORECAST: RGASS
AVIATION/MARINE: AC
CLIMATE: BELL

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






USA.gov is the U.S. government's official web portal to all federal, state and local government web resources and services.