651  
FXUS66 KMTR 261206  
AFDMTR  
 
AREA FORECAST DISCUSSION  
NATIONAL WEATHER SERVICE SAN FRANCISCO BAY AREA  
506 AM PDT MON SEP 26 2016  
   
SYNOPSIS
 
STRONG HIGH PRESSURE OVER THE REGION AND OFFSHORE  
FLOW WILL ONCE AGAIN RESULT IN EXTREMELY WARM TEMPERATURES OVER  
THE SAN FRANCISCO BAY AREA AND MONTEREY BAY REGION THIS AFTERNOON.  
MODEST COOLING IS FORECAST BY TUESDAY WITH A MORE SIGNIFICANT  
COOLING TREND EXPECTED FOR THE SECOND HALF OF THE WEEK AS AN UPPER  
LEVEL TROUGH DEEPENS ALONG THE WEST COAST.  
 

 
   
DISCUSSION...AS OF 4:28 AM PDT MONDAY
 
HEAT ADVISORY REMAINS IN  
EFFECT TODAY WITH ANOTHER ROUND OF HOT TEMPERATURES AND A GOOD  
CHANCE OF TYING OR BREAKING SOME MORE RECORDS...OR AT LEAST MAKING  
A GOOD RUN AT THEM. NOT SURPRISINGLY MOST OF THE TRENDS AT THIS  
HOUR SHOW TEMPERATURES RUNNING SEVERAL DEGREES OF WHERE THEY WERE  
THIS TIME YESTERDAY. THE SFO-WMC GRADIENT HAS EASED FROM 14 MB TO  
9 MB WITH THE NORTHERLY GRADIENT DOWN THE COAST FLAT SO WE WILL  
LOSE SOME OF THE IDEAL ADIABATIC WARMING. EITHER WAY ITS SPLITTING  
HAIRS AS ALL SIGNS POINT TO ANOTHER VERY WARM TO HOT DAY. 4 AM  
READINGS OF 68 IN THE CITY AND 71 AT DOWNTOWN OAKLAND PORTEND  
ANOTHER HOT DAY.  
 
SO THE NEXT FORECAST CHALLENGE BECOMES WHEN WILL THE COOLING TREND  
BEGIN. WE SHOULD SEE AT LEAST AN INKLING OF A SEABREEZE BY LATE  
THIS AFTERNOON AND EVENING AS WINDS BRIEFLY TURN WESTERLY. WE WILL  
LOSE THE OFFSHORE WINDS BUT NOT SEEING SIGNS OF A SOUTHERLY SURGE  
OR SIGNIFICANT COOLING FOR TUESDAY. NONETHELESS EXPECT TO SEE A  
FEW DEGREES OF COOLING INLAND ON TUESDAY BUT MORE NOTED COOLING  
ONLY NEAR THE COAST TUESDAY AFTERNOON.  
 
THE BEACHES SHOULD GET A DECENT MARINE PUSH LATER TUESDAY NIGHT  
INTO WEDS MORNING. INLAND LOCATIONS WILL THEN SEE MUCH MORE  
DRAMATIC COOLING FOR WEDS AFTERNOON. MOST PLACES WILL BE 15 TO 25  
DEGREES COOLER BY WEDS COMPARED TO THIS AFTERNOON.  
 
ECMWF SOLUTION THEN BRINGS A FAIRLY COOL TROUGH DOWN THE WEST  
COAST THE SECOND HALF OF THE WEEK...SENDING TEMPERATURES BELOW  
NORMAL THURSDAY THROUGH SATURDAY. HOWEVER, NO PRECIPITATION IS  
FORECAST WITH THE TROUGH WITH ALL LONG RANGE GUIDANCE STILL  
KEEPING THINGS DRY INTO OCTOBER.  
 

 
   
AVIATION...AS OF 5:00 AM PDT MONDAY
 
STRONG UPPER LEVEL HIGH  
OVER THE AREA. OFFSHORE FLOW HAS DIMINISHED BUT LACK OF ONSHORE  
FLOW WILL KEEP VFR CLEAR CONDITIONS.  
 
VICINITY OF KSFO...VFR.  
 
SFO BRIDGE APPROACH...VFR.  
 
MONTEREY BAY TERMINALS...VFR.  
 

 
   
FIRE WEATHER...AS OF 4:28 AM PDT MONDAY
 
FOR SAWMILL FIRE  
EXPECT ANOTHER HOT AND DRY DAY BUT THE OFFSHORE BREEZES ARE  
EASING. WINDS WILL BE LIKE A TURNSTILE TURNING LIGHT SOUTHERLY  
THIS AFTERNOON...THEN LIGHT OFFSHORE/NORTHEAST AGAIN TONIGHT. VERY  
WARM TEMPS WELL INTO THE 90S WITH HUMIDITY IN THE TEENS. ONLY  
SUBTLE COOLING TUESDAY WITH ANY SIGNIFICANT COOLING HOLDING OFF  
UNTIL WEDS.  
 
SOBERANES FIRE...NOT EXPECTING ANY OF THE STRONG SOUTHERLY WINDS  
THAT WERE OBSERVED SUNDAY. CURRENT TRENDS SHOW TEMPS STARTING OUT  
TODAY MUCH WARMER AND DRIER WITH SINGLE DIGIT HUMIDITY ALREADY IN  
PLACE. EXPECT OVER 100 DEGREES FOR TASSAJARA AND ARROYO SECO AND  
MID TO UPPER 90S EVEN FOR PORTIONS OF THE WEST OPS. REALLY NO  
CHANGES OF NOTE ON TUESDAY WITH PERHAPS A FEW DEGREES OF COOLING  
BUT STILL DRY. WILL NEED TO WAIT UNTIL WEDS FOR ANY APPRECIABLE  
INLAND COOLING BUT EVEN THAT WILL BE MODERATED FOR THE INTERIOR  
PORTIONS OF THE FIRE/FOREST.  
 

 
   
CLIMATE
 
HERE ARE THE RECORD HIGHS FOR SEPTEMBER 26.  
 
SEPTEMBER 26  
RECORD/YEAR  
BAY AREA  
 
KENTFIELD.............99/1921  
SAN RAFAEL............99/1963  
NAPA.................105/1963  
SAN FRANCISCO.........94/1992  
SFO...................95/1958  
OAKLAND MUSEUM........93/1973  
OAKLAND AIRPORT.......97/1958  
RICHMOND..............95/1963  
LIVERMORE............103/1952  
MOUNTAIN VIEW.........95/1999  
SAN JOSE..............98/1963  
GILROY...............104/1963  
 
MONTEREY BAY AREA  
 
MONTEREY...............98/1970  
SANTA CRUZ............101/1970  
SALINAS...............100/1970  
SALINAS AIRPORT........99/1970  
KING CITY.............105/1963  
 

 
   
MARINE...AS OF 03:46 AM PDT MONDAY
 
HIGH PRESSURE COVERS THE  
EASTERN PACIFIC AND THE GREAT BASIN WHILE THERMAL TROUGH LIES  
ALONG THE CALIFORNIA COAST. THE TROUGH WILL MOVE INTO THE  
CALIFORNIA INTERIOR ON TUESDAY. WINDS WILL BE LIGHT AND VARIABLE  
MONDAY THEN INCREASE FROM THE NORTHWEST TUESDAY AND WEDNESDAY.  
 

 
   
MTR WATCHES/WARNINGS/ADVISORIES
 
 
.TDAY...HEAT ADVISORY...ALL ZONES 11 AM TO 8 PM  
 

 
 

 
 
PUBLIC FORECAST: RWW  
AVIATION: W PI  
MARINE: W PI  
CLIMATE: BAM/DRP  
FIRE WEATHER: RWW  
 
VISIT US AT WWW.WEATHER.GOV/SANFRANCISCO  
 
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WWW.FACEBOOK.COM/NWSBAYAREA  
WWW.TWITTER.COM/NWSBAYAREA  
 
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