306  
FXUS66 KMTR 271208 CCA  
AFDMTR  
 
AREA FORECAST DISCUSSION  
NATIONAL WEATHER SERVICE SAN FRANCISCO BAY AREA  
502 AM PDT FRI MAY 27 2016  
   
SYNOPSIS
 
INLAND WARMING TREND WILL CONTINUE TODAY AND LAST INTO  
SATURDAY AS WARM NORTH WINDS MOVE INTO THE BAY AREA TONIGHT INTO  
SATURDAY. A BRIEF COOLING TREND SUNDAY AS THE MARINE LAYER PUSHES  
WELL INLAND AGAIN, THEN SIGNIFICANT WARMING MEMORIAL DAY AND  
TUESDAY AS WARM HIGH PRESSURE BUILDS. ANOTHER DRY UPPER TROUGH MAY  
APPROACH LATER NEXT WEEK WITH A COOLING TREND BUT NO RAIN IN THE  
FORECAST THE NEXT 7 DAYS.  
 

 
   
DISCUSSION...AS OF 3:51 AM PDT FRIDAY
 
NORTHERLY GRADIENT  
APPROACHING 6 MB AT THIS HOUR IS KEEPING SONOMA AND MARIN CLOUD  
FREE WHILE SOME LOW CLOUDS HAVE DEVELOPED IN NAPA COUNTY WITH A  
2.2 MB ONSHORE WIND PRODUCING 20 MPH WINDS IN THE DELTA EARLY THIS  
MORNING. FARTHER SOUTH LOW CLOUDS COVER THE MONTEREY BAY REGION  
BUT WILL PULL BACK TO THE COAST BY MID-MORNING. THE NORTHERLY  
GRADIENT WELL HELP TO SIGNAL A WARMING TREND FOR INLAND AREAS WITH  
TEMPERATURES FORECAST TO WARM AS MUCH AS 5-10 DEGREES FROM  
THURSDAY, SO EXPECTING MORE NUMEROUS READINGS INTO THE 80S THIS  
AFTERNOON FOR THE INLAND VALLEYS.  
 
TONIGHT SOME NORTH WINDS WILL DROP DOWN THE SAC VALLEY AND MOVE  
INTO THE NORTH AND EAST BAY HILLS AFTER MIDNIGHT. SOME FIRE  
WEATHER CONCERNS HERE WITH A WARM NIGHT AND LOW HUMIDITY IN THE  
HILLS. IN GENERAL NORTH WINDS IN THE 20-30 MPH RANGE ABOVE 1500  
FEET, STRONGEST ALONG THE NAPA COUNTY LINE. TONIGHT'S WIND SHOULD  
ERODE THE MARINE CLOUDS AND ONLY EXPECTING SOME PATCHES FROM  
THE MONTEREY PENINSULA SOUTHWARD FOR SATURDAY MORNING. THIS WILL  
SET THE STAGE FOR CONTINUED WARMING ON SATURDAY WITH HIGHS WELL  
INTO THE 80S AND AND EVEN SOME 90S FOR THE INTERIOR VALLEYS.  
 
NAM MODEL SUGGESTS WE'LL SEE A MARINE PUSH SATURDAY NIGHT INTO  
SUNDAY MORNING AS ONSHORE WINDS RETURN. SO IN GENERAL EXPECT A  
COOLING TREND, ESPECIALLY NEAR THE COAST AND BAYS ON SUNDAY BUT  
NOTHING TOO SIGNIFICANT INLAND AS 850 MB TEMPS WONT CHANGE MUCH,  
HOVERING AROUND 17 CELSIUS.  
 
ECMWF BUILDS A 585 DM HIGH TO OUR WEST BY MEMORIAL DAY WITH A  
THERMAL TROUGH ALONG THE COAST. THERE COULD BE SOME LIGHT OFFSHORE  
FLOW UNDER THE PATTERN WITH 850 MB TEMPS PUSHING 20-21 CELSIUS.  
THIS ALL SUGGESTS SOME INLAND WARMTH WELL INTO THE 90S AND PERHAPS  
EVEN SOME NEAR TRIPLE DIGIT HEAT FOR THE USUAL HOTTEST INLAND  
SPOTS. EITHER WAY MONDAY AND TUESDAY LOOKING WARM TO HOT INLAND  
WITH MINIMAL COASTAL STRATUS.  
 
NEXT UPPER TROUGH ARRIVES BY ABOUT NEXT THURSDAY WITH PERHAPS SOME  
COOLING SOUTHERLY WINDS ON WEDNESDAY AHEAD OF THE TROUGH AND  
BEHIND THE DEPARTING RIDGE. EITHER WAY THE FORECAST REMAINS DRY  
THROUGH NEXT WEEK.  
 

 
   
AVIATION...AS OF 5:00 AM PDT FRIDAY
 
STRONG NORTHERLY FLOW  
SUPPRESSING MARINE STRATUS NORTH OF PT REYES THIS MORNING. WEAK  
ONSHORE GRADIENT BETWEEN PT REYES AND HALF MOON BAY LIMITING  
INTRUSION INTO THE SF BAY AREA. FROM HALF MOON BAY SOUTHWARD, MORE  
FAVORABLE ONSHORE FLOW ALLOWING MARINE AIR MASS TO INTRUDE INLAND.  
SOUTHERLY FLOW IN SANTA CLARA VALLEY ADVECTING STRATUS NORTHWARD  
FROM THE MONTEREY BAY REGION INTO THE SAN JOSE REGION. GENERALLY  
EXPECT MOSTLY VFR NORTH OF THE SAN MATEO BRIDGE WITH MVFR POSSIBLE  
SOUTHWARD.  
ONSHORE FLOW INCREASES THIS AFTERNOON WITH SUSTAINED WINDS 15-20  
KT WITH GUSTS 20-30 KTS. FOR TONIGHT, MARINE DECK WILL BE SIMILAR TO  
THIS MORNING, WITH MOSTLY VFR FOR SF BAY AND A LATER ARRIVAL OF  
MVFR/IFR FOR MONTEREY BAY.  
 
VICINITY OF KSFO...MOSTLY VFR WITH BRIEF MVFR POSBL AROUND  
SUNRISE. ONSHORE WINDS 15-20KT GUST 25 TO 30KT AFTER IN THE  
AFTERNOON. VFR TONIGHT.  
 
SFO BRIDGE APPROACH...SIMILAR TO KSFO.  
 
MONTEREY BAY TERMINALS...MVFR CIGS WILL LINGER INTO THE LATE  
MORNING TO EARLY AFTERNOON. MVFR/IFR CIGS RETURN OVERNIGHT AFTER  
5Z.  
 

 
   
MARINE...AS OF 04:56 AM PDT FRIDAY
 
STRONG AND GUSTY NORTHWEST  
WINDS WILL CONTINUE TODAY AS HIGH PRESSURE PERSISTS OVER THE  
COASTAL WATERS. GALE FORCE WINDS WILL BE POSSIBLE FOR THE NORTHERN  
OUTER WATERS. OVER THE MEMORIAL DAY WEEKEND THIS HIGH PRESSURE  
CENTER WILL GRADUALLY WEAKEN. NORTHWEST WINDS WILL CONTINUE EARLY  
NEXT WEEK BUT ARE NOT EXPECTED TO BE QUITE AS GUSTY.  
 

 
   
MTR WATCHES/WARNINGS/ADVISORIES
 
 
.TDAY...SCA...PIGEON PT TO PT PINOS 0-10 NM FROM 9 AM  
GLW...PT ARENA TO PIGEON PT 10-60 NM  
SCA...PT PINOS TO PT PIEDRAS BLANCAS 0-10 NM UNTIL 9 AM  
SCA...PT PINOS TO PT PIEDRAS BLANCAS 0-10 NM FROM 3 PM  
SCA...PT ARENA TO PT REYES 0-10 NM  
SCA...PIGEON PT TO PT PIEDRAS BLANCAS 10-60 NM  
SCA...PT REYES TO PIGEON PT 0-10 NM  
SCA...ROUGH BAR ADVISORY FOR SF BAR  
 

 
 

 
 
PUBLIC FORECAST: RWW  
AVIATION: DRP  
MARINE: DRP  
 
VISIT US AT WWW.WEATHER.GOV/SANFRANCISCO  
 
FOLLOW US ON FACEBOOK AND TWITTER AT:  
WWW.FACEBOOK.COM/NWSBAYAREA  
WWW.TWITTER.COM/NWSBAYAREA  
 
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