286  
FXUS66 KMTR 281117  
AFDMTR  
 
AREA FORECAST DISCUSSION  
NATIONAL WEATHER SERVICE SAN FRANCISCO BAY AREA  
417 AM PDT SUN MAY 28 2017  
   
SYNOPSIS
 
DRY WEATHER AND SEASONABLE TEMPERATURES ARE FORECAST FOR  
THE REMAINDER OF THE HOLIDAY WEEKEND. SLIGHT COOLING IS EXPECTED FOR  
INLAND AREAS ON TUESDAY AND WEDNESDAY, BUT OTHERWISE LITTLE  
CHANGE IS FORECAST THROUGH THE WEEK.  
   
DISCUSSION...AS OF 3:05 AM PDT SUNDAY
 
THE MARINE LAYER HAS  
BEEN RATHER ILL-DEFINED OVERNIGHT AND LOW CLOUDS HAVE BEEN SLOW TO  
DEVELOP, ESPECIALLY FROM SANTA CRUZ COUNTY SOUTHWARD. HOWEVER,  
SATELLITE CURRENTLY SHOWS THAT LOW CLOUDS HAVE FILLED IN AROUND  
MOST OF SAN FRANCISCO BAY AND ARE GRADUALLY DEVELOPING ELSEWHERE.  
 
LOW CLOUDS ARE EXPECTED TO CLEAR FROM INLAND AREAS BY LATE THIS  
MORNING, BUT ONLY PARTIAL AFTERNOON CLEARING IS LIKELY AT THE  
COAST. THE AIRMASS ABOVE THE MARINE BOUNDARY LAYER HAS WARMED  
SINCE YESTERDAY AND THIS WILL TRANSLATE INTO WARMER AFTERNOON  
HIGHS FOR MOST INLAND AREAS. TEMPERATURES IN COASTAL AREAS TODAY  
WILL PROBABLY BE SIMILAR TO YESTERDAY.  
 
THE UPPER RIDGE CURRENTLY CENTERED OVER CALIFORNIA IS FORECAST TO  
SHIFT GRADUALLY EASTWARD OVER THE NEXT FEW DAYS. THIS IS EXPECTED  
TO RESULT IN AT LEAST MODEST COOLING IN COASTAL AREAS ON MEMORIAL  
DAY. BUT TEMPERATURES FOR INLAND AREAS ARE FORECAST TO HOLD  
STEADY. THE UPSHOT IS THAT OUR AREA CAN EXPECT ONLY MINOR CHANGES  
FOR THE REMAINDER OF THE HOLIDAY WEEKEND, WITH AREAS OF NIGHT AND  
MORNING LOW CLOUDS CONTINUING. TEMPERATURES WILL REMAIN SLIGHTLY  
COOLER THAN NORMAL IN COASTAL AREAS AND NEAR NORMAL INLAND.  
 
A WEAK UPPER TROUGH IS FORECAST TO GRADUALLY DEVELOP NEAR THE WEST  
COAST BY TUESDAY. THIS SHOULD RESULT IN AT LEAST MODEST COOLING ON  
TUESDAY AND WEDNESDAY, ESPECIALLY INLAND, AS A COOLER AIRMASS  
OVERSPREADS OUR AREA. HOWEVER, MODEL GUIDANCE, ESPECIALLY THE  
ECMWF, INDICATE VERY LITTLE CHANGE IN TEMPERATURES AS WE MOVE  
THROUGH THE WEEK.  
 
THE MODELS FORECAST PERIODIC ISOLATED LIGHT PRECIPITATION ACROSS  
NORTHERN CALIFORNIA FROM LATE MONDAY THROUGH WEDNESDAY AS THE  
UPPER TROUGH SETTLES IN. NEARLY ALL OF THIS PRECIPITATION IS  
EXPECTED REMAIN OVER THE HIGHER MOUNTAINS TO OUR NORTH AND EAST.  
HOWEVER, THE 00Z ECMWF SHOWS ISOLATED LIGHT PRECIPITATION ACROSS  
PORTIONS OF OUR AREA ON WEDNESDAY AS A SHORTWAVE TROUGH MOVES  
THROUGH. FORECAST CONFIDENCE IS NOT YET HIGH ENOUGH TO ADD RAIN  
CHANCES TO THE FORECAST. HOWEVER, PATCHY DRIZZLE IS CERTAINLY  
POSSIBLE AT TIMES IN COASTAL AREAS, PARTICULARLY FROM LATE MONDAY  
NIGHT THROUGH WEDNESDAY MORNING.  
 

 
   
AVIATION...AS OF 04:15 AM PDT SUNDAY
 
SHALLOW MARINE LAYER NEAR  
1K FT PER SODARS CONTINUES TO DEVELOP AND SPREAD EARLY THIS  
MORNING. EXPECTING A MIX OF IFR AND MVFR CONDITIONS THIS AM WITH  
VFR THIS AFTERNOON. GIVEN THE SHALLOW NATURE EXPECTING AN EARLY  
BURN OFF, WHICH FITS WITH HI-RES WRF OUTPUT. CIGS RETURN TONIGHT.  
 
VICINITY OF KSFO...MVFR CIGS CLEARING 17-18Z. CIGS RETURN TONIGHT.  
 
SFO BRIDGE APPROACH...SIMILAR TO KSFO.  
 
MONTEREY BAY TERMINALS...IFR TO MVFR CIGS THIS AM. CLEARING  
17-18Z.  
 

 
   
MARINE...AS OF 04:15 AM PDT SUNDAY
 
NORTHERLY WINDS WILL  
INCREASE ACROSS ALL WATERS TODAY AS HIGH PRESSURE BUILDS OFF THE  
WEST COAST. THE GUSTY WINDS WILL PRODUCE HAZARDOUS CONDITIONS  
WITH STEEPER WIND WAVES AND FRESH SWELL. WINDS WILL DECREASE  
TUESDAY NIGHT AS A WEAK FRONTAL SYSTEM MOVES THROUGH THE COASTAL  
WATERS.  
 

 
   
MTR WATCHES/WARNINGS/ADVISORIES
 
 
.TDAY...SCA...PT ARENA TO PT REYES 0-10 NM FROM 9 AM  
SCA...PT REYES TO PIGEON PT 0-10 NM FROM 9 AM  
SCA...PIGEON PT TO PT PINOS 0-10 NM FROM 9 AM  
SCA...PT ARENA TO PIGEON PT 10-60 NM FROM 9 AM  
SCA...PIGEON PT TO PT PIEDRAS BLANCAS 10-60 NM FROM 9 AM  
SCA...PT PINOS TO PT PIEDRAS BLANCAS 0-10 NM  
SCA...MRY BAY FROM 9 AM  
SCA...SF BAY FROM 12 PM  
 

 
 

 
 
PUBLIC FORECAST: DYKEMA  
AVIATION: MM  
MARINE: MM  
 
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