297  
AGPN40 KWNM 232035  
MIMPAC  
 
MARINE WEATHER DISCUSSION FOR N PACIFIC OCEAN  
NWS OCEAN PREDICTION CENTER WASHINGTON DC  
135 PM PDT THU MAR 23 2017  
   
FORECAST DISCUSSION
 
MAJOR FEATURES/WINDS/SEAS/SIGNIFICANT  
.WEATHER FOR THE NORTH PACIFIC N OF 30N AND E OF 150W.  
 
GRIDS: 12Z GFS INTO SATURDAY NIGHT, THEN A TRANSITION TOWARDS THE  
12Z ECMWF THEREAFTER. DISCUSSION FOLLOWS.  
 
GOES W PROVIDING SPECTACULAR VISIBLE SATELLITE IMAGERY THIS  
AFTERNOON OF STRONG LOW PRESSURE LIFTING NORTHEAST TOWARDS HAIDA  
GWAII, WHILE AT THE SAME TIME PULLING A RATHER STRONG FRONTAL  
BOUNDARY EAST ACROSS THE NORTHERN OFFSHORE WATERS OF THE E  
PACIFIC. FOR THE PAST SEVERAL DAYS LEADING UP TO THE EVENT,  
INCLUDING RECENT REGIONAL RUNS OF THE HRRR AND 4KM NAM, FORECAST  
MODELS HAVE BEEN OUTSTANDING AND CONSISTENT PINPOINTING THE  
TIMING AND STRENGTH OF THE PASSING FRONT. A VERY FORTUNATE ASCAT  
METOP-B OVERPASS JUST AFTER 18Z TODAY RETURNED GREAT COVERAGE OF  
THE FRONTAL BOUNDARY, AND AS EXPECTED WIDESPREAD GALE FORCE  
WINDS WERE DETECTED OVER PORTIONS OF ALL OPC OFFSHORE ZONES  
NORTH OF ABOUT 40N. THESE WINDS CONTINUE TO BE WELL RESOLVED IN  
LATEST GFS OUTPUT. HOURLY GFS AND 4KM NAM SWEEP THE FRONT AND ITS  
ASSOCIATED GALES EAST OF THE OPC AOR JUST AFTER 03Z THIS  
EVENING. STILL EXPECT STRONGEST WINDS TO 40 KT ACROSS THE INNER  
OR WATERS AROUND AND AFTER 21Z TODAY ASSOCIATED WITH  
STRENGTHENING LOW LEVEL JET AS THE FRONT DRAWS NEARER TO THE  
COAST. HIGHEST WINDS SHOULD REMAIN WITHIN THE COASTAL ZONES,  
WHERE GUSTS EXCEEDING STORM FORCE POSSIBLE IN THE WATERS ADJACENT  
TO TO CAPE BLANCO.  
 
FARTHER SOUTH, THE SAME ASCAT OVERPASS DID CONTAIN A SEVERAL 30  
KT WIND RETRIEVALS IN THE VICINITY OF, AND DUE SOUTH OF THE  
CHANNEL ISLANDS. WILL MAKE THE NECESSARY MINOR ADJUSTMENTS IN THE  
INITIAL GFS GRIDS TO ENSURE 30 KT ARE IN THE TONIGHT PORTION OF  
ZONE 840.  
 
AFTER LATE SATURDAY NIGHT, OFFICIAL FORECAST GRIDS WILL TRANSITION  
CLOSER TO THE 12Z ECMWF. FOR THE PAST SEVERAL DAYS, THE EURO HAS  
REMAINED VERY CONSISTENT BRINGING ANOTHER COLD FRONT OVER THE  
NORTHERN OFFSHORES SUN AND SUN NIGHT. THE GFS HAS VACILLATED  
BETWEEN WILDLY DIFFERING SOLUTIONS FOR SEVERAL CYCLES IN A ROW,  
MOST NOTABLY AT ONE POINT FORMING A SUB 995 TRIPLE POINT STALLED  
LOW OVER THE WA WATERS. MODELS ARE SEEMINGLY CONVERGING ON A  
CONSENSUS SOLUTION FOR TIMING OF THE FRONT, BUT AGAIN, FEEL IT  
BEST TO USE THE MORE STABLE ECMWF. AND BASED ON THE UNCERTAINTY  
STILL PRESENT, WILL CONTINUE CAP PRE-FRONT WINDS TO 30 KT. WOULD  
NOT BE SURPRISED TO SEE WARNING HEADLINES ADDED AS THE EVENT  
DRAWS NEARER - AND CONFIDENCE INCREASES.  
 
MON THROUGH TUE NIGHT: ALL GUIDANCE SUGGESTS A STRONG PRESSURE  
GRADIENT SETTING UP BETWEEN BUILDING EPAC HIGH PRESSURE AND  
FORMING LOW OVER THE INTERIOR GREAT BASIN, WITH WIDESPREAD  
PREVAILING N-LIES OVER OPC ZONES SOUTH OF ABOUT SAN FRANCISCO  
BAY. WITH MODELS CONTINUING TO SIGNAL THIS STRONG GRADIENT, FEEL  
COMFORTABLE BUMPING UP MAX WINDS TO THE 30 KT THRESHOLD. SHOULD  
MODELS REMAIN CONSISTENT, WOULD EXPECT TO SEE GALE WARNING  
HEADLINES INTRODUCED AT SOME POINT.  
 
SEAS: IN SIMILAR FASHION TO THE WIND GRIDS, WILL USE THE WW3 ENP  
INTO SAT NIGHT, THEN TRANSITION TOWARDS THE ECMWF WAM THEREAFTER.  
 
EXTRATROPICAL STORM SURGE GUIDANCE: N/A.  
 
   
WARNINGS
 
PRELIMINARY.  
   
PZ5 WASHINGTON/OREGON WATERS
 
   
PZZ800...INNER WATERS FROM CAPE FLATTERY TO CAPE SHOALWATER
 
 
GALE TODAY INTO TONIGHT.    
PZZ900...OUTER WATERS FROM CAPE FLATTERY TO CAPE SHOALWATER
 
 
GALE TODAY.   
PZZ805...INNER WATERS FROM CAPE SHOALWATER TO CAPE LOOKOUT
 
 
GALE TODAY INTO TONIGHT.    
PZZ905...OUTER WATERS FROM CAPE SHOALWATER TO CAPE LOOKOUT
 
 
GALE TODAY.   
PZZ810...INNER WATERS FROM CAPE LOOKOUT TO FLORENCE OR
 
 
GALE TODAY INTO TONIGHT.    
PZZ910...OUTER WATERS FROM CAPE LOOKOUT TO FLORENCE OR
 
 
GALE TODAY.   
PZZ815...INNER WATERS FROM FLORENCE OR TO POINT ST. GEORGE
 
 
GALE TODAY INTO TONIGHT.    
PZZ915...OUTER WATERS FROM FLORENCE OR TO POINT ST. GEORGE
 
 
GALE TODAY.  
   
PZ6 CALIFORNIA WATERS
 
   
PZZ820...INNER WATERS FROM POINT ST. GEORGE TO POINT ARENA
 
 
GALE TODAY INTO TONIGHT.    
PZZ920...OUTER WATERS FROM POINT ST. GEORGE TO POINT ARENA
 
 
GALE TODAY.  
 

 
 
.FORECASTER COLLINS. OCEAN PREDICTION CENTER.  
 
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