955  
AGPN40 KWNM 300328  
MIMPAC  
 
MARINE WEATHER DISCUSSION FOR N PACIFIC OCEAN  
NWS OCEAN PREDICTION CENTER WASHINGTON DC  
828 PM PDT THU APR 29 2021  
   
FORECAST DISCUSSION  
MAJOR FEATURES/WINDS/SEAS/SIGNIFICANT  
.WEATHER FOR THE NORTH PACIFIC N OF 30N AND E OF 150W.  
 
AT THIS TIME I DON'T PLAN ON MAKING ANY CHANGES TO THE CURRENT  
GRIDS OR ASSOCIATED TEXT FORECASTS.  
 
-----------------------------------------------------------------  
PREVIOUS DISCUSSION...  
 
HIGH PRESSURE WAS CENTERED TO THE W OF THE CENTRAL CA WATERS  
WITH A RIDGE EXTENDING NE OVER THE N CA AND SE OR WATERS. A COLD  
FRONT WAS TO THE W OF THE WA/OR AND N CA WATERS EARLY THIS  
AFTERNOON. THERE WAS A ASCAT PASS OVER PORTIONS OF THE OFFSHORE  
WATERS AT 17Z/10 AM PDT WHICH COVERED MUCH OF THE WA WATERS AND  
THE OUTER OR/NORTHERN CA WATERS AND ALSO THE MOST OF THE  
SOURTHERN CA WATERS. MAX WINDS WERE TO 20 KT OVER THE OUTER WA/OR  
WATERS. WINDS WERE TO 25 KT JUST W OF THE OUTER WA OFFSHORE  
WATERS. THE WEAKENING COLD FRONT MOVES E OVER THE WA/OR OUTER  
WATERS LATER THIS AFTERNOON INTO TONIGHT. THE WEAK COLD FRONT  
MOVES S AND SE INTO THE NORTHERN CA WATERS FRI, THEN INTO THE  
CENTRAL CA WATERS FRI NIGHT AND SAT THEN DISSIPATES AS IT CROSSES  
INTO THE SOUTHERN CA WATERS. A BROAD AREA OF HIGH PRESSURE  
EXPANDS AND BUILDS IN FROM THE W LATER FRI THROUGH SAT NIGHT OVER  
THE CENTRAL AREAS OF THE OFFSHORE WATERS, THEN PERSISTS INTO MON  
NIGHT AND THEN WEAKENS INTO TUE NIGHT. CURRENT HEADLINES HAVE  
GALES DEVELOPING LATER SUN AND SUN NIGHT OVER THE INNER WATERS OF  
THE CENTRAL AND S CA WATERS AND WILL MAINTAIN THEM. COULD HAVE  
GALES LASTING INTO MON, BUT WILL HAVE 30 KT FOR MON INTO MON  
NIGHT OVER THE CA WATERS DUE TO ECMWF BEING NOT AS STRONG WITH  
THE AREA OF HIGH PRESSURE. THE AREA OF HIGH PRESSURE BECOMES  
WEAKER LATER MON NIGHT THROUGH TUE NIGHT. THE RESULTANT WINDS  
GRADUALLY DIMINISH IN AREAL COVERAGE AS THIS OCCURS.  
 
FOR THE GRIDS WILL USE THE GFS OVERALL THROUGH THE FORECAST  
PERIOD WITH THE EXCEPTION OF LATE MON INTO MON NIGHT WHERE WE  
WILL CAP THE WINDS TO 30 KT ALONG THE INNER CENTRAL CA WATERS.  
 
SEAS...BOTH THE 12Z GFS WAVE GUIDANCE AND ECMWF WAM ARE  
INITIALIZED WELL OVER THE OFFSHORE WATERS EARLY THIS AFTERNOON  
AND SIMILAR THROUGH EARLY SAT. THE GFS WAVE GUIDANCE HAS HIGHER  
SEAS DEVELOPING ACROSS THE CENTRAL AND SOUTHERN CA LATER ON SAT  
INTO SAT NIGHT WITH THE ECMWF WAM CATCHING UP WITH THE GFS WAVE  
GUIDANCE LATER ON SUN INTO SUN NIGHT. FOR THE GRIDS WILL USE THE  
GFS WAVE THROUGH THE FORECAST PERIOD.  
 
THIS IS THE FINAL NORTH PACIFIC OCEAN MARINE WEATHER DISCUSSION (MIM).  
REFERENCE THE NATIONAL WEATHER SERVICE SERVICE CHANGE NOTICE:  
HTTPS://WWW.WEATHER.GOV/MEDIA/NOTIFICATION/PDF2/SCN21-35MIN_DISCONTINUE.PDF  
   
EXTRATROPICAL STORM SURGE GUIDANCE  
N/A  
 
   
WARNINGS  
PRELIMINARY.  
   
PZ5 WASHINGTON/OREGON WATERS  
 
NONE.  
   
PZ6 CALIFORNIA WATERS  
   
PZZ825...INNER WATERS FROM POINT ARENA TO PIGEON POINT  
 
GALE POSSIBLE SUNDAY NIGHT INTO MONDAY.    
PZZ830...INNER WATERS FROM PIGEON POINT TO POINT PIEDRAS BLANCAS  
 
GALE POSSIBLE SUNDAY NIGHT.   
PZZ835  
INNER WATERS FROM POINT PIEDRAS BLANCAS TO SANTA CRUZ ISLAND, CA...  
GALE POSSIBLE SUNDAY NIGHT.  
 
 
 
.FORECASTER SHAW/ROWLAND. OCEAN PREDICTION CENTER.  
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