Marine Interpretation Message
Issued by NWS

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AGPN40 KWNM 020306
MIMPAC

MARINE WEATHER DISCUSSION FOR N PACIFIC OCEAN
NWS OCEAN PREDICTION CENTER WASHINGTON DC
806 PM PDT WED APR 1 2015

.FORECAST DISCUSSION: MAJOR FEATURES/WINDS/SEAS/SIGNIFICANT
.WEATHER FOR THE NORTH PACIFIC N OF 30N AND E OF 150W.

LITTLE CHANGE APPEARS NEEDED TO THE ONGOING OPC OFF FCST THIS EVE.
GALES OVR THE INNER CENTRAL AND SRN CALIF OFF WTRS ARE FCST TO
CONT TONITE...BEFORE DIMINISHING EARLY THU. A STRONG 1035MB HIGH
IS LOCATED APPROX 500 NM W OF THE NRN CALIF OFF WTRS PER THE 00Z
OPC SFC ANALYSIS...WITH A STRONG PRES GRADIENT BETWEEN THIS HIGH
AND LOWER PRESSURES OVR THE SW U.S. A SLOW DECREASE IN WINDS IS
FCST FOR THU INTO THE WKND AS THE PRES GRADIENT WEAKENS...AS LOW
PRES SLIDES SE TOWARD THE REGION FROM THE GULF OF AK. WE WILL
TWEAK THE PREV GRIDS SLIGHTLY TO FIT THE LATEST CONDITIONS AND
NEARBY CWF AND TAFB GRIDS...BUT OTW LV PREV FCST PRETTY MUCH
ALONE FOR THE EVE UPDATE.

SEAS...SEA HTS APPEAR TO BE RUNNING UP TO A FT OR TWO HIGHER THAN
THE WV WATCH III MDL GUID PER THE LATEST OBS FROM THE REGION. WE
WILL MAKE MINOR ADJUSTMENTS TO THE PREV FCST TO FIT THESE OBS AND
ALSO TO FIT NEARBY CWF AND TAFB GRIDS A LITTLE BETTER.
OTW...LITTLE CHANGE WILL BE MADE FOR THE EVE UPDATE.

-----------------------------------------------------------------
PREVIOUS DISCUSSION...

THE 18Z SFC ANALYSIS INDICATED BROAD HIGH PRES AREA OVER MUCH OF
THE E PAC TO THE E OF 140W...WITH TROUGH ALONG THE CENTRAL AND S
CA COAST. NO RECENT ASCAT AS OF 1930Z...HOWEVER RAPID SCAT PASS
FROM 1233Z INDICATED AREA OF 25 TO 30 KT WINDS OVER THE INNER
PORTION OF THE CENTRAL/C CA OFFSHORE WATERS AND ADJACENT COASTAL
WATERS EXTENDING FROM W OF POINT CONCEPTION N TO SW OF BAY AREA.

THE 12Z MODELS CONTINUE TO BE IN VERY GOOD AGREEMENT DURING THE
SHORT TERM PERIOD FROM TONIGHT THROUGH ROUGHLY 00Z SUN. THE MODELS
THEN DIVERGE FROM 00Z SUN AND BEYOND. FOR THE SHORT TERM
PERIOD...THE MODELS CONTINUE TO INDICATE TROUGH ALONG THE CENTRAL
AND S CA COAST PERSISTING OVERNIGHT...THEN WEAKENING THU. THE 12Z
GFS/NAM NOW BOTH MAINTAIN GALES THROUGH 12Z THU AND THIS SEEMS
REASONABLE AND CONFDC IS HIGH. FOR THU THROUGH FRI...THE NEXT
COLD FRONT IS FCST TO MOVE ACROSS THE WA/OR/N CA WATERS WITH
MODELS AGAIN VERY CLOSE WITH THE TIMING. THE WINDS AHEAD OF FRONT
STILL FCST TO REMAIN JUST BELOW GALE. FOR FRI NIGHT INTO EARLY
SAT...LOW PRES WILL APPROACH THE WA/OR WATERS. LOOKING AHEAD TO
SAT NIGHT THROUGH TUE...THE MODELS CONTINUE TO DIFFER ON DETAILS
INVOLVING ANOTHER LOW FCST TO MOVE ACROSS THE WA/OR WATERS SAT
NIGHT THROUGH MON. THE GFS IS STRONGER COMPARED TO THE
UKMET/ECMWF...THOUGH THE CMC IS CLOSER TO GFS. HAVE BEEN USING A
50/50 BLEND OF GFS/ECMWF OVER THE PAST FEW CYCLES...AND GIVEN THE
MODEL DIFFERENCES AND CONSIDERING THIS IS LATE IN FCST PERIOD WILL
CONTINUE WITH THIS APPROACH. IN SUMMARY...WILL POPULATE GRIDS
USING THE 30M GFS WINDS THROUGH 00Z SUN...THEN WILL TRANSITION TO
50/50 BLEND OF GFS/ECMWF FOR THE REMAINDER OF PERIOD. SATELLITE
IMAGERY CONTINUES TO SHOW COLD AIR CU OVER PZ5 WATERS AND WILL
CONTINUE MENTION OF AT LEAST ISOLD TSTMS OVER MOST OF WA/OR WATERS
THROUGH EARLY THIS EVENING.

.SEAS...THE 18Z SEA STATE ANALYSIS INDICATED THAT OBSERVED SEAS
WERE WITHIN A FT OF THE MWW3 FCST VALUES...WITH EVEN THE CENTRAL
CA COASTAL WATERS NOW WITHIN A FT OF THE GUIDANCE. SIMILAR TO THE
WIND GRIDS...WILL POPULATE WAVE GRIDS USING THE MWW3 THROUGH 00Z
SUN...THEN WILL USE A 50/50 BLEND OF MWW3/ECMWF WAM FOR THE
REMAINDER.

.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 TONIGHT.
.PZZ830...INNER WATERS FROM PIGEON POINT TO POINT PIEDRAS BLANCAS...
     GALE TONIGHT.
.PZZ835...INNER WATERS FROM POINT PIEDRAS BLANCAS TO SANTA CRUZ ISLAND, CA...
     GALE TONIGHT.
.PZZ840...INNER WATERS FROM SANTA CRUZ ISLAND, CA TO SAN CLEMENTE ISLAND, CA...
     GALE TONIGHT.

$$

.FORECASTER MILLS/KOSIER. OCEAN PREDICTION CENTER.


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