Marine Interpretation Message
Issued by NWS

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AGPN40 KWNM 310332
MIMPAC

MARINE WEATHER DISCUSSION FOR N PACIFIC OCEAN
NWS OCEAN PREDICTION CENTER WASHINGTON DC
832 PM PDT THU JUL 30 2015

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

THE IR SAT IMG HAS MOSTLY CLR SKIES OVR THE NRN HALF OF THE FCST
WTRS WITH THIN CLDS OVR THE REST AND NO LIGHTNG ACRS THE REGION OR
EVEN THE ADJ COASTAL AREAS. THE RADAR HAS NO INDC OF TSTMS CELLS
OVR THE REGION. AT 31/00Z HGH PRES 1026 MB JUST W OF THE REGION
HAS ITS RIDGE ACRS THE NRN WTRS WITH ANOTHER RIDGE XTNDG SE ACRS
THE SRN WTRS. INLAND LOW PRES TROF CONNECTS THE LOWS ALONG THE
COASTS FROM SRN CA INTO OREG. THE PRES GRDNT IS FAIRLY SLACK AND
THE MAX OBS WINDS ARE ONLY 20 KT OVR THE CNTRL WTRS. THE SEAS ARE
HGHST WITH 10 FT PEAK OVR THE CNTRL WTRS WHILE THEY RANGE BTWN 3
AND 6 FT OVR THE FAR NRN AND SRN REGIONS. THE NWW3 MULTI GRID FITS
VERY WELL WITH THE OBSVD SEAS PATTERN AND IS IN VERY CLOSE TO THE
EAURO WV MDL.

THERE IS STILL NO MJR ENRGY OVR THE REGION TO STRENGTHEN THE
SYNOP SYSTMS. THERE IS SOME LOCALLY INDCD ENRGY JUST SW OF THE
REGION EMBDD IN AN UPPRLVL TROF THAT IS BLOCKED FROM ADVNCG E BY
AN UPPRLRVL RIDGE THAT LIES ACRS THE REGION. SOME ERNGY WIL
APPROACH THE NRN WTRS AT THE END OF FRCST PRD AND THAT WILL
TIGHTEN THE PRES GRDNT BUT WILL BE JUST AFTER THE END OF FCST PRD.

THE GLBL MDLS HV AGREED WELL ON THE FEW SYNOP FEATURES ESPCLY IN
THE SHORT TERM. JUST MNR DIFFS IN THE XTNDD PRD MAINLY IN THE
STRENGTH OF THE INLAND TROF. BUT GENERALLY THE WINDS WILL STILL
REMAIN BELOW GALE FORCE EVEN THOUGH THEY WILL INCREASE TWD END OF
FRCST PRD. IN THE SHORT TERM THE HGH PRES WILL REMAIN ANCHORED TO
THE W OF THE REGION AS INLAND TROF WEAKENS FARTHER. IN THE XTNDD
PRD THE INLAND TROF WILL STRENGTHEN AS HGH REBUILDS TO THE W AND
THAT WILL FORCE THE PRES GRDNT TO SLIGHTLY BECOME TIGHT BUT WINDS
WILL REMAIN BELOW GALE FROCE THRESHOLD.

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

GOES WV IMGRY INDC A WK UPR LOW JUST W OF THE PZ6 OFSHR
WTRS...AND A RDG OVR THE WTRS ALNG THE COAST. RSCAT FM 1245Z INDC
A LRG AREA OF N TO NE WINDS TO 20 KT OVR THE N PTN WITH A FEW SML
AREAS UP TO 25 KT...IN THE PRES GRAD BTWN SFC HIGH PRES W OF THE
AREA AND A TROF OVR THE C WTRS. CRNT SFC RPRTS INDC ABT 20 KT AS
WELL...MAINLY OVR THE N PTN N OF THE TROF. THE 12Z GFS WINDS ARE
INIT OK WHEN COMPARED WITH THE CRNT DATA...AND INDC 20 TO 25 KT
OVR THE OFSHR WTRS IN THE 30M BL WNDS...AND 20 KT IN THE 10M
WNDS. THE 10M WNDS SEEM INIT A LTL BETTER...AND THE 30M WNDS LOOK
SLGTLY OVERDONE...ESP CONSIDERING MDL STABILITY INDICES WHICH INDC
A STABLE ENVRMT...SO PREFERRING THE MORE SHALLOW 10M WNDS ATTM.
THE 12Z ECMWF/UKMET ARE SLGTLY WKR...AND AGREE SOMEWHAT WELL WITH
THE 10M GFS WNDS. THE 12Z GEM/NAM ARE A LTL STGR...THO NOT
UNEXPECTED WITH THEIR TYPICAL HIGH BIAS. FOR NOW PLANNING ON USING
THE 12Z GFS 10M WNDS IN THE SHORT TERM...AS THE GFS IS IN RSNBLY
GUD AGRMT WITH THE REST OF THE GUID.

FOR THE RMNDR OF THE PD...THE 12Z MDLS ALL INDC THE WK UPR LOW W
OF PZ5 WL PERSIST THRU THE PD...AND MAINTAIN A WK SFC LOW.
HOWEVER...THE MDLS INDC THE LOW WL DRIFT E TWD THE RGN IN THE
LATER PART OF THE PD...THO WL STAY W OF THE PZ6 WTRS. THE BIGGEST
FCST PRBLM CONT TO REVOLVE ABT ANTHR UPR LOW MOVG INTO THE EPAC FM
THE GULFAK. THE GFS HAS BEEN CONSISTENT WITH IT PASSING JUST N OF
THE PZ5 WTRS BY TUE NGT...BUT THE REST OF THE MDLS DO NOT STGLY
AGREE WITH THE TRACK OF THIS FEATURE. THE 12Z ECWMF TAKES IT
FURTHER SW...AND THE 12Z UKMET IS MUCH FURTHER N. IN FACT...THE
ONLY STG AGRMT IS WITH THE GEM...AND PREV RUNS OF THE GFS. THE
BIGGEST IMPACT AT THE SFC IS THE INTNSTY OF THE WNDS ALNG THE
COAST...AS THE LOC OF THE SFC RDG ACRS PZ5 DIFFERS IN CONTRAST
WITH THE ECWMF AND UKMET. A SFC LOW DOES PASS N OF THE AREA...WITH
WK CAA MOVG INTO THE N PTN OF THE WAS WTRS. THIS WL LOWER STATIC
STABILITY...ALLOWING A LTL DEEPER MXG. ATTM PREFERRING TO STAY
WITH THE GFS...WHICH HAS THE BEST SPRT...BUT CONFDC IS LOW.

.SEAS...THE 12Z MWW3 AND ECWMF WAM ARE INIT OK...AND AGREE WELL
INTO MON. THE ECWMF WAM DVRGS FM THE NWW3 IN CONJUNCTION WITH THE
DIFF IN WX MDLS. AS A RESULT PREFERRING TO STAY WITH THE 12Z MWW3
MDL...WHICH REFLECTS PREFERRED GFS WX MDL TRENDS.

.EXTRATROPICAL STORM SURGE GUIDANCE...N/A.


.WARNINGS...PRELIMINARY.

.PZ5 WASHINGTON/OREGON WATERS...
     NONE.

.PZ6 CALIFORNIA WATERS...
     NONE.

$$

.FORECASTER MUSONDA/KELLS. OCEAN PREDICTION CENTER.



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