Marine Interpretation Message
Issued by NWS

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000
AGNT40 KWNM 301236
MIMATN

MARINE WEATHER DISCUSSION FOR N ATLANTIC OCEAN
NWS OCEAN PREDICTION CENTER WASHINGTON DC
836 AM EDT SAT MAY 30 2015

.FORECAST DISCUSSION: MAJOR FEATURES/WINDS/SEAS/SIGNIFICANT
.WEATHER FOR THE NORTH ATLANTIC OCEAN W OF 50W FROM 30N TO 50N.

ATTM I DONT PLAN ON MAKING ANY CHANGES TO THE CURRENT GRIDS OR
ASSOCIATED TEXT FCST PKG. WEAK PATTERN EXPECTED TO PREVAIL
THROUGHOUT FCST PERIOD AND 06Z RUN OF GFS IS SIMILAR TO PRIOR
RUNS.

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

ACRS THE NT2 WTRS S OF ABT 37N ASCAT METOP-B PASS AFTR 02Z
RETURNED E-LY WINDS IN THE 10-20 KT RANGE AS THE AREA RMNS ALONG
THE SW EXTENT OF WATL SUBTRPCL RIDGE. FARTHER TO THE N...JUST AFTR
01Z...ASCAT-B RETURNED VERY LITE/VARIABLE WINDS MOSTLY 5 KT OR
LESS. NOT SURPRISINGLY SEA HEIGHTS ARE QUITE FLAT ACRS ALL ZNS
...ONLY 6 FT OR LESS...WITH HIGHEST SEAS ACRS THE FAR SRN WTRS IN
STGR E-LIES.

UPCOMING GRIDS/TEXT WL USE 00Z GFS INTO 12Z MON....THEN 00Z ECMWF
THEREAFTER. EXPLANATION FOLLOWS.

LITE WINDS ACRS NT1 ZNS WL BE SHORT LIVED AS RETURN SWLY FLOW
INCRS AHD OF A STG APRCHG CDFNT TDA AND TNGT. THE 00Z GFS REMAINS
CONSISTENT WITH TIMING AND GRADIENTS ASCD WITH THIS CDFNT...UP TO
25 KT IN GLF OF MAINE SAT AND UP TO 30 KT SAT NIGHT IN N PORTION
AS ITS STG PARENT LOW TRACKS E ACRS QUEBEC AND LABRADOR...WITH
GRADIENTS DMSHG AS LOW MOVES AWAY SUN. WITH SPRT FM OTHER 00Z
GLOBAL GUIDANCE WILL CONT USING 00Z GFS 10M WINDS. CDFNT THEN
PASSES S OF THE GLF OF MAINE AND STALLS ALONG A WSW LINE ACRS THE
SRN NT1 WTRS TO A PSN ALONG/NR MONTAUK PT MON/MON NIGHT.

THEN LOOKING BYND MON 12Z A DRASTIC CHANGE TO THE LONGER RANGE
PORTION OF THE FCST WL BE MADE. PREV GRIDS FOR SVRL SHIFTS HAD
BEEN BASED ON THE 28/12Z ECMWF WITH SUPPORT FROM 29/12Z GEFS
MEAN...HOLDING ONTO A FLATTER/FARTHER S FRONTAL SOLN THAT BROUGHT
PERSISTENT STG E-NELY FLOW TO THE NRN HALF OF THE OFSHR ZNS. THE
00Z MODELS CONT TO PAINT A MORE NRN SOLN...FIRST ONLY STALLING THE
FRONT BRIEFLY ACRS SRN NT1 MENTIONED ABOVE...BFR LIFTING THE BNDRY
BACK N AS A WRMFNT EARLY TUE. 00Z MODEL CONSENSUS THEN BRINGS A
SFC LOW EMBEDDED ALNG THE FRONT ENE FROM THE OHIO VALLEY ACRS THE
NE-ERN US AND INTO THE GLF OF ST LAWRENCE BY WED NIGHT...WHILE
PULLING A WK CDFNT ACRS THE NT1 WTRS WED AND INTO THE NRN NT2 ZNS
WED NIGHT. WL POP THESE EXTENDED GRIDS FROM 12Z ONWARDS BASED ON
00Z ECMWF GUID...WHICH IS SLIGHTLY SLOWER THAN THE 00Z GEM AND
GFS...BUT SLIGHTLY FASTER/N THAN THE 00Z UKMET. THE GFS BEEN
PLAYING CATCH-UP TO THE NON-NCEP MDLS FOR ABT THE PAST 36
HRS NOW IN THIS LNGR RANGE...AND USING THE ECMWF OFFERS A DECENT
BLENDED COMPROMISE B/W ALL 00Z MDL SOLNS.

.SEAS...SIMILAR TO THE WIND GRIDS WL USE 00Z WNA INTO 12Z MON BFR
TRANSITIONING WVHTS TO 00Z ECMWF WAM.

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



.WARNINGS...PRELIMINARY.

.NT1 NEW ENGLAND WATERS...
     NONE.

.NT2 MID ATLC WATERS...
     NONE.

$$

.FORECASTER SHAW/COLLINS. OCEAN PREDICTION CENTER.


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