Marine Interpretation Message
Issued by NWS

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AGNT40 KWNM 021954
MIMATN

MARINE WEATHER DISCUSSION FOR N ATLANTIC OCEAN
NWS OCEAN PREDICTION CENTER WASHINGTON DC
345 PM EDT MON 2 MAY 2016

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

A 12Z RAPIDSCAT OVERPASS CONFIRMED THE SURFACE LOW JUST S OF
NANTUCKET AND INDICATED STRONGEST WINDS UP TO 25 KT NE OF THE
WARM FRONT OVER GEORGES BANK AND THE GULF OF MAINE. RAPIDSCAT
INDICATED THAT 12Z GFS 10M WINDS WERE WELL INITIALIZED...AND
WILL POPULATE WITH THESE WINDS THROUGH TONIGHT. 12Z MODELS ARE
IN GENERAL AGREEMENT THAT A SERIES OF LOW PRES CENTERS WILL
TRACK NE ALONG A QUASI STATIONARY FRONT WHICH AT 18Z EXTENDED
FROM SOUTHERN NJ NE TO A 1012 MB LOW JUST E OF NANTUCKET.
FORECAST DIFFICULTY LIES IN THE TIMING OF THESE MULTIPLE SURFACE
LOWS AND ALSO STRENGTH OF WINDS E AND SE OF FRONT AND DEVELOPING
LOWS. OVER PAST COUPLE RUNS GFS HAS TRENDED WEAKER WITH SW WINDS
TUE THROUGH WED. WITH THE USUALLY UNDERDONE ECMWF SFC WINDS UP
TO 30 KT OVER THE GULF STREAM HAVE ABOUT AVERAGE FORECAST
CONFIDENCE THAT MARGINAL GALES SHOULD DEVELOP NEAR THE GULF
STREAM OVER OUTER MID ATLC WATERS N OF BALTIMORE CANYON. FOR
WIND GRIDS USED A BLEND OF THE 12Z ECMWF AND 12Z GFS BOUNDARY
LAYER WINDS TUE THROUGH WED. TRIMMED AREAS OF GALES FROM
PREVIOUS FORECAST AND WILL LIMIT TO ANZ920 ANZ910 AND ANZ905
ZONES. 12Z GFS/ECMWF/UKMET THEN ARE IN GOOD AGREEMENT THAT
STRONGER LOW WILL EMERGE OFF THE MID ATLC COAST NEAR CAPE
HATTERAS WED. GUIDANCE IS IN BETTER AGREEMENT THAT AS THIS LOW
TRACKS NE THROUGH NRN MID ATLC WATERS S WINDS WILL INCREASE TO
GALE OVER OUTER WATERS. AGAIN USED A 50/50 BLEND OF THE 12Z GFS
BOUNDARY LAYER AND 12Z ECMWF WINDS WED THROUGH THU NIGHT...WITH
GALES AGAIN DEVELOPING OVER ZONES NOTED ABOVE.

THE LATEST MODELS THEN CONTINUE TO HAVE DIFFICULTY IN THE MEDIUM
RANGE WITH DETAILS OF SURFACE LOW DEVELOPMENT(S) IN RESPONSE TO
UPPER SHORTWAVES ROTATING AROUND THE UPPER CLOSED LOW ALONG THE
COAST LATE THU INTO THE WEEKEND. GENERALLY 12Z ECMWF IS N OF THE
12Z GFS AND IS ALSO WEAKER THAN THE 12Z ECMWF. CONTINUED TO USE
A 50/50 BLEND OF 12Z GFS AND 12Z ECMWF THROUGH THE WEEKEND. OUT
OF DEFERENCE FOR THE GFS DID ADJUST THESE BLENDED WINDS UP BY
ABOUT 20 PERCENT BUT KEEPING BELOW GALE FRI/SAT.

SEAS...12Z WAVEWATCH III IS 1 TO 2 FT TOO LOW OVER GEORGES BANK
AND THE GULF OF MAINE THIS AFTERNOON. THE 12Z ECMWF WAM HAS A
BETTER HANDLE ON THE W ATLC WAVE HEIGHTS CURRENTLY. POPULATED
WITH THE 12Z ECMWF WAM TONIGHT THEN TO BE CONSISTNET WITH THE
WIND GRIDS USED A 50/50 OF 12Z WW3 AND 12Z ECMWF WAM.

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

.WARNINGS...PRELIMINARY.

.NT1 NEW ENGLAND WATERS...
     NONE.

.NT2 MID ATLC WATERS...
.ANZ920...BALTIMORE CANYON TO THE GREAT SOUTH CHANNEL...
     GALE TUE INTO TUE NIGHT.
     GALE POSSIBLE WED NIGHT.
.ANZ905...THE GREAT SOUTH CHANNEL TO THE HAGUE LINE...
     GALE TUE NIGHT.
     GALE POSSIBLE WED NIGHT INTO THU.
.ANZ910...EAST OF THE GREAT SOUTH CHANNEL AND SOUTH OF 39N...
     GALE TUE NIGHT.
     GALE POSSIBLE WED NIGHT INTO THU.

$$

.FORECASTER CLARK. OCEAN PREDICTION CENTER.


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