Marine Interpretation Message
Issued by NWS

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AGNT40 KWNM 310136
MIMATN

MARINE WEATHER DISCUSSION FOR N ATLANTIC OCEAN
NWS OCEAN PREDICTION CENTER WASHINGTON DC
936 PM EDT WED JUL 30 2014

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

18Z GFS IS LITTLE CHANGED FM PREVIOUS RUN AND CNTG TO USE WND
GRIDS BASED ON 12Z GFS WITH PREFERENCE SHFTG TO 12Z ECMWF 12Z FRI
AND BYND BASED ON MORE ENTHUSIASTIC DVLPMT OF A WAVE ON THE FNT
MOVG NW OVR THE WTRS AS A WRM FNT SEEN IN THE FOREIGN MDLS.
DURING THE PERIOD STRONGEST WNDS OF UP TO 30 KT EXPECTED IN NE NT2
OUTER WTRS TONIGHT INTO THU AHD OF A FNT WHICH OPC PRELIM 00Z ANAL
SHOWS AS A STALLED FNT. WNDS ARE BASED ON EARLIER MATCHING OF GFS
30M WNDS TO MRNG ASCAT PASS. OTHER PERIOD OF STRONGER WNDS IS IN
ELY FLOW AHD OF WRM FNT S OF NEW ENGLAND SAT...UP TO 25 KT AS IN
12Z ECMWF/UKMET BL WNDS AND ALSO 12Z CMC GEM 1000 MB WNDS.

SEAS...00Z SEA STATE ANAL MATCHES WELL WITH 18Z WNA WW3 WHICH WITH
ITS SLGTLY HIGHER SEAS THAN ECMWF VERSION IN OUTER NT2 WTRS PREFER
WNA NEAR TERM AND THEN PREFERENCE SHFTS TO BLENDED WAVE MDLS
WIGHTED TWD ECMWF WAM FRI AND BYND.
-----------------------------------------------------------------
PREVIOUS DISCUSSION...

14Z AND 1450Z HI RES ASCAT-A AND -B OVERPASSES CONTINUED TO
INDICATE S WINDS OF 25 TO 30 KT E OF COLD FRONT OVER WARMER GULF
STREAM WATERS AS WELL AS WATERS N OF GULF STREAM NAMELY ANZ905
AND ANZ910 ZONES. ALSO ASCAT SHOWED SFC LOW ALONG FRONT INVOF
37N70W. 12Z MDLS REMAINED IN VERY GOOD AGREEMENT OVER THE W ATLC
FOR THE NEXT FEW DAYS. STRONGEST S WINDS SHOULD SHIFT E OF NERN
MOST NT2 WATERS THRU THE MORNING THU AS LOW PRES MOVES NE TOWARD
NOVA SCOTIA. BASED ON ABOVE ASCAT AM STILL FAVORING SLIGHTLY
HIGHER GFS BNDRY LAYER WINDS AHEAD OF COLD FRONT TNGT INTO THU.
THEREAFTER WITH MDLS ALL MOVING HIGH PRES RIDGE OFF NEW ENGL AND
NRN MID ATLC COAST WINDS WILL BECOME 15 KT OR LESS OVER BOTH NT1
AND NT2 WATERS. WEAK PERSISTENT STNRY FRONT WILL BEGIN TO LIFT N
AND NW FIRST OVER SRN NT2 WATERS THU NGT THEN NRN MID ATLC
WATERS FRI AND FRI NGT. BY SAT 12Z ECMWF CONTINUED TO BE FASTER
IN LIFTING WEAK WARM FRONT THRU NRN MID ATLC INTO NEW ENGL
WATERS. 12Z GFS AND 12Z UKMET ARE BOTH SLOWER. ALSO WITH RESPECT
TO POTENTIAL LOW DLVPMNT LATE FRI NGT AND EARLY SAT ALONG FRONT
12Z ECMWF AND 12Z UKMET ARE MORE ENTHUSIASTIC THAN 12Z GFS WITH
THE LATTER MDLS GENERATING E TO NE WINDS UP TO 25 KT S OF LONG
ISLAND. FAVORING THESE HIGHER WINDS SO WILL POPULATE WITH 12Z
ECMWF BEGINNING 12Z FRI THRU THE MON NGT. HOWEVER AS A
COMPROMISE WITH THE TIMING OF FRONT WILL TIME SHIFT 12Z ECMWF
ABOUT SIX HRS SLOWER.

12Z MULTIGRID WAVEWATCH III SIG WV HGTS HAVE BEEN IN LINE WITH
LATEST W ATLC SHIP/BUOY OBS OVER LAST FEW HRS. IT REMAINED 2 TO
3 FT HIGHER THAN 12Z ECMWF WAVE MDL OVER AREAS WITH HIGHEST S TO
SW WINDS FOR NEXT 36 HRS. PREFER THESE HIGHER SIG WV HGTS THRU
12Z FRI. THEN WITH PREFERENCE FOR 12Z ECMWF BEGINNING FRI WILL
BE USING ROUGHLY A 3:1 12Z ECMWF WAVE TO 12Z MWW3 BLEND.

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

.WARNINGS...PRELIMINARY.

.NT1 NEW ENGLAND WATERS...
     NONE.

.NT2 MID ATLC WATERS...
     NONE.

$$

.FORECASTER BANCROFT/CLARK. OCEAN PREDICTION CENTER.


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