Marine Interpretation Message
Issued by NWS

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000
AGNT40 KWNM 311302
MIMATN

MARINE WEATHER DISCUSSION FOR N ATLANTIC OCEAN
NWS OCEAN PREDICTION CENTER WASHINGTON DC
900 AM EDT THU 31 JUL 2014

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

MDLS ARE INITIALIZING WEAK SFC LOW ALONG STNRY FRONT INVOF
39N68W AND WILL SEE ABOUT ANOTHER 6 TO 9 HRS OF S TO SW WINDS UP
TO 25 KT E OF LOW AND ASSOCIATED FRONT. MOST RECENT RUNS OF GFS
AND ECMWF HAVE COME INTO BETTER AGREEMENT WITH TIMING OF WEAK
WARM FRONT AS IT DRIFTS N AND NW OVER MID ATLC AND NEW ENGL
WATERS TNGT THRU SAT NGT. HOWEVER 00Z ECMWF CONTINUED TO BE MORE
AGRESSIVE WITH SFC LOW DVLPMNT ALONG FRONT JUST INLAND OF SE
COAST AND ALSO INDICATING BRIEF PERIOD OF E WINDS TO 25 KT S AND
SE OF LONG ISLAND EARLY SAT. WITH 00Z UKMET ALSO SUPPORTING
STRONGER SOLUTION WILL BUMP UP THESE WINDS FROM PREVIOUS
FORECAST. OTHERWISE WILL NOT BE MAJOR ADJUSTMENTS TO PREVIOUS
OFFSHORE FORECASTS/GRIDS. GIVEN SURROUNDING OBS THE 10 FT SHIP
AT 12Z NEAR 40N66W LOOKS TOO HIGH. SIG WV HGTS OVER NERN GLF OF
ME ARE ABOUT A FT HIGHER THAN 06Z MULTIGRID WAVEWATCH III.
ELSEWHERE THIS GUIDANCE LOOKS IN GOOD AGREEMENT WITH SHIP/BUOY
OBS OVER W ATLC. WILL CONTINUE TO FAVOR 00Z ECMWF WAVE MDL BUT
BEGIN EARLIER THAN PREVIOUSLY FORECAST NOW 18Z FRI.

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

0118Z ASCAT-A PASS RETURNED LIGHT WINDS N OF VA CAPES AND TO THE
S HINT OF FNTL BNDRY OUTER WTRS WITH SOME HIGHER RETURNS OF 25
KT ALG FNT BUT THERE WAS HEAVY CNVTN IN THIS AREA...AND W OF FNT
NE WNDS 15 TO 20 KT. THE PASS MISSES SUSPECTED HIGHER WNDS EXTRM
NE NT2 WTRS WHERE PREVIOUS FCST HAD SLY 30 KT. WILL USE 00Z GFS
30M WNDS TO HANDL THESE HIGHER CONDS AHD OF FNT AND IN NE FLOW
BHND FNT FOR THE FIRST PRD.

06Z NCEP SFC ANAL HAS STNRY FNT ACRDS PORTIONS OF OUTER NT2 WTRS
AND SE CORNER OF GEORGES BANK AND FNTL LOW APPRS NR 39N68W. 00Z
MDLS REMAIN IN VERY GOOD AGREEMENT OVER THE W ATLC FOR THE NEXT
FEW DAYS. STRONGEST S WINDS SHOULD SHIFT E OF FAR NE NT2 WATERS
THRU THE DAY TODAY AS THE LOW PRES WAVE MOVS NE ALG FNT TWD NOVA
SCOTIA. FM LOOKING AT ASCAT AND EARLIER ASCAT PASS STILL FAVOR
HIGHER GFS BL WNDS AHEAD AND BHND CDFNT TODAY. THEREAFTER WITH
MDLS ALL MOVING HIGH PRES RIDGE OFF NEW ENGL AND NRN MID ATLC
COAST WINDS WILL BECOME 15 KT OR LESS OVER NT1 AND NT2 WATERS.
WEAK PERSISTENT STNRY FRONT WILL BEGIN TO LIFT N AND NW FIRST
OVER SRN NT2 WATERS LATER TODAY AND TONIGHT THEN NRN MID ATLC
WATERS FRI AND FRI NGT. BY SAT 00Z ECMWF CONTS FASTER IN LIFTING
WEAK WARM FRONT THRU NRN MID ATLC INTO NEW ENGL WATERS WHILE GFS
AND CNDN ARE CLOSE AND UKMET IS SLOWER. ALSO MDLS SPRT WK WAVE
LIFTING NE THRU NT1 AREA SAT WITH GFS OFFERING COMPROMISE SOLN
AND IS MORE ENTHUSIASTIC ABOUT LOW ON FNT THAN PREVIOUS RUN.
WNDS MAY REACH BRIEFLY 20 OR 25 KT AHD OF WRNFNT AND LOW EARLY
SAT AND GFS 30M WNDS GIVE ABT 20 KT IN ELY FLOW. BEYOND SAT FCST
AREA REMAINS DOMINATED BY HIGH PRES OFSHR AND STALLED FNT ALG
CST INTO NT1 WTRS AND LIGHT WNDS. USING 00Z ECMWF LATE SUN AND
BYND WHICH IS CLOSE TO GFS AND BRING A WK CDFNT TWD NEW ENGLAND
LATER MON WHILE UKMET TRACKS ANOTHER LOW FARTHER S ALG OLD FNT.

00Z MULTIGRID WAVEWATCH III SIG WV HGTS HAVE BEEN IN LINE WITH
LATEST W ATLC SEA STATE ANL OVR MUCH OF OFSHR/CSTL WTRS AND
ECMWF VERSION IS SIMILAR...BUT BOTH MAY BE A BIT LOW FAR NE NT2
IF 06Z SHIP WITH 12 FT JUST E OF NRN NT2 AREA IS RIGHT...BUT IT
LOOKS HIGH. USING MWW3 THRU 18Z SAT EXCP USED 50/50 BLEND FOR
TONIGHT INTO FRI NIGHT. THEN USED SIMILAR BLEND THRU SUN AND
AFTER THAT ALL ECMWF WAM BASED ON USE OF ECMWF SFC FCST.

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

.WARNINGS...PRELIMINARY.

.NT1 NEW ENGLAND WATERS...
     NONE.

.NT2 MID ATLC WATERS...
     NONE.

$$

.FORECASTER CLARK/BANCROFT. OCEAN PREDICTION CENTER.


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