Marine Interpretation Message
Issued by NWS

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AGNT40 KWNM 011216
MIMATN

MARINE WEATHER DISCUSSION FOR N ATLANTIC OCEAN
NWS OCEAN PREDICTION CENTER WASHINGTON DC
816 AM EDT WED OCT 1 2014

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

NO MAJOR CHANGES ARE PLANNED FOR THE MORNING UPDATE. THE 06Z GFS
WAS VERY SIMILAR TO THE PREVIOUS 00Z RUN. THE MAIN FCST CONCERN
CONTINUES TO BE THE LOW TO THE SE OF THE SRN OFFSHORE WATERS. THE
06Z GFS CONTINUES TO BE SLIGHTLY FURTHER E THAN THE ECMWF/UKMET
AND KEEPS THE LOW JUST E OF THE OFFSHORE WATERS. THE CURRENT WIND
GRIDS STILL LOOK REASONABLE AND WILL NOT BE MAKING ANY ADJUSTMENTS
TO THE WARNINGS. THE MODELS ARE THEN IN DECENT AGREEMENT MOVING
THE LOW E OF THE AREA AS COLD FRONT APPROACHES THE AREA LATE
FRI...THEN MOCES ACROSS THE WATERS SAT. THE 09Z SEA STATE ANALYSIS
INDICATED THAT OBSERVED SEAS WERE WITHIN A FT OF THE MWW3 FCST
VALUES.

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

0130Z AND 0230Z HI RES ASCAT RETURNED NE 15 TO 20 KT OVER INNER
S OF NEW ENGL ANZ815 WATERS WHICH 00Z MDLS HAVE GOOD HANDLE ON.
HOWEVER OVER GULF STREAM FROM ABOUT 37N TO 34N AND W OF GULF
STREAM S AND SE OF CAPE LOOKOUT ASCAT ALSO HAD 15 TO 20 KT. NONE
OF 00Z MDLS SEEM TO BE PICKING UP THESE ENHANCED WINDS WITH ONLY
EXCEPTION BEING 00Z 1/4 DEG ECMWF. WILL ADJUST THESE GRIDS NEAR
TERM AT LEAST 5 KT OVER GUIDANCE. OVER THE SHORT TERM THERE
CONTINUES TO BE SIGNFICANT SPREAD AMONG MODELS FIRST WITH DVLPG
SFC LOW INVOF 32N73W MOVING NE TOWARD BERMUDA AND ALSO WITH
SECOND LOW WHICH WAS ABOUT 300 NM N OF BERMUDA AT 06Z. GFS HAS
BEEN STRONG OUTLIER WITH LOW APPROACHING BERMUDA AND LOOKS
OVERDONE WITH DVLPG GALE FORCE WINDS TONIGHT AS LOW PASSES E OF
BERMUDA. AS FAR AS NRN LOW MODEL DISCREPANCIES ARE ARTIFACT OF
DIFFICULTY WITH TIMING AND INTERACTION OF MULTIPLE UPPER SHRTWVS
ROTATING AROUND UPPER LOW CENTER NEXT FEW DAYS. AS EXPECTED
THERE IS ALSO LARGE SPREAD IN LATEST ENSEMBLES. 00Z UKMET AND
12Z/30 ECMWF ARE BOTH FURTHER N THAN GFS WITH SFC LOW THU NGT
INTO FRI NGT BUT DO RETROGRADE LOW AS FAR W AS GFS FRI AND FRI
NGT. MAJORITY OF 00Z GEFS MEMBERS ARE WNW OF 00Z DETERMINISTIC
GFS LATE THU INTO FRI. 00Z GFS IS NOT AS STRONG WITH N TO NE
WINDS OVER OUTER OFFSHORE WATERS AS PREVIOUS RUN. 00Z ECMWF THRU
48 HOURS HAS TRENDED SIGNIFICANTLY W FROM ITS PREVIOUS RUN
NEARLY INTO NERN EXTENT OF NT2 WATERS BY THU EVENING WITH GALES
OVER NW QUAD. WITH MOST GEFS MEMBERS GENERALLY BETWEEN NWRN
ECMWF AND SERN GFS PSNS PLAN TO BLEND 00Z ECMWF WITH EXISTING
GRIDS WHICH WERE 12Z GFS BNDRY LAYER WINDS. THIS WILL RESULT IN
RETAINING GALES OVER OUTER GEORGES BANK ANZ900 AND NERN NT2
ANZ905 ZONES LATE THU INTO FRI WHICH IS CONSISTENT WITH PREVIOUS
FORECASTS/ GRIDS.

WITH SHARP UPPER TROF THEN APPROACHING THE E COAST THIS WEEKEND
WEAKENING UPPER LOW SHOULD KICK E FRI NGT AND SAT. PREFER THE
00Z ECMWF HERE WHICH IS MORE PROGRESSIVE THAN GFS TO EJECT UPPER
LOW EASTWARD. 00Z GFS/UKMET/ECMWF HAVE COME INTO BETTER
AGREEMENT WITH ASSOCIATED COLD FRONT MOVING OFF THE COAST SAT
WITH 00Z GLOBAL GEM ONLY SLIGHLY MORE PROGRESSIVE. 00Z GFS IS A
BIT STRONGER THAN ECMWF OR UKMET WITH PRE FRONTAL WINDS. FOR
THIS REASON WILL USE A 50/50 BLEND OF 00Z GFS 10M WINDS AND 00Z
ECMWF WINDS FRI NGT THRU SUN NGT. THIS WILL ALSO RESULT IN
REASONABLE CONTINUITY WITH PREVIOUS GRIDS.

.SEAS...OVER OFFSHORE WATERS S OF LONG ISLAND WHERE NE WINDS IN
15 TO 20 KT RANGE LATEST BUOYS INDICATING THAT 00Z MULTIGRID
WAVEWATCH III MAY BE UP TO 1 FT TOO LOW. THE SAME IS THE CASE
OVER THE GULF OF MAINE AND COASTAL NH/MA INCLUDING CAPE COD BAY
WHERE 44013 REPORTED 5 FT AT 06Z. GIVEN MDL PREFERENCE WILL BE
USING A 50/50 BLEND OF GFS AND ECMWF WAVE MDL. HOWEVER GIVEN
MDLS TENDENCY TO BE UNDERDONE IN THESE SIGNIFICANT NE FLOW
EVENTS WILL ADD ABOUT 10 PERCENT TO BLENDED VALUES OVER AREAS
WITH 25+ KT WINDS.

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


.WARNINGS...PRELIMINARY.

.NT1 NEW ENGLAND WATERS...
.ANZ900...GEORGES BANK EAST OF 68W...
     GALE THU INTO THU NIGHT.

.NT2 MID ATLC WATERS...
.ANZ905...THE GREAT SOUTH CHANNEL TO THE HAGUE LINE...
     GALE THU NIGHT.

$$

.FORECASTER KOSIER/CLARK. OCEAN PREDICTION CENTER.


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