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000
AGNT40 KWNM 241210
MIMATN

MARINE WEATHER DISCUSSION FOR N ATLANTIC OCEAN
NWS OCEAN PREDICTION CENTER WASHINGTON DC
810 AM EDT FRI 24 MAY 2013

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

UPDATE:

SUMMARY...A COLD FNT WILL PASS E ACROSS THE OFSHR WTRS THIS AFTN
THRU SAT. LOW PRES WILL MOVE NE OVER THE SRN NT1 WTRS THIS AFTN
INTO TONITE...THEN TURN N AND PASS ACROSS THE NRN NT1 WTRS SAT
INTO SUN. THE LOW WILL MOVE OFF TO THE NE LATE SUN AND MON. RDG
WILL BLD SE INTO THE SRN NT2 WTRS SUN...EXPAND OVER THE NRN NT2
WTRS MON...THEN BLD ACROSS THE NT1 AREA TUE.

MODELS...THE 06Z NAM AND LATEST MED RNG MDLS ARE IN GUD OVERALL
AGREEMNT THRU THE FCST PRD...WITH 06Z GFS AND 00Z ECMWF IN
CLOSEST AGREEMNT ACROSS THE CSTL/OFSHR WTRS. 00Z ECMWF/UKMET
LOOK A BIT WKR WITH THE S TO SW FLOW AHD OF THE COLD FNT INTO
SAT...WHILE THE 06Z NAM/00Z GEM ARE STGR...AND 06Z GFS/00Z
NOGAPS ARE MEDIAN SOLNS WRT STRENGTH OF THE S TO SW FLOW. SINCE
THE GFS HAS STG SUPPORT FROM THE ECMWF...AND BECAUSE THE GFS
LOOKS LIKE A GUD MEDIAN SOLN...WILL BE FAVORING THE 06Z GFS FOR
THE UPCOMING OFSHR WTRS FCST PACKAGE. AM NOT PLANNING TO MAKE
ANY SIGNIF CHANGES TO THE CURRENT FCST TREND.

SEAS...BOTH THE 06Z MULTIGRID WW3 AND 00Z ECMWF WAM INITIALIZED
WELL OVER THE CSTL/OFSHR WTRS. THESE MDLS ARE IN GUD OVERALL
AGREEMNT DURING THE FCST PRD...WITH ONLY SOME MINOR DIFFS NOTED
ON SAT AND SUN. WILL USE THE MULTIGRID WW3...EXCEPT WILL GO WITH
A BLEND OF THE MULTIGRID WW3 AND ECMWF WAM ON SAT AND SUN TO
SMOOTH SOME OF THE DIFFS.

EXTRATROPICAL STORM SURGE GUIDANCE...N/A.

PREV DISCUSSION:

OVER THE SHORT TERM...AN EARLIER 0130Z HIGH RESOLUTION ASCATB
PASS CONFIRMED THAT SLY GALES WERE PRESENT INVOF THE GULF STREAM
ACRS THE BALT CNYN TO HAT CNYN WTRS. THE NEW 00Z MDLS (AND 12Z
ECMWF) RMN IN RSNBLY GOOD AGRMT AND SHARE SMLR FCST TIMING FOR A
COLD FRONT SLOWLY PUSHING E ACRS THE NT2 WTRS TODAY INTO SAT.
PLAN ON USING A 00Z GFS/12Z ECMWF FCST TIMING FOR THIS FROPA.
INADVOF THIS COLD FRONT ALL OF THE LATEST MDLS FCST SLY GALE
FORCE WINDS ACRS THE CNTRL/NRN OUTER NT2 WTRS TODAY...BCMG
LIMITED TO THE ERN BALT CNYN TO THE HAGUE LINE WTRS TONITE INTO
EARLY SAT. FURTHER N INADVOF THE FRONT...SM OF THE MDLS CONT TO
FCST SLY GALE FORCE BL WINDS ACRS THE NT1 WTRS TODAY INTO EARLY
TONITE. BUT STIL BELIEVE THE SLY WARM AIR ADVECTION OVER THESE
COLD WTRS WL MAINTAIN STRONG ENUF LOW LEVEL INVERSIONS (AS SEEN
IN THE BUFKIT SOUNDINGS) TO KEEP WINDS SUBGALE THERE. SO NO SIG
IMMED SHORT TERM CHNGS ARE PLANNED TO THE PREV OFSHR FCSTS
REGARDING THIS FROPA.

FURTHER N AS THIS COLD FRONT MOVES OFSHR...IN RESPONSE TO AN UPR
LOW FCST TO CLOSE OFF OVER SRN NEW ENGLD/NRN MID ATLC STATES...
THE LATEST MDLS ALL TO SMWHT VARYING DEGREES FCST AN ATTENDANT
SFC LOW TO FORM OVER THE NRN WTRS TODAY...THEN DRIFT SLOWLY NEWD
ACRS THE NT1 WTRS TONITE THRU SAT NITE...THEN DRIFT N OF THE
WATERS SUN INTO MON. OVERALL WL FAVOR THE 00Z GFS FCST TRACK FOR
THIS LOW WHICH LOOKS LIKE A RSNBL COMPROMISE BTWN THE SLIGHTLY
FASTER 00Z GEM/UKMET AND SLIGHTLY SLOWER 12Z ECMWF AND IS IN
LINE WITH THE LATEST WPC GUIDANCE. IN REGARDS TO THE FCST
STRENGTH OF THE FCST GRADIENTS IN THE WAKE OF THIS LOW AND IN
ITS POSTFRONTAL GRADIENT...PLAN ON COMPROMISING BTWN THE
STRONGER 00Z NAM/GFS AND SMWHT WEAKER 00Z GEM/UKMET/12Z ECMWF
FCST GRADIENTS. WL WAIT TO SEE THE 00Z ECMWF BEFORE MAKING A
FINAL DECISION...BUT ATTM AM INCLINED TO ADD THE HDSN CNYN TO
BALT CNYN WTRS TO THE PREVLY FCSTD PSBL GALE WRNGS ON SAT/SAT
NITE. SO OTHERWISE NO OTHER MAJOR LONG RANGE CHNGS ARE PLANNED
TO THE PREV OFSHR FCSTS.

SEAS...OTHER THAN ITS NORMAL BIAS OF INITIALIZING ITS SEAS SMWHT
TOO HIGH ACRS THE WTRS N OF THE GULF STREAM...OVERALL THE 00Z
WAVEWATCH III FCST SEAS LOOK REPRESENTATIVE THRU TUE.

EXTRATROPICAL STORM SURGE GUIDANCE...N/A.

.WARNINGS/FORECAST CONFIDENCE...PRELIMINARY. ANY CHANGES WILL BE
COORDINATED THROUGH AWIPS 12 PLANET CHAT OR BY TELEPHONE:

.NT1 NEW ENGLAND WATERS...
.GULF OF MAINE...NONE.
.GEORGES BANK...NONE.
.SOUTH OF NEW ENGLAND...NONE.

.NT2 MID ATLC WATERS...
.HUDSON CANYON TO BALTIMORE CANYON...GALE SAT INTO EARLY SUN...
LOW CONFDC.
.BALTIMORE CANYON TO HAGUE LINE...GALE THIS AFTN INTO SUN...MOD
TO HIGH CONFDC.
.BALTIMORE CANYON TO HATTERAS CANYON...GALE THIS AFTN E
PORTION... HIGH CONFDC.
.HATTERAS CANYON TO CAPE FEAR...NONE.
.CAPE FEAR TO 31N...NONE.
$$

.FORECASTER SCOVIL/VUKITS. OCEAN PREDICTION CENTER.