Marine Interpretation Message
Issued by NWS

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AGNT40 KWNM 230641
MIMATN

MARINE WEATHER DISCUSSION FOR N ATLANTIC OCEAN
NWS OCEAN PREDICTION CENTER WASHINGTON DC
241 AM EDT SAT MAY 23 2015

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

OVER THE SHORT TERM...THE NEW 00Z MDLS PRESENT NO MAJOR FCST
PROBLEMS. THE MDLS CONT TO SHARE SMLR FCST TIMING FOR A COLD
FRONT TO PUSH SE INTO THE NRN NT2 WTRS THIS MORNING...CONT S ACRS
THE CNTRL NT2 WTRS LATER TODAY...THEN DSIPT ACRS THE SRN NT2 WTRS
TONITE. IN THE POSTFRONTAL GRADIENT ASCD WITH THIS FROPA...IT STIL
LOOKS MARGINAL WHETHER THE PREVLY FCSTD NWLY GALES WL DVLP ACRS
THE ERN GULF OF MAINE EARLY TODAY. WITH THE CONSISTENT 00Z
NAM/GFS/GEM FCSTG MARGINAL GALE FORCE BL WINDS IN THIS GRADIENT
AND THE USUALLY CONSERVATIVE 00Z UKMET FCSTG SOLID 25-30 KT WL
START THE TODAY FCST PERIOD WITH LOW FCST CONFIDENCE MARGINAL
GALES ACRS THESE WTRS...THEN BCM SUBGALE BY LATE MORNING.
THEREFORE SMLR TO THE PREV FCST PACKAGES WL POPULATE WITH THE
STRONGER 00Z GFS 30M BL WINDS FOR THIS GRADIENT TODAY. THEN BY
LATER TODAY/TONITE THE 00Z MDLS REMAIN IN GOOD AGRMT THAT A STRONG
SFC HIGH WL BUILD IN N OF THE FRONT OFF THE MID ATLC COAST...TRACK
E ACRS THE CNTRL NT2 WTRS SUN...THEN ESTABLISH A W-E RIDGE BACK
INTO THE CNTRL NT2 WTRS SUN NITE. N OF THIS RIDGE AS THE MDLS FCST
A WKNG COLD FRONT TO APRCH FM THE NW SAT NITE/SUN TO VARYING
DEGREES THEY ALL FCST A STRENGTHENING SWLY GRADIENT TO DVLP ACRS
THE NT1 WTRS. OVERALL BELIEVE THE 00Z GFS SOLUTION FOR THIS
GRADIENT LOOKS LK A RSNBL COMPROMISE BTWN THE SMWHT STRONGER 00Z
NAM/GEM AND WEAKER 00Z UKMET/ECMWF SOLUTIONS. THEREFORE TO BETTER
ACCOUNT FOR THE ASCD WARM AIR ADVECTION OVER THE COLD NRN WTRS WL
TRANSITION TO POPULATING WITH THE WEAKER 00Z GFS 10M BL WINDS FOR
TONITE THRU SUN NITE. SO AS A RESULT ANTICIPATE MAKING ONLY MINOR
SHORT TERM CHNGS TO THE PREV OFSHR FCSTS.

IN THE LONG RANGE...THE 00Z MDLS FCST A QUIET SUMMER LIKE PATTERN
TO CONT. IN RESPONSE TO AN UPR RIDGE FCST TO BUILD NR THE E COAST
MON INTO TUE...THEN PERSIST TUE NITE INTO WED NITE THE 00Z MDLS
ARE IN GNRL AGRMT THAT THE ASCD SFC HIGH PRES RIDGE WL PERSIST
ACRS THE CNTRL NT2 WTRS MON INTO WED NITE WHL GRADLY WKNG. N OF
THIS RIDGE THE 00Z MDLS CONT TO DIFFER SMWHT IN THEIR FCST
STRENGTH OF THE SWLY GRADIENT ACRS THE NRN WTRS. AS A FRONT IS
FCST TO BCM QSTNRY ACRS SE CANADA WITH A SERIES OF WEAK FRONTAL
WAVES TRACKING NE ALONG IT THE 00Z MDLS IN GNRL AGREE THAT THE
SWLY GRADIENT WL PULSATE SMWHT STRONGER DURING THE DAY TUE AND
AGAIN DURING THE DAY WED. SINCE IT HAS THE SPRT OF THE 00Z
UKMET/ECMWF...WL CONT TO FAVOR THE 00Z GFS SOLUTION FOR THIS
GRADIENT (THE 00Z GEM LOOKS LIKE A STRONG OUTLIER SOLUTION). SO
AGAIN TO BETTER ACCOUNT FOR THE WARM AIR ADVECTION OVER THE COLD
NRN WTRS WL CONT TO POPULATE WITH THE MR CONSERVATIVE 00Z GFS 10M
BL WINDS FOR MON THRU WED NITE. SO PER THESE FCST WINDS PLAN ON
MAKING ONLY MINOR LONG RANGE CHNGS IN THE NEXT OFSHR FCST PACKAGE.

.SEAS...WITH THE DIFFERENCES BTWN THE TWO MDLS RMNG MINIMAL
(GNRLY WITHIN 1-2 FT) WL USE A 50/50 BLEND OF THE 00Z WAVEWATCH
III AND 00Z ECMWF WAM FOR TODAY THRU MON NITE. THEN BLV THE 00Z
ECMWF WAM STARTS TO OVERFCST SEAS ACRS THE COLDER NRN WTRS IN THE
MOD STRONG SWLY GRADIENT...SO WL TRANSITION TO ALL 00Z WAVEWATCH
III FCST SEAS ON TUE THRU WED NITE.

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

.WARNINGS...PRELIMINARY.

.NT1 NEW ENGLAND WATERS...
.ANZ800...GULF OF MAINE...
     GALE TODAY.

.NT2 MID ATLC WATERS...
     NONE.

$$

.FORECASTER VUKITS. OCEAN PREDICTION CENTER.


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