Marine Interpretation Message
Issued by NWS

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AGNT40 KWNM 270028
MIMATN

MARINE WEATHER DISCUSSION FOR N ATLANTIC OCEAN
NWS OCEAN PREDICTION CENTER WASHINGTON DC
828 PM EDT TUE MAY 26 2015

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

A HIGH PRES RIDGE EXTENDING INTO THE CNTRL NT2 WTRS CONTS TO BE
THE DOMINANT WEATHER FEATURE AFCTG THE WTRS AS IT MAINTAINS LITE
WINDS THRUT THE NT2 WTRS. IN THE SWLY GRADIENT N OF THE RIDGE MAX
WINDS REMAIN GNRLY IN THE 15-25 KT RANGE ACRS THE NT1 WTRS. MAX
SEAS THRUT THE WTRS CONT TO BE IN THIS SWLY GRADIENT ACRS THE NRN
WTRS AND ARE IN THE 5-7 FT RANGE...HIGHEST ACRS THE ERN GULF OF
MAINE...WHICH ARE RUNNING SLIGHTLY LOWER THAN FCST BY THE 18Z
WAVEWATCH III AND THE 12Z ECMWF WAM MDLS AT THE MOMENT.

OVER THE SHORT TERM...THE LATEST MDLS REMAIN IN RSNBLY GOOD AGRMT
THAT LTL CHNG WL OCCUR IN THE PATTERN WITH THE HIGH PRES RIDGE
FCST TO REMAIN IN PLACE ACRS THE CNTRL NT2 WTRS TONITE THRU THU
MAINTAINING THE MOD STRONG (UP TO 20 OR 25 KT) SWLY GRADIENT ACRS
THE NT1 WTRS. THE 12Z/18Z GFS 10M BL WINDS...WHICH ARE VERY SMLR
TO THE 12Z ECMWF...STIL LOOK LK A RSNBL COMPROMISE SOLUTION FOR
THIS GRADIENT VS THE STRONGER 12Z/18Z NAM/12Z GEM AND WEAKER 12Z
NAVGEM/UKMET SOLUTIONS. THEN LATE THU/THU NITE THE MDLS WITH
SLIGHT TIMING DIFFERENCES ALL FCST A WEAK COLD FRONT TO MOV OFSHR
INTO THE NT1 WTRS. IN COMPARISON WITH THE 12Z UKMET/ECMWF...THE
12Z/18Z GFS LIKELY FCST THIS FRONT TO PUSH A LTL TOO FAR S...BUT
BY FRI MORNING ITS ASCD FCST GRADIENTS BCM SO WEAK THAT THE PREVLY
USED 12Z GFS 10M BL WINDS STIL LOOK FINE. SO OVERALL ANTICIPATE
MAKING ONLY MINOR SHORT TERM CHNGS TO THE PREV OFSHR FCSTS.

IN THE LONG RANGE...THE LATEST GLOBAL MDLS AGREE THAT THE MOST SIG
WEATHER FEATURE WL BE ANOTHER SMWHT STRONGER COLD FRONT MOVG OFSHR
INTO THE NRN WTRS SAT NITE INTO SUN NITE. THE 12Z/18Z GFS AND 12Z
GEM/UKMET ARE SMLR AND MR PROGRESSIVE WITH THIS FROPA THAN THE
SLOWER 12Z NAVGEM/ECMWF. AS A COMPROMISE AM TEMPTED TO TIME SHIFT
THE PREVLY POPULATED 12Z GFS 10M BL WINDS FOR THIS FROPA 6 HRS
SLOWER. BUT FOR NOW WITH THIS BEING DAY 5 WL LEAVE THE CURRENT
FCST TIMING OF THIS FROPA IN PLACE AND WL THEN REEVALUATE ITS FCST
TIMING AGAIN LATER WHEN THE 00Z MDLS COME IN. SO AGAIN DO NOT PLAN
ON MAKING ANY MAJOR LONG RANGE CHNGS IN THE NEXT OFSHR FCST
PACKAGE.



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

SUMMARY...THE QUIET WX PATTERN IS EXPECTED TO CONTINUE THRU THE
ENTIRE FCST PRD ACROSS THE OFSHR ZONES...WITH MAINLY LIGHT WINDS
AND SEAS 8 FT OR LESS. LATEST AVAIL ASCAT PASSES FROM 1350Z TO
1353Z...AND FROM 1530Z TO 1533Z ARE STILL SHOWING LIGHT WINDS OVER
THE CSTL/OFSHR WTRS. A HI PRES RIDGE WILL PERSIST OVER THE NT2
WTRS FOR TONITE THRU SAT NITE. AREAS OF LOW PRES WILL PASS N OF
THE NT1 AREA TONITE THRU WED NITE. A WEAK COLD FNT WILL MOVE SE
AND APRCH THE NEW ENG COAST THU...THEN DSIPT OVER THE GULF OF
MAINE THU NITE. A HI PRES RIDGE WILL BUILD SE OVER THE NT1 WTRS
FRI...THEN PASS SE ACROSS THE NT1 AREA FRI NITE INTO SAT. A STGR
COLD FNT WILL MOVE SE AND APRCH THE NEW ENG COAST LATE SAT AND SAT
NITE...THEN MOVE SE OVER THE NT1 AND NRN NT2 WTRS SUN AND SUN NITE.

MODELS...THE 12Z MED RNG MDLS ARE IN GUD OVERALL AGREEMNT ACROSS
THE OFSHR WTRS THRU THE FCST PRD...EXCEPT THE 12Z GFS 30M SOLN IS
JUST A BIT OVERDONE WITH STRENGTH OF THE SW FLOW OVER THE NRN NT1
WTRS ON WED...THEN AGAIN LATE SAT. THERE ARE SOME RELATIVELY MINOR
DIFFS WITH TIMING OF THE COLD FNT ON SUN AND SUN NITE...BUT THE
12Z GFS 10M APRS TO BE THE MOST REPRESENTATIVE MDL SOLN...AND
WILL BE USED TO POPULATE THE WIND GRIDS FOR THE ENTIRE FCST PRD.
AM NOT PLANNING TO MAKE ANY SIGNIF CHANGES TO THE CURRENT FCST
TREND.

.SEAS...THE 12Z MULTIGRID WAVEWATCH III MDL AND 12Z ECMWF WAM
BOTH INITIALIZED WELL ACROSS THE CSTL/OFSHR WTRS. THESE MDLS ARE
IN VRY GUD AGREEMNT OVER THE OFSHR WTRS THRU THE ENTIRE FCST
PRD...EXCEPT THE MWW3 IS TRENDING A COUPLE OF FEET HIGHER OVER THE
SRN NT1/NRN NT2 WTRS FOR LATE SUN AND SUN NITE. WILL BE USING A
50/50 BLEND OF THE 12Z MWW3/ECMWF WAM TO SMOOTH THE DIFFS.

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


.WARNINGS...PRELIMINARY.

.NT1 NEW ENGLAND WATERS...
     NONE.

.NT2 MID ATLC WATERS...
     NONE.

$$

.FORECASTER COLLINS/VUKITS/SCOVIL. OCEAN PREDICTION CENTER.


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