Marine Interpretation Message
Issued by NWS

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AGNT40 KWNM 240023
MIMATN

MARINE WEATHER DISCUSSION FOR N ATLANTIC OCEAN
NWS OCEAN PREDICTION CENTER WASHINGTON DC
823 PM 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.

AS STRONG HIGH PRES BUILDS OFF THE MID ATLC COAST LITE WINDS HV
DVLPD IN ITS VCNTY. N OF THE HIGH ACRS THE NRN MOST NT1 AND S OF
THE HIGH ACRS THE SRN MOST NT2 WTRS THE SW AND E GRADIENTS
RESPECTIVELY HV MAX ASCD WINDS UP TO 20 OR 25 KT PRETTY MUCH AS
PREVLY FCSTD. MAX SEAS THRUT THE WTRS ARE LEFT OVER FM AN EARLIER
COLD FROPA AND ARE IN THE 6-9 FT RANGE...HIGHEST ACRS THE SE MOST
NT1 AND NE MOST NT2 WTRS WHICH ARE BEING UNDERFCST SLIGHTLY BY
BOTH THE 18Z WAVEWATCH III AND 12Z ECMWF WAM MDLS AT THE MOMENT.

THE LATEST MDLS PRESENT NO SIG FCST PROBLEMS OVER THE NEXT SVRL
DAYS. IN RESPONSE TO AN UPR RIDGE FCST TO BUILD TWDS THE E COAST
TONITE THRU TUE...THEN GRADLY FLATTEN AND WEAKEN TUE NITE INTO THU
NITE...THE MDLS ARE IN RSNBLY GOOD AGRMT THE THE SFC HIGH WL DRIFT
E ACRS THE NT2 WTRS TONITE/SUN...THEN MAINTAIN A W-E RIDGE BACK
ACRS THE CNTRL NT2 WTRS SUN NITE THRU THU NITE...WHL GRADLY
WEAKENING. N OF THIS RIDGE THE MDLS GNRLY AGREE THAT A MOD STRONG
(GNRLY UP TO 20-25 KT) SWLY GRADIENT WL PULSATE UP AND DOWN SMWHT
IN FCST STRENGTH. OVERALL BLV THE 18Z/12Z GFS SOLUTION LOOKS LIKE
A RSNBL COMPROMISE FOR THIS SW GRADIENT BTWN THE STRONGER 18Z/12Z
NAM/12Z GEM AND SLIGHTLY WEAKER 12Z NAVGEM/UKMET/ECMWF SOLUTIONS.
THEREFORE PLAN ON CONTG TO USE THE PREVLY POPULATED 12Z GFS 10M
BL WINDS THRU THU NITE WITH JUST SM MINOR ADDITIONAL EDITS IN
DEFERENCE TO THE 18Z GFS AND 12Z ECMWF. SO ANTICIPATE MAKING ONLY
MINOR CHNGS IN THE NEXT OFSHR FCST PACKAGE.


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

SUMMARY...A COLD FRONT WILL PASS SE ACROSS THE NT2 AREA LATER
TODAY. A TROF WILL MOVE SE AND APRCH THE GULF OF MAINE TONITE AND
SUN...THEN PASS E OVER THE NRN NT1 WTRS SUN NITE INTO MON. A WARM
FRONT WILL PASS NW AND N OF THE NT1 AREA MON NITE INTO TUE. A
SERIES OF LOWS WILL PASS N OF THE NT1 AREA TUE NITE INTO THU.
OTHW...A HI PRES RIDGE WILL BUILD OFSHR TONITE...THEN PERSIST SUN
THRU THU NITE.

MODELS...THE 12Z MED RNG MDLS ARE IN VRY GUD AGREEMNT ACROSS THE
CSTL/OFSHR WTRS THRU THE ENTIRE FCST PRD. THE REPRESENTATIVE 12Z
GFS 10M SOLN WILL BE USED TO POPULATE THE WIND GRIDS THRU THU
NITE. AM NOT PLANNING TO MAKE ANY SIGNIF CHANGES TO THE CURRENT
FCST TREND.

.SEAS...DIFFS BTWN THE 12Z WAVEWATCH III MDL AND 12Z ECMWF WAM
ARE MAINLY MINIMAL (1 TO 2 FT) DURING THE FCST PRD...SO WILL USE
A 50/50 BLEND OF THE 12Z WAVEWATCH III/ECMWF WAM FOR TONITE INTO
EARLY TUE. THEN THE 12Z ECMWF WAM STARTS TO OVERFCST THE SEA HTS
OVER THE COOLER NRN NT1 WTRS IN FAIRLY STG SW FLOW LATER TUE...SO
WILL GO WITH ALL 12Z WAVEWATCH III FCST SEA HTS FOR THE LATER TUE
THRU THU NITE TIMEFRAME.

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


.WARNINGS...PRELIMINARY.

.NT1 NEW ENGLAND WATERS...
     NONE.

.NT2 MID ATLC WATERS...
     NONE.

$$

.FORECASTER VUKITS/SCOVIL. OCEAN PREDICTION CENTER.


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