Marine Interpretation Message
Issued by NWS

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AGNT40 KWNM 041317
MIMATN

MARINE WEATHER DISCUSSION FOR N ATLANTIC OCEAN
NWS OCEAN PREDICTION CENTER WASHINGTON DC
917 AM EDT FRI SEP 4 2015

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

A COLD FRONT NR 40N CONTS TO PUSH S PRETTY MUCH AS PREVLY FCSTD.
IN THE POSTFRONTAL NELY GRADIENT MAX WINDS AT THE MOMENT ARE GNRLY
IN THE 15-20 KT RANGE. MAX SEAS BHND THE FRONT HV BUILT UP TO THE 3-5
FT RANGE...HIGHEST IN THE GULF OF MAINE...WHICH ARE BEING HANDLED
SLIGHTLY BETTER BY THE 00Z ECMWF WAM VS THE 06Z WAVEWATCH III.

OVER THE SHORT TERM...THE LATEST MDLS SHARE SMLR FCST TIMING FOR
THE COLD FRONT TO CONT S ACRS THE NRN NT2 WTRS TODAY...THEN WASH
OUT ACRS THE CNTRL NT2 WTRS TONITE AS MOD STRONG HIGH PRES BLDS IN
FM THE N. IN THE NELY GRADIENT N OF THE FRONT...THE 06Z NAM/GFS
RMN CONSISTENT IN FCSTG MAX ASCD WINDS UP TO 20 OR 25 KT...WHICH
OVERALL ARE SPRTD BY THE OTHER 00Z MDLS. THEREFORE WL STAY THE
COURSE THRU THE SHORT TERM AND CONT TO USE THE 00Z GFS 30M BL
WINDS INTO SUN NITE WITH JUST SM MINOR ADDITIONAL EDITS IN
DEFERENCE TO THE 06Z GFS AND 00Z ECMWF.

IN THE LONG RANGE...THE LATEST MDLS ALL FCST A QUIET PATTERN TO
CONT. WL CONT TO DISREGARD THE 00Z CANADIAN GLOBAL GEM SOLUTION OF
FCSTG A MOD STRONG SFC LOW (FORMERLY T.S. ERIKA?) TO LIFT N INTO
THE SRN/CNTRL NT2 WTRS SUN NITE INTO TUE NITE. THE 06Z GFS RMNS
CONSISTENT VS ITS PREV 00Z RUN IN FCSTG A WEAK SFC LOW TO DVLP
INVOF HAT CNYN MON NITE...THEN DRIFT NE TUE/TUE NITE WHL WKNG. THE
00Z UKMET/ECMWF JUST FCST A CSTL TROF DRIFTING OFSHR THEN. THE
PREV OFSHR FCST PACKAGE USED THE 00Z GFS 10M BL WINDS IN THE LONG
RANGE. SO PER THE 06Z GFS WL CONT TO USE THESE 00Z GFS 10M BL
WINDS BUT WL TWEAK THEM DOWN SMWHT OVER THE NT2 WTRS IN DEFERENCE
TO THE 00Z UKMET/ECMWF.

ALSO OF NOTE...EVEN THO THE FCSTD WAVE HEIGHTS ARE EXPECTED TO BE
LOW...THE 06Z WAVEWATCH III REMAINS CONSISTENT IN FCSTG LONG
PERIOD (GREATER THAN 10 SECONDS) ELY SWELL TO SPREAD INTO THE NT1
WTRS SAT NITE/SUN...THEN SPREAD FURTHER INTO THE NT2 WTRS SUN NITE
THRU MON NITE.



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

SUMMARY...00Z NCEP SFC ANALYSIS SHOWS A COLD FNT SWEEPING SE
ACROSS THE GULF OF MAINE...WITH WEAK LOW PRES TROFNG INDICATED
OVER THE REMAINDER OF THE OFSHR WTRS. LATEST AVAIL ASCAT PASSES
FROM THIS MRNG SHOW LIGHT WINDS OF 15 KT OR LESS OVER THE OFSHR
AND COASTAL WTRS. LIGHTNING DENSITY PRODUCT DATA AT 0650Z SHOWS
AREAS OF SCT SHOWERS/TSTMS OVER THE CNTRL/SRN NT2 WTRS. A
RELATIVELY WEAK SUMMERTIME PATTERN WILL PREVAIL ACROSS THE OFSHR
WTRS THRU TUE NITE...WITH WINDS TO 25 KT AND SEAS TO 7 OR 8 FT.

MODELS...00Z MED RNG MDLS ARE IN GUD OVERALL AGREEMNT ACROSS THE
OFSHR WTRS THRU THE FCST PRD. THE CONSISTENT AND REPRESENTATIVE
00Z GFS 30M SOLN WILL BE USED FOR THE WIND GRIDS THRU SUN
NITE...FOLLOWED BY THE 00Z GFS 10M SOLN FOR MON THRU TUE NITE. AM
NOT PLANNING TO MAKE ANY SIGNIF CHANGES TO THE CURRENT FCST TREND.

SEAS...WNA VERSION OF 00Z WAVEWATCH III MDL AND 00Z ECMWF WAM
BOTH INITIALIZED VRY WELL OVER THE OFSHR WTRS...AND THESE MDLS ARE
IN GUD AGREEMNT THRU THE ENTIRE FCST PRD. WILL USE THE 00Z WNA
WAVEWATCH III MDL THRU TUE NITE FOR THE SEA HT GRIDS.

.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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