

561 

AGNT40 KWNM 251338

MIMATN



MARINE WEATHER DISCUSSION FOR N ATLANTIC OCEAN

NWS OCEAN PREDICTION CENTER WASHINGTON DC

938 AM EDT THU AUG 25 2016



.FORECAST DISCUSSION: MAJOR FEATURES/WINDS/SEAS/SIGNIFICANT

.WEATHER FOR THE NORTH ATLANTIC OCEAN W OF 50W FROM 30N TO 50N.



LTST NCEP SFC ANALYS INDC A HIGH PRES RDG ACRS THE OFSHR WTRS...A

WK STNRY FRNTL BNDRY JUST E OF THE AREA NR BERMUDA...AND A COLD

FRONT INLAND OVER THE GREAT LAKES REGION MOVING E TWD NT1. ASCAT

FM 02Z LAST NGT INDC VARIABLE WINDS 5 TO 15 KT OVR THE N PTTN

UNDER THE RIDGE...AND NE FLOW OVR SRN NT1...TO THE NW OF THE STNRY

FRONT E OF THE AREA. CRNT SFC RPRTS INDC SFC WINDS HAVE NOT

CHANGED MUCH FROM THE TIME OF THE ASCAT PASS...THO THE COVERAGE OF

20 KT WINDS IS A LTL SMALLER. THE 06Z GFS WINDS ARE INIT OK WHEN

COMPARED WITH THE CRNT DATA...AND INDC THE AFOREMENTIONED CD FRONT

WL APRCH THE NT1 WATERS TNGT INTO FRI...BEFORE MOVING OFFSHORE

LATE FRI INTO FRI NGT. THE 00Z ECWMF/NAM/GEM/UKMET AGREE SOMEWHAT

WELL ON THE TMG AND INTNSTY OF THE FRONT...THO THE NAM/GEM/GFS ARE

A BIT STGR WTIH THE SW WINDS AHD OF THE FRONT...RANGING BTWN 25

AND 30 KT. THE 00Z ECMWF AND UKMET ARE WKR...AND INDC ONLY 15 TO

20 KT. BUOY REPORTS CRNTLY INDC SSTS IN THE MID 60S TO 70 DEG F IN

THE GULF OF MAINE..AND THE GFS STABILITY INDICES INDC THAT THE

NORMALLY STABLE ENVIRONMENT OVER THE CD SHELF WATERS IN THE GULF

OF MAINE IS NOT QUITE AS STABLE WITH THE WARMER SSTS.

HOWEVER...WITH THE GFS INDCG ONLY ABT 25 KT IN SW FLOW AT 925

MB...THINKING THAT 25 KT AND HIGHER IS OVERDONE...SO PLANNING ON

CAPPING WINDS AT 20 KT IN THE UPDATE PKG. 



OTRW...THE 06Z GFS HAS NOT CHANGED SIGNIFICANTLY FROM THE PREV

RUN...AND INDC HIGH PRES WL BUILD OVER THE AREA ON SAT AND SUN

AFTER THE WK CD FRONT MOVES E OF THE REGION. THE MDLS HAVE BEEN

IN DECENT AGRMT ON ANOTHER WK FRONT MOVG INTO NT1 MON...WITH SOME

DIFFS ON THE TMG. HOWEVER...THE 06Z GFS HAS NOT CHANGED MUCH FM

THE PREV RUN...WHICH WAS USED IN THE PREV FCST...SO ATTM PLANNING

ON STAYING WITH CONTINUITY FOR THE REMAINDER OF THE FCST PD.



-----------------------------------------------------------------

PREVIOUS DISCUSSION...



SUMMARY...00Z NCEP SFC ANALYSIS SHOWS A LARGE HIGH PRES RIDGE

OVER THE OFSHR WTRS...WITH A STATIONARY FRONT EXTNDG NE TO SW

ACROSS THE WTRS BETWEEN THE SRN NT2 ZONES AND BERMUDA. LATEST

AVAILABLE ASCAT AND ASCAT HI-RES PASSES FROM EARLIER THIS MORNING

SHOW AREAS OF WINDS TO 20 KT IN NE FLOW OVER THE SRN NT2

ZONES...BUT OTHERWISE INDICATE LIGHT WINDS OF 15 KT OR LESS IN THE

REMAINING OFSHR WTRS. LIGHTNING DENSITY PRODUCT DATA AT 0650Z DID

NOT SHOW ANY SHOWER OR TSTM ACTIVITY IN THE COASTAL/OFSHR WTRS.



MAIN WEATHER FEATURES...THE WEAK SUMMERTIME PATTERN IS EXPECTED TO

CONTINUE THRU THE FCST PERIOD...WITH WINDS NOT EXPECTED TO EXCEED

20 TO 25 KT IN THE OFSHR WTRS. A HI PRES RIDGE WILL PASS E OVER

THE OFSHR WTRS TODAY INTO FRI. A COLD FRONT WILL APPROACH THE

COAST FROM THE NW FRI...THEN MOVE SE OVER THE OFSHR AREA FRI NITE

INTO SAT NITE WHILE WEAKENING. ANOTHER RIDGE WILL BUILD SE OVER

THE OFSHR WTRS LATE SAT AND SAT NITE...THEN E ACROSS THE NT1 WTRS

SUN AND SUN NITE. A WEAKENING COLD FRONT WILL PASS SE OVER THE NT1

AREA MON AND MON NITE. T.S. GASTON IS FORECAST TO TRACK NW TOWARDS

THE BERMUDA AREA THRU MON NITE WHILE STRENGTHENING. GASTON IS

EXPECTD TO PUSH LONG PERIOD SW SWELL INTO THE OFSHR WTRS DURING

THE SAT THRU MON NITE TIMEFRAME. REFER TO LATEST NATIONAL

HURRICANE CENTER ADVISORY FOR ADDITIONAL INFORMATION.



MODELS...THE 00Z MED RNG MDLS ARE IN VERY GUD OVERALL AGREEMNT

ACROSS THE OFSHR WTRS THRU THE FCST PERIOD...EXCEPT THE 00Z GEM

DOES NOT HAVE A COLD FRONT CROSSING THE NT1 WTRS ON MON AND MON

NITE. THE 00Z GFS 10M SOLN LOOKS REPRESENTATIVE ENUF TO BE USED

FOR THE WIND GRIDS THRU AT LEAST MON NITE. AM NOT PLANNING TO MAKE

ANY SIGNIF CHANGES TO THE CURRENT FCST TREND.



SEAS...THE 00Z WNA WAVEWATCH III MDL AND THE 00Z ECMWF WAM BOTH

INITIALIZED WELL OVER THE OFSHR WTRS VERSUS THE RA1 SEA STATE

ANALYSIS. THE MDLS BOTH LOOK REASONABLE AND GENERALLY STAY WITHIN

1 TO 2 FEET OF EACH OTHER THRU THE ENTIRE FCST PERIOD...SO WILL GO

WITH A 50/50 BLEND OF THE 00Z WNA WAVEWATCH III/ECWMF WAM FOR THE

WAVE HT GRIDS AS A COMPRIMISE SOLN.



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



.WARNINGS...PRELIMINARY.



.NT1 NEW ENGLAND WATERS...

     NONE.



.NT2 MID ATLC WATERS...

     NONE.



$$



.FORECASTER KELLS/SCOVIL. OCEAN PREDICTION CENTER.

