

362 

AGNT40 KWNM 091314

MIMATN



MARINE WEATHER DISCUSSION FOR N ATLANTIC OCEAN

NWS OCEAN PREDICTION CENTER WASHINGTON DC

914 AM EDT TUE AUG 9 2016



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

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



GOES WV IMGRY INDC AN UPR SHORTWAVE TROF OVER FAR SE CANADA...WITH

THE TAIL END EXTENDING SW TO JUST E OF THE OFSHR WTRS. THE IMGRY

ALSO INDC AN UPR RDG MOVG INTO THE ERN CONUS...AND THE LTST NCEP

SFC ANALYS INDC HIGH PRES BUILDING OVER THE N PORTION OF THE OFSHR

WTRS...WITH A STNRY FRONT ACRS THE S PORTION. THE LGTNG DENSITY

PROD INDC ISOLATED SHOWERS AND TSTMS ALONG THE FRONT...AND ALSO

OVER FAR SW NT2 IN SRLY SLOW. THE PREV FCST INDC SHOWERS AND TSTMS

IN THE GRIDS...DCSRG IN INTNSTY AS THE HIGH IS XPCTD TO BUILD AND

THE FRONT WKNS...SO PLANNING ON KEEPING PREV MENTIONS IN THE

UPDATE PKG. 



ALSO...THE CRNT SFC DATA INDC WINDS TO 15 KT IN NT2...AND ASCAT

WIND RETRIEVALS FM 0245Z INDC 20 TO 25 KT IN THE SRLY FLOW RIGHT

ALONG THE SC COAST. THE PASS IS FAIRLY OLD AT THIS POINT...AND THE

06Z GFS 10M WINDS ARE INIT OK AND INDC UP TO 15 KT IN THE OFSHR

WTRS. THIS AGREES WELL WITH THE PREV FCST...SO PLANNING ON

STARTING OUT AT THAT INTNSTY IN THE UPDATE PKG. THE GFS THEN

AGREES WELL WITH THE 00Z ECMWF THRUT THE FCST PD ON THE OVERALL

PTTN...WITH ONLY MINOR DIFFS ON THE TMG OF A FRONTAL BNDRY THRU

NT1 WED NGT INTO THU. THE GFS AND ECWMF ARE MIDWAY BETWEEN THE

SLOWER 00Z UKMET AND THE FASTER 00Z GEM...AND BOTH SEEM VRY RSNBL.

THE 00Z ECMWF IS A LTL WKR WITH THE SW WINDS OVER NT1 AHD OF THE

FRONT...WHICH IS PREFERABLE GIVEN THE HIGHER STATIC STABILITY OVER

THE COLD SHELF WATERS. THE PREV FCST FAVORED THE 00Z GFS IN THE

SHORT TERM...AND THEN SWITCHED TO THE 00Z ECMWF IN THE EXTENDED...

WHICH STILL SEEMS VRY RNSBL...SO PLANNING ON STAYING WITH

CONTINUITY IN THE UPDATE PKG.



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

PREVIOUS DISCUSSION...



SUMMARY...THE LATEST ASCAT PASSES AND OBS MATCH UP QUITE WELL

WITH THE 00Z GFS 10M WINDS OVR THE OFF WTRS WITH THE STRONGEST

WINDS NR 20 KT OCCURRING OVR WTRS OFF THE GEORGIA AND FAR SRN S

CAROLINA COASTS. THE 00Z GFS REMAINS QUITE CONSISTENT AND HAS

GOOD SUPPORT FROM THE VARIOUS NON-GFS MDLS TODAY THRU MOST OF

FRI. WE WILL THEREFORE REMAIN CLOSE TO THE 00Z GFS THRU MOST OF

FRI AS WELL FOR THE EARLY AM FCST PACKAGE. THIS WILL RESULT IN NO

MAJOR CHANGES FROM THE PREV FEW OPC FCSTS. A WEAK STNRY FRONT

PERSISTS FROM NEAR CAPE HATTERAS EASTWARD OVR CENTRAL NT2 WTRS

WITH A WEAK HIGH PRES AREA CENTERED N OF THE FRONT OVR FAR NRN

NT2 WTRS. THE LATEST SATELLITE IMGRY AND LIGHTNING DENSITY DATA

INDICATES A FEW TSTMS NEAR THE FRONT MAINLY OVR THE INNER OFF

ZONES OF ANZ828...830...AND INTO OUTER ZONE 925. THE LATEST SREF

TSTM GUIDANCE SUGGESTS THAT THIS ACTIVITY WILL WEAKEN SOMEWHAT BY

THE AFTN HRS. LOCALLY GUSTY WINDS AND ROUGH SEAS MAY OCCUR IN OR

NEAR ANY OF THE TSTMS. OVERALL...THERE WILL BE CHANCE FOR SCTD

SHWRS AND TSTMS NR THE FRONT AND EVEN S INTO THE SRN NT2 WTRS FOR

THE NEXT COUPLE OF DAYS AS THE FRONT SLOWLY WEAKENS...AND THE

HIGH SLIDES E OF THE WTRS. A COLD FRONT IS FCST TO APPROACH NT1

WTRS FROM THE NW THU NITE...AND THEN STALL OVR NRN OR CENTRAL NT1

WTRS FRI THRU SAT NITE AS WEAK LOWS TRACK E ALONG THE FRONT. FOR

THE FRI NITE INTO SAT NITE TIME PERIOD WE WILL RELY ON THE 00Z

ECMWF MDL GUID AS IT LIES BETWEEN THE SLOWER 00Z UKMET AND FASTER

00Z GFS REGARDING THE FRONT OVR NT1 WTRS LATE IN THE WEEK INTO

THE WKND. THIS SOLUTION IS ALSO IN PRETTY GOOD AGREEMENT WITH THE

LATEST MEDIUM RANGE GUIDANCE FROM WPC.



SEAS...SEA HEIGHTS RANGE FROM NR 5 FT OVR SRN AND ERN NT2 WTRS TO

2 FT OVR NW NT2 AND WRN NT1 WTRS PER THE LATEST OBS AND RA1 SEA

STATE ANALYSIS GRAPHIC. THESE SEA HEIGHTS ARE WITHIN A FT OR SO

OF BOTH THE 00Z WNA WAVE WATCH III...AND THE ECMWF WAM WAVE MDL

OUTPUT. FOR THE EARLY AM PACKAGE WE WILL USE A 50-50 BLEND OF THE

WW3 AND WAM MDLS INTO FRI...AND THEN AS WE TRANSITION TOWARD THE

ECMWF FOR WINDS FRI NITE INTO SAT...ALSO TRANSITION TO JUST THE

ECMWF WAM FOR THE WAVE HEIGHT FCST LATE IN THE WEEK INTO THE WKND.



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





.WARNINGS...PRELIMINARY.



.NT1 NEW ENGLAND WATERS...

     NONE.



.NT2 MID ATLC WATERS...

     NONE.



$$



.FORECASTER KELLS/MILLS. OCEAN PREDICTION CENTER.

