

542 

AGNT40 KWNM 231323

MIMATN



MARINE WEATHER DISCUSSION FOR N ATLANTIC OCEAN

NWS OCEAN PREDICTION CENTER WASHINGTON DC

923 AM EDT TUE AUG 23 2016



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

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



GOES IR/VIS IMGRY INDC A FRNTL BNDRY ACRS FAR SRN NT2...AND THE

LTNG DENSITY PROD INDC A FEW TSTMS ALONG THE FRONT. THE PREV FCST

HAD MENTION OF TSTMS AND SHOWERS IN SRN NT2...SO PLANNING ON

KEEPING IT FOR THE UPDATE PKG. IN ADDITION...THE EARLIER ASCT FM

02Z INDC N TO NW WINDS OVR A MAJORITY OF THE OFSHR WTRS...IN THE

CAA BEHIND THE FRONT. ASCAT HAD INDC 25 KT OVR THE GULF OF

MAINE...AND CRNT SFC RPRTS INDC SSTS NR 70 DEG IN THE GULF OF

MAINE...WHICH HAS LOWERED STATIC STABILITY IN THE GULF OF MAINE

AND ALLOWED DEEPER VERT MIXING THE CAA. HOWEVER...THE LTST NCEP

SFC ANALYS INDC THE FRONT AND STGST CAA HAS MOVED E OF THE 

AREA...CRNT SFC RPRTS INDC WINDS TO 15 KT OVR NT1. THE 06Z GFS

INDC 15 KT AT 12Z IN NT1...AND IS INIT WELL OVER THE GULF OF MAINE

IN THE CAA...AND OVER THE REMAINDER OF THE W ATLC WHEN COMPARED

WITH THE CRNT DATA. THE MDLS ALL INDC THE WINDS WL DCRS AS THE

FRONT MOVES OFF THE E...AS HIGH PRES BUILDS OVER THE REGION. THE

PREV FCST FLWD THE GFS IN THE SHORT TERM...WHICH STILL LOOKS

GUD...SO PLANNING ON STAYING WITH IT IN THE SHORT TERM.



IN THE EXTENDED...THE MDLS ALL INDC ANOTHER WK FRONT WL MOVE INTO

NT1 FRI INTO SAT...AND THE 06Z GFS AGREES WELL WITH THE 00Z

ECWMF/UKMET ON THE TMG OF THE FRONT. THE 00Z GEM WAS A

PROGRESSIVE OUTLIER...SO PLANNING ON STAYING NR THE BULK OF THE

GUID. IN ADDITION...THE MDLS DIFFER SOME ON FIONA TO THE S OF NT2

IN THE EXTENDED. WL STAY NR NHC GUID FOR THE OFFICIAL FCST ON THIS

SYSTEM. ALSO...THE PREV FCST STAYED NR THE 00Z GFS THRUT THE

RMNDR OF THE FCST PD...AND WITH NOT MUCH DIFF IN THE 06Z RUN...NOT

PLANNING ON MKG SIG CHANGES.



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

PREVIOUS DISCUSSION...



SUMMARY...00Z NCEP SFC ANALYSIS SHOWS A COLD FRONT EXTNDG W TO SW

ACROSS THE SRN NT2 WTRS...WITH A HIGH PRES RIDGE BUILDING E

TOWARDS THE COAST. LATEST AVAILABLE ASCAT AND ASCAT HI-RES PASSES

FROM EARLIER TONITE SHOW WINDS TO 25 KT OVER THE GULF OF

MAINE...WITH WINDS TO 20 KT OVER MOST OF THE NT1 AND NRN NT2

WTRS...WITH LIGHT WINDS 15 KT OR LESS INDICATED ACROSS THE

REMAINING OFSHR WTRS. LIGHTNING DENSITY PRODUCT DATA AT 0630Z

SHOWS A LINE OF SCATTERED SHOWERS AND TSTMS JUST S OF THE NT2

WTRS.



MAIN WEATHER FEATURES...THE COLD FRONT WILL PASS S AND SE OF THE

NT2 WTRS BY THIS MORNING. A LARGE HIGH PRES RIDGE WILL BUILD E

OVER THE OFSHR WTRS TODAY AND TONITE...THEN MOVE E ACROSS THE

OFSHR AREAS WED INTO FRI. ANOTHER COLD FRONT WILL APPROACH THE

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

INTO SAT NITE. POST-TROPICAL FIONA WILL MOVE NW TOWARD THE NT2

AREA BY LATE THU. REFER TO LATEST ADVISORY FROM THE NATIONAL

HURRICANE CENTER 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

LOOKS TOO FAST/PROGRESSIVE FOR FRI NITE THRU SAT NITE. THE 00Z GFS

10M SOLN LOOKS REPRESENTATIVE ENUF TO BE USED FOR THE WIND GRIDS

THRU AT LEAST SAT NITE. AM NOT PLANNING TO MAKE SIGNIF CHANGES TO

THE CURRENT FCST TREND.



SEAS...THE 00Z WNA WAVEWATCH III MDL INITIALIZED WELL OVER THE

OFSHR WTRS...WHILE THE 00Z ECMWF WAM LOOKS OVERDONE BY A FOOT OR

TWO IN PARTS OF THE NT1 AND NRN NT2 WTRS. THE MDLS ARE IN

REASONABLY GUD AGREEMNT THRU FRI NITE...WITH SOME DIFFERENCES

SHOWING UP MAINLY IN THE SRN NT2 WTRS FOR SAT AND SAT NITE. IN

ORDER TO REMAIN CONSISTENT WITH THE PREFERRED 00Z GFS...AM GOING

TO USE THE 00Z WNA WAVEWATCH III FOR THE WAVE HT GRIDS DURING THE

FCST PERIOD.



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





.WARNINGS...PRELIMINARY.



.NT1 NEW ENGLAND WATERS...

     NONE.



.NT2 MID ATLC WATERS...

     NONE.



$$



.FORECASTER KELLS/SCOVIL. OCEAN PREDICTION CENTER.

