

993 

AGNT40 KWNM 281620

MIMATN



MARINE WEATHER DISCUSSION FOR N ATLANTIC OCEAN

NWS OCEAN PREDICTION CENTER WASHINGTON DC

1220 PM EDT SUN AUG 28 2016



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

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



UPDATE...THE SAT IMG INDC HIGH PRES RIDGE OVER THE NRN WATERS.

THE OBSERVATIONS HAVE HIGHER WINDS OVER S-ERN PARTS. AT 12Z

STATIONARY FRONT LIES ACROSS THE CENTRAL WATERS AND THE PRES

GRADIENT IS FAIRLY SLACK. LOW PRES TO THE SE HAS NOW BECOME

TROPICAL DEPRESSION EIGHT. SEE THE NHC FOR MORE AND LATEST

INFORMATION ON TD EIGHT. THE MODELS HAVE INITIALIZED WELL THE 12Z

OBSERVATIONS BUT THEY HAVE SOME DIFFERENCES ON THE PATH AND

STRENGTH OF THE TD EIGHT IN THE SHORT TERM. GFS AND ECMWFHR HAVE

TD EIGHT MOVING TWD THE SC COAST AND SO ARE CMC/UKMETHR BUT THE

LATER INDC MUCH STRONGER SYSTEM AS IT PASSES THRU THE BALT CANYON.

THE SEAS RANGE BETWEEN 2 AND 6 FT ACROSS THE WATERS AND NWW3 MULTI

GRID FITS WELL WITH THE OBSERVED SEAS PATTERN. NWW3 IS ALSO CLOSE

TO THE ECMWFWAVE MODEL. BOTH WAVE MODELS ARE UNDERDONE NEAR AND

AROUND THE TROPICAL DEPPRESION AND WILL ADJUST SEAS AROUND THE TD.

OTHERWISE WILL START OF WITH NWW3 AS THE MAIN WAVE MODEL GUIDANCE.



GFS/CMC/UKMETHR/ECMWFHR/NOGAPS/JMA AGREE WELL INITIALLY BUT THE

DIFFRENCES EXIST IN THE SHORT TERM IN AREAS AROUND THE TROPICAL

DEPRESSION AND THE FEW LOWS THAT WILL DEVELOP AND AFFECT THE

WATERS IN THE EXTENDED PERIOD. FOR THIS UPDATE WILL STAY WITH GFS

THE MODEL THAT IS CLOSER TO THE TD EIGHT.



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

PREVIOUS DISCUSSION... 



THE 01Z AND 02Z ASCAT OVERPASSES ACROSS THE NRN MID ATLC WATERS 

INDICATED A LARGE SWATH OF NE WINDS TO 20 KT...NEAR THE NWRN 

EXTENT AND N OF THE GULF STREAM. 00Z MODELS ARE CONSISTENT IN 

INDICATING THAT AS THE STATIONARY FRONT ACROSS THE CENTRAL NT2 

WATERS WEAKENS AND LATER DISSIPATES THE NE WINDS N OF THE 

BOUNDARY WILL DIMINISH TODAY. ELSEWHERE THESE SAME ASCAT PASSES 

SHOWED A SURFACE LOW NEAR 31N68W OR ABOUT 170 NM SW OF BERMUDA 

HAD MAXIMUM WINDS OF 25 KT OVER ITS N QUADRANT. THE 00Z MODELS 

CONTINUED TO BE INITIALLY UNDERDONE WITH THESE WINDS. WILL 

CONTINUE TO GO HIGHER WITH THE WINDS ACROSS THE SRN NT2 WATERS 

TODAY THROUGH MON AS LOW SLOWLY TRACKS ENE TOWARD THE NORTH 

CAROLINA COAST. THE PREVIOUSLY FORECAST MAX WINDS OF 25 KT LOOK 

REASONABLE HERE. THE 00Z GFS AND 00Z ECMWF ARE IN DECENT 

AGREEMENT THAT THE WEAKENING LOW SHOULD STALL NEAR THE NC COAST 

TUE...THEN ACCELERATE NE ACROSS THE NT2 WATERS TUE NIGHT THROUGH 

WED NIGHT. BY WED/WED NIGHT THE 00Z ECMWF HAS TRENDED TOWARD THE 

STRONGER UKMET WHICH WAS CONSISTENT WITH ITS PREVIOUS 12Z/27 RUN 

IN ADVERTISING GALES WITH LOW ACROSS THE OUTER NT2 WATERS. GIVEN 

THIS TREND PLAN TO POPULATE WITH THE 00Z ECMWF WED THROUGH THU 

NIGHT BUT WILL LIMIT WINDS WITH LOW WED/THU TO 25 KT.   



OVER THE NEW ENGLAND WATERS 00Z MODELS ARE CONSISTENT THAT A 

WEAK COLD FRONT WILL MOVE OFFSHORE MON AND LIKE THE CURRENT 

FRONT... STALL ACROSS THE NRN NT2 WATERS MON NIGHT/TUE...AND 

DISSIPATE TUE NIGHT. MODEL DISCREPANCY ARISES WITH RESPECT TO 

THE NEXT FRONT FORECAST TO MOVE OFF THE NEW ENGLAND AND NRN MID 

ATLC COAST LATE WED NIGHT/THU. AT THIS TIME AM FAVORING THE 

SLOWER ECMWF/UKMET. 



.SEAS...THE 00Z WAVEWATCH III AND 00Z ECMWF WERE BOTH WELL 

INITIALIZED WITH WAVE HEIGHTS ACROSS OFFSHORE AND COASTAL ZONES 

THIS MORNING...HOWEVER SEAS CONTINUE TO BE 4 FT OR LESS. THE 

LONG PERIOD E TO SE SWELL ASSOCIATED WITH TROPICAL STORM GASTON 

HAS REACHED BUOY 41048 W OF BERMUDA...AND THE WAVEWATCH III LOOK 

OK WITH THE TIMING. IT HAS BEEN VERY CONSISTENT WITH THIS SWELL 

OVER THE PAST SEVERAL RUNS. SEEMS REASONABLE THAT SWELL SHOULD 

TOP OUT AT 6 OR 7 FT ACROSS OUTER OFFSHORE WATERS. WILL POPULATE 

WITH THE 00Z WW3 THROUGH TUE NIGHT WITH ONLY MODIFICATION BEING 

TO BUMP UP WAVE HEIGHTS ASSOCIATED WITH LOW OVER SRN NT2 WATERS 

BY 15 PERCENT OR SO. WED THROUGH THU NIGHT USED A 50/50 BLEND OF 

THE 00Z WW3 AND 00Z ECMWF WAM. WANTED TO INCORPORATE SOME OF THE 

HIGHER ECMWF WAM VALUES AS LOW MOVES NE ACROSS NRN NT2 WATERS 

WED INTO THU. 



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







.WARNINGS...PRELIMINARY.



.NT1 NEW ENGLAND WATERS...

     NONE.



.NT2 MID ATLC WATERS...

.ANZ915...HUDSON CANYON TO THE GREAT SOUTH CHANNEL...

     TROPICAL STORM POSSIBLE WED NIGHT.

.ANZ920...BALTIMORE CANYON TO THE GREAT SOUTH CHANNEL...

     TROPICAL STORM POSSIBLE WED INTO WED NIGHT. 

.ANZ905...THE GREAT SOUTH CHANNEL TO THE HAGUE LINE...

     TROPICAL STORM POSSIBLE WED NIGHT INTO THU. 

.ANZ910...EAST OF THE GREAT SOUTH CHANNEL AND SOUTH OF 39N...

     TROPICAL STORM POSSIBLE WED NIGHT INTO THU. 

.ANZ828...INNER WATERS FROM CAPE CHARLES LIGHT TO CURRITUCK BEACH LIGHT...

     TROPICAL STORM POSSIBLE TUE NIGHT.

.ANZ925...OUTER WATERS FROM BALTIMORE CANYON TO HATTERAS CANYON...

     TROPICAL STORM POSSIBLE TUE NIGHT INTO WED. 

.ANZ830...INNER WATERS FROM CURRITUCK BEACH LIGHT TO CAPE HATTERAS...

     TROPICAL STORM POSSIBLE TUE INTO TUE NIGHT. 

.ANZ833...INNER WATERS FROM CAPE HATTERAS TO CAPE FEAR...

     TROPICAL STORM MON NIGHT.

     TROPICAL STORM POSSIBLE TUE.

.ANZ930...OUTER WATERS FROM HATTERAS CANYON TO CAPE FEAR...

     TROPICAL STORM MON NIGHT.

     TROPICAL STORM POSSIBLE TUE INTO TUE NIGHT. 



$$



.FORECASTER MUSONDA/MUSONDA/CLARK. OCEAN PREDICTION CENTER.

