

010 

AGNT40 KWNM 280130

MIMATN



MARINE WEATHER DISCUSSION FOR N ATLANTIC OCEAN 

NWS OCEAN PREDICTION CENTER WASHINGTON DC

930 PM EDT SAT 27 AUG 2016 



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

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



THIS MORNINGS 1450Z ASCAT OVERPASS INDICATED 25 TO 30 KT WINDS 

ACROSS THE N QUADRANT OF THE SURFACE LOW WHICH AT 00Z WAS INVOF 

31N68W AND IS MOVING WNW AT AROUND 10 KT. ASCAT WINDS WERE AT 

LEAST 5 TO 10 KT HIGHER THAN 12Z MODELS INITIALIZED. LATEST 

MODELS ARE IN GOOD AGREEMENT THAT THE LOW WILL APPROACH THE SRN 

NT2 WATERS SUN AND SLOWLY MOVE WNW ACROSS THE AREA SUN EVENING 

THROUGH MON NIGHT...APPROACHING THE NC COAST TUE. BUMPED UP THE 

PREVIOUS ASSOCIATED WINDS...NOW UP TO 25 KT SUN INTO SUN NIGHT. 

LATER IN THE WEEK 12Z UKMET WAS A STRONG OUTLIER AS IT 

STRENGTHENS LOW INTO A GALE ACROSS CENTRAL NT2 WATERS WED. LATER 

WED AND THU THE PAST FEW RUNS OF THE GFS ARE CLOSER TO THE ECMWF 

WITH A DEVELOPING LOW NEAR NE FL WED AND THEN TRACKING NE ACROSS 

SRN NT2 ZONES ALONG THE COLD FRONT WED NIGHT INTO THU NIGHT. AM 

LEANING MORE TOWARD THE MORE CONSISTENT ECMWF FROM WED ONWARD.   



THE 12Z/18Z WAVEWATCH III AND 12Z ECMWF WERE BOTH WELL 

INITIALIZED WITH WAVE HEIGHTS ACROSS OFFSHORE AND COASTAL ZONES 

THIS EVENING...HOWEVER SEAS WERE 4 FT OR LESS. THE LONG PERIOD E 

TO SE SWELL ASSOCIATED WITH TROPICAL STORM GASTON HAS YET TO 

REACH BUOY 41048 W OF BERMUDA...OR GEORGES BANK BUOY 44011. THE 

WAVEWATCH III HAS BEEN VERY CONSISTENT WITH THIS SWELL OVER THE 

PAST SEVERAL RUNS. WILL GET BETTER IDEA OF HOW THE WW3 IS 

HANDLING THE TIMING OVER THE NEXT FEW HOURS AS SWELL SHOULD 

ARRIVE AT BUOYS NOTED ABOVE. SEEMS REASONABLE THAT SWELL SHOULD 

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



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

...PREVIOUS DISCUSSION...



THE SAT IMG STILL INDC A HIGH PRES RIDGE TO THE NW BUILDING INTO 

THE REGION. ALL THE OBSERVATIONS INCLUDING ASCAT PASS SHOW MAX 

WINDS 20 KT MAINLY OVER NT1 WATERS AND MIN WINDS 5 TO 10 KT OVER 

THE CENTRAL REGION. AT 18Z THE NCEP MAP HAS HIGH PRES 1025 MB 

CENTERED OVER THE CENTRAL ATLC WITH ITS RIDGE EXTENDING W INTO 

MOST OF THE CENTRAL AND SRN REGIONS AND THE PRES GRADIENT IS 

FAIRLY SLACK ACROSS THE REGION. A COLD FRONT ALSO EXTENDS SW 

FROM COMPLEX LOW PRES 1004 MB JUST E OF NEW FOUNDLAND CANADA 

INTO THE BALT CANYON WATERS THEN THROUGH THE CENTRAL WATERS INTO 

SRN VA. ANOTHER LOW PRES 1012 MB IS SLOWLY APPROACHING THE S-ERN 

WATERS FROM THE E. THE MODELS HAVE GENERALLY CONTINUED TO 

INITIALIZE WELL WITH THESE FEW SYNOP FEATURES. THE MODELS 

GFS/UKMETHR/CMC/ ECMWFHR/NOGAPS/JMA HAVE A DECENT AGREEMENT IN 

THE SHORT TERM PUSHING THE COLD FRONT FARTHER E AND DISSIPATE 

IT. THE MODELS ALSO AGREE ON BUILDING A HIGH PRES RIDGE BEHIND 

THE FRONT ACROSS THE REGION. IN THE EXTENDED PERIOD THERE ARE 

MINOR DIFFERENCES MAINLY ON THE TIMING AND TRACK OF THE LOW PRES 

THAT WILL DEVELOP INLAND AND THEN MOVE E ACROSS THE SRN WATERS. 

THE WINDS WILL REMAIN BELOW GALE FORCE THRESHOLD AND THE MODELS 

HAVE DIFFERENCES IN WIND SPEED WITHIN 5 KT THRU MOST OF THE 

PREIOD. SO WILL JUST STAY WITH GFS LIKE IN THE PREVIOUS 

FORECASTS. 



.SEAS...THE SEAS RANGE BETWEEN 2 AND 4 FT OVER THE NT1 WATERS 

AND THEY RANGE BETWEEN 3 AND 6 FT OVER THE NT2 WATERS. NWW3 WAVE 

MODEL FITS WELL WITH THE OBSERVED SEAS PATTERN AND HAS BEEN 

QUITE CONSISTENT IN THE PREVIOUS RUNS WITH THE FORECAST AND HAS 

ALSO BEEN IN GOOD AGREEEMNT WITH THE ECMWFWAVE ESPCIALLY IN THE 

SHORT TERM WITH JUST MINOR DIFFERENCES IN THE EXTENDED PERIOD. 

WILL STAY CLOSE TO NWW3 FOR THE SEAS. LONG PERIOD SWELL 

GENERATED BY GASTON WILL AFFECT THE WATERS THRU WED. 



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



.WARNINGS...PRELIMINARY. 



.NT1 NEW ENGLAND WATERS... 

     NONE. 



.NT2 MID ATLC WATERS... 

     NONE. 



$$ 



.FORECASTER CLARK/MUSONDA. OCEAN PREDICTION CENTER.

