

111 

AGNT40 KWNM 270128

MIMATN



MARINE WEATHER DISCUSSION FOR N ATLANTIC OCEAN 

NWS OCEAN PREDICTION CENTER WASHINGTON DC

930 PM EDT FRI 26 AUG 2016 



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

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



TODAYS MODEL RUNS CONTINUED TO BE IN VERY GOOD AGREEMENT ACROSS 

THE FAR WRN ATLC FOR THE NEXT COUPLE DAYS AND WERE GENERALLY 

CONSISTENT WITH LAST NIGHTS RESPECTIVE RUNS. AT 00Z A COLD FRONT 

WAS LOCATED ALONG THE NEW ENGLAND COAST AND WILL MOVE SE TONIGHT 

THROUGH SAT NIGHT...BEFORE DISSIPATING ACROSS THE NT2 WATERS 

EARLY SUN. GFS/NAM/ECMWF/UKMET ALL CONTINUED TO MOVE THE WEAK 

SURFACE LOW CURRENTLY ABOUT 100 NM S OF BERMUDA WNW MOVING 

ACROSS THE SRN NT2 WATERS SAT NIGHT INTO TUE. MODEL DISCREPANCY 

INCREASES BY TUE/WED NEXT WEEK. THE 12Z ECMWF LIKE ITS PREVIOUS 

FEW RUNS MOVES OR REDEVELOPS A SURFACE LOW INVOF NE FL AND THEN 

TRACKS LOW ACROSS THE SRN NT2 WATERS WED AND WED NIGHT WITH 

WINDS UP TO 25 OR 30 KT. GFS IS NOW ALSO AKIN TO THIS IDEA BUT 

MUCH WEAKER AND SLOWER THAN ECMWF. FOR THIS EVENINGS UPDATES 

WILL STAY WITH CONTINUITY AND RELY ON THE GFS...AND MONITOR THE 

00Z MODEL TRENDS. 



THE 18Z WAVEWATCH III AND 12Z ECMWF WAM WERE WELL INITIALIZED 

WITH THE W ATLC WAVE HEIGHTS THIS EVENING. PAST FEW RUNS OF THE 

WW3 WERE CONSISTENT WITH PREVIOUS REASONS WITH RESPECT TO THE 

ARRIVAL OF THE LONG PERIOD SWELL FROM GASTON. 



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

...PREVIOUS DISCUSSION...



THE LATEST SAT IMG STILL INDC WEAK HIGH PRES AREA OVER MOST OF 

THE FORECAST WATERS. DENSE LIGHTNING STILL REPORTED OVER THE FAR 

S-ERN WATERS. THE LATEST OBSERVATIONS INCLUDING ASCAT PASS AT 

1415Z SHOW MAX WINDS TO 20 KT OVER THE FAR S-ERN WATERS WITH 

LIGHT AND VARIABLE WINDS OVER THE CENTRAL REGION AND SW WINDS 10 

TO 15 KT OVER THE NRN WATERS. AT 18Z THE NCEP MAP HAS A COLD 

FRONT STRETCHING S FROM LOW PRES 1006 MB OVER CANADA NEAR 49N67W 

AND IT PASSES JUST W OF THE NT1 WATERS. AREA OF WEAK HIGH PRES 

OVER THE CENTRAL WATERS EXTENDS N ACROSS THE NRN WATERS AND S 

ACROSS THE SRN WATERS. THOUGH THE 12Z MODELS HAVE INITIALIZED 

GENERALLY WELL WITH THE THE 18Z OBSERVATIONS IN BOTH THE PRES 

FIELDS AND WINDS...THERE ARE STILL MINOR DIFFERENCES IN THE 

CENTRAL PRES VALUE AND THE WIND SPEED. CMC STILL HAS HIGHER 

WINDS THAN THE OBS OVER THE NRN WATERS BY 10 KT WHILE GFS AND 

ECMWFHR ARE 5 KT HIGHER AND UKMETHR AND NOGAPS MATCH THE OBS 

WITH JMA BEING 5 KT LOWER THAN THE OBS. MODELS ARE IN DECENT 

AGREEMENT THE REST OF THE SHORT PERIOD WITH JUST MINOR 

DIFFERENCES IN THE EXTENDED PERIOD MAINLY ON THE TIMING OF A 

WEAK LOW OR TROUGH OVER THE FAR SRN WATERS EARLY NEXT WEEK. 

OTHERWISE MODELS AGREE ON THE PERSISTENCY OF A HIGH PRES RIDGE 

ACROSS THE REST OF THE WATERS. EVEN WITH THESE MINOR DIFFERENCES 

THE SYNOP PATTERN DOES NOT SHOW ANY NOTABLE VARIATIONS AND SO 

WILL NOT DEVIATE MUCH FROM THE PREVIOUS FORECASTS AND WILL 

CONTINUE WITH GFS WINDS. IN THE SHORT TERM LOW PRES OVER CANADA 

WILL ZOOM E AND THAT WILL FORCE THE COLD FRONT TO MOVE E ACROSS 

THE NRN WATERS. A HIGH PRES RIDGE WILL BUILD BEHIND THE FRONT 

AND ALLOW E TO NE WINDS TO PREVAIL OVER MOST OF THE FORECAST 

WATERS. ANOTHER COLD FRONT WILL APPROACH THE NRN WATERS IN THE 

EXTENDED PERIOD. 



.SEAS...THE SEAS ARE STILL SMALL AND CONTINUE TO RANGE BETWEEN 3 

AND 5 FT OVER THE NRN AND SRN WATERS BUT RANGE BETWEEN 1 AND 3 

FT OVER THE CENTRAL WATERS. NWW3 WAVE MODEL STILL FITS VERY WELL 

WITH THE OBSERVED SEAS PATTERN AND CONTINUE TO BE CLOSE TO THE 

ECMWFWAVE. BOTH WAVE MODELS HAVE BEEN QUITE CONSISTENT IN 

PREVIOUS RUNS AND THEY ARE IN DECENT AGREEMENT THROUGH THE 

FORECAST PERIOD. WILL CONTINUE WITH NWW3 FOR THE SEAS. THE SEAS 

WILL REMAIN BELOW 8 FT THRU MOST OF THE FORECAST PERIOD. LONG 

PERIOD SWELL TO BE GENERATED BY GASTON WILL BUILD SEAS TO 8 FT 

OVER THE FAR ERN PORTIONS IN THE EXTENDED PERIOD. SEE THE LATEST 

NHC ADVISORY ON GASTON. 



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





.WARNINGS...PRELIMINARY. 



.NT1 NEW ENGLAND WATERS... 

     NONE. 



.NT2 MID ATLC WATERS... 

     NONE. 



$$ 



.FORECASTER CLARK/MUSONDA. OCEAN PREDICTION CENTER.

