

964 

AGNT40 KWNM 050117

MIMATN



MARINE WEATHER DISCUSSION FOR N ATLANTIC OCEAN 

NWS OCEAN PREDICTION CENTER WASHINGTON DC

915 PM EDT THU 4 AUG 2016 



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

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



THE 18Z GFS AND 18Z NAM WERE VERY CONSISTENT WITH THEIR 

RESPECTIVE PREVIOUS RUNS AND CONTINUED TO BE IN VERY GOOD 

AGREEMENT WITH LATEST ECMWF/UKMET. THE LAST FEW VISIBLE 

SATELLITE IMAGES OF THE DAY CLEARLY SHOWED LOW PRES CENTERED 

NEAR 35N70W ALONG THE FRONT. OTHER THAN SOME ISOLATED TSTMS NEAR 

THE LOW CENTER SCATTERED CONVECTION IS GENERALLY LIMITED TO THE 

OFFSHORE WATERS S OF CAPE FEAR THIS EVENING. PREVIOUS OPC WIND 

GRIDS WHICH WERE BASED ON THE 12Z GFS LOOK REASONABLE AND WILL 

NOT BE MAKING MUCH ADJUSTMENT FOR THIS EVENINGS UPDATES. THE 18Z 

WAVEWATCH III AND 12Z ECMWF WAM ARE FAIRLY WELL INITIALIZED WITH 

THE W ATLC WAVE HEIGHTS. ONLY DISCREPANCY IS ACROSS THE GULF OF 

MAINE...AND WATERS FROM GEORGES BANK EASTWARD TO THE GRAND 

BANKS...WHERE BUOY OBSERVATIONS ARE ABOUT 1 FT HIGHER THAN 

GUIDANCE.     



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

...PREVIOUS DISCUSSION...



SUMMARY...THE 12Z NCEP SFC ANALYSIS SHOWS A WEAK LOW CENTERED IN 

THE NT2 AREA NEAR 34N72W...WITH A WARM FRONT EXTNDG E FROM THE 

LOW AND A COLD FRONT EXTNDG SW FROM THE LOW AND ACROSS THE SRN 

NT2 WTRS TO THE SAVANNAH RIVER. THE ANALYSIS ALSO SHOWS A HI 

PRES RIDGE OVER THE NT1 AND NRN NT2 WTRS. LATEST AVAIL ASCAT AND 

ASCAT HI-RES PASSES FROM THIS MORNING SHOW MAINLY 15 TO 20 KT 

WINDS OVER THE OFSHR WTRS...EXCEPT FOR LIGHT WINDS OF 15 KT OR 

LESS ACROSS MUCH OF THE NT1 AREA...AND SOME GUSTS TO 25 KT IN 

THE OUTER ZONES OF THE SRN NT2 WTRS. LIGHTNING DENSITY PRODUCT 

DATA FROM 1840Z SHOWS SCATTERED SHOWERS AND ISOLATED TSTMS OVER 

THE SRN NT2 WTRS. 



MAIN WEATHER FEATURES...A WEAK LOW WILL MOVE E ACROSS THE SRN 

NT2 WTRS THIS EVENING AND TONITE...THEN PASS E OF THE OFSHR WTRS 

FRI. A COLD FRONT WILL APPROACH THE COAST FRI NITE AND 

SAT...MOVE SE OVER THE OFSHR WTRS LATE SAT THRU SUN NITE...THEN 

STALL ACROSS THE SRN NT2 WTRS MON AND MON NITE WHILE WEAKENING. 

OTHERWISE...HI PRES RIDGING WILL PREVAIL OVER THE OFSHR WTRS 

DURING THE FCST PERIOD. 



MODELS...THE 12Z MED RNG MDLS ARE IN VRY GUD OVERALL AGREEMENT 

THRU TUE NITE...AND THE MAX WINDS ARE NOT EXPECTED TO EXCEED 25 

KT. THE 12Z GFS 10M SOLN LOOKS REPRESENTATIVE ENUF TO BE USED 

FOR THE WIND GRIDS OVER THE ENTIRE FCST PERIOD. AM NOT PLANNING 

TO MAKE ANY SIGNIF CHANGES TO THE CURRENT FCST TREND. 



SEAS...12Z WNA WAVEWATCH III AND 12Z ECMWF WAM BOTH INITIALIZED 

WELL OVER THE OFSHR WTRS...AND ARE IN GUD OVERALL AGREEMNT WITH 

ONE ANOTHER THRU THE FCST PERIOD WITH ONLY A FEW MINOR DIFFS 

NOTED. SO WILL USE A 50/50 BLEND OF THE 12Z WNA WAVEWATCH 

III/ECMWF WAM THRU THE FCST PERIOD TO SMOOTH OUT THE MDL DIFFS. 



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



.WARNINGS...PRELIMINARY. 



.NT1 NEW ENGLAND WATERS... 

     NONE. 



.NT2 MID ATLC WATERS... 

     NONE. 



$$ 



.FORECASTER CLARK/SCOVIL. OCEAN PREDICTION CENTER.

