

691 

AGNT40 KWNM 271954

MIMATN



MARINE WEATHER DISCUSSION FOR N ATLANTIC OCEAN 

NWS OCEAN PREDICTION CENTER WASHINGTON DC

345 PM EDT WED 27 JUL 2016 



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

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



ALTHOUGH THEY MISSED THE MAJORITY OF THE OUTER OFFSHORE WATERS 

THE 1430Z AND 1530Z ASCAT OVERPASSES RETURNED HIGHEST WINDS OF 

15 KT S OF CAPE HATTERAS. OVER THE NEAR TERM THE 12Z MODELS ARE 

IN VERY GOOD AGREEMENT ACROSS THE W ATLC...WITH ONLY MINOR 

POSITION DIFFERENCES WITH THE PERSISTENT QUASI STATIONARY FRONT 

WHICH AT 18Z EXTENDED OFF THE MID ATLC COAST NEAR THE DELMARVA 

PENINSULA WITH WINDS N OF HATTERAS 10 KT OR LESS THROUGH 

TONIGHT. FRONT IS LIKELY TO DRIFT N THU WHILE SEVERAL WEAK LOWS 

MAY DEVELOP ALONG THE NRN MID ATLC AND SRN NEW ENGLAND COASTS. 

AS HAS BEEN THE CASE FOR THE LAST COUPLE DAYS GIVEN MODEL 

AGREEMENT PLAN TO USE THE 12Z GFS WINDS THROUGH THU. BY THU 

NIGHT AND INTO THE WEEKEND MODELS HAVE NOT SHOWN MUCH RUN TO RUN 

CONSISTENCY AND ARE HAVING DIFFICULTY WITH THE TIMING OF A FEW 

DEVELOPING (MOSTLY WEAK) SURFACE LOWS TO MOVE E ACROSS THE NRN 

NT2 AND SRN NT1 WATERS ALONG THE FRONT. WITH THE STRONGEST LOW 

LATE FRI INTO EARLY SAT THE 12Z UKMET HAS TRENDED TOWARD THE 

MORE PROGRESSIVE GFS AND NAM SOLUTIONS. 12Z NAM IS A STRONG 

OUTLIER THOUGH. THE 12Z ECMWF HAD A CONSISTENT TIMING WITH ITS 

PREVIOUS RUNS BUT WAS STRONGER THAN ITS 00Z RUN. 



WITH THE SLOWER ECMWF FAVORED...AS THE LOW PASSES NE THROUGH NT1 

WATERS LATE FRI AND FRI NIGHT AND E OF THE AREA EARLY SAT...THE 

ASSOCIATED COLD FRONT WILL PUSH SE THROUGH THE NRN AND CENTRAL 

NT2 WATERS. MODELS ARE PRETTY CONSISTENT IN SHOWING 20 KT WINDS 

S OF COLD AND EVENTUAL STATIONARY FRONT LATER SAT AND SUN. WITH 

THESE 12Z MODEL TRENDS IN MIND AND TO KEEP SOME CONTINUITY WITH 

PREVIOUS OPC FORECASTS PLAN TO BLEND 50 PERCENT OF THE 12Z ECMWF 

WITH PREVIOUS OFFICIAL OPC GRIDS THU NIGHT THROUGH SUN. 12Z 

MODELS THEN INDICATE THAT ANOTHER LOW WILL APPROACH THE LATE 

SUN/ SUN NIGHT AND PASS E ALONG THE FRONT MON/MON NIGHT. GFS HAS 

BEEN FLATTER THAN ECMWF/UKMET. WITH UKMET BETTER SUPPORTING 

SLIGHLY STRONGER AND MORE NRN ECMWF PLAN TO FAVOR BLEND OF 

00Z/12Z ECMWF SUN NIGHT THROUGH MON NIGHT WHICH WILL AGAIN 

RESULT IN SOME 25 KT WINDS ACROSS NT2 WATERS S OF THE COLD FRONT 

SUN NIGHT INTO MON NIGHT.     



SEAS...THE 12Z WAVEWATCH III AND 12Z ECMWF WAM ARE REASONABLY 

WELL INITIALIZED WITH WAVE HEIGHTS ACROSS THE W ATLC THIS 

AFTERNOON WITH SEAS 4 FT OR LESS ACROSS BOTH NT1 AND NT2 WATERS. 

THE ABOVE GUIDANCE IS IN VERY GOOD AGREEMENT OVER THE NEXT 

COUPLE DAYS THEN BY LATE FRI AND THE WEEKEND THE WW3 AND ECMWF 

WAM DIVERGE GIVEN THE TIMING DIFFERENCES WITH THE DEVELOPING 

SURFACE LOW DISCUSSED ABOVE. TO BE CONSISTENT WITH WINDS WENT 

WITH THE 12Z WW3 THROUGH THU...THEN BLEND OF 12Z ECMWF WAM WITH 

PREVIOUS OPC GRIDS THU NIGHT THROUGH SUN...AND FINALLY BLEND OF 

00Z AND 12Z ECMWF WAM FROM SUN NIGHT ONWARD. 



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



.WARNINGS...PRELIMINARY. 



.NT1 NEW ENGLAND WATERS... 

     NONE. 



.NT2 MID ATLC WATERS... 

     NONE. 



$$ 



.FORECASTER CLARK. OCEAN PREDICTION CENTER.

