

822 

AGNT40 KWNM 220110

MIMATN



MARINE WEATHER DISCUSSION FOR N ATLANTIC OCEAN

NWS OCEAN PREDICTION CENTER WASHINGTON DC

910 PM EDT SUN AUG 21 2016



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

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



THE LATEST RADAR...SATELLITE...LIGHTNING DENSITY IMAGERY

INDICATES HEAVY TSTMS EXTENDING FROM LONG ISLAND S AND SW TOWARD

THE DELMARVA COAST AND VIRGINIA BEACH...ALL MOVG OFF TO THE E.

ADTL ACTIVITY IS LOCATED FURTHER TO THE S AND SW OVR ERN NORTH

CAROLINA...ALSO MOVG E. THE LATEST SREF TSTM GUIDANCE INDICATES A

GOOD CHANCE FOR HEAVY TSTMS FROM SRN NT1 WTRS SOUTHWARD TONITE

INTO MON NEAR AND AHEAD OF A COLD FRONT. ANY OF THE HEAVIER TSTMS

CAN PRODUCE WIND GUSTS EXCEEDING GALE FORCE AND VRY ROUGH SEAS

THROUGH TONITE INTO MON.



OTW...FOR THE EVE UPDATE WE WILL TWEAK GRIDS AND THE FCST SOMEWHAT

TO FIT CURRENT CONDITIONS OVR THE OFFSHORE WTRS AND ALSO TO FIT

NEARBY COASTAL WTRS AND TAFB FCSTS A LITTLE BETTER. THE PRELIM

00Z OPC-WPC-NCEP SFC ANALYSIS INDICATES WEAK LOW PRES OVR NRN NEW

JERSEY WITH A WARM FRONT EXTENDING SE FROM THE LOW AND A TRAILING

COLD FRONT EXTENDING S-SW ACROSS THE DELMARVA INTO THE CAROLINAS

AND NRN GEORGIA. THE LOW WILL TRACK NE WITH THE FRONT PUSHING

OFFSHORE TONITE AND MON. THE 18Z MDL GUID SUGGEST THAT NO MAJOR

CHANGES WILL BE REQUIRED FOR THE EVE UPDATE...EXCEPT FOR THOSE

NOTED PREVIOUSLY.



SEAS...SEAS HEIGHTS RANGE FROM NR 6 FT OFF THE NORTH CAROLINA

COAST TO 2 FT OFF THE MAINE COAST PER THE LATEST OBS AND 00Z RA1

OPC SEA STATE ANALYSIS. WE WILL MAKE SOME MINOR ADJUSTMENTS TO

THE PREV FCST...MAINLY TO ADD A FT OR TWO TO THE ONGOING FCST OFF

THE CAROLINA COAST TONITE...BUT OTW...MAKE NO MAJOR CHANGES TO

THE PREV FCST FOR THE EVE UPDATE.



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

PREVIOUS DISCUSSION...



THE 12Z SFC ANALYSIS INDICATED STATIONARY FRONT OVER THE CENTRAL

NT2 WATERS ALONG 35N...WITH WEAK LOW ALONG FRONT NEAR 35N71W.

SATELLITE IMAGERY AND LIGHTNING DATA INDICATE SCATTERED TSTMS

PERSISTING OVER SRN NT2 ZONES S OF STATIONARY FRONT. ASCAT PASSES

FROM LATE SUN MORNING WITH VERY GOOD COVERAGE OVER

OFFSHORE/COASTAL WATERS INDICATED WINDS LESS THAN 20 KT OVER

NEARLY ENTIRE AREA. A SMALL AREA OF 20 TO 25 KT WAS NOTED OVER THE

FAR SE NT2 ZONES IN AREA OF CONVECTION MENTIONED ABOVE.



THE 12Z MODELS CONTINUE TO BE IN VERY GOOD AGREEMENT WITH FEATURES

OVER THE OFFSHORE/COASTAL WATERS DURING THE FCST PERIOD. DURING

THE SHORT TERM PERIOD THROUGH WED...WELL DEFINED COLD FRONT INLAND

AND AS DEPICTED BY SATELLITE/SFC ANALYSIS WILL CONTINUE TO MOVE E

OVERNIGHT THROUGH MON...AND EVENTUALLY BECOMING STATIONARY JUST E

OF THE OFFSHORE WATERS MON NIGHT AND TUE. AS HAS BEEN THE CASE THE

PAST FEW MODEL RUNS...EXPECT STRONGEST WINDS POST-FRONTAL AND TO

ABOUT 25 KT MAINLY OVER THE HUDSON TO BALT CANYON AND S OF LONG

ISLAND ZONES. THE MODELS CONTINUE TO BE VERY CLOSE WITH THE TIMING

OF THIS FROPA. HIGH PRES RIDGE WILL THEN BUILD OFFSHORE AND

PERSIST THROUGH WED NIGHT. THE RIDGE WILL THEN WEAKEN THU AND THU

NIGHT AS ANOTHER COLD FRONT APPROACHES THE AREA LATE FRI AND MOVES

OFFSHORE FRI NIGHT. ALTHOUGH THIS DOES NOT IMPACT OFFSHORE/COASTAL

WATERS...THERE ARE DIFFERENCES WITH HANDLING OF CURRENT T.S. FIONA

WHICH IS FCST TO BE A DEPRESSION BY 12Z MON. THE UKMET KEEPS THE

POST-TROPICAL LOW ON A WESTWARD COURSE...WHILE THE GFS KEEPS LOW

STRONGER WHILE MOVING TO THE N AND NE. THE ECMWF IS WEAKEST AND

JUST INDICATES AN OPEN TROUGH. WILL DEFER MORE TO ECMWF FROM 00Z

THU AND BEYOND AS THIS MATCHES UP WELL WITH WPC MEDIUM RANGE

PROGS. IN SUMMARY...WILL POPULATE WIND GRIDS USING 12Z GFS 10M

WINDS THROUGH 00Z THU...THEN WILL USE 00Z ECMWF FOR REMAINDER OF

PERIOD. 



.SEAS...THE 18Z SEA STATE ANALYSIS INDICATES THAT OBSERVED SEAS

CONTINUE TO MATCH UP WELL WITH THE MWW3/ECMWF WAM FCST VALUES.

SIMILAR TO WIND GRIDS...PLAN ON USING MWW3 THROUGH 00Z THU...THEN

WILL TRANSITION TO ECMWF WAM FOR REMAINDER OF PERIOD. 



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





.WARNINGS...PRELIMINARY.



.NT1 NEW ENGLAND WATERS...

     NONE.



.NT2 MID ATLC WATERS...

     NONE.



$$



.FORECASTER MILLS/KOSIER. OCEAN PREDICTION CENTER.

