

365 

AGNT40 KWNM 061927

MIMATN



MARINE WEATHER DISCUSSION FOR N ATLANTIC OCEAN 

NWS OCEAN PREDICTION CENTER WASHINGTON DC

325 PM EDT TUE 6 SEP 2016 



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

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



A 1530Z ASCAT OVERPASS S OF LONG ISLAND RETURNED MAX WINDS OF 35 

KT ASSOCIATED WITH POST-TROPICAL HERMINE...AND ONLY OVER ITS W 

QUADRANT. WITH COASTAL WINDS LESS THAN TROPICAL STORM FORCE NHC 

JUST ISSUED THE LAST ADVISORY FOR HERMINE. AS A RESULT THE 

PREVIOUS TROPICAL STORM WARNINGS ACROSS THE S OF NEW ENGLAND 

OFFSHORE WATERS AND WRN NT2 ZONES N OF BALTIMORE CANYON WILL BE 

CONVERTED TO GALE WARNINGS. 12Z MODELS ALL CONTINUED WITH THE 

WEAKENING TREND...A CONSISTENT TREND OVER THE LAST COUPLE DAYS. 

THE 12Z ECMWF AND 16Z RAP APPEAR TO BE THE BEST INITIALIZED WITH 

WINDS THIS AFTERNOON. REMAINING GUIDANCE NAMELY THE 12Z GFS AND 

16Z HRRR ARE SOMEWHAT OVERDONE WITH WINDS ASSOCIATED WITH 

POST-TROPICAL HERMINE. FOR THIS REASON AM FAVORING THE QUARTER 

DEGREE 12Z ECMWF FOR WINDS OVER THE NEAR TERM. 12z GUIDANCE IS 

ALSO IN GOOD AGREEMENT THAT HERMINE WILL DISSIPATE JUST E AND NE 

OF CAPE COD AHEAD OF THE APPROACHING COLD FRONT THU EVENING. WE 

WILL BE PROVIDING SOME FORECAST POINTS AND MAXIMUM WINDS WHILE 

POST-TROPICAL HERMINE MAINTAINS AT LEAST GALE FORCE WINDS. THIS 

FORECAST INFORMATION IS PROVIDED BELOW.



IN THE EXTENDED THE 12Z GFS AND 12Z ECMWF ARE IN DECENT 

AGREEMENT WITH THE WEAK COLD FRONT FORECAST TO MOVE OFF THE NEW 

ENGLAND COAST FRI. THIS FRONT SHOULD STALL NEAR 1000 FM OR JUST 

S OF GEORGES BANK EARLY SAT BEFORE LIFTING BACK N ACROSS THE NT1 

WATERS AS A WARM FRONT LATER SAT AND SAT NIGHT. OPC PREFERENCE 

WILL CONTINUE WITH THE 12Z ECMWF THROUGH 09Z/11. THEN BY SUN/SUN 

NIGHT PREFER THE TIMING OF THE SLIGHTLY LESS PROGRESSIVE 12Z GFS 

WITH THE NEXT COLD FRONT...SO WILL POPULATE ITS WINDS BEGINNING 

12Z/11 THROUGH THE REMAINDER OF THE FORECAST PERIOD.    





POST-TROPICAL CYCLONE HERMINE

FORECAST POSITIONS...CENTRAL PRESSURE...MAX WINDS



INITIAL 06/1800Z    39.4N 72.3W  1000 MB  35 KT 	

12HR VT 07/0600Z    39.2N 72.2W  1001 MB  35 KT

24HR VT 07/1800Z    39.7N 72.1W  1003 MB  35 KT

36HR VT 08/0600Z    39.8N 71.5W  1006 MB  35 KT

48HR VT 08/1800Z    41.1N 70.0W  1007 MB  25 KT

72HR VT 09/1800Z...DISSIPATED





.SEAS...THE 12 WAVEWATCH III AND THE 12Z ECMWF WAM BOTH APPEAR A 

COUPLE FT UNDERDONE WITH WAVE HEIGHTS INVOF POST-TROPICAL 

HERMINE THIS AFTERNOON. THE 14 FT SHIP REPORT ACROSS THE NWRN 

PART OF THE GULF STREAM AT 18Z LOOKED GOOD. USED A 50/50 BLEND 

OF THE 12Z WW3 AND 12Z ECMWF WAM THROUGH THU...AND BASED ON 

MODELS CURRENT PERFORMANCE BUMPED UP THE HIGHER WAVE HEIGHTS BY 

ABOUT 10 PERCENT. LIKE PREFERENCE FOR WINDS USED THE 12Z ECMWF 

WAM THROUGH SAT NIGHT...THEN TRANSITIONED TO THE 12Z WW3.  



.EXTRATROPICAL STORM SURGE GUIDANCE...WITH POST-TROPICAL HERMINE 

CONTINUING TO WEAKEN THE DIMINISHING TRENDS SEEN IN THE LATEST 

ETSS AND ESTOFS ALONG LONG ISLAND LOOK REPRESENTATIVE. BOTH THE 

12Z ETSS AND 12Z ESTOFS INDICATE SURGE DROPPING BELOW 1 FT THIS 

EVENING INTO TONIGHT...WITH WATER LEVELS ALONG THE NRN MID ATLC 

AND NEW ENGLAND COASTS REMAINING BELOW MAX ASTRONOMICAL TIDE 

LEVELS FOR THE NEXT FEW DAYS. 



.WARNINGS...PRELIMINARY. 



.NT1 NEW ENGLAND WATERS...

.ANZ810...SOUTH OF NEW ENGLAND...

     GALE WED NIGHT.

.ANZ815...SOUTH OF LONG ISLAND...

     GALE TODAY INTO WED NIGHT. 



.NT2 MID ATLC WATERS...

.ANZ820...HUDSON CANYON TO BALTIMORE CANYON...

     GALE TODAY INTO WED. 

.ANZ915...HUDSON CANYON TO THE GREAT SOUTH CHANNEL...

     GALE TODAY INTO WED NIGHT. 

.ANZ920...BALTIMORE CANYON TO THE GREAT SOUTH CHANNEL...

     GALE TODAY INTO TONIGHT. 



$$ 



.FORECASTER CLARK. OCEAN PREDICTION CENTER.

