

287 

AGNT40 KWNM 071351

MIMATN



MARINE WEATHER DISCUSSION FOR N ATLANTIC OCEAN 

NWS OCEAN PREDICTION CENTER WASHINGTON DC

950 AM EDT WED 7 SEP 2016 



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

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



THE OVERNIGHT GFS/ECMWF CONTINUED TO TREND WEAKER WITH THE WINDS 

ASSOCIATED WITH POST-TROPICAL CYCLONE HERMINE TODAY INTO 

TONIGHT. WITH THIS MORNINGS NT1/NT2 FORECASTS WILL BE DROPPING 

THE GALE WARNINGS OVER ALL ZONES EXCEPT ANZ915...AND WILL ONLY 

BE CARRYING GALES INTO THE EARLY AFTERNOON THROUGH 18Z OVER THIS 

ZONE. THE 00Z/06Z GFS AND 00Z ECMWF WERE CONSISTENT WITH THE 

FIRST COLD FRONT FORECAST TO MOVE OFF THE NEW ENGLAND AND NRN 

MID ATLC COASTS FRI. THEN WITH THE NEXT COLD FRONT OVER THE 

WEEKEND THE 00Z ECMWF IS WEAKER AND LESS PROGRESSIVE THAN THE 

00Z GFS/UKMET/ CMC. THE LATEST GEFS AND ECMWF EPS SUPPORT THE 

MODEL CONSENSUS AND WILL NOT BE MAKING ANY CHANGES TO THE 

PREVIOUS GRIDS WHICH WERE BASED ON THE 00Z GFS. LATEST WATER 

LEVEL OBS ACROSS LONG ISLAND SOUND INDICATING THAT SURGE IS 

CLOSE TO 1 FT...AND 06Z ESTOFS APPEARS TO HAVE A GOOD HANDLE ON 

THIS. BOTH THE 06Z WAVEWATCH III AND 00Z ECMWF WAM ARE WELL 

INITIALIZED WITH WAVE HEIGHTS THIS MORNING.  



POST-TROPICAL CYCLONE HERMINE FORECAST POSITIONS...CENTRAL 

PRESSURE...MAX WINDS 



INITIAL 07/1200Z 39.3N 72.3W 1005 MB 35 KT 

12HR VT 08/0000Z 40.0N 71.6W 1007 MB 30 KT 

24HR VT 08/1200Z 40.7N 70.5W 1008 MB 25 KT 

36HR VT 09/0000Z...DISSIPATED 





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

...PREVIOUS DISCUSSION...



THE SAT IMG STILL INDC POST-TROPICAL CYCLONE HERMINE OVER ZONE 

ANZ820 ABOUT 80 NM SE OF SANDY HOOK NJ WHILE A HIGH PRES RIDGE 

STILL DEPICTED OVER THE SRN WATERS. THE LATEST OBSERVATIONS 

INCLUDING ASCAT PASS AT 0245Z NOW SHOW HIGHER WINDS OVER THE 

CENTRAL WATERS EXTENDING SE. AT 06Z THE NCEP MAP HAS 

POST-TROPICAL HERMINE NEAR 39N72W WITH A FRONT EXTENDING NE 

ACROSS THE NRN WATERS. HIGH PRES 1035 MB OVER THE CENTRAL ATLC 

STILL HAS ITS RIDGE EXTENDING W TO END JUST E OF THE WATERS. 

ANOTHER RIDGE STILL EXTENDS FROM THE S-ERN STATES THRU THE MID 

ATLC STATES INTO NEW ENGL. THE PRES GRADIENT IS STILL FAIRLY 

TIGHT OVER THE CENTRAL WATERS WHERE THE WINDS ARE IN THE GALE 

FORCE RANGE BUT QUITE RELAXED ELSEWHERE. 



THE MODELS GFS/ECMWFHR/UKMETHR/CMC STILL INDC SOME ENERGY IN AN 

UPPERLEVEL CUT-OFF LOW OVER THE CENTRAL WATERS WITH HIGH PRES 

CENTERS TO THE E AND W. IN THE SHORT TERM THE MODELS AGREE ON 

WEAKENING THE HIGH PRES TO THE E AND THAT WILL FORCE THE ENERGY 

TO BE SPREAD OUT AND WEAKEN THE SYTEM. IN ADDITION MORE ENEGRY 

ASSOCIATED WITH AN UPPERLELVEL TROF TO THE NW WILL SHIFT E AND 

MERGE WITH THE ENERGY OVER THE WATERS. HERMINE IS NOW N OF THE 

GULF STREAM AND IS EXPECTED TO REMAIN IN THE COOL WATERS. AS 

SUCH WINDS ASSOCATED WITH HERMINE SHOULD CONTINUE TO DIMINISH TO 

BELOW WARNING THRESHOLD TONIGHT. 



THE MODELS GFS/ECMWFHR/UKMETHR/CMC HAVE INITIALIZED FAIRLY WELL 

WITH THE 06Z OBSERVATIONS IN PARTICULAR THE PRESS FIELD BUT THEY 

STILL HAVE MINOR DIFFERENCES ON THE INTENSITY AND AREAL 

EXTENSION OF THE WIND FIELD. ALL THE MODELS NOW AGREE ON HIGHER 

WINDS IN THE SE SECTOR. IN ADDITION GFS AND CMC STILL HAVE WINDS 

HIGHER THAN THE OTHER MODELS. ECMWFHR HAS A SMALLER AREA OF 

WARNING CRITERIA WINDS AND THESE SIMILAR DIFFERENCES CONTINUE IN 

THE SHORT TERM. OTHERWISE ALL THE MODELS ARE NOW IN GOOD 

AGREEMENT ON PUSHING THE SYSTEM N ACROSS THE WRN PARTS OF THE 

NRN WATERS AND THEN ACCELERATE NE AS IT WEAKENS AND DISSIPATE IN 

THE SHORT TERM. IN THE LONG RANGE A HIGH PRES RIDGE WILL EXTEND 

FROM THE W INTO THE SRN WATERS WHILE A COUPLE OF FRONTS WILL 

PASS E ACROSS THE NRN WATERS AND WINDS WILL REMAIN BELOW GALE 

FORCE. WILL POP WINDS INITIALLY WITH ECMWFHR BUT ADJ WINDS TO 

DEPICT GALES THRU TONIGHT BECAUSE GFS IS RATHER TOO FAST 

INITIALLY WITH HE SYSTEM. WILL USE GFS IN THE LONG RANGE. 



.SEAS...THE SEAS ARE STILL LARGE OVER THE CENTRAL WATERS WITH 

NOW 13 FT PEAKS JUST OUTSIDE THE CENTER. THE NWW3 WAVE MODEL 

FITS FAIRLY WELL WITH THE 06Z OBSERVED SEAS PATTERN BUT IS STILL 

UNDERDDONE NEAR HERMINE ON THE PEAK VALUE NOW BY 2 FT. THE 

ECMEWWAVE HAS ALSO INITIALIZED WELL WITH THE OBS SEAS PATTERN 

BUT ALSO UNDERDONE NOW BY A FOOT COMPARED WITH THE OBSERVED PEAK 

VALUE. OTHERWISE BOTH WAVE MODELS HAVE CONTINUED TO BE QUITE 

CONSISTENT AND STILL NEED TO BE BUMPED UP BY A SMALL PERCENTAGE 

TO EQUALL THE OBSERVATIONS AND FORECAST. I PLAN ON STAYING CLOSE 

TO THE CURRENT FORECAST SEAS SINCE THE FORECAST TRACK OF HERMINE 

AND INTENSITY OF THE WINDS ARE VERY CLOSE TO THE FORECAST AND NO 

MAJOR CANGES TO THE PREVIOUS TRACK AND FORECAST ARE EXPECTED. 

WILL STILL DO MINOR ADJ TO THE SEAS TO FIT HERMINE INTENSITY 

FORECAST. SO WILL POP WAVE GRIDS WITH WNA INITIALLY WITH MINOR 

ADJ THEN USE NWW3 THRU THE LONG RANGE. 



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

CONTINUED TO WEAKEN AND THE DIMINISHING TRENDS DEPICTED IN THE 

LATEST ETSS AND ESTOFS ALONG LONG ISLAND LOOK RESOANABLE. BOTH 

THE ETSS AND ESTOFS INDICATE DROPPED SURGE TO BELOW 1 FT...WITH 

WATER LEVELS ALONG THE NRN MID ATLC AND NEW ENGLAND COASTS TO 

REMAIN BELOW MAX ASTRONOMICAL TIDE LEVELS FOR THE NEXT FEW DAYS. 





.WARNINGS...PRELIMINARY. 



.NT1 NEW ENGLAND WATERS...

     NONE.



.NT2 MID ATLC WATERS...

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

     GALE TODAY.



$$ 



.FORECASTER CLARK/MUSONDA. OCEAN PREDICTION CENTER.

