

516 

AGNT40 KWNM 061422

MIMATN



MARINE WEATHER DISCUSSION FOR N ATLANTIC OCEAN 

NWS OCEAN PREDICTION CENTER WASHINGTON DC

1020 AM 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. 



WINDS AT BUOY 44017 JUST DROPPED BELOW SUSTAINED TROPICAL STORM 

FORCE BUT BOTH THIS BUOY AND 44025 S OF LONG ISLAND CONTINUE TO 

REPORT GALE (OR TROPICAL STORM) FORCE GUSTS. THE MODELS ARE ALL 

INDICATING THAT POST-TROPICAL HERMINE WILL MAKE A SWRD TURN THIS 

AFTERNOON AND EVENING BEFORE THEN TURNING BACK NE TONIGHT. 

DURING THIS TIME AM ANTICIPATING THAT THE GRIDDED TCM WINDS WILL 

NOT PICK UP ON THIS SOUTHWARD TURN...SO WILL LIKELY NEED TO MAKE 

SOME SIGNIFICANT MANUAL EDITS FROM 21Z TODAY THROUGH 06Z WED. 

GUIDANCE IS ALSO IN GOOD AGREEMENT THAT HERMINE WILL DISSIPATE 

JUST E AND NE OF CAPE COD AHEAD OF THE APPROACHING COLD FRONT 

THU NIGHT. IN THE EXTENDED THE 00Z/06Z GFS AND 00Z ECMWF ARE IN 

GOOD AGREEMENT WITH COLD FRONT AT THE END OF THE WEEK INTO THE 

WEEKEND. THE 00Z/06Z WAVEWATCH III AND THE 00Z ECMWF WAM BOTH 

APPEAR UNDERDONE WITH WAVE HEIGHTS THIS MORNING. 



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

...PREVIOUS DISCUSSION...



THE CURRENT SAT IMG INDC A HIGH PRES RIDGE OVER THE SRN WATERS 

AND SHOW POST-TROPICAL CYCLONE HERMINE OVER THE NRN OFFSHORE 

WATERS. THE LATEST OBSERVATIONS INCLUDING ASCAT PASS AT 0120Z 

SHOW HIGHER WINDS OVER THE NRN WATERS. AT 22Z A SHIP THAT WAS 

LOCATED NEAR 41N 72W REPORTED NNE WINDS 63 KT. BUOY 44017 

MONTAUK POINT NEAR LONG ISLAND NY HAS REPORTS IN THE LAST FEW 

HOURS OF 40 KT WINDS AND GUSTS TO 45 KT. THE 06Z NCEP MAP HAS 

POST-TROPICAL CYCLONE HERMINE NEAR THE BOUNDARIES OF ZONES 

ANZ810 ANZ815 AND ANZ915. HIGH PRES 1032 MB NEAR 40N52W EXTENDS 

A RIDGE NW AND THAT 

CONNECTS WITH ANOTHER RIDGE THAT EXTENDS FROM INLAND HIGH PRES 

NEAR THE MID ATLC STATES. THE PRES GRADIENT IS STILL FAIRLY 

RELAXED OVER THE SRN WATERS AND NATURALLY TIGHT OVER THE NRN 

WATERS BUT HAS ALSO RELAXED SLIGHTLY. 



THE 00Z RUN MODELS SUGGEST SOME ENERGY STILL TRAPPED IN AN UPPER 

LEVEL CUT-OFF LOW OVER THE WATERS AND THAT WILL LINGER FOR 

ANOTHER 36 HOURS. THE ENERGY WILL THEN SHIFT NE AS THE CUT-OFF 

LOW OPENS UP INTO A TROUGH TO THE N. THOUGH THE MODELS SUGGEST 

RAPID WEAKENING OF HERMINE AT SURFACE THE SYTEM HAS POTENTIAL TO 

WARRANT KEEPING WINDS IN THE WARNING THRESHOLD BEFORE LEAVING 

GEORGES BANK. 



THE MODELS HAVE INITIALIZED WELL AT 06Z WITH THE OBSERVATIONS 

BUT STILL DIFFER SLIGHTLY ON THE EXTENT AND INTENSITY OF THE 

WINDS. GFS AND CMC ARE MORE AGGRESIVE IN WIND SPEED WITH THE 

ECMWFHR BEING THE WEAKEST. IN THE SHORT TERM THE MODELS HAVE NOW 

AGREED WELL AND GFS AND THE ECMWFHR ARE MUCH CLOSER TO EACH 

OTHER THAN TO UKMETHR AND CMC. THE GFS AND ECMWFHR HAVE INSISTED 

ON SHIFTING THE CENTER OF HERMINE TO THE W FROM PREVIOUS AND SO 

IS UKMETHR THOUGH ITS E OF THE LATER TWO. SINCE THE MODELS HAVE 

AGREED BETTER THAN THE PREVIOUS RUNS WILL NOW GO WITH MOSTLY GFS 

BUT WILL STILL STAY CLOSE TO THE OFFICIAL TRACK OF HERMINE AND 

BLEND WITH ECMWFHR. 



.SEAS...THE HIGHEST SEAS ARE NEAR HERMINE WITH PEAK NOW TO 24 

FT. THE SEAS ARE STILL LESS THAN 12 FT S OF 35N. THE NWW3 WAVE 

MODEL FITS WELL WITH THE 06Z OBSERVATIONS SEAS PATTERN JUST OK 

AND IS STILL UNDERDONE OVER THE NRN WATERS. THE NWW3 PEAK VALUE 

COMPARED WITH THE OBS VALUE IS LOWER BY 6 FT. ECMWFWAVE HAS ALSO 

INITIALIZED JUST LIKE THE NWW3 BUT ONLY UNDERDONE BY 4 FT 

COMPARING PEAK VALUES. APART FROM THE INITIAL DIFFERENCES NWW3 

AND ECMWFWAVE HAVE A GOOD AGREEMENT MOST OF THE FORECAST PERIOD 

EVEN THOUGH THEY APPEAR TO STILL BE UNDERDONE WITH THE FORECAST 

PEAK VALUES. I PLAN ON NOT DEVIATING FROM THE PREVIOUS SEAS AND 

SO I WILL RETAIN MOST OF THE SEAS SIMILAR TO THE PREVOUS 

FORECAST AND WILL MAKE ADJUSTMENTS MOSTLY IN THE SHORT TERM IN 

THE VICINITY OF HERMINE. 



.EXTRATROPICAL STORM SURGE GUIDANCE...WITH HERMINE FORECAST TO 

WEAKEN THE DIMINISHING TRENDS SEEN IN THE LATEST ETSS AND ESTOFS 

ALONG LONG ISLAND LOOK REPRESENTATIVE. IT APPEARS THAT WATER 

LEVELS ACROSS THE NEW ENGLAND COAST WILL NOW REMAIN BELOW MAX 

ASTRONOMICAL TIDE LEVELS.    



.WARNINGS...PRELIMINARY. 



.NT1 NEW ENGLAND WATERS...

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

     TROPICAL STORM TODAY.

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

     TROPICAL STORM TODAY INTO WED NIGHT. 



.NT2 MID ATLC WATERS...

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

     TROPICAL STORM TODAY INTO WED NIGHT. 

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

     TROPICAL STORM TODAY INTO WED. 

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

     TROPICAL STORM TODAY INTO WED. 



$$ 



.FORECASTER CLARK/MUSONDA. OCEAN PREDICTION CENTER.

