

765 

AGNT40 KWNM 031457

MIMATN



MARINE WEATHER DISCUSSION FOR N ATLANTIC OCEAN 

NWS OCEAN PREDICTION CENTER WASHINGTON DC

1100 AM EDT SAT 3 SEP 2016 



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

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



BUOY 44014 HAS BEEN REPORTING SUSTAINED 40 TO 46 KT WINDS OVER 

THE PAST COUPLE HOURS...WITH PEAK GUSTS CLOSE TO 60 KT. BUOY 

ALSO HAD 20 FT AT 13Z WHICH WAS SEVERAL FT HIGHER THAN THE 06Z 

WAVEWATCH III. FURTHER N ALSO HAD TWO SHIPS REPORTING E GALES 

ABOUT 90 AND 160 NM E OF CAPE MAY AT 12Z. BOTH SHIPS LOOKED LIKE 

GOOD OBSERVERS WITH MEAN WIND SPEED ERRORS LESS THAN 5 KT. THERE 

CONTINUED TO BE CONSIDERABLE VARIABILITY BETWEEN THE MODELS WITH 

THE TRACK AND INTENSITY FORECAST OF HERMINE...MAINLY WHERE THE 

SYSTEM WILL SLOW AND CYCLONICALLY LOOP ACROSS THE NRN NT2 WATERS 

SUN THROUGH MON NIGHT. ON THE LATEST SATELLITE IMAGERY HERMINE 

APPEARS TO STARTED TO BECOME POST TROPICAL...AND SHOULD CONTINUE 

THIS TRANSITION TO HYBRID TYPE SYSTEM LATER TODAY AND TONIGHT.  

THE HRRR AS WELL AS EVEN THE COARSER RESOLUTION GFS/ECMWF ARE 

ALREADY INDICATING THE STRONGEST WINDS SHOULD BECOME ALIGNED 

WITH THE BENT BACK FRONT NW OF THE CENTER BY LATE THIS AFTERNOON 

AND EVENING...A SIGNATURE THAT THE INTENSIFICATION IS BECOMING 

DRIVEN BY BAROCLINIC PROCESSES. IN ADDITION AS THIS OCCURRS THE 

TROPICAL STORM FORCE OR GALE FORCE WIND FIELD SHOULD EXPAND 

SIGNIFICANTLY. OVER THE NE QUADRANT OF HERMINE WAVE HEIGHTS ARE 

SEVERAL FT HIGHER THAN THE 06Z WW3 AND 00Z ECMWF WAM. HOWEVER 

BOTH SETS OF GUIDANCE APPEAR SOMEWHAT OVERDONE ACROSS THE SE 

QUADRANT THIS MORNING. WILL USE THE SLIGHLTY HIGHER 00Z ECMWF 

WAM FOR WAVE HEIGHT GRIDS OVER THE NEAR TERM...BUT THIS FIELD 

WILL NEED SIGNIFICANT MANUAL ADJUSTMENTS.   



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

...PREVIOUS DISCUSSION...



THE LATEST SAT IMG INDC A WEAK RIDGE ACROSS THE NRN WATERS WITH 

TROPICAL CYCLONE HERMINE ABOUT TO ENTER THE WATERS NEAR VA 

COAST. BUOY 41004 SE OF CHARLESTON SC EARLIER HAD WINDS 40 KT 

WITH GUSTS TO 55 KT AT 22Z WITH 19 FT SEAS. BUOY 44064 FIRST 

LANDING VA HAS WINDS INCREASING NOW AT 30 KT AND GUSTS TO 40 KT 

WITH 7 FT SEAS WHILE CBBV2 CHESAPEAK BAY BRIDGE TUNNEL VA HAS 

REPORTS AT 10M WINDS 35 KT WITH GUSTS TO 40 KT . ALL THE LATEST 

OBS INCLUDING ASCAT PASS NOW SHOW HIGHER WINDS OVER THE WRN 

PARTS OF THE CENTRAL REGION. AT 0600Z THE NCEP MAP HAS HERMINE 

OVER VA WHILE A WEAK STATIONARY FRONT LIES ACROSS THE CENTRAL 

WATERS. THE PRES GRADIENT IS STILL FAIRLY RELAXED OVER THE 

WATERS N OF THE FRONT AND STILL VERY TIGHT OF COURSE OVER THE 

CENTRAL REGION. 



THE GLOBAL MODELS HAVE INITIALIZED WELL THE 06Z OBSERVATIONS 

WITH JUST MINOR DIFFERENCES IN WIND SPEEDS OVER THE CENTRAL 

WATERS. THE MODELS STILL HAVE SOME DIFFERENCES IN THE SHORT TERM 

REGARDING THE TRACK OF HERMINE AND THESE DIFFERENCES HAVE 

INCREASED WITH TIME. THE MODELS DIVERGE MOSTLY IN THE EXTENDED 

PERIOD. GFS WILL STAY WITH THE OFFICIAL TRACK AND WILL USE BOTH 

GFS AND THE ECMWFHR TO ADJUST WINDS ACCORDINGLY. I PLAN ON NOT 

MAKING ANY MAJOR CHANGES TO THE REST OF THE FORECAST WATERS AND 

SO WILL USE THE FRCST WINDS AND RETAIN MOST OF THE FORECAST. IN 

THE SHORT TERM THE CENTRAL AND SRN WATERS WILL CONTINUE TO BE 

HEAVILY IMPACTED BY HERMINE WHILE A RIDGE WILL PERSIST OVER THE 

NRN WATERS. 



.SEAS...THE NCEP MAP FOR WAVEHEIGHTS AT 06Z HAD HIGHER SEAS WITH 

PEAKS TO 23 FT OVER WATERS ADJACENT TO VA COAST. SEAS ARE LESS 

THAN 8 FT OVER THE NRN WATERS WITH MAINE STILL HAVING SEAS 

BETWEEN 2 AND 4 FT. THE NWW3 WAVE MODEL STILL FITS VERY WELL 

WITH THE OBSVERVED SEAS PATTERN AND MATCHES THE PEAK VALUE OVER 

THE CENTRAL WATERS. NWW3 IS STILL VERY CLOSE TO THE ECMWFWAVE 

AND BOTH WAVE MODELS HAVE BECOME BETTER AT MATCHING THE PEAK 

SEAS. WILL CONTINUE WITH NWW3 FOR SEAS. IN THE SHORT TERM SEAS 

WILL REMAIN LEVATED OVER THE CENTRAL WATERS BUT WILL START TO 

SUBSIDE IN THE EXTENDED PERIOD. 



.EXTRATROPICAL STORM SURGE GUIDANCE...WITH MOST OF THE MODELS 

FCSTG HERMINE TO SLOW AND NEARLY STALL OFF THE NRN MID ATLC AND 

SRN NEW ENGLAND COASTS SUN INTO TUE...THERE IS A HIGH LIKELIHOOD 

OF SIGNIFICANT AND POSSIBLY LIFE THREATENING FROM THE DELMARVA 

PENINSULA TO THE SOUTHERN NEW ENGLAND COAST TODAY INTO NEXT 

WEEK. FOR FURTHER DETAILS AND GUIDANCE PLEASE SEE THE STORM 

SURGE SECTION OF THE NHC PUBLIC ADVISORY AND THE NHC PROTOTYPE 

STORM SURGE WATCH/WARNING GRAPHIC AT: 

WWW.HURRICANES.GOV/GRAPHICS_AT4.SHTML?WSURGE (ALL LOWERCASE). 



NHC KEY MESSAGES: 



1. HERMINE IS EXPECTED TO BECOME A POST-TROPICAL CYCLONE WHILE 

STILL PRODUCING HAZARDOUS WINDS AND STORM SURGE OVER LAND.  NWS 

POLICY ALLOWS NHC TO WRITE ADVISORIES ON AND ISSUE TROPICAL 

STORM WATCHES AND WARNINGS FOR POST-TROPICAL CYCLONES, WHEN THE 

SYSTEM CONTINUES TO POSE A SIGNIFICANT THREAT TO LIFE AND 

PROPERTY. NHC AND THE NWS EASTERN REGION HAVE DECIDED THAT THIS 

OPTION WILL BE INVOKED FOR HERMINE.  AFTER HERMINE BECOMES A 

POST-TROPICAL CYCLONE, NHC WILL CONTINUE TO ISSUE ITS FULL SUITE 

OF ADVISORY AND WARNING PRODUCTS FOR AS LONG AS THE SYSTEM 

REMAINS A SIGNIFICANT THREAT TO LAND.



2. THERE IS STILL CONSIDERABLE UNCERTAINTY AS TO HOW MANY OF THE

CHARACTERISTICS OF A TROPICAL CYCLONE HERMINE WILL HAVE WHILE IT 

IS OFF OF THE COAST OF THE MID-ATLANTIC AND NEW ENGLAND STATES.

REGARDLESS OF ITS STRUCTURE, HERMINE IS EXPECTED TO BE A VIGOROUS

STORM WITH A LARGE WIND FIELD THAT WILL CAUSE WIND, STORM SURGE  

AND SURF HAZARDS ALONG THE COAST.



.WARNINGS...PRELIMINARY. 



.NT1 NEW ENGLAND WATERS...

.ANZ805...GEORGES BANK WEST OF 68W...

     TROPICAL STORM TONIGHT INTO SUN NIGHT. 

     TROPICAL STORM POSSIBLE TUE INTO WED NIGHT. 

.ANZ900...GEORGES BANK EAST OF 68W...

     TROPICAL STORM SUN.

     TROPICAL STORM POSSIBLE TUE NIGHT INTO WED NIGHT. 

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

     TROPICAL STORM TONIGHT INTO SUN NIGHT. 

     TROPICAL STORM POSSIBLE MON INTO MON NIGHT. 

     HURRICANE POSSIBLE TUE.

     TROPICAL STORM POSSIBLE TUE NIGHT INTO WED NIGHT. 

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

     TROPICAL STORM TONIGHT INTO SUN NIGHT. 

     HURRICANE POSSIBLE MON INTO TUE. 

     TROPICAL STORM POSSIBLE TUE NIGHT INTO WED NIGHT. 



.NT2 MID ATLC WATERS...

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

     TROPICAL STORM TODAY INTO SUN. 

     HURRICANE SUN NIGHT.

     HURRICANE POSSIBLE MON INTO TUE. 

     TROPICAL STORM POSSIBLE TUE NIGHT INTO WED. 

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

     TROPICAL STORM TODAY INTO TONIGHT. 

     HURRICANE SUN INTO SUN NIGHT. 

     HURRICANE POSSIBLE MON INTO TUE. 

     TROPICAL STORM POSSIBLE TUE NIGHT INTO WED NIGHT. 

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

     TROPICAL STORM TODAY INTO TONIGHT. 

     HURRICANE SUN INTO SUN NIGHT. 

     HURRICANE POSSIBLE MON.

     TROPICAL STORM POSSIBLE MON NIGHT INTO WED. 

.ANZ905...THE GREAT SOUTH CHANNEL TO THE HAGUE LINE...

     TROPICAL STORM TONIGHT INTO SUN NIGHT. 

     TROPICAL STORM POSSIBLE MON INTO WED NIGHT. 

.ANZ910...EAST OF THE GREAT SOUTH CHANNEL AND SOUTH OF 39N...

     TROPICAL STORM TODAY INTO SUN NIGHT. 

     TROPICAL STORM POSSIBLE MON INTO WED. 

.ANZ825...INNER WATERS FROM BALTIMORE CANYON TO CAPE CHARLES 

LIGHT...

     TROPICAL STORM TODAY INTO SUN NIGHT. 

     TROPICAL STORM POSSIBLE MON INTO TUE. 

.ANZ828...INNER WATERS FROM CAPE CHARLES LIGHT TO CURRITUCK 

BEACH LIGHT...

     TROPICAL STORM TODAY INTO SUN NIGHT. 

.ANZ925...OUTER WATERS FROM BALTIMORE CANYON TO HATTERAS 

CANYON...

     TROPICAL STORM TODAY INTO SUN NIGHT. 

     TROPICAL STORM POSSIBLE MON INTO TUE. 

.ANZ830...INNER WATERS FROM CURRITUCK BEACH LIGHT TO CAPE 

HATTERAS...

     TROPICAL STORM TODAY INTO TONIGHT. 

.ANZ833...INNER WATERS FROM CAPE HATTERAS TO CAPE FEAR...

     TROPICAL STORM TODAY.

.ANZ930...OUTER WATERS FROM HATTERAS CANYON TO CAPE FEAR...

     TROPICAL STORM TODAY INTO TONIGHT. 



$$ 



.FORECASTER CLARK/MUSONDA. OCEAN PREDICTION CENTER.

