

013 

AGNT40 KWNM 020117

MIMATN



MARINE WEATHER DISCUSSION FOR N ATLANTIC OCEAN

NWS OCEAN PREDICTION CENTER WASHINGTON DC

917 PM EDT THU SEP 1 2016



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

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



NOTE: OPC IS PROVIDING POST-TROPICAL FORECAST SUPPORT TO NHC FOR 

HURRICANES GASTON AND HERMINE...SO THIS DISCUSSION WILL BE 

BRIEF. 



IN REGARDS TO HERMINE...NO DRAMATIC CHNGS SEEN IN THE NEW 18Z

GFS. IN RGRDS TO THE EXPECTED FCST TRACK OF HERMINE...THRU THE

NEXT 48HRS WULD FAVOR A COMPROMISE 18Z GFS/GEFS MEAN AND 12Z

ECMWF/ECENS MEAN COMPROMISE. THEN FOR 48-96 HRS WULD COMPROMISE

BETWEEN THE QUITE SIMILAR 18Z GFS/GEFS MEAN AND 12Z ECENS MEAN

(WHICH INDICATES THAT THE 12Z ECMWF MAY BE TOO FAR W DURING THIS

PERIOD). THEN AS THE SPREAD INCREASES BTWN THE LATEST GLOBAL MDLS

BYND 96HRS...WITH SIGLY LOWER FCST CONFIDENCE WULD FAVOR A

COMPROMISE BTWN THE MR NRN 18Z GFS/GEFS MEAN AND MR SRN 12Z

ECMWF/ECENS MEAN SOLUTIONS. SO WITH THIS IN MIND AND WITH HERMINE

EXPECTED TO MOVE SO SLOWLY ONCE IT ENTER THE NT2 WTRS...DO NOT

EXPECT NHC TO MAKE ANY MAJOR CHNGS IN THEIR NEXT FCST ADVSRY.



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

PREVIOUS DISCUSSION... 



NOTE: OPC IS PROVIDING POST-TROPICAL FORECAST SUPPORT TO NHC FOR 

HURCN GASTON AND T.S. HERMINE...SO THIS DISCUSSION WILL BE 

BRIEF. 

AT 18Z A DEVELOPING SURFACE LOW WAS CENTERED NEAR 35N72W OR 

ABOUT 170 NM E OF CAPE HATTERAS AND IS MOVING NE AT ABOUT 20 KT. 

ALTHOUGH THE 12Z GFS TRENDED STRONGER WITH THE WINDS ASSOCIATED 

WITH THIS LOW...THE PAST SEVERAL RUNS OF THE HIGHER RESOLUTION 

HRRR/RAP CONTINUE TO BE INITIALIZED MUCH HIGHER THAN GFS/NAM/ 

UKMET/ECMWF. THIS MORNINGS ASCAT OVERPASSES MISSED THESE SRN NT2 

WATERS. HOWEVER BASED ON HRRR/RAP...WILL MAINTAIN GALE WARNING 

ACROSS OUTER ANZ930 AND ANZ925 WATERS INTO THIS EVENING. OVER 

THE NEAR TERM THROUGH TONIGHT WILL BE POPULATING WINDS WITH THE 

13KM RAP.



FORECAST THEN OBVIOUSLY SHIFTS TO HERMINE AS MODELS ARE 

BEGINNING TO CONVERGE SOMEWHAT THAT SYSTEM WILL RE EMERGE 

OFFSHORE ALONG THE NC COAST EARLY SAT. NHC FORECAST HAS BEEN IN 

LINE WITH ECMWF THROUGH 48 HOURS. MODELS ARE IN GOOD AGREEMENT 

THAT SYSTEM WILL SLOW AND NEARLY STALL OFF THE NRN MID ATLC AND 

SRN NEW ENGLAND COASTS AS IT INTERACTS WITH MID/UPPER LEVEL 

CLOSED LOW SUN THRU MIDWEEK. THERE IS MUCH UNCERTAINTY AS TO THE 

TRACK AND STRENGTH OF HERMINE AT DAYS 3 THROUGH 5. 



.SEAS...THE 12Z WAVEWATCH III AND 12Z ECMWF WAM ARE WELL 

INITIALIZED WITH THE W ATLC WAVE HEIGHTS THIS AFTERNOON. 



.EXTRATROPICAL STORM SURGE GUIDANCE...WITH MODELS ALL INDICATING 

THAT HERMINE WILL SLOW AND NEARLY STALL OFF THE NRN MID ATLC AND 

SRN NEW ENGLAND COASTS SUN THROUGH NEXT WEEK...THERE IS A HIGH 

LIKLIHOOD THAT A SIGNIFICANT SURGE EVENT WILL DEVELOP. RECENT 

RUNS OF THE ESTOFS ARE MUCH HIGHER THAN THE ETSS AND AT THIS 

TIME THESE HIGHER VALUES LOOK MORE REPRESENTATIVE. 





.WARNINGS...PRELIMINARY.



.NT1 NEW ENGLAND WATERS...

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

     TROPICAL STORM POSSIBLE TUE.

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

     TROPICAL STORM POSSIBLE SUN INTO TUE. 

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

     TROPICAL STORM POSSIBLE SAT NIGHT INTO TUE. 



.NT2 MID ATLC WATERS...

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

     TROPICAL STORM SAT.

     TROPICAL STORM POSSIBLE SAT NIGHT INTO TUE. 

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

     TROPICAL STORM POSSIBLE SAT NIGHT INTO TUE. 

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

     TROPICAL STORM SAT.

     TROPICAL STORM POSSIBLE SAT NIGHT INTO TUE. 

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

     TROPICAL STORM POSSIBLE TUE.

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

     TROPICAL STORM POSSIBLE TUE.

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

     TROPICAL STORM SAT.

     TROPICAL STORM POSSIBLE SAT NIGHT INTO SUN NIGHT. 

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

     TROPICAL STORM FRI NIGHT INTO SAT. 

     TROPICAL STORM POSSIBLE SAT NIGHT.

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

     GALE TONIGHT.

     TROPICAL STORM SAT.

     TROPICAL STORM POSSIBLE SAT NIGHT INTO MON. 

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

     TROPICAL STORM FRI NIGHT INTO SAT. 

     TROPICAL STORM POSSIBLE SAT NIGHT.

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

     TROPICAL STORM FRI NIGHT INTO SAT. 

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

     TROPICAL STORM SAT.

     TROPICAL STORM POSSIBLE SAT NIGHT.

.ANZ835...INNER WATERS FROM CAPE FEAR TO 31N...

     TROPICAL STORM FRI INTO FRI NIGHT. 



$$



.FORECASTER VUKITS/CLARK. OCEAN PREDICTION CENTER.

