

453 

AGNT40 KWNM 060231

MIMATN



MARINE WEATHER DISCUSSION FOR N ATLANTIC OCEAN

NWS OCEAN PREDICTION CENTER WASHINGTON DC

1031 PM EDT MON SEP 5 2016



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

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



THE SAT IMG INDC A HIGH PRES RIDGE OVER THE SRN WATERS AND POST-

TROPICAL CYCLONE HERMINE OVER THE NRN OFFSHORE WATERS. THE LATEST

OBSERVATIONS EARLIER ASCAT PASS SHOW HIGHER WINDS OVER THE NRN

WATERS. A SHIP LOCATED NEAR 41N 72W REPORTED NNE WINDS 63 KT AT

2200Z. THE 00Z NCEP MAP HAS POST-TROPICAL CYCLONE HERMINE OVER

ZONE ANZ915. HIGH PRES 1031 MB NEAR 41N50W 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 FAIRLY RELAXED

OVER THE SRN WATERS AND NATURALLY TIGHT OVER THE NRN WATERS. THE

HIFHEST SEAS ARE NEAR HERMINE WITH PEAK TO 26 FT. THE SEAS ARE

LESS THAN 12 FT S OF 35N. THE NWW3 WAVE MODEL FITS WITH THE

OBSERVES SEAS PATTERN JUST OK AND IS UNDERDONE OVER THE NRN

WATERS. THE NWW3 PEAK VALUE COMPARED WITH THE OBS VALUE IS LOWER

BY 8 FT.



THE MODELS HAVE INITIALIZED WELL 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 STILL HAVE NOT AGREED VERY WELL BUT THE ARE CLOSE

ENOUGH. THE GFS AND ECMWFHR HAVE SUGGESTED A SHIFT OF THE CENTER

OF HERMINE TO THE W FROM PREVIOUS AND EVEN UKMETHR BUT LIES E OF

THE TWO. SINCE THE MODELS HAVE AGREED BETTER THAN THE PREVIOUS

RUNS WILL NOW GO WITH MOSTLY GFS BUT WILL STAULL STAY CLOSE TO THE

OFFICIAL TRACK OF HERMINE AND BLEND WITH ECMWFHR.



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

PREVIOUS DISCUSSION...



THE LTST GOES VIS IMGRY INDC POST-TROPICAL CYCLONE HERMINE IN THE

NRN OFSHR WATERS...WITH STG N TO NE FLOW W AND NW OF THE CENTER.

ASCAT FM 15Z INDC 50 KT IN THE NW QUADRANT OF THE LOW...AND GALE

FRC WINDS IN ALL QUADRANTS. CRNT BUOY RPRTS INDC WINDS UP TO 40 KT

N OF THE LOW CENTER...WITH ONE SHOP REPORTING CLOSE TO 65 KT IN SW

GEORGES BANK NEAR TSTMS. THE 12Z GFS/ECMWF/UKMET ARE ALL INITIALIZED

FAIRLY WELL WITH THE WINDS...INDICATING STORM OR NEAR STORM FRC

WINDS W AND NW OF THE LOW...IN THE REGION BTWN THE LOW AND A RDG

TO THE N. THE 12Z GLOBAL MODELS ARE IN RSNBLY GUD AGRMT IN THE

SHORT TERM...AND THE GFS/ECMWF REMAIN IN GUD AGRMT ON THE TRACK OF

HERMINE...THO BOTH HAVE TRENDED A LTL SLOWER FM THEIR PREV

RESPECTIVE RUNS. THE 12Z UKMET/GEM CONT TO BE A LTL MOR

PROGRESSIVE ON THE TRACK THAN THE GFS/ECMWF...SO STILL SOME

UNCERTAINTY ON IT. AS A RESULT...WL USE NEXT NHC ADVISORY ON

HERMINE...BUT WL FAVOR THE TMG OF THE GFS/ECWMF FOR OTHER FEATURES

INTO THU NIGHT.



IN THE EXTENDED...THE 12Z MODELS ALL INDC A WK CDFNT WL MV THRU

THE AREA LATE THU NGT INTO FRI NGT...AND THE GFS IS A BIT FASTER

THAN THE REST OF THE 12Z GUID WITH THE LOW. THE GFS HAS TRENDED

FASTER FM THE 06Z RUN...AND IS NOW AN OUTLIER SOLN WITH THE FRONT.

THE 12Z ECMWF/UKMET/GEM ALL SHOW ANOTHER CDFNT MOVG THRU THE W

ATLC LATE SAT INTO SUN...AND AGREE WELL WITH EACH OTHER ON THE TMG

AND INTNSTY. THE GFS IS SLOWER THAN THE REST OF THE GUID...THO IS

A LTL FASTER THAN THE 06Z RUN. ATTM FAVORING THE 12Z ECMWF SOLN IN

THE EXTENDED PD...AS IT HAS BEEN THE MOST CONSISTENT...AND HAS THE

GREATER SUPPORT FROM THE REST OF THE 12Z MODELS.



.SEAS...THE 12Z WAVEWATCH AND ECMWF WAM ARE BOTH INITIALIZED A LTL

LOW OVER NT2...WHEN COMPARED WITH A 1630 UTC ALTIMETER PASS...AND

BUOY 41002 IN FAR SRN NT2. ALSO WAVEWATCH SEAS ARE A LTL

UNDERDONE NR HERMINE...BY UP TO 4 FT INITIALLY...THO THE 12Z ECMWF

WAM IS A LTL CLOSER. IN CONJUNCTION WITH THE PREFERRED WX

MDL...PLANNING ON USING THE 12Z ECWMF WAM FOR THE SEAS...AND WL MK

ADJUEMENTS WHERE INITIALIZED POORLY.



.EXTRATROPICAL STORM SURGE GUIDANCE...WITH THE 12Z MODELS

FORECASTING HERMINE TO HAVE N TO NE WINDS OFF THE MID ATLC COAST

OVER THE NEXT CPL OF DAYS...THE ETSS INDC A SURGE UP TO 2 FT OFF

MID ATLC TO SRN NEW ENGLAND COASTS THROUGH AT LEAST

WED...IMPACTING THE COAST FROM THE NRN NC COAST INTO NEW ENGLAND 

EARLY THIS 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). ALSO

SEE THE NHC KEY MESSAGES CONCERNING STORM SURGE BELOW.



NHC KEY MESSAGES:



NONE AT THIS TIME.





.WARNINGS...PRELIMINARY.



.NT1 NEW ENGLAND WATERS...

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

     TROPICAL STORM TONIGHT INTO TUE. 

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

     TROPICAL STORM TONIGHT.

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

     TROPICAL STORM TONIGHT INTO WED. 

     TROPICAL STORM POSSIBLE WED NIGHT.

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

     TROPICAL STORM TONIGHT INTO WED. 

     TROPICAL STORM POSSIBLE WED NIGHT.



.NT2 MID ATLC WATERS...

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

     TROPICAL STORM TONIGHT INTO WED. 

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

     TROPICAL STORM TONIGHT INTO WED. 

     TROPICAL STORM POSSIBLE WED NIGHT.

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

     TROPICAL STORM TONIGHT INTO TUE NIGHT. 

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

     TROPICAL STORM TONIGHT INTO TUE. 

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

     TROPICAL STORM TONIGHT.



$$



.FORECASTER MUSONDA/KELLS. OCEAN PREDICTION CENTER.

