

774 

AGNT40 KWNM 222031

MIMATN



MARINE WEATHER DISCUSSION FOR N ATLANTIC OCEAN

NWS OCEAN PREDICTION CENTER WASHINGTON DC

431 PM EDT MON AUG 22 2016



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

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



THE LATEST SAT IMG STILL INDC A FRONTAL BOUNDARY BUT NOW ACROSS

THE FAR ERN PORTIONS OF THE NRN AND CENTRAL WATERS WITH HEAVIER

TSTMS STILL OVER THE CENTRAL REGION. ALL THE OBSERVATIONS

INCLUDING ASCAT PASSES AROUND 14Z AND 15Z INDC NW TO W WINDS OVER

THE CENTRAL AND SRN WATERS BUT S TO SW WINDS AHEAD OF THE FRONT

OVER THE NRN AND ERN PORTIONS OF THE CENTRAL WATERS. MAX NW WINDS

TO 25 KT ARE STILL BEHIND THE FRONT BUT WINDS ARE EVEN HIGHER IN

TSTMS. AT 18Z THE NCEP MAP NOW HAS LOW PRES 1007 MB JUST NE OF THE

MAINE WATERS WITH ITS COLD FRONT STILL EXTENDING S ACROS THE

WATERS. BROAD INLAND HIGH PRES STILL HAS ITS RIDGE INTO FAR WRN

PORTIONS OF THE SRN WATERS. THE PRES GRADIENT HAS REAMAINED FAIRLY

RELAXED.



A WEAK UPPERLEVEL RIDGE WITH LITTLE ENERGY COVERS MOST OF THE

FORECAST WATERS. THE FAR NW PORTION HAS SOME ENRGY THAT IS PART OF

THE ENERGY EMBEDDED IN THE UPPERLEVEL CUT-OFF LOW OVER CANADA THAT

EXTENDS A TROF SE. THE MODELS INDC THAT THESE ENERGY WILL QUICKLY

MOVE E AND THAT WILL RESULT IN THE SFC LOW PRES NE OF MAINE TO

MOVE NE WITH IT. BEHIND THE TROF IS UPPERLEVEL RIDGE WITH LITTLE

ENERGY THAT EXTENDS FROM HIGH PRES OVER THE SRN STATES. THE MODELS

INDC THAT THE HIGH PRES WILL REMAIN TO THE W OF THE WATERS THRU

THE FORECAST PERIOD AND ITS ERN RIDGE EXTENSION WILL BLOCK ENEGRY

FROM THE N FROM REACHING THE WATERS. AN UPPER LEVEL ZONAL FLOW

ACROS THE REGION INDC THAT THE SYNOP SYSTEMS WILL MOVE FAST ACROS

THE WATERS.



THE 12Z RUN SHOW THAT GFS/UKMETHR/ECMWFHR/NOGAPS/CMC/JMA HAVE

CONTINUED TO INITIALIZE WELL WITH THE OBSERVED PRES FIELDS. THE

MODELS ARE IN GOOD AGREEMNT IN THE SHORT TERM BUT MINOR DIFFRENCES

IN THE EXTENDED PERIOD ARE ON THE CENTRAL PRES VALUES AND THEIR

POSITIONS MAINLY INLAND AND ARE WITHIN 2 MB...WITH CMC HAVING THE

LOWEST VALUE AND NOGAPS AND UKMETHR HAVING THE LARGEST WHILE

GFS/ECMWFHR AND JMA ARE IN THE MIDDLE. OTHERWISE THE MODELS AGREE

WELL ON GENERAL PRES PATTERN. THE MODELS HAVE ALSO INITIALIZED

WELL WITH THE WIND SPEED AND DIRECTION WITH JUST MINOR DIFFERENCES

IN WIND SPEED WITH THE OBSERVATIONS WITHIN 5 KT. THE MODELS HAVE

REMAINED IN GOOD AGREEMENT IN THE SHORT TERM BUT DIFFER IN THE

EXTENDED PERIOD AS THE HIGH PRES CENTER MOVES INTO THE WATERS. THE

VARIATIONS ARE MORE IN AREAS OF WINDS LESS THAN 10 KT. ALTHOUGH

THE MODELS SHOW THESE MINOR DIFFERENCES THE GENERAL SYNOP PATTERN

REMAINS VERY CLOSE. EITHER GFS OR THE ECMWFHR COULDBE USED SINCE

THESE TWO MODELS YIELD THE AVERAGE VALUES OF ALL THE MODELS. THERE

IS NO MAJOR SHIFT IN THE SYNOP PATTERN THRU THE PERIOD SO WILL

JUST STAY WITH GFS. IN THE SHORT TERM THE MODEL AGREE WELL ON

MOVING THE LOW NEAR MAINE TWD NE AS A COLD FRONT OVER THE WATERS

MOVES E WITH THE SRN PORTION STALLING OVER THE FAR S. HIGH PRES

WILL MOVE E JUST BEHIND THE FRONT AND THAT WILL ALLOW WINDS TO

SHIFT TO N TO NE OVER MOST OF THE REGION EXCEPT NW TO N WINDS OVER

PARTS OF THE NRN WATERS.



POST-TROPICAL FIONA WILL CONTINUE TO MOVE TWD THE WATERS TO A PSN

NEAR 31N69W PER LATEST NHC ADVISORY...BY THU NITE AS IT

DISSIPATES. THE CURRENT POSITION IS 25.1N 61.3W. FOR ADDITIONAL

INFORMATION PLS SEE THE LATEST ADVISORY FROM THE NATIONAL

HURRICANE CENTER.



.SEAS...THE OBSERVED SEAS ARE STILL LESS THAN 6 FT ACROSS THE

REGION. THE NWW3 MULTI GRID WAVE MODEL CONTINUES TO FIT VERY WELL

WITH THE OBSERVED SEAS PATERN AND MATCHES VERY WELL THE PEAK

VALUES. NWW3 IS ALSO VERY CLOSE TO THE ECMWFWAVE MODEL. BOTH

MODELS ARE IN GOOD AGREEMENT IN THE SHORT TERM AND THE DIFFERENCES

IN THE EXTENDED PERIOD ARE WITHIN A FOOT AND SO FOR THIS PACKAGE

WNA WILL BE FOLLOWED CLOSELY. THE SEAS WILL REMAIN BELOW 8 FT THE

ENTIRE FORECAST PERIOD. RELATIVELY HIGHER SEAS WILL BE OVER THE

SRN WATERS DUE TO LARGE PERIOD SWELLS FROM THE SYSTEMS S OF 30N.





.EXTRATROPICAL STORM SURGE GUIDANCE...N/A.



.WARNINGS...PRELIMINARY.



.NT1 NEW ENGLAND WATERS...

     NONE.



.NT2 MID ATLC WATERS...

     NONE.



$$



.FORECASTER MUSONDA. OCEAN PREDICTION CENTER.

