Marine Interpretation Message
Issued by NWS

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AGNT40 KWNM 271412
MIMATN

MARINE WEATHER DISCUSSION FOR N ATLANTIC OCEAN
NWS OCEAN PREDICTION CENTER WASHINGTON DC
1012 AM EDT SAT AUG 27 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 TO THE NW BUILDING INTO THE
REGION. ALL THE OBSERVATIONS INCLUDING AN EARLIER ASCAT PASS SHOW
MAX WINDS 20 KT MAINLY OVER NT1 WATERS AND MIN WINDS 5 TO 10 KT
OVER THE CENTRAL REGION. AT 12Z THE NCEP MAP HAS HIGH PRES 1026 MB
CENTERED OVER THE CENTRAL ATLC WITH ITS RIDGE EXTENDING W INTO
MOST OF THE OF THE CENTRAL AND SRN REGIONS AND THE PRES GRADIENT
IS FAIRLY SLACK ACROSS THE REGION. A COLD FRONT EXTENDS SW FROM
LOW PRES 1005 MB OVER NEW FOUNDLAND CANADA INTO THE BALT CANYON
WATERS THEN THROUGH THE CENTRAL WATERS INTO SRN VA. THE MODELS
HAVE GENERALLY INITIALIZED WELL WITH THESE FEW SYNOP FEATURES. THE
SEAS RANGE BETWEEN 2 AND 4 FT OVER THE NT1 WATERS AND THEY RANGE
BETWEEN 3 AND 6 FT OVER THE NT2 WATERS. NWW3 WAVE MODEL FITS WELL
WITH THE OBSERVED SEAS PATTERN AND HAS BEEN QUITE CONSISTENT IN
THE PREVIOUS RUNS WITH THE FORECAST AND HAS ALSO BEEN IN GOOD
AGREEEMNT WITH THE ECMWFWAVE ESPCIALLY IN THE SHORT TERM WITH JUST
MINOR DIFFERENCES IN THE EXTENDED PERIOD. WILL CONTINUE WITH NWW3
FOR THE SEAS. THE MODELS GFS/UKMETHR/CMC/ ECMWFHR/NOGAPS/JMA HAVE
A DECENT AGREEMENT IN THE SHORT TERM PUSHING THE COLD FRONT
FARTHER E AND DISSIPATE IT. THE MODELS ALSO AGREE ON BUILDING HIGH
PRES RIDGE BEHIND THE FRONT ACROSS THE REGION. WILL STAY WITH GFS
LIKE IN THE PREVIOUS FORECAST.

-----------------------------------------------------------------
PREVIOUS DISCUSSION...

LAST EVENINGS ASCAT OVERPASSES ACROSS THE OFFSHORE WATERS
RETURNED WINDS OF 15 KT OR LESS. THE COLD FRONT HAS SINCE MOVED
OFFSHORE AND EXTENDED ACROSS GEORGES BANK/S OF NEW ENGLAND
WATERS AND INLAND NEAR THE SRN NJ COAST AT 06Z. 00Z MODELS
REMAINED GENERLLY CONSISTENT ACROSS THE FAR WRN ATLC FOR THE
NEXT FEW DAYS. THE AFOREMENTIONED COLD FRONT SHOULD CONTINUE
MOVING S AND SE ACROSS THE WATERS TODAY AND TONIGHT...BEFORE
DISSIPATING ACROSS THE CENTRAL NT2 WATERS EARLY SUN. GUIDANCE IS
IN GOOD AGREEMENT THAT AS HIGH PRES BUILDS TO THE NEW ENGLAND
COAST AND ACROSS THE NT1 WATERS LATE TODAY INTO EARLY SUN...WILL
SEE SOME NE WINDS REACH 20 KT N OF THE FRONT AT THAT TIME MAINLY
OVER THE NRN NT2 ZONES. 00Z GFS/NAM/ECMWF/UKMET ALL CONTINUED TO
MOVE THE WEAK SURFACE LOW CURRENTLY ABOUT 140 NM OR SO SSW OF
BERMUDA SLOWLY WNW THROUGH EARLY NEXT WEEK...AND ACROSS THE SRN
NT2 WATERS SUN NIGHT THROUGH TUE NIGHT. MODELS ALL INDICATE THAT
AS THE FEATURE APPROACHES THE COAST IT SHOULD WEAKEN INTO AN
INVERTED TROUGH TUE/TUE NIGHT. THE 00Z GFS WAS SLIGHLY HIGHER...
UP TO 20 KT...WITH ITS ASSOCIATED SURFACE WINDS VERSUS ITS
PREVIOUS RUNS. THE 00Z UKMET/ECMWF ARE SIMILAR...BOTH TRENDING
SLIGHLY STRONGER FROM RESPECTIVE PREVIOUS RUNS. NHC INDICATED
THAT THE NASA GLOBAL HAWK MEASURED WINDS TO 30 KT OVER E OF THE
CENTER LIKELY WITHIN THE INCREASING CONVECTION. WILL POPULATE
WITH THE 00Z GFS WINDS THROUGH 15Z/28...THEN PREFER HOW THE 00Z
ECMWF HANDLES THE ABOVE DISCUSSED LOW...THAT IS A BIT MORE
CONSOLIDATED AND SLIGHTLY STRONGER THAN THE GFS/UKMET. BEGINNING
18Z/28 WILL TRANSITION WINDS GRIDS TO THE 00Z ECMWF THROUGH MON
NIGHT.

THE 00Z GFS/ECMWF/UKMET ARE ALL IN GOOD AGREEMENT WITH THE
TIMING OF ANOTHER WEAK COLD FRONT FORECAST TO MOVE OFF THE NEW
ENGLAND COAST MON. THE 00Z GFS APPEARS TOO STRONG WITH THE POST
FRONTAL GRADIENT ACROSS THE GULF OF MAINE MON NIGHT. MODEL
DISCREPANCY INCREASES BY TUE/WED. THE 12Z ECMWF LIKE ITS
PREVIOUS FEW RUNS MOVES OR REDEVELOPS A SURFACE LOW INVOF NE FL
AND THEN TRACKS LOW ACROSS THE SRN NT2 WATERS WED AND WED NIGHT
WITH WINDS UP TO 25 OR 30 KT. HOWEVER THE 00Z ECMWF TRENDED MUCH
SLOWER FROM ITS PREVIOUS RUNS. THE PAST COUPLE RUNS OF THE GFS
ARE NOW SOMEWHAT AKIN TO THIS IDEA BUT MUCH WEAKER AND SLOWER
THAN ECMWF. PLAN TO STAY WITH CONTINUITY AND RELY ON THE GFS AT
THAT TIME.

.SEAS...THE 00Z WAVEWATCH III AND 00Z ECMWF WAM WERE WELL
INITIALIZED WITH THE W ATLC WAVE HEIGHTS THIS MORNING. THE PAST
SEVERAL RUNS OF THE WW3 ARE CONSISTENT WITH PREVIOUS RUNS WITH
RESPECT TO THE ARRIVAL OF THE LONG PERIOD SWELL FROM GASTON.
FAVORED THE 00Z WW3 THROUGH THE FORECAST PERIOD...EXCEPT USED A
75 PERCENT ECMWF WAM/25 PERCENT WW3 BLEND BEGINNING 18Z/28
THROUGH 00Z/30.

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


.WARNINGS...PRELIMINARY.

.NT1 NEW ENGLAND WATERS...
     NONE.

.NT2 MID ATLC WATERS...
     NONE.

$$

.FORECASTER MUSONDA/CLARK. OCEAN PREDICTION CENTER.



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