Marine Interpretation Message
Issued by NWS

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AGNT40 KWNM 010016
MIMATN

MARINE WEATHER DISCUSSION FOR N ATLANTIC OCEAN
NWS OCEAN PREDICTION CENTER WASHINGTON DC
816 PM EDT TUE JUN 30 2015

.FORECAST DISCUSSION: MAJOR FEATURES/WINDS/SEAS/SIGNIFICANT
.WEATHER FOR THE NORTH ATLANTIC OCEAN W OF 50W FROM 30N TO 50N.

UPDATE...

SUMMARY...18Z NCEP SFC ANALYSIS SHOWS A STNRY FNT EXTNDG NE TO SW
ACROSS THE NRN NT2 WTRS...AND A TROF EXTNDG N TO S OVER THE CNTRL
AND SRN NT2 WTRS. LATEST AVAIL ASCAT PASSES FROM 1419Z TO 1423Z
SHOWED LIGHT WINDS...EXCEPT WINDS TO 20 KT OVER THE OUTER ZONES OF
THE CNTRL/SRN NT2 WTRS AND WINDS TO 25 KT IN THE FAR SE PART OF
THE NT2 AREA IN SW FLOW AHEAD OF THE TROF. LIGHTNING DENSITY
PRODUCT DATA AT 2300Z INDICATES A FEW ISOLD SHOWERS IN VARIOUS
PARTS OF ERN AND SRN NT2 WTRS.

MODELS...THE MED RNG MDLS ARE IN GUD OVERALL AGREEMNT DURG THE
FCST PRD. THE GFS HAS VRY GUD SUPPORT FROM THE GEM/UKMET MDLS...SO
THE REPRESENTATIVE GFS 10M SOLN WILL BE USED TO POPULATE THE WIND
GRIDS FOR THE ENTIRE FCST PRD. AM NOT PLANNING TO MAKE ANY SIGNIF
CHANGES TO THE CURRENT FCST TREND.

SEAS...LATEST RA1 SEA STATE ANALYSES INDICATE THAT WNA VERSION OF
WW3 MDL AND ECMWF WAM INITIALIZED WELL VERSUS THE OBSVD SEA HTS.
ALTHO THE MDLS ARE IN GUD OVERALL AGREEMNT ACROSS THE OFSHR WTRS
FOR MOST OF THE FCST PRD...THERE ARE A FEW MINOR DIFFS AT VARIOUS
TIMES...SO A 50/50 BLEND OF THE WNA WW3/ECMWF WAM WILL BE USED FOR
THE SEA HT GRIDS THRU THE FCST PRD IN ORDER TO SMOOTH OUT THESE
DIFFS.

EXTRATROPICAL STORM SURGE GUIDANCE...N/A.

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

THE 12Z SFC ANALYSIS INDICATED A STATIONARY FRONT EXTENDING ACROSS
THE NRN AND CENTRAL MID ATLANTIC WATERS...WITH ANOTHER WEAK FRONT
FURTHER N JUST NW OF THE NEW ENGLAND WATERS. AN ASCAT PASS FROM
AROUND 1505Z INDICATED THE STRONGEST WINDS NEAR AND E OF THE
FRONTAL BOUNDARY IN THE 20 TO 25 KT RANGE. THERE WAS A SMALL AREA
OF 25 TO 30 KT OVER THE FAR S WATERS...THOUGH THIS WAS ASSOCIATED
WITH CONVECTION IN THE VCNTY.

THE 12Z MODELS ARE IN DECENT AGREEMENT THROUGH THE FCST PERIODWITH
REGARD TO SFC FEATURES...WITH ONLY SOME SUBTLE DIFFERENCES NOTED.
THE FRONTAL BOUNDARY WILL MOVE LITTLE THE NEXT 24 TO 36 HOURS
BEFORE WASHING OUT. ANOTHER FRONT WILL MOVE ACROSS THE AREA LATE
WED NIGHT INTO THU BEFORE BECOMING STATIONARY OVER THE CENTRAL MID
ATLANTIC WATERS. SEVERAL WEAK LOWS WILL MOVE NE ALONG THE FRONT
THU THROUGH SAT NIGHT. THE 12Z GFS HAS BACKED OFF ON THE WINDS
OVER THE NRN NT2 WATERS LATER WED AND WED NIGHT...AND NOW KEEPS
WINDS BELOW GALE SIMILAR TO THE OTHER MODELS. WITH THIS IN
MIND...WILL POPULATE THE WIND GRIDS USING THE 12Z GFS 10M WINDS
THROUGH THE PERIOD...WITH NO WARNING HEADLINES THROUGH THE FIVE
DAY FORECAST.

.SEAS...THE LATEST SEA STATE ANALYSIS INDICATED THAT THE OBSERVED
SEAS MATCHED UP WELL WITH THE MWW3/ECMWF WAM GUIDANCE. WILL
CONTINUE TO USE A 50/50 BLEND OF MWW3/ECMWF WAM THROUGH THE
PERIOD...SO OVERALL FEW CHANGES FROM EXISTING FCST.

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

.WARNINGS...PRELIMINARY.

.NT1 NEW ENGLAND WATERS...
     NONE.

.NT2 MID ATLC WATERS...
     NONE.

$$

.FORECASTER SCOVIL/KOSIER. OCEAN PREDICTION CENTER.



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