Marine Interpretation Message
Issued by NWS

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AGNT40 KWNM 040039
MIMATN

MARINE WEATHER DISCUSSION FOR N ATLANTIC OCEAN
NWS OCEAN PREDICTION CENTER WASHINGTON DC
839 PM EDT TUE MAY 3 2016

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

UPDATE...18Z NCEP SFC ANALYSIS SHOWS A STATIONARY FRONT EXTNDG NE
TO SW ACROSS THE NRN NT2 WTRS AND INTO THE MID ATLC COAST...WITH
SEVERAL LOW PRES CENTERS ANALYZED ALONG THE FRONTAL BOUNDARY. A
LOW PRES TROF WAS INDICATED JUST OFF THE CAROLINA COAST...WITH A
HI PRES RIDGE OVER THE OUTER ZONES OF THE CENTRAL AND SRN NT2
WTRS. ASCAT DATA IS STILL NOT AVAILABLE DUE TO COMMS
PROBLEMS...BUT LATEST AVAIL RAPIDSCAT PASSES FROM THIS MORNING
SHOW A BROAD AREA OF 20 TO 30 KT WINDS IN S TO SW FLOW OVER THE
NT2 WTRS S OF THE STATIONARY FRONT. LIGHTNING DENSITY PRODUCT DATA
AT 2300Z SHOWS SCATTERED SHOWERS AND TSTMS OVER THE OUTER ZONES OF
THE SRN NT2 WTRS.

MAIN WEATHER FEATURES...THE STATIONARY FRONT WILL PERSIST OVER THE
NRN NT2 WTRS TONITE AND WED...AS A SERIES OF WEAK LOWS MOVE NE
ALONG THE FRONTAL BOUNDARY. A STRONGER LOW WILL PASS NE OVER THE
NT2 WTRS WED INTO THU...WHILE PULLING A STRONG COLD FRONT E
ACROSS THE NT2 AREA...AND THE LOW WILL MOVE NE OVER THE NT1 WTRS
LATE THU. ANOTHER LOW WILL FORM NEAR THE MID ATLC COAST LATER
THU...THEN DRIFT NE OVER THE NT2 AREA THU NITE INTO SAT WHILE
WEAKENING. ANOTHER STRONG COLD FRONT WILL MOVE SE AND APPROACH
THE COAST SAT NITE...THEN MOVE E ACROSS THE OFSHR WTRS SUN AND SUN
NITE.

MODELS...THE MED RNG MDLS ARE IN GUD OVERALL AGREEMNT ACROSS THE
OFSHR WTRS FOR TONITE THRU SAT NITE...AND THE GFS 10M LOOKS LIKE
A VERY GUD MEDIAN MDL SOLN SO IT WILL BE USED TO POPULATE THE WIND
GRIDS FOR THIS PRD. THE GFS IS FASTER THAN OTHER MED RNG MDLS WITH
THE COLD FRONT ON SUN AND SUN NITE...THUS THE MORE REPRESENTATIVE
ECMWF WILL BE USED FOR THIS TIMEFRAME. THE GEM LOOKS LIKE AN
OUTLYER SOLN FOR SUN NITE BECAUSE IT BRINGS A DEEP LOW NE INTO
THE GULF OF MAINE...WHILE THE OTHER MDLS KEEP THE LOW INLAND AND
TAKE IT NE UP INTO NEW BRUNSWICK. AM NOT PLANNING TO MAKE ANY
SIGNIF CHANGES TO THE CURRENT FCST TREND.

SEAS...THE WNA WAVEWATCH III MDL AND ECMWF WAM BOTH INITIALIZED
REASONABLY WELL OVER THE OFSHR WTRS. IN ORDER TO STAY CONSISTENT
WITH THE WIND GRIDS...WILL USE THE WNA WAVEWATCH III MDL FOR
TONITE THRU SAT NITE...THEN GO WITH THE ECMWF WAM FOR SUN AND SUN
NITE.

EXTRATROPICAL STORM SURGE GUIDANCE...N/A.

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

THE 12Z SFC ANALYSIS INDICATED LOW PRES JUST E OF THE DELAWARE
COAST WITH STATIONARY FRONT EXTENDING E ACROSS THE NRN NT2 WATERS.
SATELLITE IMAGERY AND LIGHTNING DATA CONTINUES TO INDICATED SCT
CONVECTION OVER AREA...WITH MOST CONCENTRATED AREA OVER THE SRN
NT2 WATERS.

THE 12Z MODELS ARE IN DECENT OVERALL AGREEMENT DURING MOST OF THE
FCST PERIOD...WITH MOST SIGNIFICANT DIFFERENCES APPEARING TOWARD
THE END OF PERIOD...SUN AND SUN NIGHT. FOR TONIGHT THROUGH SAT THE
MODELS ALL AGREE THAT THERE WILL BE A SERIES OF LOWS MOVING
OFFSHORE ALONG THE FRONTAL BOUNDARY. WILL MAINTAIN GALES OVER NRN
NT2 WATERS LATE THIS AFTERNOON AND EVENING AS INITIAL LOW MOVES
NE...PASSING NE OF THE AREA LATER TONIGHT. THE STRONGEST OF THESE
LOWS APPEARS TO BE LATE WED NIGHT INTO THU WITH ALL OF THE MODELS
INDICATING GALES OVER THE NE NT2 WATERS. THEN ANOTHER LOW WILL
DRIFT NE ALONG THE MID ATLANTIC COAST THU NIGHT INTO FRI NIGHT
WITH WINDS BELOW GALE WITH THIS LOW. LOOKING AHEAD TO SAT THROUGH
SUN NIGHT...MODELS ALL INDICATE A FRONT WILL MOVE OFFSHORE THOUGH
THERE ARE TIMING DIFFERENCES WITH THE FRONT...AND THE 12Z GFS
UNLIKE THE PAST FEW RUNS IS INDICATING A STRONGER LOW MOVING
ACROSS THE NT1 WATERS AND DOES BRING POST-FRONTAL GALES INTO
PORTIONS OF AREA SUN/SUN NIGHT. NONE OF THE OTHER MODELS ARE AS
STRONG WITH THIS LOW AND FOR THIS REASON PREFER ECMWF/UKMET. FOR
TONIGHT THROUGH SAT NIGHT...THE 10M GFS WINDS LOOK REASONABLE AND
WILL USE TO POPULATE WINDS GRIDS. THEN FOR SUN/SUN NIGHT WILL USE
ECMWF WINDS.

.SEAS...THE 18Z SEA STATE ANALYSIS INDICATED THAT OBSERVED SEAS
WERE WITHIN A FT OF THE MWW3 FCST VALUES. SIMILAR TO THE WIND
GRIDS...PLAN ON USING THE MWW3 THROUGH SAT NIGHT...THEN WILL
TRANSITION TO ECMWF WAM FOR SUN/SUN NIGHT.

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

.WARNINGS...PRELIMINARY.

.NT1 NEW ENGLAND WATERS...
     NONE.

.NT2 MID ATLC WATERS...
.ANZ920...BALTIMORE CANYON TO THE GREAT SOUTH CHANNEL...
     GALE TODAY.
.ANZ905...THE GREAT SOUTH CHANNEL TO THE HAGUE LINE...
     GALE TONIGHT.
     GALE THU.
.ANZ910...EAST OF THE GREAT SOUTH CHANNEL AND SOUTH OF 39N...
     GALE THU.

$$

.FORECASTER SCOVIL/KOSIER. OCEAN PREDICTION CENTER.



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