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000
AGNT40 KWNM 200100
MIMATN

MARINE WEATHER DISCUSSION FOR N ATLANTIC OCEAN
NWS OCEAN PREDICTION CENTER WASHINGTON DC
855 PM EDT SUN 19 MAY 2013

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

A WARM FRONT EXTENDS SSE FROM THE MID ATLC COAST THIS EVE...WITH
HIGH PRES DRIFTING E FROM E OF GEORGES BANK. THE FRONT WILL CONT
TO LIFT N AND NE OVR THE OFF WTRS OVRNGT INTO MON. THE LATEST
SATELLITE...RADAR AND LGTNG DATA SHOW SCTD TSTMS FROM E OF THE
DELMARVA AND CP HAT SOUTHWARD OVR SRN NT2 OFF WTRS. MOST OF THESE
TSTMS ARE MOVG TO THE N IN ASSOC WITH THE WARM FRONT. MOSTLY
LIGHT RAIN IS INDICATED FURTHER TO THE N...N OF BALT CANY.
OVERALL WE WILL NOT BE MAKING SIG CHANGES TO THE PREV FCST FOR
THE EVE UPDATE. WE WILL ADJUST FCST SLIGHTLY TO FIT CURRENT
CONDITIONS NOTED OVR THE REGION...BUT OTW IT APPEARS AS IF NOT
MAJOR UPDATES ARE NEEDED THIS EVE.

SEAS....SEA HTS ARE RUNNING QUITE CLOSE TO THE MWW3 AND WNA
VERSION OF THE WW3 MDL GUID THIS EVE PER THE LATEST OBS NOTED OVR
THE OFF WTRS. AGAIN...FOR THE EVE UPDATE LITTLE CHANGE WILL BE
MADE TO THE PREV OPC FCST.

==============================================================

PREV DISCUSSION...

1530Z HI RES ASCAT OVERPASS INDICATED HIEST WINDS OF 20 TO 25 KT
NWRN BALT TO HATTERAS CNYNS. OVERNGT ASCAT ALSO RETURNED SE 20
TO 25 KT OVER BALT TO HATTERAS CNYNS. WITH PREVIOUS NT2 ISSUANCE
HAD BUMPED UP WINDS BY A FEW KT OVER GLF STREAM. ALSO HAD 25 KT
SHIP REPORT JUST SE OF CAPE HATTERAS AT 14Z. 12Z MDLS ARE IN
DECENT AGREEMENT THAT WARM FRONT WILL LIFT NE ALONG MID ATLC
COAST AND INTO NEW ENGL WATERS TNGT INTO EARLY MON. THE PAST FEW
RUNS OF GFS HAVE BEEN STRONGEST WITH WINDS ASSOC WITH TRPLE PT
LOW DVLPMNT OVER NEW ENGL WATERS LATE TNGT THRU MON. THERE
APPEARS TO BE SOME POSSIBLE GRIDSCALE FEEDBACK IN THESE LAST FEW
RUNS ESPECIALLY BY MON NGT AS SFC LOW PASSES E OF OFFSHORE
WATERS AND MDLS SHOW SUSPECT SMALL SCALE 45 OR 50 KT BNDRY LAYER
WINDS. OPC PREFERENCE CONTINUES WITH LESS AGRESSIVE 12Z ECMWF.
AND WILL LIMIT THE 30 KT WINDS TO BALT CNYN TO HAGUE LINE WATERS
MON INTO MON NGT. 12Z GFS/ECMWF THEN STALL ASSOC COLD FRONT
FURTHER N THAN RESPECTIVE PREVIOUS RUNS.

12Z GFS TRENDED TOWARD STRONGER ECMWF WITH UPPER LOW/TROF
SWINGING S AND SE FROM HUDSON BAY TO QUEBEC WED INTO THU. MDLS
ARE NOW IN BETTER AGREEMENT WITH INCREASING S TO SW WINDS
WED/THU. MAIN MDL DIFFERENCES THEN DEAL WITH PSSBL DVLPG SFC LOW
OFF FL/SERN US COAST AND INTO NT2 WATERS THU INTO FRI. 12Z UKMET
ALSO SHOWS DVLPG LOW BUT LIKE PAST COUPLE RUNS OF GLOBAL GEM IS
MUCH SLOWER THAN GFS. NOT BUYING INTO 12Z GFS AND ITS GALE FORCE
BNDRY LAYER WINDS THU INTO FRI...INSTEAD PREFERRING 12Z ECMWF
WHICH IS ALSO IN LINE WITH WPC MED RANGE GUIDANCE. OF THE 90
MEMBERS FROM THE 00Z ECMWF EPS/GEFS/CANADIAN THERE WAS LITTLE
SUPPORT FOR THIS LOW DVLPMNT. SO FOR NOW WILL BUMP UP WINDS
SLIGHTLY OVER 12Z ECMWF OVER SRN NT2 WATERS...BUT ONLY TO 25 KT
OR SO AND WELL BELOW WINDS SHOWN BY 12Z GFS.

SEAS...THE 12Z MULTIGRID WAVEWATCH HAS APPEARED REASONABLE WHEN
COMAPRED TO W ATLC SHIP/BUOY OBS OVER PAST FEW HRS. WILL
CONTINUE BLEND MWW3 AND ECMWF WAVE MDL BEYOND
24HRS...PROGRESSIVELY WEIGHTING THE ECMWF MORE UP TO 3 TO 1
BLEND WITH MWW3 BY END OF FORECAST PERIOD FRI.

EXTRATROPICAL STORM SURGE MODEL...N/A.

.WARNINGS/FORECAST CONFIDENCE...PRELIMINARY. ANY CHANGES WILL BE
COORDINATED THROUGH AWIPS 12 PLANET CHAT OR BY TELEPHONE:

.NT1 NEW ENGLAND WATERS...
.GULF OF MAINE...NONE.
.GEORGES BANK...NONE.
.SOUTH OF NEW ENGLAND...NONE.

.NT2 MID ATLC WATERS...
.HUDSON CANYON TO BALTIMORE CANYON...NONE.
.BALTIMORE CANYON TO HAGUE LINE...NONE.
.BALTIMORE CANYON TO HATTERAS CANYON...NONE.
.HATTERAS CANYON TO CAPE FEAR...NONE.
.CAPE FEAR TO 31N...NONE.
$$

.FORECASTER MILLS/CLARK. OCEAN PREDICTION CENTER.