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000
AGNT40 KWNM 160139
MIMATN

MARINE WEATHER DISCUSSION FOR N ATLANTIC OCEAN
NWS OCEAN PREDICTION CENTER WASHINGTON DC
939 PM EDT WED MAY 15 2013

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

A HIGH PRES CENTER WAS OVER THE SE NT2 WITH A RIDGE EXTENDING NE
JUST E OF THE OFFSHORE AREAS. A WARM FRONT OVER THE MID ATLANTIC
REGION EXTENDED TO THE COAST N OF CAPE HATTERAS. WINDS ACROSS THE
WATERS AT 00Z WERE SW 20 TO 30 KT FROM HATTERAS CANYON TO
BALTIMORE CANYON AND S TO SW 15 TO 25 KT ELSEWHERE. THE 00Z SEAS
STATE ANALYSIS INDICATED 3 TO 6 FT S OF CAPE FEAR AND OVER NT1 AND
6 TO 10 FT ACROSS THE REST OF NT2.

THE HIGH PRES CENTER WILL WEAKEN OVERNIGHT AS THE WARM FRONT MOVES
NE ALONG THE COAST. AN APPROACHING COLD FRONT WILL MOVE OFF THE
COAST BY MORNING THEN STALL ACROSS THE NRN NT2 WATERS LATE IN THE
DAY. ANOTHER COLD FRONT WILL MOVE OFF THE COAST THU NIGHT MERGE
WITH THE STALLED FRONT AND MOVE SE INTO THE CENTRAL WATERS FRI.
THE COLD FRONT WILL STALL NEAR CAPE HATTERAS LATER FRI INTO SAT.

FOR THE SHORT TERM THE MODELS ARE CLOSE SO PLAN NO CHANGES. WINDS
SHOULD INC TO GALE FORCE IN THE SE PORTION OF BALTIMORE CANYON TO
THE HAGUE LINE. THE 18Z GFS IS WEAKER BUT ALL THE MODELS ARE
SHOWING AT LEAST 30 KT LATE TONIGHT INTO THU. FOR SEAS THE MODELS ARE
WITHIN A 1 FT OF CURRENT OBS FOR SEAS.

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

S TO SW WINDS HAVE BEGUN TO INCREASE THIS AFTERNOON OFF SC/NC
COASTS. 1420Z AND 15Z ASCAT OVERPASSES RETURNED UP TO 20 KT CAPE
FEAR TO N OF BALT CNYN. 12Z UKMET AND 00Z ECMWF SEEM TO HAVE
BEST HANDLE ON WINDS THIS AFTERNOON...THAT IS ABOUT 5 KT WEAKER
THAN 12Z GFS/NAM/GEM GLOBAL. 12Z NAM/GEM GLOBAL REMAIN STRONG
OUTLIERS OVER THE NEXT 24HRS. THE 12Z UKMET/00Z ECMWF SFC WINDS
LOOK THE MOST REASONABLE IN TAKING INTO ACCOUNT THE SST GRADIENT
FROM THE WARMER BALT CNYN TO HAGUE LINE WATERS WHICH
INCORPORATES NERN PORTION GLF STREAM TO COLDER NEW ENGL AND
SHELF WATERS...AND HOW IT SHUD AFFECT LOW LVL WINDS. SO WILL NOT
BE MAKING MUCH ADJUSTMENT FROM PREVIOUS NT1/NT2
FORECASTS...WHICH LIMIT GALES TO BALT CNYN TO HAGUE LINE WATERS.

IN THE MED RANGE SAT THRU MON...ALHTO THE 00Z GFS HAD TRENDED
TWRD THE UKMET...WHICH IS WEAKER WITH ANY SFC LOWS DLVPG AND
MOVING E OFF MID ATLC COAST AND ALNG STRNY FRNT SUN. HOWEVER THE
06Z/12Z GFS ARE BACK TO ADVERTISING WINDS UP TO 30 OR 35 KT
WINDS ASSOC WITH SERIES OF LOWS/WARM FRNT SUN AND MON. WITH VERY
LITTLE 00Z/06Z ENSEMBLE SUPPORT AND ECMWF CONSISTENTLY WASHING
OUT FRONT AS IT BEGINS TO LIFT N SUN...PLAN TO MAINTAIN FORECAST
CONTINUITY WITH PREFERENCE FOR ECMWF/UKMET BLEND...BUT WITH MORE
WEIGHT ON ECMWF...AND WILL LIMIT SUN/MON WINDS TO 20 KT OR LESS.

12Z MULTIGRID WAVEWATCH III SIG WV HGTS LOOK REASONABLE WHEN
COMPARED TO W ATLC SHIP/BUOY OBS OVER PAST FEW HRS. FOR TNGT INTO
THU PREFER THE SLIGHTLY HIER ECMWF WV MDL THO. WILL ALSO BE
RELYING MORE ON THE ECMWF WAVE MDL DAYS 3 THRU 5...ABOUT A 3 TO 1
BLEND WITH THE 12Z MWW3.

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...GALE TNGT INTO THU...MOD CONFDC.
.BALTIMORE CANYON TO HATTERAS CANYON...NONE.
.HATTERAS CANYON TO CAPE FEAR...NONE.
.CAPE FEAR TO 31N...NONE.
$$

.FORECASTER OSZAJCA/CLARK. OCEAN PREDICTION CENTER.