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000
AGNT40 KWNM 181302
MIMATN

MARINE WEATHER DISCUSSION FOR N ATLANTIC OCEAN
NWS OCEAN PREDICTION CENTER WASHINGTON DC
900 AM EDT SAT 18 MAY 2013

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

06Z GFS/NAM WERE MOSTLY CONSISTENT WITH THEIR RESPECTIVE
PREVIOUS RUNS OVER THE W ATLC FOR THE NEXT FEW DAYS. GFS 10M
WINDS LOOK REASONABLE AND ARE SUPPORTED BY 00Z ECMWF/UKMET. 06Z
NAM OVERDONE WITH SW WINDS OFFSHORE OVER NRN MID ATLC WATERS SUN
NGT AND MON...UP TO 30 TO 35 KT BALT CNYN TO HAGUE LINE ZONE.
00Z ECMWF/ UKMET ARE SLIGHTLY SLOWER THAN GFS IN DROPPING COLD
FRONT S OFF NEW ENGL COAST LATE MON INTO TUE. THESE MDLS THEN
ALL MOVE WEAK SFC LOWS E ALNG FRONT THRU SRN NEW ENGL WATERS
WED. OVERALL WILL NOT BE MAKING MAJOR CHANGES FROM PREVIOUS
NT1/NT2 FORECASTS IN THIS MORNINGS UPDATES. 06Z MULTIGRID
WAVEWATCH SIG WV HGTS FIT WELL WITH LATEST W ATLC SHIP/BUOY OBS.
IN THE MED RANGE TUE/WED WILL BLEND 06Z MWW3 WITH ECMWF WAVE MDL
TO ACCOUNT FOR SOME MINOR SIG WV HGT DIFFERENCES.

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

A COLD FRONT EXTENDED FROM E TO W ACROSS THE NT2 WATERS NEAR
34N. A HIGH PRES CENTER WAS N OF THE FRONT OVER NRN NT2 AND A
HIGH PRES RIDGE WAS S OF THE FRONT OVER SRN NT2. WINDS ACROSS
THE AREA WERE E TO NE 10 TO 20 KT FROM THE FRONT N TO 40N...S TO
SW 5 TO 15 KT S OF THE FRONT TO 31N AND VARIABLE 5 TO 10 KT N OF
40N. THE 06Z SEAS STATE ANALYSIS INDICATED 2 TO 7 FT WITH THE
HIGHEST E OF 68W.

SHORT TERM...THE COLD FRONT WILL STALL JUST S OF CAPE HATTERAS
OVERNIGHT...THEN REMAIN THROUGH TONIGHT BEFORE LIFTING NE ACROSS
THE AREA AS A WARM FRONT SUN AND SUN NIGHT. THE HIGH PRES CENTER
N OF THE FRONT WILL DRIFT SLOWLY E LATE TONIGHT THROUGH SUN
NIGHT.

THE MODELS ARE IN GOOD AGREEMENT WITH THE SHORT TERM PATTERN.
THE NAM AND GEM ARE HIGHER WITH WINDS OVER THE NRN WATERS BY SUN
NIGHT. BOTH HAVE SMALL AREAS OF 35 KT. THIS LOOKS OVERDONE WITH
THE COLD WATERS AND THE WAA. PREFER THE WEAKER SOLUTION WITH
WINDS IN THE SLY FLOW 15 TO 25 KT.

LONG TERM...THE NRN PART OF THE HIGH PRES RIDGE WEAKENS AND MOVE
TO THE SE MON. A 3PT LOW DEVELOPS ON A FRONT N OF THE NRN WATERS
MON. THE LOW MOVES WELL E OF THE AREA PULLING A COLD FRONT S
INTO THE NT1 WATERS TUE. THE FRONT STALLS NEAR 40N LATER TUE.
SEVERAL WEAK LOW PRES CENTERS DEVELOP AND MOVE E ALONG THE FRONT
TUE. THEN THE FRONT LIFTS BACK N AS A WARM FRONT WED.

THE MODELS SPLIT ON THE LONG TERM PATTERN. THE GFS/ECWMF AND
UKMET STALL THE FRONT TUE AND LIFT IT BACK N WED. THE 00Z GEM
TAKES THE FRONT MOVE S OF 40N TUE AND STALLS IT WED. ALL THE
MODELS KEEP WINDS TO 25 KT OR LESS S OF THE FRONT WITH THE
STRONGEST WINDS S OF ANY LOW PRES CENTERS PASSING ALONG THE
FRONT. PLAN TO USE THE FRONT AS THE BOUNDARY AND NOT TRY TO TIME
ANY LOW PRES CENTERS CROSSING THE AREA.

SEAS...00Z MULTIGRID WW3 AND THE 12Z ECWMF WAM HAVE INITIALIZED
WELL OVER THE CSTL/OFSHR WTRS...THE MODELS ARE WITHIN ONE FOOT
OF THE BUOY OBS. PLAN TO USE THE MULTIGRID WW3 MDL FOR THE OFSHR
FCSTS. FOR THE HIGHEST SEAS ON MON THE MODELS ARE WITHIN ONE FT
OF EACH OTHER. THE 00Z ECWMF WAS NOT AVAILABLE YET.

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 CLARK/OSZAJCA. OCEAN PREDICTION CENTER.