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000
AGNT40 KWNM 191251
MIMATN

MARINE WEATHER DISCUSSION FOR N ATLANTIC OCEAN
NWS OCEAN PREDICTION CENTER WASHINGTON DC
850 AM 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.

OVERNGT HI RES ASCAT OVERPASS RETURNED SE 20 TO 25 KT OVER BALT
TO HATTERAS CNYNS LAST NIGHT...WHICH WAS SLIGHTLY HIER THAN EVEN
THE STRONGEST GFS BNDRY LAYER WINDS OF LAST NGTS MDL RUNS. THE
25 KT WINDS WERE CONFINED OVER THE GLF STREAM...THEN DROPPED OFF
TO 15 KT OVER COLDER SHELF WATERS. FOR THIS REASON WILL BE
MAKING SOME MINOR MODIFICATIONS TO INCREASE WINDS OVER GLF
STREAM THIS AFTERNOON AND TNGT. 00Z/06Z GFS THEN ARE STRNGER
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 ECMWF/UKMET. WILL NOT BE MAKING MAJOR ADJUSTMENTS TO
PREVIOUS NT1/NT2 FORECASTS IN MED RANGE LATE TUE THRU THU. ALTHO
NOT AS STRONG AS THE 00Z RUN...THE 06Z GFS CONTINUED TO MOVE A
DVLPG SFC LOW OFF FL COAST AND INTO SRN NT2 WATERS BY
FRI...WHICH NOT SUPRISINGLY THE 00Z GEM GLOBAL WAS LONE MDL TO
SUPPORT SUCH A SOLUTION. AGAIN OPC PREFERENCE REMAINS WITH
ECMWF/UKMET. 06Z MULTIGRID WAVEWATCH III HAS BEEN IN GOOD
AGREEMENT WITH MOST W ATLC SHIP/BUOY OBS OVER LAST FEW HRS.

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

SUMMARY...A HIGH PRES RIDGE IS LOCATED OVR THE ERN PARTS OF THE
OFF WTRS EARLY THIS AM PER THE LATEST ASCAT AND OSCAT DATA AND
OBS OVR THE SW N ATLC. A STRNY FRONT EXTENDS FROM THE NC COAST
SE TOWARD BERMUDA. AN AREA OF SE WINDS AROUND 20 KT IN NOTED
JUST N OF THE FRONT OVR THE CENTRAL NT2 OFF WTRS...WITH WINDS
GNRLY LESS THAN 20 KT ELSEWHERE. THE RIDGE WILL DRIFT E AND SE
THRU TNGT AS THE FRONT LIFTS N AS A WEAK WARM FRONT. SHWRS AND
TSTMS ARE LKLY NR THE FRONT THRU TNGT. BEYOND TNGT THE MAIN WX
FEATURE WILL BE A LOW PRES AREA FCST TO MOVE SE FROM SE CANADA
AND EMERGE TO THE E OF THE OFF WTRS BY MON NGT. THIS LOW WILL
PULL A COLD FRONT S OVR NT1 WTRS MON...AND PSBLY INTO NRN NT2
WTRS TUE. THIS FRONT WILL THEN STALL AND RETURN N AS A WARM
FRONT WED INTO THU. THE NEXT LOW PRES SYSTEM WILL THEN MOVE E
FROM THE GRT LKS AND MIDWEST THU. A COLD FRONT ASSOC WITH THIS
SYSTEM WILL LKLY APPROACH THE COAST THU NGT.

MODELS...OF THE AVAILABLE 00Z MDLS THERE IS GUD AGREEMENT THRU
SUN NGT. AS A RESULT...WE WILL REMAIN CLOSE TO THE PREV OPC FCST
AND 00Z GFS THRU SUN NGT FOR THE EARLY AM FCST PACKAGE. MDL
DIFFERENCES INCREASE FOR MON THRU THU OVR THE WTRS. THE 00Z GFS
REMAINS THE STRONGEST REGARDING THE LOW MOVG SE FROM SE CANADA
MON INTO TUE...ALTHO THE REMAINING NON-GFS SOLUTIONS DID SHOW A
TREND TOWARD THIS STRONGER SOLUTION. ANY GALES THAT FORM WITH
THIS LOW ARE EXPECTED TO REMAIN E OF THE OFF WTRS MON INTO TUE.
WE WILL GNRLY FAVOR A SOLUTION CLOSER TO THE 00Z UKMET FOR MON
INTO THU OF THIS WK...OR SIMILAR TO THE 12Z SAT ECMWF. THIS
SOLUTION APPEARS TO FIT THE BEST WITH THE PREV OPC FCST. ALSO OF
NOTE...THE 00Z GFS BRINGS LOW PRES NE FROM FLORIDA INTO THE SRN
NT2 WTRS LATE THU AND THU NGT. AS WE ARE MORE CLOSELY FOLLOWING
THE 00Z UKMET MDL FOR THIS PACKAGE WE WILL NOT SHOW THIS LOW
IMPACTING THE SRN NT2 WTRS LATE IN THE FCST PERIOD. ALSO THIS
WILL GNRLY RESULT IN ONLY MINOR CHANGES FROM THE PREV OPC FCST
FOR THE EARLY AM PACKAGE.

SEAS...THE 00Z MULTIGRID AND WNA WAVEWATCH MDL IS PERFORMING
OKAY OVR THE OFF WTRS CURRENTLY...ALTHO IT MAY BE A FT OR TWO ON
THE HIGH SIDE INITIALLY. OVERALL...WE WILL NOT MAKE SIG CHANGES
TO THE PREV FCST FOR THE EARLY AM PACKAGE...AND CONT TO BLEND
THE WV WATCH III MDL WITH THE LATEST ECMWF WAM WV GUID THRU THE
FCST PERIOD.

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/MILLS. OCEAN PREDICTION CENTER.