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AGNT40 KWNM 250650

Marine Weather Discussion for N Atlantic Ocean
NWS Ocean Prediction Center Washington DC
250 AM EDT Tue Apr 25 2017

.FORECAST DISCUSSION...Major features/winds/seas/significant
.weather for the North Atlantic Ocean W of 50W from 30N to 50N.

Over the short term, earlier high resolution 0148Z ASCAT-A and
0242Z ASCAT-B scatterometer passes confirmed that gale force
winds (up to 45 kt in NT2 zone ANZ930) were present between 33N
and 36N from 71W to 76W in the ESE gradient N of the complex low
pressure system over the Srn NT2 waters. The new 00Z models are
in reasonable agreement that this system will consolidate into
one surface low that will become vertically stacked with its
associated closed upper low over N Carolina today and drift NE,
continue NNE off the mid Atlantic coast tonight/Wed and then to
near Cape Cod by late Wed night, then dissipate Thu. Overall
would favor the more consistent and similar 00Z GFS/ECMWF
forecasts tracks for this low, which are supported by the 00Z
GEFS Mean. In regards to the associated forecast gradients, based
on the scatterometer passes would favor the stronger 00Z GFS/GEM
solutions versus the weaker 00Z UKMET/ECMWF solutions.
Therefore, as was done previously, will populate our forecast
wind grids with our smart tool that will place stronger 00Z GFS
first sigma level winds in unstable areas and weaker 00Z GFS 10m
winds in stable areas (which will be primarily from the gulf
stream Nwd) for today through Thu.

In the long range, the 00Z global models generally agree that a
quiet weather pattern will develop and persist. With minor
timing differences, the models all forecast a high pressure ridge
to build W across the Srn NT2 waters Thu night through Fri
night, then persist Sat/Sat night while a cold front pushes
offshore across the NT1 waters with moderately strong (generally
up to 20 or 25 kt) associated gradients developing. As a
compromise will populate with a 50/50 blend of the 00Z GFS 10m
and 00Z ECMWF boundary layer (BL) winds on Thu night and Fri.
Then prefer a solution closer to the 00Z UKMET/ECMWF for the cold
fropa so will transition to populating with all 00Z ECMWF BL
winds on Fri night through Sat night.

Seas...A compromise between the similar 00Z Wavewatch and 00Z
ECMWF WAM initializes the current seas best at the moment. With
this in mind, and since their associated 00Z GFS/ECMWF solutions
are similar, will populate our forecast wave grids with a 50/50
blend of the 00Z Wavewatch and the 00Z ECMWF WAM for today
through Fri. Then Fri night through Sat night, since the 00Z
ECMWF solution will become favored, will populate with all 00Z
ECMWF WAM seas then.

.Extratropical Storm Surge Guidance...As the strong Ely gradient
is forecast to shift Nwd up the coast in advance of the surface
low today into Wed, the 00Z ESTOFS remains consistent in
forecasting a more significant surge to develop along the mid
Atlantic and Srn New England coasts than forecast by the 00Z
ETSS. Overall, would favor the higher ESTOFS solution.


.NT1 New England Waters...

.NT2 Mid-Atlantic Waters...
.ANZ920...Baltimore Canyon to the Great South Channel...
     Gale today into Wednesday.
.ANZ910...East of the Great South Channel and south of 39N...
     Gale today into Wednesday.
.ANZ825...Inner Waters from Baltimore Canyon to Cape Charles Light...
     Gale today.
.ANZ828...Inner Waters from Cape Charles Light to Currituck Beach Light...
     Gale today.
.ANZ925...Outer Waters from Baltimore Canyon to Hatteras Canyon...
     Gale today into tonight.
.ANZ830...Inner Waters from Currituck Beach Light to Cape Hatteras...
     Gale today.
.ANZ930...Outer Waters from Hatteras Canyon to Cape Fear...
     Gale today.


.Forecaster Vukits. Ocean Prediction Center. is the U.S. government's official web portal to all federal, state and local government web resources and services.