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AGNT40 KWNM 221331

.Marine Weather Discussion for N Atlantic Ocean
.NWS Ocean Prediction Center Washington DC
930 AM EDT TUE 22 AUG 2017

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

The latest models remained consistent with the timing of the
cold front forecast to approach the northern mid Atlantic and
New England coasts today/tonight, and move offshore Wed/Wed
night. The guidance is also consistent with the increasing
southwest winds, to 20 to 25 kt, set to occur offshore over the
next 24 hours or so. The short term wind grids were updated with
the 00Z ECMWF as the previously favored blend appeared somewhat
underdone. The southeast swell, 4 to 5 ft at 9 to 10 seconds,
across the outer mid Atlantic zones is about 1 to 2 ft higher
than the 06Z Wavewatch III/00Z ECMWF WAM this morning. Elsewhere
across the west Atlantic, the above models appear well

...Previous Discussion...

Summary...The 00z ncep surface analysis shows a stationary front
extending roughly E to W across the central and southern nt2
waters, with high pres ridging elsewhere over the offshore
waters. Latest available ascat hi-res and ascat passes from a
few hours ago show 5 to 15 kt winds over the offshore waters.

Models...The 00z medium range models are in good overall
agreement across the offshore waters through the forecast
period, and the only exception to this is the strength of the S
to SW flow over the Gulf of Maine for late Tue and Tue night.
The 00z gem/gfs 30m are stronger with the S to SW flow and have
max winds of 30 to 35 kt, while the 00z ecmwf/gfs 10m/ukmet are
weaker and have max winds of 25 kt. Given the stability
considerations, will be continuing to favor the weaker models
for late Tue and Tue night. Am continuing to monitor Blake Ridge
and the waters just S of the nt2 area, since all of the models
suggest formation of a weak tropical low in this area for Sat
and Sat night, with the exception of the 00z gem which develops
a much stronger low. Overall the 00z ecmwf/gfs 10m are in the
best agreement, so will be using a representative 50/50 blend of
these models for the wind grids during the forecast period.

Seas...The 00z wna wavewatch and 00z ecmwf wam both initialized
well over the offshore waters, and are in good overall agreement
with only minor differences noted. A 50/50 blend of the 00z wna
wavewatch/ecmwf wam will be used for the sea height grids
through Sat night, in order to smooth out the model differences
and maintain consistency with the preferred 00z gfs/ecmwf

.Extratropical Storm Surge Guidance...N/A.


.NT1 New England Waters...

.NT2 Mid-Atlantic Waters...


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