000
AGNT40 KWNM 260712
MIMATN

Marine Weather Discussion for N Atlantic Ocean
NWS Ocean Prediction Center Washington DC
312 AM EDT Mon Jun 26 2017

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

Ascat wind retrievals from late last night between 0100 and 0300
UTC indicated SW winds up to 20 kt in the offshore waters ahead
of a weak cold front moving through the area and a few 25 kt
barbs just SE of the nrn NT2 waters in the vicinity of the Gulf
Stream. Current surface observations show up to 15 kt in the SW
flow, though no data is currently near where the Ascat overpass
indicated 25 kt earlier. The 00Z GFS 10m winds are initialized
well, along with the 00Z ECMWF/UKMET surface winds. The models
all indicate the winds will weaken today over the offshore waters
as the front weakens across NT2. The models agree fairly well on
the winds and the timing of the front, and all are indicating
weak low pres will move NE along the front. The 00Z GFS seems
representative of the model consensus, so planning on using the
00Z GFS in the short range.

The 00Z GFS/ECMWF remain in reasonably good agreement throughout
the forecast period, and the models indicate a few additional
weak surface boundaries will pass through the NT1 waters today
into Thu. The GFS/ECMWF both indicate winds of 20 kt or less up
to that point, so planning on staying with the 00Z GFS into Thu
as a result of the good overall agreement. The models then
indicate a stronger cold front will approach the area from the NW
Thu night, and move over the Gulf of Maine by Fri night. The GFS
is indicating the winds will increase in the SW flow between the
front a ridge to the SE, but seems a little overdone when
compared with the 00Z ECMWF/UKMET and with taking into
consideration the stable boundary layer over the cooler shelf
waters. There is, however, some disagreement on the timing of
weak low pres centers passing north of the area. The 00Z GFS is
in marginally better agreement with the 00Z UKMET/GEM solutions
than the 00Z ECMWF, and model trends favor the GFS solution. The
ECMWF is also a little north with the front in NT1 than the rest
of the guidance. As a result, planning on favoring the 00Z GFS
solution through the extended period, but will cap winds at 25 kt
Thu night into Fri night.

.Seas...Recent altimeter overpasses in the W Atlc this morning
indicated significant wave heights up to 9 ft just southeast of
the nrn NT2 waters, and current surface reports indicate seas up
to 5 ft in the offshore waters. The 00Z Wavewatch and ECMWF WAM
are initialized within a ft of the current data, and remain in
overall good agreement throughout the forecast period. As a
result, planning on using a 50/50 blend of the two throughout
the forecast period.

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

.WARNINGS...Preliminary.

.NT1 New England Waters...
None.

.NT2 Mid-Atlantic Waters...
None.

$$

.Forecaster Kells. Ocean Prediction Center.