Marine Interpretation Message
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AGNT40 KWNM 232004 CCA
MIMATN

Marine Weather Discussion for N Atlantic Ocean...CORRECTED
NWS Ocean Prediction Center Washington DC
404 PM EDT Thu Mar 23 2017

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

There was an ASCAT pass at about 1445Z with a swath across the
far ern waters of Georges Bank and into the far ern waters of the
nrn Mid Atlantic waters. Winds were at bit stronger than grid
values in this region with 35 kt while we had 30 kt in this area.
There was a ship observation just W of this area which had 25 kt
although could not find any QC history with this observation. In
any case the area of gales should have moved E of the waters
several hours ago.

In the early afternoon at 18Z High pressure was centered over the
Delmarva peninsula and will be moving E into the offshore waters
through tonight and Friday. The center of high pressure moves E
of the offshore waters by Friday afternoon while becoming weaker.
With regards to winds over the offshore waters winds become
light at 15 kt or less throughout most of the region by 8 am
Friday. By late Friday a warm front will move NE towards the wrn
New England waters. GEM/UKMET/GFS are consistent with having
winds to 30 kt by late Friday with the approaching warm front.
Models are consistent with low pressure developing N of the New
England waters Friday night and strengthening while passing E of
the waters. Associated cold front moves S over the New England
waters late Friday night into Saturday...then crossing into the
nrn Mid Atlantic waters later on Saturday before stalling over
the nrn Mid Atlantic through about Sunday night. Models are
similar with high pressure building in from the NW over the New
England waters late Saturday into Saturday night...then settling
across the area Sunday...before passing E of the New England
waters Sunday night and Monday. By Monday an upper shortwave will
move across the PA/NY state and then E into the offshore waters
late Monday and Monday night while becoming weaker. As this
occurs the stalled front moves back to the N over the New England
waters with weak low pressure dissipating as it moves E into the
waters by early Tuesday. By late Tuesday and Tuesday night models
diverge with low pressure that approaches and crosses into the
waters. Prefer the GFS which is slower than the ECMWF with
moving the low pressure into the waters. There is some agreement
from the UKMET on a slower solution. Also the Weather Prediction
Center has accepted the idea of the slower progress of low
pressure moving E into the waters.

For the Grids plan to favor the GFS initially through early
Friday...then use the ECMWF through about Monday night...then
use GFS from early Tuesday into Tuesday night. The GFS seems
overly strong with Ely winds by late Tuesday and Tuesday night over
the New England waters...and will limits winds since no other
guidance is as strong with winds over the nrn New England waters.

Seas...For seas earlier observations from 14 and 15Z just along
and E of the New England waters showed 17 ft with buoy 44011 and
20 ft with buoy 44024. These observations were much better
depicted by the ECMWF wam over the . Over Georges Bank the ECMWF
wam matched with the ECMWF wam...but was about 3 to 4 ft lower
just E of the New England waters with the 20 ft seas. By
comparison the WWIII was about 4 ft too low with 44011 and about
8 ft too low with buoy 44024. Will use the ECMWF wam across the
offshore for tonight....then use a 50/50 blend of the WWIII and
ECMWF wam from Friday into Monday...then use the WWIII although
will cut seas down by late Tuesday with seas seeming too high
over the New England waters.


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



.WARNINGS...Preliminary.

.NT1 New England Waters...
     None.

.NT2 Mid-Atlantic Waters...
     None.

$$

.Forecaster Rowland. Ocean Prediction Center.



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