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AGNT40 KWNM 261338
MIMATN

Marine Weather Discussion for N Atlantic Ocean
NWS Ocean Prediction Center Washington DC
938 AM EDT Sun May 26 2019

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

No significant changes to the forecast anticipated at this time.

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PREVIOUS DISCUSSION...

An ASCAT pass from last evening indicated generally light winds
across the offshore waters, generally 20 kt or less, as high
pressure moves E and SE away from the waters, and a cold front
approaches from the W and NW. The main concern across the waters
for the next few days will likely continue to be the threat for
locally very gusty winds, possibly exceeding gale force, and
very rough seas in and near any of the stronger thunderstorms
that develop and cross the waters.

The latest GOES-IR satellite imagery, radar, and lightning
density data indicate showers and scattered thunderstorms, some
strong, extending from the Delmarva coast and southern portions
of Chesapeake Bay NE into the New England waters, moving
generally off to the E. This activity has developed in advance
of a warm front currently located from eastern Virginia
northward toward Vermont. A cold front is moving E and SE over
the Midwest and central Great Lakes according to the preliminary
06Z WPC-OPC surface analysis. The cold front is still forecast
to push E and move off the New England and Mid-Atlantic coasts
later today into tonight, then push further S and SE and reach
central NT2 waters early Mon, before drifting further S and
eventually dissipating later Mon or Mon night into early Tue.

Weak low pressure is then forecast to develop near the Delmarva
coast Tue night, and drift NE Wed into Wed night, and dissipate
by Thu as a high pressure ridge strengthens some over the
southern portion of the waters eastward toward Bermuda, and a
stronger low pressure system tracks eastward over the SE Canada.
A cold front associated with this low will approach the region
from the W and NW Thu night into Fri. At this time, we still
expect winds to remain below gale force over the region for the
next few days, except for the very gusty winds in and near
periodic thunderstorm activity. The latest SREF thunderstorm
guidance suggests that the activity currently moving over the
waters will weaken later this morning. Additional locally strong
thunderstorms are possible near the cold front crossing the
waters tonight into Mon.

As for the 00Z model guidance, for the most part, it remains
quite consistent, and in generally good agreement over the
waters, with the 00Z ECMWF trending more toward the GFS solution
regarding the timing and strength of weather systems forecast to
impact the region over the next few days. We will populate grids
with the 00Z GFS winds for today through Thu night over the
waters, and use the smart tool which places the slightly
stronger first sigma layer winds over the unstable areas and
slightly lower 10 meter winds over the more stable locations.
This will generally result in little change from the past few OPC
forecasts, with winds up to 25 kt or so possible over the New
England and Mid-Atlantic waters today into tonight ahead of the
cold front, and again by Wed into Thu night, near the weak low
described above, and then with the strengthening pressure
gradient ahead of an approaching cold front later in the week.
There is some potential for winds reaching 30 kt especially by
later in the week, and this possibility will be monitored over
the next few days. Overall, forecast confidence is above
average.

.SEAS...The 00Z Wavewatch guidance appears to have initialized
quite well over the region early this morning with sea heights
ranging from 9 feet over the far outer northern NT2 waters, to 6
feet over the Gulf of Maine, to 2 to 4 ft over the inner portion
of the offshore waters from the Mid-Atlantic waters southward.
For the early morning package we will populate the wave height
grids with a 50/50 blend of the previous grids and 00Z Wavewatch
guidance, with no major change from the past few OPC forecasts.

.EXTRATROPICAL STORM SURGE GUIDANCE...N/A.


.WARNINGS...Preliminary.

.NT1 New England Waters...
     None.

.NT2 Mid-Atlantic Waters...
     None.

$$

.Forecaster Achorn/Mills. Ocean Prediction Center.


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