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002
AGNT40 KWNM 062021
MIMATN

.Marine Weather Discussion for N Atlantic Ocean
.NWS Ocean Prediction Center Washington DC
215 PM EST TUE 6 DEC 2016

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

This mornings Ascat overpasses missed the areas of the southeast
coast with the strongest winds. At 18Z the vigorous upper level
shortwave was located over the Tennessee Valley and the 12Z
models are in good agreement that it should reach the coast near
the Virginia tidewater area this evening. The lead surface low
was centered near Frying Pan Shoals at 18Z and should continue
to track northeast tonight. The higher resolution HRRR and 4km
NAM seem to have a better handle on the winds and also the main
surface low associated with the upper level shortwave noted
above...that is forecast to emerge off the mid Atlantic coast
near Currituck Sound this evening. Over the short term through
Wednesday night will be starting with the previous official
grids which were mostly based on the stronger 00Z ECMWF and best
reflect the favored 4km NAM. Versus their respective previous
runs the 12Z GFS and 12Z ECMWF were slighly faster in moving the
weakening low east of the NT2 waters late Wednesday and
Wednesday night. To account for the slightly faster timing
blended in the 12Z GFS Wednesday and Wednesday night. However
even with this blend the gale warnings across the NT2 waters
will remain unchanged.

Models then all indicate an amplified upper level long wave
trough will approach the east coast Thursday and Thursday night
before moving offshore Friday...with an arctic front ushering in
the coldest airmass yet this winter season. Over the last couple
days the models have all trended weaker with this upper feature
as well as with the post frontal northwest winds Thursday into
the weekend. We have trimmed down the areas of gales over the
past few forecast cycles but at this time am choosing to keep
continuity and retain the possible gales across the offshore
waters north of Baltimore Canyon beginning Thursday night and
extending through Friday night. The 12Z ECMWF continued to show
winds up to 30 kt and given its low bias in strong cold air
advection...still have above average forecast confidence with
these forecast gales. The 12Z models then are in good agreement
a strong high pressure ridge will reach the coast early Sunday.
The 12Z GFS and 12Z ECMWF then both show another cold front will
upper level trough will move into the northeaster US late in the
weekend into early next week. The 12Z GFS is more progressive
than the 12Z ECMWF with the 12Z GEFS suggesting that the GFS is
too progressive. Again am favoring the 12Z ECMWF late in the
forecast period.

.Seas...The Wavewatch III and ECMWF WAM are both underdone with
wave heights off the North and South Carolina coasts north of
the warm front in the easterly gales...and appear overdone east
of the cold front in the south to southwest flow. Buoys 41025
and 44014 reported 10 ft and 9 ft respectively last hour. The
previously favored 75% ECMWF WAM/25% Wavewatch III blend looks
reasonable through the short term. Continued with this blend
through Sunday night, but did adjust wave heights up by about
15% over areas with the northwest gales north of Baltimore
Canyon Thurday night through Friday night.

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

.Warnings...Preliminary.

.NT1 New England Waters...
.ANZ800...Gulf of Maine...
     Gale Possible Friday into Friday night.
.ANZ805...Georges Bank west of 68W...
     Gale Possible Friday into Friday night.
.ANZ900...Georges Bank east of 68W...
     Gale Possible Thursday night into Friday night.
.ANZ810...South of New England...
     Gale Possible Friday into Friday night.
.ANZ815...South of Long Island...
     Gale Possible Friday into Friday night.

.NT2 Mid-Atlantic Waters...
.ANZ820...Hudson Canyon to Baltimore Canyon...
     Gale tonight into Wednesday.
     Gale Possible Thursday night into Friday night.
.ANZ915...Hudson Canyon to the Great South Channel...
     Gale tonight.
     Gale Possible Thursday night into Friday night.
.ANZ920...Baltimore Canyon to the Great South Channel...
     Gale tonight into Wednesday.
     Gale Possible Thursday night into Friday night.
.ANZ905...The Great South Channel to the Hague Line...
     Gale Possible Thursday night into Friday night.
.ANZ910...East of the Great South Channel and south of 39N...
     Gale Wednesday.
     Gale Possible Thursday night into Friday night.
.ANZ825...Inner Waters from Baltimore Canyon to Cape Charles
Light...
     Gale tonight into Wednesday.
.ANZ828...Inner Waters from Cape Charles Light to Currituck
Beach Light...
     Gale tonight into Wednesday.
.ANZ925...Outer Waters from Baltimore Canyon to Hatteras
Canyon...
     Gale tonight into Wednesday.
.ANZ830...Inner Waters from Currituck Beach Light to Cape
Hatteras...
     Gale tonight into Wednesday.
.ANZ833...Inner Waters from Cape Hatteras to Cape Fear...
     Gale tonight.
.ANZ930...Outer Waters from Hatteras Canyon to Cape Fear...
     Gale today into Wednesday.
.ANZ835...Inner Waters from Cape Fear to 31N...
     Gale today.
.ANZ935...Outer Waters from Cape Fear to 31N...
     Gale today into tonight.

$$

.Forecaster Clark. Ocean Prediction Center.



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