Marine Interpretation Message
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293
AGNT40 KWNM 220809
MIMATN

Marine Weather Discussion for N Atlantic Ocean
NWS Ocean Prediction Center Washington DC
309 AM EST SUN JAN 22 2017

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

A strong low pressure system will impact the offshore waters
tonight into Tuesday night with widespread gale to storm force
winds likely with this system. There will be another threat for
gales over mainly NT2 waters Thursday as a strong cold front
crosses the waters.

Over the short term, the 00Z models are in very good agreement.
We will continue to use the GFS and use the 00Z cycle and also
continue to use the smart tool which places the stronger first
sigma layer winds over unstable areas and 10 meter winds over
stable waters for today through early Tuesday. The 00Z cycle is
similar to the previous cycles with only slight differences in
both timing and intensity noted. For the early morning package we
will manually edit the grids slightly to keep the previous
headlines going, as the 00Z gfs has backed off slightly with
forecast wind speeds, but not enough to warrant backing off on
any warnings at this time. The 00Z UKMET and 00Z ECMWF are a
little stronger than the 00Z GFS regarding the strong low
pressure system. Therefore, we continue to have near to above
normal confidence in keeping the warnings pretty much the same as
the past few OPC forecasts. The latest satellite, radar and
lightning data indicates that the strong thunderstorms over
central and southern NT2 waters have weakened somewhat since last
evening. Additional heavy thunderstorms are occurring further to
the southwest of the NT2 waters, back toward the gulf states, and
this activity will likely overspread the NT2 waters today, and
then persist into Monday. Local wind gusts exceeding gale force
and very rough seas will be likely in or near the heavier
thunderstorms. Currently, a weak low in advance of the main low
pressure system is located over eastern North Carolina. This low
will track northeast into central NT2 waters today, then dissipate
tonight. The main low is forecast to move east from the southern
plains and reach the Delmarva by later Monday. High pressure will
build over southeast Canada tonight into Tuesday. The low will
track northeast just off the mid-Atlantic and New England coasts
Monday night and Tuesday, with the strongest winds, potentially
reaching storm force, occurring with the strong low level flow to
the north and northeast of the strong low pressure center, from
far northwest NT2 waters northward over western NT1 waters Monday
into Monday night. Gales will occur elsewhere over most of the
offshore waters beginning tonight, and persisting into Monday
night. Wind gusts approaching hurricane force appear possible
mainly for the coastal waters of southern New England Monday into
Monday night. Improving conditions are forecast to develop from
southwest to northeast over the waters beginning Tuesday as high
pressure slides east from the gulf states.

Over the long term, later Tuesday through Thursday night, the 00Z
models are remaining in very good agreement. We will populate the
forecast with the 00Z GFS as a result, and continue to rely on
the tool which places the stronger first sigma level winds over
the unstable areas, and lower 10 meter winds over stable areas.
The strong low pressure system will move northeast away from the
waters later Tuesday and Tuesday night as a weak high pressure
ridge moves east into the region. The ridge will move east away
from the waters Wednesday into Wednesday night as a strong cold
front approaches from the west and northwest. This front will
cross the waters Thursday, and pass east of the region Thursday
night. Marginal gales, especially near the Gulf Stream, appear
likely with the passage of the front over mainly central NT2
waters on Thursday. Further adjustments in these gales can be
expected over the next few days.

.Seas...Both the 00Z ECMWF WAM and 00Z Wave-watch III models have
initialized well over the offshore waters per the latest
observations and altimeter data. The WAM appears to build the sea
heights a little faster and a few feet higher than the Wavewatch
with the strong low pressure system moving over the region
tonight into Tuesday, and these higher seas tend to match up a
little better with the nearby coastal WFO forecasts. As a result,
we will use a 20 percent wavewatch III/80 percent WAM blend for
the early morning forecast package.

.Extratropical Storm Surge Guidance...In the strong easterly
gradient north of the strong low pressure system we continue to
favor the slightly higher 00Z ESTOFS guidance verses the slightly
less ETSS guidance tonight into Tuesday.

.WARNINGS...Preliminary.

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

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

$$

.Forecaster Mills. Ocean Prediction Center.



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