Marine Interpretation Message
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000
AGNT40 KWNM 172026
MIMATN

Marine Weather Discussion for N Atlantic Ocean
NWS Ocean Prediction Center Washington DC
326 PM EST Fri Nov 17 2017

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

The latest ASCAT imagery, coupled with the most recent low-level
satellite plots, would indicate gale-force winds along and north
of ANZ915 to ANZ905, with a likelihood of gale-force winds based
on GOES satellite winds into at least ANZ910, with a value of
40kt at 15UTC. A surface marine observation along the Maine coast
earlier this afternoon has a peak wind gust to 43kt. For the
overnight hours, will continue with the gale warnings as they
were as noted during the morning update. 925mb winds at or above
gale-force should move east of the northern offshore waters by
06UTC and the timing of the gales diminishing at that point
continues to look good. Ridging aloft builds over the offshore
waters tonight, and with high pressure on Saturday, the gradient
will be slack and winds should be well below hazards for much of
the day.

Winds will start to increase late Saturday and into Saturday
night as the gradient tightens ahead of a cold front that will
move through the waters very late Saturday night and Sunday.
925mb winds increase to from the southwest to around 60kt from
the coastal waters off of North Carolina north to Massachusetts
by 12UTC Sunday, followed by winds at that level increasing to 55
to 65kt close to the Gulf Stream in the eastern offshore zones
of ANZ905 and ANZ910 by Sunday afternoon. Gale-force winds seem
to be a high probability over most zones, possibly with a little
lesser confidence toward ANZ935 but will maintain the hazard
headline there for continuity. In the greater instability toward
ANZ905 and ANZ910, some of the guidance alludes to the potential
for storm-force winds, particularly just ahead of the cold front
moving through during the afternoon. Seems to be a good
likelihood that the front will be accompanied by deep convection
as it moves east across the offshore waters Sunday, and
regardless of the sustained wind, winds associated with deep
convection could easily mix down some storm-force gusts with the
higher probability of that from off of the mid-Atlantic coast and
toward the east. Provided it is available, will review the very
latest ECMWF adjusted 10M guidance just prior to product
issuance. Gales should occur in good cold-air advection behind
the strong cold front over the northern waters into Monday and
Monday night.

Guidance differences increase greatly in the very long term, and
for the gridded data beyond Tuesday, leaned toward the GFS but
tempered in the southern waters from its raw output. The ECMWF
forecasts an odd, compact low moving northeast over the offshore
waters as the low develops along the cold front Wednesday. The
GFS has wave along the front but much weaker and farther east,
which currently seems to be a little more reasonable given the
strength of the front, but then the GFS produces a wave later in
the week, less compact than the ECMWF, by Friday. Given the
output of both sets of guidance some type of wave is probable in
the southwest flow aloft late in the week, but timing and
strength are questionable, so kept conditions below hazards that
far out in the forecast.

Regarding seas, leaned toward the higher guidance throughout the
forecast period, except much more toward the Wavewatch toward
the end of the gridded forecasts. Adjusted waves upward near the
Gulf Stream in and around ANZ905, ANZ910, and ANZ920 for late
Sunday and Sunday evening. Indications are a few waves could
reach around 20 feet in spots then.

.EXTRATROPICAL STORM SURGE GUIDANCE...The latest guidance from
the ETSS and ESTOFS would suggest surge values overnight
Saturday into Sunday a foot or less from the mid-Atlantic to Long
Island. Farther north, consensus of the two sets of guidance
would suggest values around a foot possible. Despite the expected
very gusty winds associated with the front, the front should be
quite progressive.

.WARNINGS...Preliminary.

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

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

$$

.Forecaster Figurskey. Ocean Prediction Center.


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