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000
AGNT40 KWNM 190228
MIMATN

.Marine Weather Discussion for N Atlantic Ocean
.NWS Ocean Prediction Center Washington DC
930 PM EST WED 18 JAN 2017

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

At 00Z the upper low center was in the vicinity of 36N71W or
across the outer portion of the offshore waters east of Hatteras
Canyon. The latest high resolution models including the 00Z HRRR
and 18Z/18 4km NAM are in good agreement that gales across the
outer NT2 zones should slowly shift eastward, finally shifting
east of these waters early Thursday. Blended in some of the 00Z
NAM into wind grids for tonight into Thursday to extend gales
over these outer waters slightly longer than in the previous NT2
forecast. The ship which reported 37 kt at 00Z near NOAA buoy
41048 has a mean wind speed error around +4 kt, but we would
believe gales in the area given its proximity to the organized
line of thunderstorms to its northwest and possibility of an
outflow boundary ahead of this line. The latest models continued
in very good agreement across the west Atlantic into the
weekend, and are in above average agreement into early next
week. Model discrepancies appear late in the weekend into early
next week with the upper low forecast to move through the
southeastern US Sunday and Sunday night impacting the mid
Atlantic and New England waters Sunday into the middle of next
week. Will not be making any significant adjustments to the OPC
grids in the medium range. The higher 12Z ECMWF WAM has been
better initialized with wave heights across the west Atlantic.
Although it even is a couple ft low across coastal and offshore
Maine, and north of Cape Cod Bay where buoys have been reporting
9 to 10 ft.

----------------------------------------------------------------
...Previous Discussion...

Developing low pres has accelerated and moved near the ern areas
of the nrn mid Atlc waters early this afternoon while high pres
remains to the NE over ern Canada. There was an ASCATB pass at
15Z with a swath across much of the offshore waters E of 74W.
Strongest winds where there was data was just SE of Cape
Hatteras with winds to 35 kt in the SW quadrant of the low.
Elsewhere over the central mid Atlc waters winds were W to NW at
30 kt and over the ern areas of the New England offshore winds
were E to NE at 30 kt due to influence of the high pres NE of
area. The one exception was along the ern edge of the swath just
SE of Georges Bank over the ern areas of the nrn mid Atlc waters
with NE winds to 35 kt. Over the Gulf of ME seas in the NEly
flow were to 11 ft which is several feet higher than either the
WWIII or ECMWF wam. Elsewhere over the mid Atlc waters seas were
close to wave guidance while in the NEly flow n of the low pres
and fronts seas were somewhat higher than guidance. Model
guidance is similar with the developing low pres strengthening E
of the offshore waters tonight and Thu...then moving NE Thu
night and Fri. The GFS has been quicker than other guidance with
the rate of deepening with other guidance deepening the low
later on Fri and Fri night. Will favor the GFS for tonight into
Thu night as a weakening high pres ridge moves E into the
waters. Models are similar into Fri night with the a weak low
pres moving E into mid Atlc waters by Sat. Differences occur by
later into Mon as strong low pres approaches the coast Mon
night. Preference at the moment is with the 12Z ECMWF which
tracks low pres near Long island by 12Z Tue. GEM model is
somewhat similar with this track while the GFS is further S and
near the outer banks of NC.

Seas...Will boost seas higher than WWIII/ECMWF wam over the nrn
areas of the New England waters initially tonight due to the
NEly flow elsewhere will stay close to the ECMWF wam which
builds seas higher than the WWIII. Will use a 50/50 blend of the
WWIII/ECMWF wam from late Thu through Sat night...then use the
ECMWF wam Sun through the end of the forecast period.

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

.WARNINGS...Preliminary.

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

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

$$

.Forecaster Clark/Rowland. Ocean Prediction Center.



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