Marine Interpretation Message
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000
AGNT40 KWNM 200749
MIMATN

Marine Weather Discussion for N Atlantic Ocean
NWS Ocean Prediction Center Washington DC
249 AM EST Mon Nov 20 2017

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

There were several ASCAT passes over and just E of the offshore
waters this past night. There was an ASCAT pass at about 00:30Z
just E of the waters which showed gales in advance of the strong
cold front and just W of the cold front with gales. Another later
pass from 02Z where data was available between 68W and 75W did
show gales to 35 kt over the wrn edge E of the Delmarva coast
about 45 nm. Elsewhere winds were to 30 kt over much of the
remainder of the area N of 36N.

Early this morning a strong cold front has moved E of the
offshore waters while a broad area of high pressure was building
E from the mid Atlantic coast. There was a ship observation
about 3 hrs ago or 03Z N of the Gulf Stream E of the Delmarva
coast which had 40 kt winds which was located where ASCAT data
had gales. For today into tonight will stay with prior grids and
have gales throughout in the cold air advection over the
northern areas of offshore waters until later tonight as the high
pressure ridge moves offshore. By late Tue and Tue night a cold
front will move towards the offshore waters. The 00Z GFS/ECMWF
are in decent agreement with an upper shortwave trough moving E
across the southeastern US and forming low pressure over the srn
mid Atlc waters Tue night and then moving NE Wed while the cold
front moves offshore. The GFS/ECMWF are similar with the trends,
and fairly close with the track. The ECMWF is further W with the
surface low early Wed near the SE coast and then near Georges
Bank by Wed evening. The GFS is in similar agreement with the
position by this time, although the ECMWF is deeper. Will use the
00Z ECMWF from Tue night into Thu. Will likely have strong gale
force by Wed night near Georges Bank. Both the GFS and ECMWF do
agree with another low pressure forming E or just S of the
southern waters late Wed or Wed night and moving to the NE. The
main area of concern will be primarily with the first low while
the second low should stay E of waters. Models agree with high
pres building off the SE coast late Thu into Fri. The ECMWF is
showing another surface low pres moving NE across FL and then
into the srn Mid Atlc waters. Prefer the GFS/UKMET which have
weak high pres over the SE states with any low pres forming along
or just SE of the outer waters of the srn Mid Atlc waters.

Seas...Will use the ECMWF wam for today into tonight with its
higher seas extending further W than the WWIII. Otherwise will
use a 50/50 blend of the guidance from Tue 12Z through 12Z Wed,
then will favor the ECMWF wam since will be use ECMWF from 12Z
Wed through 00Z Fri, then favor the WWIII the remainder of
forecast period.


.EXTRATROPICAL STORM SURGE GUIDANCE...n/a.



.WARNINGS...Preliminary.

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

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

$$

.Forecaster Rowland. Ocean Prediction Center.



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