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000
AGNT40 KWNM 211440
MIMATN

Marine Weather Discussion for N Atlantic Ocean
NWS Ocean Prediction Center Washington DC
1040 AM EDT Thu Sep 21 2017

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

Note: Warnings are preliminary, and will be modified based on
the next NHC advisories for Tropical Storm Jose and Hurricane
Maria.

NOAA buoy 44008 which is about 80 nautical miles northwest of
the center of Jose this morning has been reporting 1-minute
winds close to 40 kt for the last several hours. In addition a
ship near the Gulf Stream about 180 nautical miles or so south
of the center has been reporting 35 to 40 kt over at least the
past 12 hours. Last nights Ascat overpasses confirmed these ship
obsevations and indicated that the tropical storm force winds
extended at least 180 nm to 200 nm from the center except within
the northeast quadrant. With a lack of any mid level steering
flow the latest models are generally consistent that Jose will
not move very much over the next few days, while gradually
weakening. The 00Z ECMWF/UKMET indicate Jose will drift west to
near 70W over the next 48 hours, before drifting back eastward
over the weekend. Will be updating the wind grids based on the
15Z NHC advisory on Jose this morning. However, we do not
anticipate there will be much change from the previous NHC
advisory. In the medium range, the overnight models generally
trended eastward with the track of Maria as it approaches the
southern outer NT2 waters Sat night into early next week. Will
also be updating the wind grids Sun/Mon based on the updated NHC
advisory on Maria. A 0730Z altimeter pass just east of the
northern NT2 waters, which returned wave heights up to 25 ft,
suggests that both the 06Z Wavewatch III and the 00Z ECMWF WAM
are about too low at least with the seas east of Jose. The
guidance seems to have a better handle on the wave heights
northwest of Jose.

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

The latest GOES-E infrared satellite imagery indicates Tropical
Storm Jose over the nrn NT2 offshore waters with the impacts
extending into the NT1 offshore waters. Ascat wind retrievals
from 0200 UTC last night indicated a large area of tropical
storm force winds in the offshore waters up to 45 kt, with the
highest winds over the warmer SSTs in the Gulf Stream. Previous
wind and hazard grids based off the previous NHC advisory had
tropical storm warnings and winds associated with Jose in the
offshore waters. The 00Z GFS indicated Jose will continue to
meander over the W Atlc over the forecast period due to a lack
of upper level steering, and the 00Z ECMWF/UKMET also indicate a
lack of steering. The 00Z global models generally agree that the
system will remain in the W Atlc while slowly weakening, though
there are some differences on the track in the medium range. The
00Z GFS/NAM/ECMWF/UKMET/GEM solutions agree generally well over
the next 48 hours on Jose, so planning on starting out with the
previous wind grids and making adjustments based on the next NHC
advisory. For the medium range, the previous NHC advisory took
Jose very slowly to the W while gradually weakening it. However,
the 00Z ECMWF/UKMET/GEM all take the low E of the previous track
while the 00Z GEM/NAM are W. The 00Z ensemble guidance is
showing a fair amount of spread, so uncertainty in the overall
track increases with the range of the forecast. This overall
trend looks reasonable given the trends in the guidance. At this
time have a slight preference with the solutions that take the
low to the E, but confidence is very low.

Toward the end of the forecast period, the last NHC advisory
indicated that Hurricane Maria will move into the srn offshore
waters by Mon. There are some differences between the global
models on the overall track, but generally they take the
hurricane slowly N while moving it to the E of the srn NT2
waters. The 00Z ECMWF solutions is about the best compromise on
the timing and track, so planning on starting out with it and
making adjustments bases on the next NHC advisory for Maria.
Otherwise, will generally follow along the lines of the 00Z
ECMWF for the remainder of the forecast period and in areas not
impacted by the tropical systems.

Seas...The 00Z Wavewatch and ECMWF WAM are both initialized
within a few ft of the current observations, and remain in
somewhat decent agreement with the seas associated with Tropical
Storm Jose. At this time am planning on incorporating the 00Z
ECMWF WAM into the previous wave height grids, but will adjust
based on the official track and intensity of the two tropical
systems.

.Extratropical Storm Surge Guidance...Please refer to the latest
NHC advisory and local NWS WFO guidance in reference to any
potential tropical storm surge.

Key messages for Tropical Storm Jose:

1. Tropical-storm-force winds, especially in gusts, are occuring
within the tropical storm warning area.  These conditions are
expected to continue through tonight.

2. Minor coastal flooding is possible along portions of the coast of
southern New England during the next few days.  Please see products
issued by local National Weather Service forecast offices.

3. Swells generated by Jose are affecting Bermuda and much of the
U.S. east coast, and will likely cause dangerous surf and rip
current conditions for the next few days in these areas.

.WARNINGS...Preliminary.

.NT1 New England Waters...
.ANZ805...Georges Bank west of 68W...
     Tropical Storm today into tonight.
     Gale Friday into Friday night.
     Gale Possible Saturday.
.ANZ900...Georges Bank east of 68W...
     Tropical Storm today into tonight.
     Gale Friday.
.ANZ810...South of New England...
     Tropical Storm today into tonight.
     Gale Friday into Friday night.
     Gale Possible Saturday.
.ANZ815...South of Long Island...
     Tropical Storm today into tonight.
     Gale Friday into Friday night.

.NT2 Mid-Atlantic Waters...
.ANZ915...Hudson Canyon to the Great South Channel...
     Tropical Storm today into tonight.
     Gale Friday into Friday night.
     Gale Possible Saturday.
.ANZ920...Baltimore Canyon to the Great South Channel...
     Tropical Storm today into tonight.
     Gale Friday into Friday night.
.ANZ905...The Great South Channel to the Hague Line...
     Tropical Storm today into tonight.
     Gale Friday into Friday night.
     Gale Possible Saturday.
.ANZ910...East of the Great South Channel and south of 39N...
     Tropical Storm today into tonight.
     Gale Friday into Friday night.
     Gale Possible Saturday.
.ANZ925...Outer Waters from Baltimore Canyon to Hatteras Canyon...
     Tropical Storm Possible Monday night into Tuesday.
.ANZ930...Outer Waters from Hatteras Canyon to Cape Fear...
     Tropical Storm Possible Sunday night into Tuesday.
.ANZ935...Outer Waters from Cape Fear to 31N...
     Tropical Storm Possible Sunday night into Monday night.

$$

.Forecaster Clark/Kells. Ocean Prediction Center.


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