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000
AGNT40 KWNM 262104
MIMATN

Marine Weather Discussion for N Atlantic Ocean
NWS Ocean Prediction Center Washington DC
504 PM EDT Tue Sep 26 2017

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

Note: Warnings below are preliminary, and will be modified based
on the next NHC advisory for Hurricane Maria.

The focus in the near term is Maria, now downgraded to a strong
tropical storm as of the 21Z NHC advisory, located near 34.1N
73.0W at 5 PM EDT this afternoon and moving N or 360 degrees at 6
kt. Winds have been coming down at southern buoys such as 41002
and 41048 and as of 20Z the highest report is at 41025 near Cape
Hatteras with N 33 kt with peak gusts of 45 kt. The latest
advisory has that area in tropical storm conditions. A 1421Z
ASCAT-A pass has a swath of retrievals from the western NT1
waters SSW through Maria and indicate highest wind retrievals
north and west of the center of around 50 kt, amd retrievals of
35 kt appear extending into the central Outer Banks coastal
waters. Winds drop off abruptly N of 38N to 15 kt or less where
there is a weak high pressure ridge with axis near 40-41N. The
12Z GFS 10m winds indicated up to 58 kt or so in the outer zones
ESE of Cape Hatteras while the normally conservative 12Z ECMWF
surface winds indicated up to 50 kt. The 12Z GFS/ECMWF/UKMET/GEM
models all forecast Maria to move slowly N over the next 36 hours
and take the center of Maria to roughly 140 NM to the E of Cape
Hatteras Wed night. The models then indicate an upper trough
moving off the New England coast will steer the tropical system
off to the E NE. The models agree well on the track through
Wed night, then start diverging on the timing of the trough and
the associated E NE turn of Maria. The 12Z ECMWF and UKMET have
trended slower with the trough and the subsequent track of
Maria, and is a bit of a slow outlier solution. The 12Z GFS
agrees somewhat well with the timing of the 12Z GEM/NAM while
Maria is in the W Atlc, so planning on starting out with the 12Z
GFS 10m winds for the background wind grids in next forecast.
However, will need to adjust the timing of it to match the next
official forecast from NHC.

The 12Z GFS also indicates a cold front will pass SE over the
waters in the medium range, and takes it SE through the NT2 by
the end of the forecast period. The 12Z ECMWF is a bit slower
than the overall consensus of the 12Z GFS/UKMET, mainly due to
the aforementioned slower trough associated with steering Maria
off to the E. As a result of the better model support, am
planning on continuing with the 12Z GFS through the remainder of
the forecast period.

Seas...The 12Z Wavewatch and ECMWF are initialized within a ft
or two of the current data, and are in reasonably good agreement
in the short range mainly due to the good agreement of the
associated weather models. The Wavewatch then becomes faster with
taking the seas associated with Hurricane Maria off to the E in
conjunction with the faster GFS solution. However, with the 12Z
ECMWF becoming a slow outlier, planning on starting out with a
2:1 blend of the 12Z Wavewatch and 12Z ECMWF WAM through tonight
and after that the 12Z Wavewatch, and make timing adjustments
based on the next NHC advisory.

.Extratropical Storm Surge Guidance...For surge information
related to Maria please see the latest information provided by
NHC and local WFO coastal offices.

KEY MESSAGES:

1. Maria is forecast to continue moving northward, paralleling
the U.S. east coast for the next 36 hours, and will likely bring
some direct impacts to portions of the North Carolina coast
through Wednesday where a tropical storm warning is in effect.

2. Storm surge flooding, especially along the sound side of the
North Carolina Outer Banks, is expected, and a storm surge
warning and watch are in effect for portions of eastern North
Carolina.

3. Swells generated by Maria are affecting much of the east
coast of the United States.  These swells are also affecting
Bermuda, the Turks and Caicos Islands, and the Bahamas.  These
swells are likely to cause life-threatening surf and rip current
conditions.  Please consult products from your local weather
office for more information.

.WARNINGS...Preliminary.

.NT1 New England Waters...
     None.

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

$$

.Forecaster Bancroft. Ocean Prediction Center.



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