Marine Interpretation Message
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000
AGNT40 KWNM 230115
MIMATN

Marine Weather Discussion for N Atlantic Ocean
NWS Ocean Prediction Center Washington DC
915 PM EDT Fri Sep 22 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 advisory for Hurricane Maria.

Post-Tropical Cyclone Jose was located near 40N 69W per the
preliminary 00Z OPC-NCEP surface analysis, with an estimated
pressure of 1002 mb. Observations are rather sparse around this
system with a few buoy reports indicating winds around 25 kt
with gusts near gale force. The National Hurricane Center issued
the final advisory for Jose at 5 PM EDT this afternoon. Jose
appears to be nearly stationary, with a slow motion toward the
southeast and east expected by tomorrow, with the system
dissipating over NE NT2 waters by later Sun or early Mon. We
will adjust the ongoing forecast based on observations and ASCAT
data just prior to forecast issuance time later this evening.
Any gale force winds associated with this system will likely
diminish later tonight or early Sat per the latest model guidance
and trends.

Otherwise, the main weather system expected to impact the
offshore waters is Hurricane Maria. It is expected to approach
the southern NT2 waters from the south and southeast Sat night
into Sun, with the hurricane spreading tropical storm to
hurricane conditions over the outer NT2 waters Sun night into
Wed night. The forecast will be adjusted to fit the latest NHC
advisory for Maria. Please closely monitor the latest NHC
advisory, OPC and coastal WFO forecasts for the latest
information.

As far as sea heights are concerned we will adjust the previous
grids and forecast to fit current conditions and also to fit
nearby coastal WFO wave height grids, and the latest TAFB and
NHC forecast prior to forecast issuance later this evening.
Per the 00Z RA1 OPC sea state analysis sea heights range from
near 15 feet over northern NT2 waters associated with Post-
Tropical Cyclone Jose, to 3 to 6 feet or so closer to the North
Carolina, South Carolina and Georgia coasts.

-----------------------------------------------------------------
PREVIOUS DISCUSSION...

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

This mornings 14Z and 15Z Ascat overpasses continued to show
tropical storm force winds up to 40 kt across the west and
northwest quadrants of Jose, including the waters near Cape Cod
Bay. Elsewhere, across the east semicircle and south quadrant
winds were less than 34 kt. The 12Z GFS/NAM/ECMWF were all
reasonably well initialized with these winds this morning. The
12Z models remained consistent with post-tropical Jose, that the
system will move very little over the next couple days remaining
across the northern NT2 zones, while gradually weakening. We
will be carrying gales into tonight across ANZ815, ANZ810 and
ANZ915, which is supported by the latest 12Z GFS/NAM/ECMWF, and
subsequently with NHC issuing the final advisory on Jose, will
transition to gale warning headlines. The 12Z models are then in
pretty good agreement with the track of Hurricane Maria through
about 60 hours, but begin to diverge as the system is forecast
to approach the southern outer NT2 waters late this weekend.
Versus its previous few runs, the 12Z GFS trended westward and
slower. These westward and slower trends were also noted in the
12Z ECMWF and 12Z UKMET. The latest NHC forecast appears to be
the closest to the 12Z ECMWF. The previous NHC track forecast
only moved Maria as far west as 71W across the outer NT2 waters,
and based on the latest guidance, there could be a westward
shift in the 21Z NHC forecast. Will be using the 12Z ECMWF winds
as a background before running the TCM wind tool Sun through
Wed.

The 12Z Wavewatch III and 12Z ECMWF WAM are reasonably well
initialized with the offshore and coastal wave heights this
afternoon. The notable exception continues to be across the
waters near Cape Cod Bay where NOAA buoy 44013 is reporting 12
ft. Used a 50/50 blend of the above guidance for the OPC wave
height grids through Sun, before transitioning to the 12Z ECMWF
WAM thereafter. However, we had to make some timing adjustments
to the 12Z ECMWF WAM to better match the NHC forecast for Maria.

.Extratropical Storm Surge Guidance...The surge along the
western Long Island, New Jersey and Delmarva coasts appears to
be running about 1 ft higher than is forecast by the latest
ESTOFS or ETSS. As post-tropical Jose continues to weaken over
the next 12 hours, these values should diminish as well.


.WARNINGS...Preliminary.

.NT1 New England Waters...
.ANZ810...South of New England...
     Gale tonight.
.ANZ815...South of Long Island...
     Gale tonight.

.NT2 Mid-Atlantic Waters...
.ANZ915...Hudson Canyon to the Great South Channel...
     Gale tonight.
.ANZ925...Outer Waters from Baltimore Canyon to Hatteras Canyon...
     Tropical Storm Possible Tuesday.
     Hurricane Possible Tuesday night into Wednesday.
.ANZ930...Outer Waters from Hatteras Canyon to Cape Fear...
     Tropical Storm Possible Sunday night into Monday.
     Hurricane Possible Monday night into Wednesday.
.ANZ935...Outer Waters from Cape Fear to 31N...
     Tropical Storm Possible Sunday night into Monday.
     Hurricane Possible Monday night into Tuesday.
     Tropical Storm Possible Tuesday night.

$$

.Forecaster Mills/Clark. Ocean Prediction Center.



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