Marine Interpretation Message
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AGXX40 KNHC 250839 CCA
MIMATS

Marine Weather Discussion...Corrected
NWS National Hurricane Center Miami FL
357 AM EDT Mon Sep 25 2017

Corrected Caribbean Sea and Tropical N Atlantic section

Marine Weather Discussion for the Gulf of Mexico, Caribbean Sea,
and Tropical North Atlantic from 07N to 19N between 55W and 64W
and the Southwest North Atlantic including the Bahamas.

...GULF OF MEXICO...

A thermal trough will develop each evening over the NW Yucatan
Peninsula, move W-NW across the SW Gulf during the overnight
hours and dissipate over the SW Gulf waters by late each
morning. Expect the trough to be accompanied by a surge of
moderate to locally fresh winds that shift from NE to SE along
with brief seas to 4 ft through early Tuesday. Expect a tighter
pressure gradient on Tuesday evening with a fresh to locally
strong wind shift along the trough axis and seas possibly to 5
ft through early Wednesday. Elsewhere, weak high pressure will
continue to support mainly gentle E-SE winds and 1-3 ft seas
through Wednesday night. The flow increase slightly on Thursday
and through Friday over the S Central and and far western
portions of the Gulf, with seas increasing a little.

The first cold front of the autumn season is depicted by model
guidance to move across the northern and western Gulf waters on
Thursday, and reach a position from northern Florida to the
central and SW Gulf waters on Friday. Currently, it appears that
this front will be rather shallow as it is expected to be
followed by mainly moderate NE winds and seas of 1-3 ft, except
for higher seas of 3-5 ft over the far western Gulf waters.

...CARIBBEAN SEA AND TROPICAL N ATLANTIC FROM 07N TO 19N BETWEEN
55W AND 64W...

Ascat data from 0216Z last showed gentle to locally moderate
winds across the basin W of about 70W, and a little tighter E of
70W with moderate to locally fresh E-SE winds. Seas are rather
low W of 70W where 1-3 ft seas are occurring, and 4-5 ft seas E
of 70W as noted in recent altimeter pass and in recent and
current buoy observations. Slightly higher seas of 5-6 ft are
over the tropical N Atlantic zones. The pressure gradient has
begun to tighten some across the eastern and central Caribbean
Sea, and will begin to tighten across the tropical N Atlantic
waters this afternoon and evening as central Atlantic high
pressure builds southwestward towards the tropical N Atlantic
waters and NE Caribbean Sea in the wake of Hurricane Maria
exiting the forecast waters of the SW N Atlantic.

The 0214Z Ascat pass indicated that E-SE trades have increased
to the 20-25 kt S of about 15N to near the coast of Venezuela
and between 65W-71W. Presently seas with these trades are
up to 7 ft, but are forecast max out to 8 ft as the 20-25 kt
trades expand westward in coverage towards much of the central
Caribbean into late Wednesday morning before diminishing on
Thursday. Winds are also expected to increase to 20-25 kt across
the Gulf of Honduras during the evening hours beginning with
this evening. Seas are forecast to build to 6-7 ft during the
period of strongest winds.

Long period northerly swell is expected to reach the waters E of
the Leeward Island on Tuesday, and E of the Windward Islands on
Wednesday, with building seas to 7-8 ft. The swell will decay on
Thursday allowing for these seas to lower below 8 ft.

...SW N ATLANTIC INCLUDING THE BAHAMAS...

Hurricane Maria is pulling off to the N with time, and as of
2 AM EDT was located about 330 nm SSE of Cape Hatteras, North
Carolina moving N or 360 degrees at 7 kt with maximum sustained
winds of 75 kt with gusts to 90 kt, and a minimum central
pressure of 954 mb. Maria is moving N at 8 kt. This general
motion with some decrease in forward speed is expected through
Tuesday. On the forecast track, the core of Maria will be moving
well east of the southeast coast of the United States during the
day or so. The latest NHC forecast advisory has Maria exiting the
forecast region around this evening. An Ascat pass from 0218Z
last night nicely highlighted winds of 20-33 kt covering most of
the forecast waters N of 25N and NE of the Bahamas. Both
altimeter data and buoy reports reveal that seas 12 ft or greater
are occurring to the N of 24N between 66W-80W. Buoy 41047
located at 27.5N71.5W is currently reporting SW winds to near 35
kt along with combined seas of 17 ft. Just a short while ago, it
reported combined seas of 21 ft. Although Maria is soon on its
way out of the basin, the main issue that will plague much of the
forecast waters will be swell with primary direction from the
NW, except in mixed directions over the waters N and NE of the
Bahamas. In addition, seas of 8 ft are along the entrances to the
Bahamas passages. Wave model guidance suggests that the swell
will slowly decay through the end of the week while the bulk of
the swell group shifts to the NE portion of the basin. The seas
of 8 ft along the entrances to the Bahamas passages will subside
to less than 8 ft by late on Tuesday.

Of note, swells generated by Maria are increasing along portions
of the southeastern United States coast and Bermuda and will be
increasing along the Mid-Atlantic coast today. Swells also
continue to affect Puerto Rico, the Virgin Islands, the northern
coast of Hispaniola, the Turks and Caicos Islands, and the
Bahamas. These swells are likely to cause life-threatening surf
and rip current conditions. Otherwise, in the wake of Maria a
surface trough will extend from the N-central forecast waters SW
to near the Central Bahamas through Wednesday night then become
diffuse Thursday as central Atlantic high pressure builds
westward across the eastern portion of the area. Scattered
showers and thunderstorms are possible with the trough. On
Friday, the ridge is forecast to extend E to W near 26N as a
weak cold front approaches the SE United States coast, and far
NW waters.

$$

.WARNINGS...Any changes impacting coastal NWS offices will be
coordinated through AWIPS II Collaboration Chat, or by
telephone:

.GULF OF MEXICO...
     None.

.CARIBBEAN SEA AND TROPICAL N ATLANTIC FROM 07N TO 19N BETWEEN
55W AND 64W...
     None.

.SW N ATLANTIC INCLUDING THE BAHAMAS...
.AMZ113...ATLANTIC FROM 27N TO 31N BETWEEN 70W AND 77W...
    Hurricane Warning today.
    Tropical Storm Warning tonight into Tue.
.AMZ115...ATLANTIC FROM 27N TO 31N BETWEEN 65W AND 70W...
     Tropical Storm Warning tonight.

$$

*For detailed zone descriptions, please visit:
http://www.nhc.noaa.gov/abouttafbprod.shtml#OWF

Note: gridded marine forecasts are available in the National
Digital Forecast Database (NDFD) at:
http://www.nhc.noaa.gov/marine/grids.php

For additional information, please visit:
http://www.nhc.noaa.gov/marine

$$

.Forecaster Aguirre. National Hurricane Center.


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