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AGXX40 KNHC 111017 AAA
MIMATS

Marine Weather Discussion...updated
NWS National Hurricane Center Miami FL
517 AM EST SUN DEC 11 2016

updated Gulf of Mexico section for forecast cold front position

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...updated

MODEL PREFERENCE: Global model consensus. High confidence.

The 06Z surface analysis has a stationary front draped from
northwest Cuba southwest to inland the northern Yucatan
peninsula. A trough extends from 24N96W southeast to 18N93W.
Strong high pressure ridging is sliding eastward over the
northern gulf east of 93W. The tight pressure gradient along the
coast of Mexico south of 21N, and within 60 nm of the coast of
Veracruz is relaxing. Northwest to north winds there have
diminished to 20-25 kt with seas in the 9-11 ft range as
depicted in the 0318Z Ascat pass. This Ascat pass also showed a
swath of fresh to strong northeast winds roughly from 22N to 25N
east of 93W, including the Straits of Florida. Seas with these
winds are in the 8-9 ft range per recent altimeter data, except
for higher seas of 9-10 ft in the Straits of Florida where
northeast flow counter to the loop current is helping to
maintain these seas. Seas elsewhere are in the range of 4-7 ft,
except for lower seas of 2-3 ft in the far northern waters.

Water vapor imagery continues shows ample upper-level moisture
streaming eastward across much of the southern portion of
central gulf, and the southeast part of the eastern gulf in
broad upper level southwest flow. Upper-level jet stream energy
riding along this flow is helping to trigger off scattered
showers across these area. Scattered showers and isolated tstms
are confined to the Bay of Campeche.

The strong high pressure will continue to shift eastward and
weaken through early on Monday. A weaker gradient will set up
over the area through the next few days allowing for seas to
considerably subside to 2-3 ft throughout by late MOnday, except
for 3-5 ft seas in the approach to the Yucatan channel, and in
the Yucatan channel. The 3-5 ft seas then subside to 2-3 ft
Wednesday through Thursday.

A cold front is forecast to approach the northern gulf Tuesday
night, then become stationary through Wednesday. Models indicate
that strong high pressure surges south over the southeast
U.S. pushing the cold front across the northern and eastern gulf
Wednesday night through Thursday night. Northerly flow will
increase behind the front during this time as the high pressure
broadens, and increases the pressure gradient over much of the
northern and eastern gulf.

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

MODEL PREFERENCE: Global model consensus. High confidence.

The 0136 Ascat pass showed fresh northeast winds between 67W and
79W and also south of 16N between 79W and 82W. Similar winds are
in the windward passage where a ship earlier again confirmed
these winds as well. A small pocket of strong northeast to east
winds is along the coast of Colombia, and in the Gulf of
Venezuela. Seas are in the 8-11 ft range over the central
Caribbean, except for 10-12 ft within 90 nm of coast of
Colombia. Both buoy and Ascat data show moderate to fresh
northeast to east winds elsewhere, with seas in the 5-7 ft
range, except for 3 to 4 ft west of 79W and higher seas of 5-7
ft in the windward passage.

A well-defined surface trough, resembling an easterly wave, is
analyzed at 06Z along 78W from the coast of Panama north to 17N.
It is moving westward at 10-15 kt. A tight gradient in the wake
of the trough is helping to contribute to the aforementioned
fresh northeast winds over the central Caribbean. Numerous
showers and thunderstorms are occurring within 180 nm east of
the trough south of 15N. Scattered showers and isolated
thunderstorms are elsewhere south of 17N between 74W and 83W.
The surface trough will move across the western Caribbean sea
through Monday night before moving inland central America.

A stationary front extending from the northern Yucatan peninsula
northeastward to western Cuba will dissipate this afternoon as
strong high pressure behind it continues to slide eastward.
The fresh northeast winds in the central Caribbean will become
mostly strong, and expand in coverage through Monday night, then
diminish on Tuesday. Strong northeast to east trades are
expected to materialize across the tropical north Atlantic zone
AMZ127 Sunday night through most of Tuesday. Combined seas up to
12 ft in zone AMZ031 will continue through Monday before
subsiding thereafter. Seas are forecast to build to 8-10 ft in
the tropical north Atlantic zone Monday and Monday night before
they begin to subside on Tuesday.

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

MODEL PREFERENCE: Global model consensus. High confidence.

Strong high pressure is sliding eastward from the Carolinas into
the western Atlantic in the behind a slow moving cold front
currently extending from near 25N65W to 25N70W where it becomes
stationary to northwest Cuba. A tight gradient between the ridge
and front is producing strong northeast winds from 24N to 27N
west of 71W, with seas of 8-10 ft. The highest of these seas is
west of 78W, including the Straits of Florida. The cold front
will weaken through tonight as it moves east-southeastward, and
while at the same time the stationary portion dissipates. The
strong northeast winds will then response by diminishing to
fresh category, but at the same time veer around to a southerly
component as the high pressure slides eastward. The high will
shift to the eastern part of the basin by Tuesday in response to
a cold front that approaches the southeast U.S. East to
southeast winds will increase to strong intensity over much of
the central and eastern waters tonight through early on Monday,
then diminish later on Monday. By that time, a tight gradient
will be confined to the southeast portion of the basin where
fresh to strong east winds will materialize. These winds and
associated seas then diminish on Tuesday as a weaker pressure
gradient becomes establised over the area.

The previously mentioned cold front is expected to brush the far
northern waters Monday through Tuesday night. Presently, model
guidance highlights mainly fresh south to southwest winds ahead
of this front, and gentle to moderate west to northwest winds
behind it becoming light and variable Tuesday night and
Wednesday. Seas of 5-7 ft are expected east of the front within
the fresh to south to southwest winds, and 4-5 ft behind the
front. A stronger cold front is expected to move into the far
northwest corner late Wednesday night, and reach the eastern
waters late Thursday. This front is forecast to be preceded by
fresh to strong southerly winds, and seas possibly up to 8 ft.
Northerly winds behind the front are forecast to be mainly in
the fresh range, but this is subject to change based on guidance
from future model runs.

$$

.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...
None.

$$

*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.hurricanes.gov/marine

$$

.Forecaster Aguirre. National Hurricane Center.

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