[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 231631
TWDAT

Tropical Weather Discussion
NWS National Hurricane Center Miami FL
1131 AM EST Sat Dec 23 2017

Tropical Weather Discussion for North America, Central America
Gulf of Mexico, Caribbean Sea, northern sections of South
America, and Atlantic Ocean to the African coast from the
Equator to 32N. The following information is based on satellite
imagery, weather observations, radar and meteorological analysis.

Based on 1200 UTC surface analysis and satellite imagery through
1715 UTC.

...Gale Warning in the Gulf of Mexico...

As of 1500 UTC, a cold front extends from SE Louisiana to near
Tampico, Mexico that is reporting strong northerly winds with
gusts to 38 kt. The front will reach from the Mississippi Delta
to the western Bay of Campeche this evening, then slow from the
Florida Panhandle to the Eastern Bay of Campeche early Sun as a
secondary cold front surges S into the northern waters reaching
from Straits of Florida to near Veracruz, Mexico on Mon night.
Minimal gale force winds and seas of 8-9 ft are expected in the
wake of the main front today. Fresh to strong N-NE winds will
follow the secondary front Sunday night into Monday with seas of
6-7 ft, mainly across the north and SW Gulf waters. By Monday
night, gentle to moderate easterly winds will dominate most of the
Gulf region with seas of 4-6 ft. Please read the latest NHC High
Seas Forecast under AWIPS/WMO headers MIAHSFAT2/FZNT02 KNHC for
more details.

...ITCZ/MONSOON TROUGH...

The monsoon trough enters the Atlantic Ocean through Nigeria and
and continues to 04N at the Prime Meridian to 04N17W. The ITCZ
extends from 04N17W to 03N30W to 03N45W to NE Brazil near 02N51W.
Scattered moderate convection is south of the trough to the
Equator between the Prime Meridian and 20N. Similar convection is
noted N of the ITCZ from 04N-06N between 23W-35W.

...DISCUSSION...

GULF OF MEXICO...

A cold front is moving across the Gulf waters. Please, see Special
Features section for details. E of the front, a ridge from the
Atlantic Ocean extends across Florida into the eastern Gulf of
Mexico, and provides a gentle to moderate southerly return flow E
of 90W while a tighter pressure gradient in the western part of
the Gulf, ahead of the front, supports moderate to strong southerly
winds. The aforementioned ridge will continue to bring mostly
clear skies, light winds, and warm temperatures across South
Florida the remainder of the weekend. On Monday, a cold front
will move across South Florida and the Florida Keys.

CARIBBEAN SEA...

Latest scatterometer data continue to show fresh to strong winds
across the central Caribbean, while moderate to fresh NE winds
persist across the Windward Passage. An altimeter pass indicated
seas of 11-12 ft with the strongest winds near the coast of
Colombia. Patches of low level clouds, embedded in the trade wind
flow, are producing isolated to scattered passing showers over
Hispaniola, Puerto Rico and the Lesser Antilles. High pressure N
of the area will maintain strong trades over the Central and SW
Caribbean through Wed, with near gale force nocturnal winds near
the coast of Colombia. Fresh to strong NE winds are expected
through the Windward Passage as well. Large E swell will build
seas to 9 ft E of the Lesser Antilles on Mon night, with these
swells reaching the E Atlantic passages on Tue evening. At that
time, expect building seas to 10 ft.

...HISPANIOLA...

Low-topped trade wind showers will continue to move across the
island the remainder of the weekend. High pressure over the
Atlantic will continue to support pulses of fresh to locally
strong winds across the Windward Passage through Sunday.

ATLANTIC OCEAN...

A ridge dominates the western Atlantic, including the Bahamas and
the State of Florida. A frontal trough extends from a very weak
low pressure of 1023 mb located near 31N55W to 24N54W to the near
the Leeward Islands. These features are forecast to dissipate over
the next 12-24 hours. Isolated to scattered showers are along the
trough axis. E of the frontal trough, a strong 1039 mb high
pressure centered just E of the Azores extends a ridge across the
remainder of the Atlantic. The pressure gradient between this
strong high pressure and lower pressure in the vicinity of the
monsoon trough/ITCZ is supporting fresh to strong winds mainly N
of 11N between the coast of Africa and 40W, with seas of up to 12
ft based on altimeter data. This high pressure has displaced the
monsoon trough/ITCZ farther south.

For additional information please visit
http://www.hurricanes.gov/marine

$$
GR
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