[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 182331
TWDAT

Tropical Weather Discussion
NWS National Hurricane Center Miami FL
631 PM EST Mon Dec 18 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 1800 UTC surface analysis and satellite imagery through
2315 UTC.

...SPECIAL FEATURES...

...Gale Warning in the Caribbean Sea...

Pulsing nocturnal NE-to-E winds to gale-force are expected again
near the coast of Colombia during the overnight tonight and early
morning hours on Tuesday, particularly from 10N to 13N between
74W and 78W. Expect sea heights to range from 10 to 14 ft. Wind
will diminish below gale-force by Tuesday afternoon, and are
expected to reach again minimal gale force at night. Thereafter,
strong to near gale force winds will persist near the coast of
Colombia each night this week. 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 near 07N12W and
continues to 05N20W. The ITCZ extends from 05N20W to 04N43W to
NE Brazil near 02N51W. Scattered moderate convection is noted
within about 30 nm on either side of the ITCZ between 20W and
27W. Similar convection is from 04N-06N between 34W-39W.

...DISCUSSION...

...GULF OF MEXICO...

As of 2100 UTC, a stationary front extends across the basin from
southern Lousiana to 28N96W. Mosaic Doppler Radar from the SE U.S.
shows scattered showers and isolated tstms over the NW Gulf, and
just north of the of the front, forecast to drift northwestward
into Texas tonight. A trough is over the far western Gulf and
stretches from near 28N96W to 20N95W. A recent scatterometer pass
clearly indicated the wind shift associated with this trough. The
remainder of the Gulf is under the influence of a ridge, with a
1023 mb high pressure located near Tampa Bay, Florida. The ridge
is forecast to persist through Tuesday night. A weak cold front
will reach the coast of Texas Wednesday, and stall across the N
Gulf Thu before moving N as a warm front Thursday night. Looking
ahead, a stronger cold front will reach the NW Gulf on Friday.
Fresh southerly return flow is expected across the western Gulf
ahead of the front.

...CARIBBEAN SEA...

Please refer to the Special Features section for details about
the gale warning near the coast of Colombia during the next two
nights. The most recent scatterometer data indicated fresh to
strong winds over the central Caribbean, and across the Windward
Passage. Moderate to fresh winds are seen elsewhere. An altimeter
pass indicated seas of 11 ft over the SW Caribbean in association
with the strong trades. Patches of low level moisture embedded in
the trade wind flow are observed on visible satellite imagery,
more concentrated over the central Caribbean. Broad mid-level
anticyclonic wind flow and strong subsidence dominates the entire
Caribbean Sea.

...HISPANIOLA...

A broad mid to upper-level high covering the Caribbean Sea and
very dry air aloft will support mostly stable conditions across
the island. However, shallow moisture embedded in the trade wind
flow will move across Hispaniola to produce isolated to scattered
passing showers tonight and Tuesday.

...ATLANTIC OCEAN...

A deep layer trough in the central Atlantic is supporting a cold
front that extends from 31N40W to 22N62W. The front dissipates
west of 22N62W to the north of Hispaniola. Mainly low-level
clouds with isolated to scattered showers are along the frontal
boundary. Strong high pressure building west of the front will
prevail over the area through mid-week. This pattern will keep
South Florida mostly dry and warm through the weekend. E of the
front, the Azores high extends a ridge across the eastern
Atlantic.

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

$$
GR
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