[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 251739
TWDAT

Tropical Weather Discussion
NWS National Hurricane Center Miami FL
1239 PM EST Mon Dec 25 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.

...ITCZ/MONSOON TROUGH...

The monsoon trough extends from Liberia, Africa and continues to
05N11W. The ITCZ axis extends from 05N11W to 05N23W to NE Brazil
at 01N51W. Scattered moderate convection is from 04N-06N between
18W-26W, and from 01N-05N between 30W-40W.

...DISCUSSION...

GULF OF MEXICO...

As of 1500 UTC, a cold front extends from south Florida to 25N90W
to 23N95W where it becomes stationary to the western Bay of
Campeche near Veracruz, Mexico. A well defined band of mainly low
clouds with enmbedded showers is associated with the front across
the Gulf region. Broken low clouds are pooled against the Sierra
Madre Mountains as seen on visible satellite imagery from recently
upgraded GOES-E. Lines of low clouds in a northerly flow are
moving across the Isthmus of Tehuantepec. Fresh to strong NE-E
winds and seas of 5-7 ft are behind the front across the northern
Gulf waters while mainly fresh northerly winds are noted west of
the front over the SW Gulf. The cold front will reach south Florida
this afternoon producing a wind shift, and little change in
temperatures. The western half of the front will lift N as a warm
front across the W Gulf beginning tonight, and stall across the
far NW and N-Central waters on Thu. A low may form along the
frontal boundary over the western Gulf on Wednesday.

CARIBBEAN SEA...

The most recent scatterometer data show strong to near gale force
winds are across the south-central Caribbean near the coast of
Colombia, and fresh to strong winds across the remainder of the
central Caribbean. Moderate to locally fresh trades are noted
elsewhere across the basin. Patches of low level moisture embedded
in the trade wind flow are producing isolated to scattered
passing showers across the Greater and Lesser Antilles from time
to time. This cloudiness is more concentrated over the NW Caribbean
between the Cayman Islands and the Gulf of Honduras. Little
change in this weather pattern is forecast over the next two or
three days. Strong trades will persist over the Central and SW
Caribbean through Thu, with near gale force nocturnal winds near
the coast of Colombia. Locally strong NE winds are expected
through the Windward Passage on Tue evening. Large E swell will
build seas to 9 ft E of the Lesser Antilles along 55W tonight and
reach the E Atlc passages on Tue evening through Thu evening.

...HISPANIOLA...

Low-topped trade wind showers will continue to move across the
island. Mostly dry and stable conditions are expected to persist
over the next couple of days under the influence of a mid-upper
level ridge and associated strong subsidence.

ATLANTIC OCEAN...

As of 1500 UTC, a cold front enters the forecast area near 31N74W
and extends SW across south Florida into the Gulf of Mexico.
Mainly low clouds with embedded showers are related to the
frontal boundary. Latest scatterometer data indicate fresh to
strong SW winds within about 75 nm ahead of the front N of 29N,
and mainly fresh NW winds in the wake of the front, forecast to
stall from 29N65W to the Straits of Florida tonight into early
Tue, then gradually weaken through Thursday. An area of showers
and tstms is observed E of the Leeward Islands covering roughly
the waters from 16N-22N between 50W-61W. This convective activity
is at the western end of an elongated upper-level trough extending
mainly E to W across the E and central Atlantic Ocean. The remainder
of the forecast area is under the influence of a ridge anchored
by a 1033 mb high located near the Azores. This system will
undergo occasional intensity fluctuations, resulting in a rather
tight pressure gradient across the waters N of the ITCZ/Monsoon
Trough between the coast of Africa and the Lesser Antilles through
at least Wednesday. Recent ASCAT passes provide observations of
moderate to fresh winds around the southern periphery of the ridge
E of the Lesser Antilles. Seas are in the 8-10 ft range within
this area of winds based on altimeter passes.

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

$$
GR
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