[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 221630
TWDAT

Tropical Weather Discussion
NWS National Hurricane Center Miami FL
1129 AM EST Fri Dec 22 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 enters the Atlantic Ocean through Sierra Leone
and continues to 05N20W. The ITCZ extends from 05N20W to 03N30W to
01N40W to 00N51W. Scattered moderate convection is from 02N-06N
between 13W- 25W.

...DISCUSSION...

GULF OF MEXICO...

A ridge extending from the SE CONUS dominates the Gulf waters
producing a gentle to moderate southerly return flow. These winds
are forecast to increase to 15-20 kt across the western Gulf later
today ahead of the next cold front that will enter the basin
tonight. The front will reach from SE Louisiana to near Tampico,
Mexico Saturday morning, and from the western Florida Panhandle
to 23N94W to the central Bay of Campeche by Saturday night. Fresh
to strong northerly winds and building seas of 8 or 9 ft are
expected in the wake of the front on Saturday, with winds diminishing
to 10-15 kt by Saturday night. Weak high pressure behind the
front will be reinforcing by stronger high pressure on Sunday,
pushing the front to a position from Tampa, Florida to 23N94W to
the central Bay of Campeche by Sunday night. At that time, expect
fresh to strong winds across the northern Gulf waters, mainly N of
27N with seas of 6-7 ft. The front is then forecast to extend
from south Florida to near 22N96W to 22N96W to 18N94W on Monday
while weakening. Patches of dense fog were noted this morning near
the northern Gulf coast from eastern Texas to the Big Bend of
Florida due to a moist onshore flow. Aloft, a ridge dominates the
Gulf region, and the State of Florida. Moderate to strong upper
level subsidence and implied dry air mass is noted within the
ridge.

CARIBBEAN SEA...

The most recent scatterometer data provided observations of fresh
to strong winds across the central Caribbean, and mainly fresh
winds in the lee of eastern Cuba, and in the Windward Passage.
Patches of low level clouds, embedded in the trade wind flow, are
noted across the basin producing isolated to scattered passing
showers. High pressure N of the region will maintain strong trade
winds over the central and southwest Caribbean, with near gale
force winds near the coast of Colombia each night through this
weekend. Fresh to strong NE winds are expected through the Windward
Passage as well.

...HISPANIOLA...

A broad mid to upper-level ridge along with deep layer dry air
continue to support mostly fair weather conditions over the
island. High pressure over the west Atlantic will support pulses
of fresh to locally strong winds across the Windward Passage
through the weekend. Low-topped trade wind showers will continue
to affect the island from time to time.

ATLANTIC OCEAN...

A cold front extends from a weak 1016 mb low pressure located
near 32N56W to 26N70W to another 1008 mb low pressure situated
near 32N78W. This front will drift south and dissipate rapidly
through early Sat. Recent scatterometer data indicate fresh to
strong winds in the wake of the front but N of 30N between 62W
and 70W. An area of showers is ahead of the front N of 27N between
54W and 58W. The easternmost low pressure is forecast to move SE
into the forecast area, and open up into a trough on Saturday.
The remainder of the western Atlantic is under the influence of a
ridge anchored by a 1026 mb high pressure located over the
Carolinas. E of the front, a 1044 mb high pressure centered NE of
the Azores extends a ridge across most of the E and central 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 between the coast of Africa and 40W.

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

$$
GR

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