Tropical Weather Discussion
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AXNT20 KNHC 091803

Tropical Weather Discussion
NWS National Hurricane Center Miami FL
103 PM EST Sat Dec 9 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
1745 UTC.


A cold front extends across the Florida Straits from 25N80W SW to
23N82W then across western Cuba into the Gulf of Honduras near
16N86W. Strong high pressure continues to build-in west of the
front maintaining a strong pressure gradient and resulting in near
gale to gale force NW to N winds generally S of 24N W of the
front to 91W. These winds in the Gulf of Mexico are forecast to
diminish below gale-force this afternoon. Near gale NW winds with
frequent gusts are occurring in the NW Caribbean west of the
front along with 10 ft seas. The front is forecast to extend from
eastern Cuba to the SW Caribbean waters on Sunday morning, leading
to gale force winds in the offshore waters of Nicaragua and
Honduras. See the latest NWS High Seas Forecast under AWIPS/WMO
headers MIAHSFAT2/FZNT02 KNHC for more details.


The monsoon trough extends from the African coast near 07N13W to
05N19W. The Intertropical Convergence Zone axis extends from
05N19W to 03N36W to 02N51W. Scattered moderate convection is from
01N to 06N between the prime meridian and 18W.



The main feature across the basin is the Special Features cold
front extending across the Florida Straits. Aside from the near
gale to gale force winds, scattered showers are occurring ahead of
the front, including the South Florida peninsula. Isolated showers
are in the Yucatan channel. The cold front is forecast to move off
the SE basin later this afternoon and winds are expected to
diminish below gale-force. However, strong to near gale NW winds
will continue across the E and SW Gulf...gradually diminishing
from the NW to SE through early Sunday. Thereafter, gentle to
moderate N winds will prevail as high pressure builds in across
the western waters early next week.


Divergent middle to upper level flow is noted over the western
Caribbean between the upper level trough over the Gulf of Mexico
and an upper level anticyclone centered over northern Colombia.
The tail of a strong cold front extends across western Cuba to
22N82W to 20N85W to the Gulf of Honduras near 16N86W and lies
underneath this environment aloft, which is supporting scattered
showers and tstms N of 18N ahead of the front to 76W. In the SW
basin, an elongated area of low pressure anchored by a 1010 mb low
near 11N78W support similar convection S of 17N W of 75W. Near
gale force to frequent gusts winds are occurring W of the front.
The front will continue to move SE and is forecast to extend from
eastern Cuba to the SW Caribbean by Sunday morning. Gale force
winds will be on Nicaragua and Honduras adjacent waters. Heavy
showers with potential for flooding and mudslides are forecast
for Costa Rica and Panama. The front is forecast to stall across
the western Caribbean Sunday night through Tuesday and gradually
weaken by mid-week. The trades will weaken gradually across the
eastern Caribbean by Sunday as a ridge N of the area weakens and
retreats northward.


Fair weather conditions prevail across the island as a surface
high centered in the central Atlc extends ridging across the area.
Scattered showers are forecast for the Windward Passage Sunday to
early next week associated with a cold front moving across Cuba
and the W Caribbean.


Southwesterly flow aloft is noted on water vapor imagery over the
SW North Atlc between a middle to upper level trough over the
eastern CONUS and Gulf of Mexico and an upper level ridge anchored
over the central Caribbean Sea. The trough supports the Special
Features cold front which extends from a 1005 mb low centered off
the coast of the Carolinas near 33N76W to 30N78W to South Florida
near 25N80W. Scattered showers and tstms are occurring generally
within 210 nm E of the front as the entire system moves rapidly
off to the NE. Otherwise, the remainder of the SW North Atlc
waters is under the influence of a surface ridge anchored by a
1027 mb high centered near 32N53W. In the central basin, a cut-
off middle to upper level low supports a 1015 mb low centered
near 25N38W and associated trough extending from the low to
24N35W to 18N43W. Scattered showers and tstms are occurring E of
the low center from 20N to 29N between 28W and 34W. The low is
forecast to gradually weaken through tonight and then drift
westward as a surface trough across the central Atlc through

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