Tropical Weather Discussion
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AXNT20 KNHC 092344

Tropical Weather Discussion
NWS National Hurricane Center Miami FL
644 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 1800 UTC surface analysis and satellite imagery through
2330 UTC.


A cold front extends across the Florida Straits from 25N80W across
western Cuba into the Gulf of Honduras near 16N85W. Strong high
pressure continues to build west of the front maintaining a
strong pressure gradient and resulting in near gale northerly
winds over the Yucatan Channel. These winds are forecast to
diminish this evening. The front is forecast to extend from
eastern Cuba to the southwest 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
06N20W. The Intertropical Convergence Zone extends from 06N20W to
00N50W. No significant convection is observed with these
boundaries at this time.



The cold front described in the Special Features section is
exiting the basin this evening, extending across the Florida
Straits. Scattered moderate convection prevails along and within
210 nm east of the front. Surface ridging prevails across the
Gulf waters anchored by a 1035 mb high centered over northeastern
Mexico. Strong to near-gale northerly winds will continue across
the Gulf, gradually diminishing through early Sunday. Thereafter,
gentle to moderate north winds will prevail as high pressure
builds in across the western waters early next week.


Divergent mid 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 end of a strong cold front extends across western Cuba to
22N82W to the Gulf of Honduras near 16N85W and lies underneath
this environment aloft, which is supporting scattered moderate
convection along and within 210 nm east of the front. A pre
frontal trough extends from 17N81W to 10N81W with scattered
moderate convection. To the east, an elongated area of low
pressure anchored by a 1010 mb low near 11N78W supports scattered
showers south of 14N between 76W-80W. Fair weather prevails
elsewhere. Near-gale force to frequent gusts winds are occurring
west of the front over the Yucatan Channel. The front will
continue to move east 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


Fair weather conditions prevail across the island as a surface
high centered in the central Atlantic extends across the area.
Scattered showers are forecast for the Windward Passage on 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
west Atlantic between a mid 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 1002 mb low
centered off the coast of the Carolinas near 35N74W to 30N78W to
near 25N80W. Scattered moderate convection is occurring generally
within 210 nm east of the front. The remainder of the west
Atlantic is under the influence of a surface ridge anchored by a
1026 mb high centered near 34N52W. In the central basin, a cut-
off mid to upper-level low supports a 1015 mb low centered near
25N39W and associated trough extending from the low to 18N45W.
Scattered moderate convection is occurring east of the low center
from 20N-30N between 30W-38W. This low is forecast dissipate
during the next 24 hours. Surface ridging also dominates the far
eastern Atlantic, anchored by a 1032 mb high centered near

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