Tropical Weather Discussion
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AXNT20 KNHC 121148

Tropical Weather Discussion
NWS National Hurricane Center Miami FL
648 AM EST Fri Jan 12 2018

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
1145 UTC.


A cold front extends along 90W over the Gulf of Mexico. A strong
pressure gradient has developed between the front and a strong
ridge building across the central United States, supporting
strong to gale-force northwesterly winds over the northwestern
Gulf waters behind the front. These winds will spread to the
southwest Gulf through this evening. See the latest NHC High Seas
Forecast under AWIPS/WMO headers MIAHSFAT2/FZNT02 KNHC for more


The monsoon trough extends from the coast of Africa near 06N10W
to 02N22W to 02N33W. The ITCZ continues from 02N33W to 01N50W.
Scattered moderate showers are from 03S to 04N E of 05W, from 04S
to 06N between 23W and 32W, and from 02N to 06N between 38W and



Moderate to locally fresh return flow is over the eastern half of
the Gulf ahead of a cold front that extends across the central
Gulf waters. Gale-force NW winds are behind the cold front over
the NW basin waters as indicated by the latest scatterometer pass.
Strong to gale-force winds will spread to the SW Gulf waters
through this evening. A reinforcing cold front will move across
the north-central and NE basin during the evening hours and
across Florida Sat. Strong northerly winds in the wake of the
front will start to diminish Sat. See the Special Features
section for further details on the front and the gale winds.


Deep layer dry air over the NW Caribbean support fair weather.
Southwesterly flow aloft continue to advect moisture from the EPAC
and northern South America into the central Caribbean, thus
supporting cloudiness with possible isolated showers for Puerto
Rico and Hispaniola as well as adjacent southern waters. Shallow
moisture in the tradewind flow support isolated showers in the
Lesser Antilles. Latest scatterometer data show moderate to fresh
winds in the eastern half of the basin and light to gentle ESE
flow in the western half of it. A cold front will enter the NW
Caribbean waters Friday night with fresh to strong winds. The
front will then stall from eastern Cuba SW to NE Nicaragua
adjacent waters Sat evening. A strong pressure gradient developing
over northern Central America will support near gale-force winds
behind the front continuing through Sunday.


Southwesterly flow aloft supports cloudiness and possible isolated
showers across the island and southern adjacent waters. In the
northern waters, upper level diffluence in the SW N Atlc waters
support scattered showers NE of the Dominican Republic. This
activity is forecast to continue through early Sat morning.


Diffluent flow generated by a short-wave trough over the Bahamas
and a ridge to the east of it continue to support scattered heavy
showers NE of the central Bahamas from 23N to 28N between 71W and
75W. These showers extends to NE Dominican Republic adjacent
waters. Farther east, a broad middle to upper level trough support
a cold front that enters the north-central Atlc waters near 30N36W
continuing SW to 25N48W. Scattered to isolated showers are within
120 nm either side of the boundary. Otherwise, surface ridging
dominates the remaining Atlc waters N of 10N. The next cold front
will come off Florida tonight, will extend from near 30N72W across
the central Bahamas to north-central Cuba Sat night and then
stall. A reinforcing cold front will follow the leading front and
move across Florida Sat then merge with the leading front Sat
night over the SW N Atlc waters.

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