Tropical Weather Discussion
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AXNT20 KNHC 121721

Tropical Weather Discussion
NWS National Hurricane Center Miami FL
1221 PM 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
1715 UTC.


A cold front extends across the Gulf of Mexico from 30N87W to
24N90W to 18N94W. A strong pressure gradient has developed
between the front and a surface ridge that extends from the
north-central CONUS to eastern Mexico. These conditions support
strong to gale-force northwesterly winds over the western Gulf
waters behind the front. These winds will prevail through this
afternoon. See the latest NHC High Seas Forecast under AWIPS/WMO
headers MIAHSFAT2/FZNT02 KNHC for more details.


The monsoon trough extends from the coast of Africa near 06N10W
to 01N33W. The ITCZ continues from 01N33W to 00N50W. Scattered
showers are noted along these boundaries between 30W-51W.



Moderate to locally fresh return flow prevails over the eastern
half of the Gulf ahead of a cold front that extends across the
central Gulf waters. Gale-force northwesterly winds are behind
the cold front over the western Gulf. These conditions will
continue through this afternoon. Please refer to the section
above for more details about the Gale Warning. To the east of the
front, a surface trough extends from 30N86W to 22N88W with
scattered showers. Expect for a reinforcing front to move across
the northern portion of the basin tonight and across Florida on
Saturday. Strong northerly winds in the wake of the front will
diminish by then.


Deep-layer dry air over the west Caribbean supports fair weather
west of 80W. To the east, southwesterly flow aloft continues to
advect moisture from the EPAC and northern South America into the
central Caribbean supporting cloudiness with scattered showers
affecting Jamaica, Hispaniola and Puerto Rico. Shallow moisture
in the tradewind flow supports isolated showers over the Lesser
Antilles. Latest scatterometer data shows moderate to fresh winds
in the eastern half of the basin while light to gentle easterly
flow prevails over the western half. A cold front will enter the
northwest Caribbean waters tonight with fresh to strong winds.
The front will then stall from eastern Cuba to northeast
Nicaragua adjacent waters by Saturday evening. A strong pressure
gradient will develop over northern Central America supporting
near gale-force winds behind the front continuing through the


Southwesterly flow aloft supports cloudiness and scattered showers
across the island and southern adjacent waters. This activity is
forecast to continue through the next 24 hours.


Diffluent flow generated by a short-wave trough over the Bahamas
and a ridge to the east of it continues to support scattered
showers from 22N-28N between 70W-75W. Farther east, a broad
middle to upper level trough support a stationary front that
enters the north-central Atlantic waters near 30N27W to 24N49W.
Scattered showers are within 120 nm on either side of the
boundary. Elsewhere, surface ridging dominates the remaining of
the area anchored by a 1040 mb high centered near 38N53W. The
next cold front is expected to move offshore tonight, reaching the
west Atlantic waters with convection and fresh to strong winds.
A reinforcing cold front will follow the leading front and move
across Florida early this weekend then merge with the leading
front over the west Atlantic waters.

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