Tropical Weather Discussion
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AXNT20 KNHC 240004

Tropical Weather Discussion
NWS National Hurricane Center Miami FL
704 PM EST Mon Jan 23 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
2315 UTC.


...GALE WARNING Gulf of Mexico...

Strong low pressure moving across the Mid-Atlantic states is
resulting in NW winds of 25-35 KT over the Gulf N of 24.5N and E
of 86W. These strong winds have resulted in seas of 12 to 20 FT
across this portion of the Gulf. Winds are forecast to decrease
below gale force tonight.

...GALE WARNING Southwest North Atlantic...

Strong low pressure over the Mid-Atlantic states is dragging a
cold front through 32N73W to Andros Island to 22N79.5W. SW winds
of 30-40 KT and seas of 10-16 FT were occurring within 150 NM
east of the front and N of 23N. Winds shifted to the NW at 25-35
KT west of the front with seas to 13 FT. Gale force winds are
forecast to remain associated with the front through 48 hours.

Please refer to the latest High Seas Forecast under AWIPS/WMO
headers MIAHSFAT2/FZNT02 KNHC for more details.


The Monsoon Trough passes through Liberia near 06N10W to 05N15W.
The ITCZ continues from 05N15W through 02N25W and 04N32W, to the
equator along 40W. Scattered moderate convection was noted from
02N to 06N between 26W and 42W. Scattered to numerous strong
convection was noted over interior sections of NE Brazil.



The axis of a sharp deep layered trough has moved E of the Gulf
of Mexico to along 75W. Broad deep layered W to NW flow with
very strong subsidence was occurring in the wake of the trough.
An upstream ridge axis was over the upper Texas coast along 95W.
Strong to gale force W to NW winds were occurring over the Gulf
E of 90W while winds W of 90W were decreasing to 10-15 KT. Refer
to the special features section above for additional details on
the Gale over the Gulf. Clear skies prevailed over the Gulf which
became scattered to locally broken in stronger winds E of 90W.
High pressure builds eastward over the Gulf on Tue with winds
decreasing over all areas and southerly return flow develops W of


Upper level westerly winds prevailed over the entire Caribbean
Sea with strong subsidence noted throughout the basin. At the
surface a cold front extended from 21N78W to the far eastern tip
of Honduras and Nicaragua. Scattered showers were noted within
45-60 NM east of the front N of 20N. Moderate to fresh, locally
strong NW winds were occurring behind the front in the NW
Caribbean. The presence of the front and the absence of High
pressure to the north of the area resulted in sub-normal E to SE
trades over the basin E of the cold front.


Mid-to-upper level W to NW flow characterized by strong subsidence
was noted over Hispaniola. Freshening southerly surface winds were
noted in the area with patches of scattered low clouds embedded in
the flow. The 12Z rawindsonde from Santo Domingo showed a strong
capping inversion at 772 MB and low level 20-25 KT winds from the
SSW. As the cold front approaches the island on Tue, expect an
increase in showers and thunderstorms.


The overall flow over the Atlantic was amplified with a series of
troughs and ridges. A sharp negatively-tilted upper trough
extended from a deep cyclone over the Carolinas SSE through
32N76W to a base over the central Bahamas. Strong upper level
difluence was noted E of the trough axis over the Atlantic N of
25N between 65W and 73W. This trough supported a cold front which
extended from 32N74W SSW across Andros Island to the N coast of
Cuba near 22N79W. Scattered moderate to strong convection was
noted within 90-120 NM east of the front and N of 25N. Gale force
winds were occurring in the area of strong convection and also
N of 25N and west of the front. Refer to the special features
section above for additional details.

Further east, a surface ridge extends from a 1029 mb high
pressure centered 33N22W, through 25N35W to 17N55W. This ridge was
bridging through a surface trough which extended from 32N40W
through 24N50W to 22N60W. Weak high pressure was located NW of
the surface trough near 26N55W.

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