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Atlantic Tropical Weather Discussion

AXNT20 KNHC 202344

Tropical Weather Discussion
NWS National Hurricane Center Miami FL
744 PM EDT THU OCT 20 2016

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.


An elongated area of low pressure is located near 25.5N/73.0W. Although
visible satellite imagery and surface observations suggest that the
low-level circulation has become a little better defined since
yesterday, preliminary reports from a NOAA reconnaissance aircraft
indicate that the system does not have a well-defined center.
Isolated showers prevail near the low center while scattered
moderate convection is observed from 15N-30N between 61W-75W
supported by a diffluent flow aloft. Scatterometer data depicts
near gale winds prevailing within 150 nm in the northwest
quadrant. The system could still become a subtropical or tropical
cyclone before it merges with a cold front over the western
Atlantic, well offshore of the United States east coast by Friday
night. The chance of formation into a tropical cyclone remains in
the medium category.

Gale force winds are expected to develop in the southwest Gulf of
Mexico Friday night associated with a cold front that will enter
the northwest waters by early Friday morning. Northwest to north gale
force winds are forecast for the area S of 22N and west of the
front with seas to 12 ft. Please see the High Seas Forecast under
AWIPS/WMO headers MIAHSFAT2/FZNT02 KNHC for more details.


An Atlantic tropical wave extends its axis from 16N43W to 06N43W,
moving westward 10 to 15 knots. The wave coincides with a 700 mb
trough depicted by model guidance and abundant moisture is in the
wave's environment as noted in TPW imagery. Scattered moderate
convection prevails from 07N-13N between 39W-48W.


The Monsoon Trough passes through the coast of Africa reaching the
eastern Atlantic near 14N17W to 08N27W to 10N40W. Aside of the
convection related to the tropical wave, isolated showers prevail
within 100 nm on either side of the boundary between 34W-39W. 



A diffluent flow aloft prevails across the northwest Gulf
supporting scattered moderate convection mainly north of 24N and west
of 94W. At the surface, a trough extends from 27N96W to 29N95W.
Another trough extends across the Bay of Campeche from 25N97W to
18N94W. No significant convection is observed with this feature at
this time. Fair weather prevails across the remainder of the basin
with light to gentle easterly winds as noted in scatterometer
data. Expect during the next 24 hours for a cold front to enter
the northwestern portion of the basin enhancing convection/winds.
Gale force winds are expected over the Bay of Campeche behind the
cold front.


A 1008 mb surface low is centered over the southwest Caribbean
near 15N83W. A surface trough extends from the low to 18N77W.
Scattered moderate convection is observed near the low center from
14N-17N and west of 80W. To the east; a diffluent flow aloft
related to the Special Features low described above, is enhancing
convection across the northeastern waters affecting Hispaniola,
the Mona Passage, and adjacent waters north of 15N between 67W-
75W. Scatterometer data depicts light to gentle easterly winds
across the western half of the basin while moderate to fresh
southeasterly winds prevail east of 75W. Expect during the next 24
hours for the low in the southwest Caribbean to dissipate. The
convection over Hispaniola will weaken and drift northward as the
surface low in the Atlantic moves northeast.


Please refer to the Special Features section for more information
about an Atlantic Ocean's surface low pressure related to the
convection currently affecting the island. This activity will
weaken and drift northward during the next 24 hours as the surface
low in the Atlantic moves northeast.


The 1004 mb surface low located in the west Atlantic is described
in the Special Features section above. A tropical wave is moving
across the eastern Atlantic waters. Please refer to the section
above for details. A surface trough extends across the central
Atlantic ahead of a cold front from 27N47W to 29N39W. No
significant convection is related to this trough at this time. 

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