Tropical Weather Discussion
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AXNT20 KNHC 112304

Tropical Weather Discussion
NWS National Hurricane Center Miami FL
604 PM EST Sat Nov 11 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
2115 UTC.

The monsoon trough extends from the African coast near 12N16W to
10N20W. The Intertropical Convergence Zone axis extends from
10N20W to 08N40W to 06N53W. Scattered moderate convection is from
05N-12N between 23W-32W. Isolated moderate convection is within
120 nm either side of a line from 08N51W to 15N34W.


Water vapor imagery indicates an upper level trough axis extends
from over the SW North Atlc and central Florida peninsula into the
central Gulf near 26N90W then southward to a base over southern
Mexico near 17N93W. The troughing over the Gulf remains relatively
tranquil...however supports a cold front across the SW North Atlc
waters to the Florida peninsula near 27N80W then northwestward to
the Florida panhandle near 30N84W. This backdoor cold front will
bring stronger...fresh to strong...E-NE winds to the eastern Gulf
overnight into Sunday. By Sunday night...the front is expected to
weaken somewhat with moderate to fresh NE winds prevailing Monday
and Tuesday. Otherwise...a surface trough with widely scattered
showers is analyzed along the Mexico coast from 19N95W to 25N97W.
The shallow shower activity remains generally W of 95W this

Generally broad lower pressure is noted across much of the
Caribbean this evening focused on a 1007 mb low centered off the
coast of Nicaragua near 13N82W in the western waters. A surface
trough extends N-NE from the low to 18N81W. Water vapor imagery
indicates the surface low and troughing is supported aloft by mid-
level energy stretching from the Windward Passage region SW to the
waters SW of Jamaica near 16N80W. In addition...a favorable
divergent environment remains over the western and central
Caribbean...including the Windward Passage and Hispaniola. As a
result...scattered showers and widely scattered tstms are
occurring primarily N of 14N between 66W-88W...however a few
isolated showers and tstms are occurring S of 13N between 79W-
84W. This synoptic pattern will be slow to modify through Monday
as the upper level troughing over the Gulf of Mexico and SW North
Atlc will be slow to weaken into early next week. Otherwise...
moderate to occasional fresh trades E of 75W will persist.

Scattered showers and isolated tstms continue across the island
this evening as the region remains in a favorable middle to upper
level divergent environment within generally west-southwesterly
flow aloft. Upper level troughing is expected to persist to the NW
over the SE Gulf of Mexico and SW North Atlc through Sunday night
with persistent convection expected across the island...adjacent
coastal waters...and much of the north-central Caribbean Sea.
Potential hazards of localized flooding and life-threatening mud
slides are possible...especially if stronger convection develops
during peak daytime heating and instability Sunday and Monday.

A cold front extends across the SW North Atlc from 32N64W near
Bermuda SW to 28N72W then to the Florida coast near 27N80W. A
pre-frontal surface trough is analyzed to the E of the front from
28N67W to 31N64W. While only a few isolated showers are possible
in association with the cold front...low-level moisture
convergence in the vicinity of the surface trough and a favorable
divergent environment aloft are generating scattered showers and
isolated tstms from 19N-28N between 59W-75W...and from 28N-33N
between 56W-67W. To the east...another surface trough extends
from 20N34W to 28N30W supported aloft by a broad middle to upper
level low centered near 30N35W. Widely scattered showers and
isolated tstms are noted from 24N-33N between 26W-37W. The surface
trough remains within the southern periphery of a surface ridge
anchored by a 1034 mb high centered NE of the Azores near 42N21W.

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