Tropical Weather Discussion
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AXNT20 KNHC 171027

Tropical Weather Discussion
NWS National Hurricane Center Miami FL
627 AM EDT Tue Oct 17 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 0600 UTC surface analysis and satellite imagery through
0945 UTC.

A cold front extends from the Florida Big Bend region SW to 26N90W
to 23N95W to 18N94W. Strong high pressure continues to build in
across the NW Gulf waters and eastern Mexico generating a strong
pressure gradient. This pressure gradient is inducing near gale
to gale force N to NW winds S of 21N W of 95W. A recent ASCAT
pass around 17/0302 UTC indicated this wind field. The front is
expected to gradually weaken through Wednesday night with winds
decreasing below gale force by Tuesday night. See latest NWS High
Seas Forecast under AWIPS/WMO headers MIAHSFAT2/FZNT02 KNHC for
more details.

A tropical wave extends from 06N54W to 14N52W moving W at 10-15
kt. The wave coincides with shortwave 700 mb troughing between
51W-56W and a maximum in 850 mb relative vorticity along the wave
axis near 10N. Isolated moderate convection is from 08N-12N
between 51W-57W.

A tropical wave extends from 07N62W to 15N60W moving W at 10-15
kt. The wave coincides with shortwave 700 mb troughing between
59W-63W and a maximum in 850 mb relative vorticity along the wave
axis near 13N. Widely scattered moderate convection is from 12N-
16N between 58W-63W.

A tropical wave extends from 04N78W to 16N78W moving W at 10-15
kt. The wave coincides with broad 700 mb troughing between 71W-
81W. Dry northerly flow aloft is noted on water vapor imagery on
the eastern periphery of an upper level ridge anchored near
16N79W. Scattered moderate and isolated strong convection is from
06N-12N between 74W-83W.

The monsoon trough extends from the African coast near 09N13W to
08N24W. The Intertropical Convergence Zone axis extends from
08N24W to 06N45W to 06N53W. Scattered moderate convection is from
07N-13N between 19W-28W...and from 04N-11N between 31W-50W.


As mentioned above...a cold front extends from the Florida Big
Bend region SW to 26N90W to 23N95W to 18N94W. The front is
supported aloft by an upper level trough progressing E-SE over the
lower Mississippi River valley and portions of the NW Gulf this
morning. Most convection...scattered showers and isolated
tstms...are occurring across eastern portions of the basin E of
90W and S of 23N W of 91W. The front is expected to drift SE
through the next couple of days and gradually become diffuse by
Wednesday night. Fresh to strong N-NE winds will prevail through
early Wednesday and then weaken slightly into moderate to
occasional fresh through early Thursday. Surface ridging is
expected to remain in place across the SE CONUS the remainder of
the week.

An upper level anticyclone is centered over the western Caribbean
near 16N79W and is providing mostly dry air aloft between 69W-
83W. Widely scattered showers and isolated tstms are occurring N
of 14N across inland portions of Central America and the Yucatan
peninsula as well as coastal area off the coast of Honduras and
Belize. Otherwise...the tropical wave along 78W continues to move
W and along with the close proximity to the monsoon trough
axis...generating scattered showers and strong tstms S of 12N
between 74W-83W. Farther east...upper level troughing dips
southward from the SW North Atlc over portions of the NE Caribbean
with the base of the trough noted near 17N68W. Upper level
divergence along with low-level moisture convergence in the
vicinity of a tropical wave along 61W are generating scattered
showers and tstms from 12N-16N between 60W-63W. Elsewhere
moderate to fresh trades prevail and are expected to persist
through early Wednesday.

An upper level trough axis extends from east of the Bahamas near
24N73W to a base near 17N68W. Divergence aloft is expected to
interact with local sea breeze dynamics during the afternoon and
evening hours today to initiate isolated showers and tstms across
the island. Looking ahead...a tropical wave will move across
Hispaniola by Wednesday and bring additional potential for showers
and tstms.

The special features cold front extends across far NW portions of
the SW North Atlc from 32N76W to 30N81W. Scattered showers and
isolated tstms are occurring within 120 nm either side of the
front. Farther upper level trough axis extends along
71W and supports a surface trough from 26N72W to 32N70W.
Scattered showers and tstms are focused to the E of the boundary
occurring N of 21N between 64W-71W. The remainder of the central
and eastern Atlc are under the influence of a surface ridge
anchored by a 1030 mb high centered near 34N38W.

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