Atlantic Tropical Weather Discussion (Text)

AXNT20 KNHC 200514

Tropical Weather Discussion
NWS National Hurricane Center Miami FL
114 AM EDT Fri Oct 20 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 0000 UTC surface analysis and satellite imagery through 
0445 UTC.

A tropical wave extends from 06N41W to 17N37W moving W at 10-15 
kt. The wave coincides with 700 mb troughing between 33W-41W and 
a maximum in 850 mb relative vorticity along the wave axis near 
16N. Scattered moderate convection is from 11N-21N between 30W- 
42W. This convection is being enhanced by an upper level low
centered to the NW of the wave axis near 22N42W.

A tropical wave extends from 08N70W to 19N68W moving W at 10-15 
kt. The wave coincides with shortwave 700 mb troughing between 
63W-72W and a maximum in 850 mb relative vorticity along the wave
axis near 13N. Isolated moderate convection is from 07N-11N 
between 69W-72W.

A tropical wave extends from 10N79W to 21N77W moving W at 15-20 
kt. The wave coincides with 700 mb troughing between 74W-81W and 
a weak maximum in 850 mb relative vorticity along the wave axis 
near 16N. Widely scattered moderate convection is from 15N-21N 
between 73W-80W.

The monsoon trough extends from the African coast near 08N13W to 
06N16W to 06N22W. The Intertropical Convergence Zone axis extends
from 06N22W to 09N40W to 08N59W. Widely scattered moderate 
convection is from 04N-10N between 08W-15W. Isolated moderate
convection is from 04N-08N between 20W-34W.


Middle to upper level ridging is noted on water vapor imagery over
much of the Gulf while to the west...an upper level trough axis
extends from over New Mexico near 25N107W SE to a base over
southern Texas near 28N99W. The troughing supports a weak surface
trough analyzed across the NW Gulf waters from 23N95W to 29N97W
with scattered showers and widely scattered tstms occurring from
24N-31N between 90W-96W. Farther south...additional isolated
showers and tstms are occurring S of 22N between 87W-95W.
Otherwise...much of the basin lies on the southern periphery of a
surface ridge anchored across the SE CONUS by a 1026 mb high.
Moderate to occasional fresh NE to E winds prevail E of 90W and
gentle to moderate E to NE winds prevail in the vicinity of the
surface troughing. By Saturday...moderate to fresh E-SE flow will
re-establish across the Gulf as an area of low pressure develops
across the Central Plains.

An upper level anticyclone is centered over the western Caribbean
near 17N83W providing an overall divergent environment W of 70W.
The divergence along with two tropical waves moving across the
basin are generating scattered showers and tstms from 15N-19N
between 68W-80W...and from 10N-21N between 80W-89W...including
inland portions of Central America. Plenty of atmospheric moisture
in associated with the ridge and will likely continue to produce
relatively active convection through the weekend. Otherwise... 
fresh to strong trades prevail E of 80W as the pressure gradient 
strengthens while strong high pressure moves off the Mid-Atlc 
coast and into the western North Atlc. The trades are expected to
remain strong through Monday night.

A tropical wave will skirt across the island tonight into Friday 
bringing scattered showers and isolated tstms to southern portions
of the island and the adjacent southern coastal waters. Fresh to 
strong trades are expected through the weekend as high pressure 
builds in across the region.

A stationary front extends from 32N61W west into a 1014 mb low
centered near 32N67W. The front continues SE to the central
Bahamas near 25N76W with a pre-frontal trough extending to the
east of the front along 73W. The low and associated fronts are
providing focus for scattered showers and tstms N of 30N between
50W-68W...and scattered showers and isolated tstms from 24N-30N
between 60W-73W. This system is supported aloft by an upper level
trough extending from 34N66W to 26N74W and a reinforcing upper
level trough swinging east-southeastward off the Carolina coast
this evening. The remainder of the eastern Atlc is under the 
influence of a surface ridge anchored by a 1027 mb high centered 
near 31N33W.

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Page last modified: Friday, 20-Oct-2017 05:14:54 UTC