Atlantic Tropical Weather Discussion (Text)

AXNT20 KNHC 201020

Tropical Weather Discussion
NWS National Hurricane Center Miami FL
620 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 0600 UTC surface analysis and satellite imagery through 
0915 UTC.

A tropical wave extends from 08N43W to 18N40W moving W at 10-15 
kt. The wave coincides with 700 mb troughing between 34W-45W and 
a maximum in 850 mb relative vorticity along the wave axis near 
16N. Scattered moderate convection is from 10N-23N between 28W- 
41W. This convection is being enhanced by an upper level low 
centered N of the wave axis near 23N41W.

A tropical wave extends from 10N70W to 20N72W moving W at 10-15 
kt. The wave coincides with shortwave 700 mb troughing between 
68W-74W and a weak maximum in 850 mb relative vorticity along the
wave axis near 16N. Scattered moderate convection is from 14N- 
19N between 70W-77W.

A tropical wave extends from 09N79W to 20N80W moving W at 10-15 
kt. The wave coincides with 700 mb troughing between 76W-83W and 
a weak maximum in 850 mb relative vorticity along the wave axis 
near 17N. Widely scattered moderate convection is from 09N-20N 
between 78W-84W.

The monsoon trough extends from the African coast near 08N13W to 
06N23W. The Intertropical Convergence Zone axis extends from 
06N23W to 05N30W to 08N42W to 07N58W. Widely scattered moderate 
convection is within 90 nm either side of a line from 03N08W to 
10N16W. Scattered moderate convection is from from 04N-09N 
between 21W-35W. Isolated moderate convection is from 08N-12N 
between 53W-61W.


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 over the southern Plains to a base over the NW Gulf near
27N96W. The troughing aloft supports scattered showers and tstms 
occurring within 90 nm either side of a line from 23N90W to
30N94W...including inland portions of eastern Texas and far 
western Louisiana. Farther south...additional isolated showers 
and tstms are occurring S of 22N between 91W-95W in the vicinity
of a surface trough boundary extending from 18N93W to 22N97W. 
Otherwise...much of the basin lies on the southern periphery of a 
surface ridge anchored across the SE CONUS by a 1025 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 itself 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 17N82W 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 14N-20N 
between 70W-78W...and from 09N-22N between 78W-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 today bringing 
scattered showers and 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 warm front extends from 34N60W SW into a 1011 mb low centered 
near 32N65W. A cold front continues SW to 28N72W then becomes
stationary to the central Bahamas near 25N78W. A pre-frontal
surface trough extends from the cold front near 28N71W to eastern
Cuba near 21N77W. The low and associated boundaries continue to
provide focus for scattered showers and tstms N of 30N between 
50W-65W...and scattered showers and isolated tstms from 24N-30N 
between 62W-75W generally E of the front. 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 morning. The remainder 
of the eastern Atlc is under the influence of a surface ridge 
anchored by a 1025 mb high centered near 31N33W.

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Page last modified: Friday, 20-Oct-2017 10:20:50 UTC