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Atlantic Tropical Weather Discussion

AXNT20 KNHC 221036

Tropical Weather Discussion
NWS National Hurricane Center Miami FL
535 AM EST Wed Nov 22 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 1011 mb low is centered near 27N92W and will merge Wednesday 
with a cold front currently analyzed across SE Texas bringing near
gale to gale force northerly winds generally W of a line from 
29N90W to 22N97W. The gale force wind field is expected to persist
until Thursday night then diminish into strong to near gale force
strength by the late Thursday night into early Friday. See the 
latest NWS High Seas Forecast under AWIPS/WMO headers MIAHSFAT2/ 
FZNT02 KNHC for more details.

The monsoon trough extends from the African coast near 10N14W to 
07N20W. The Intertropical Convergence Zone extends from 07N20W to
05N26W to 06N40W to 08N49W. Widely scattered moderate and 
isolated strong convection is from 01N-10N between 02W-24W. 
Widely scattered moderate convection is from 08N-14N between 26W- 
33W...and from 03N-11N between 33W-51W. A surface trough is 
analyzed at the western extent of the ITCZ from 05N51W to 11N49W.


Overall middle to upper level troughing is present over the basin
this morning with focus on two stronger mid-level shortwave 
troughs noted over the NW Gulf waters. This vigorous troughing 
aloft is supporting the special features cold front currently 
across SE well as a 1011 mb low centered near 27N92W
and the associated surface trough extending from the low to
23N96W. Scattered showers and tstms are occurring N of 22N 
between 87W-97W. Farther east...a 1012 mb low is centered near 
29N85W with the associated surface trough extending S-SW from the 
low center to 26N85W. Scattered showers and isolated tstms are 
occurring from 24N-27N between 83W-87W. This low will remain
nearly stationary and merge with the progressive front and low
impacting the western Gulf waters on Wednesday. As noted above...
strong to gale force northerly winds are forecast west of the 
front through Thursday night as the area of low pressure and front
sweep across the central and eastern Gulf waters and then moves 
NE into the SW North Atlc waters by late Friday night. Surface 
ridging is expected to build in behind the front Saturday and 
influence the basin the remainder of the weekend.

Southwesterly flow aloft prevails over the western and central
Caribbean this morning between an upper level trough over the 
Gulf of Mexico and an anticyclonic circulation anchored over the 
eastern Caribbean near 13N64W. A surface trough is analyzed across
the western Caribbean from 11N80W to 16N81W and across Cuba near
22N78W. This surface boundary is providing focus for scattered 
showers and isolated tstms between 74W-84W in the vicinity of the
trough axis. Moisture and cloudiness continues to advect 
northward over this corridor into the SW North Atlc in advance of
the approaching upper level trough currently influencing the Gulf
of Mexico this morning. Otherwise...conditions remain relatively 
tranquil within moderate to fresh trades E of the surface trough. 
This overall synoptic pattern is forecast to persist through the 

Clear skies and relatively tranquil conditions are noted across
the island this morning. Ongoing convective activity is expected 
to remain W of the island as surface troughing along 80W will be 
nearly stationary through the upcoming weekend.

Southwesterly and divergent middle to upper level flow prevails
over the SW North Atlc this morning between an upper level trough
over the Gulf of Mexico and upper level ridging anchored over the
central Atlc. The troughing to the west supports a 1012 mb low 
centered in the NE Gulf of Mexico near 29N85W with the associated 
stationary front extending east then northeast along 29N81W to
32N77W. Isolated showers are possible within 60 nm either side of
the front. This front links into a 1013 mb low centered off the
coast of the Carolinas near 34N76W with fresh to strong S-SE winds
occurring N of 24N between 58W-74W and scattered showers and 
tstms noted N of 20N between 65W-76W. The warm front links up 
with a weakening cold front within the southern periphery of a 
surface ridge across the central Atlc from 32N43W to 29N52W
becoming stationary to 29N60W to 31N69W. Isolated showers are 
occurring within 60 nm either side of the front. Farther south...a
middle to upper level low is noted on water vapor imagery near 
22N38W supporting a 1012 mb low nearly collocated with the upper 
level feature centered near 22N41W. A stationary front extends 
E-NE from the low to 24N30W and SW from the low to 18N42W to
18N53W. Isolated showers and possible isolated tstms are 
occurring near the low from 18N-25N between 35W-42W.

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