National Hurricane Center - Tropical Weather Discussion (Atlantic)
AXNT20 KNHC 250555
Tropical Weather Discussion
NWS National Hurricane Center Miami FL
205 AM EDT Tue Sep 25 2018
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
Subtropical Depression Leslie was centered near 33.1N 47.1W at
0300 UTC, or about 1020 nm W of the Azores, moving E at 3 kt.
Estimated minimum central pressure is 1007 mb. Maximum sustained
winds are 30 kt with gusts to 40 kt. Widely scattered moderate
convection is E-SE of the center from 29N-35N between 43W-48W.
Leslie is expected to become a powerful post-tropical cyclone
beginning later today, after it merges with a cold front over
the central Atlantic. See the latest NHC forecast/advisory under
AWIPS/WMO headers MIATCMAT3/WTNT23 KNHC for more details.
A broad 1012 mb low is centered NE of the Bahamas near 30N74W. A
surface trough extends S from the low to 26N75W. Scattered
moderate isolated strong convection is NE of the center from 30N-
35N between 71W-76W. Environmental conditions may become more
conducive for development during the next day or so while the
system moves west-northwestward to northwestward. By Tuesday
night and Wednesday, upper-level winds are expected to increase,
limiting the chances for additional development. There is a
medium chance of tropical cyclone formation within 48 hours.
The remnants of Kirk are analyzed as a tropical wave along 43W
from 03N to 16N, moving W at 20 kt. Scattered moderate to strong
convection is associated with the wave. Winds to gale force are
in the northern portion of the wave. This system could redevelop
into a tropical cyclone during the next two days before it
encounters unfavorable upper-level winds east of the the
Caribbean Sea. For more information on this system, see High
Seas Forecasts issued by the National Weather Service.
A tropical wave is along the coast of W Africa along 19W from
03N-16N, moving west at 15 kt. A 700 mb trough associated with
this wave is well depicted in model guidance, and there is
evidence of cyclonic curvature in the winds near the surface.
Deep convection is limited due to the presence of Saharan air.
A tropical wave is along 55W from 03N-17N, moving west at 15 kt.
The wave corresponds with a moisture maximum in TPW imagery.
Model analyses also depicts an associated 700 mb trough.
Scattered showers are located from 09N-12N between 53W-57W.
The monsoon trough extends from the African coast near 11N15W to
06N23W. The ITCZ continues from 06N23W to 07N35W to 11N42W, then
resumes west of the remnants of Kirk near 08N45W to the coast of
South America near 05N54W. Scattered moderate convection is from
03N to 07N between 27W-34W.
GULF OF MEXICO...
A stationary front over the NW Gulf has dissipated. A thermal
trough is near the west coast of the Yucatan peninsula, with
scattered showers within 60 nm of the trough axis. This trough
will drift westward across the Bay of Campeche this morning.
Gentle to moderate E to SE winds and seas 3 ft or less will
prevail across most of the basin through the middle of the week.
A surface trough moving into the eastern Caribbean extends from
18N61W to 12N62W. Scattered moderate convection is within 90 nm
east of the trough axis. The eastern Pacific monsoon trough
combined with diffluence aloft continues to enhance scattered
moderate showers in the SW Caribbean south of 13N west of 78W.
Elsewhere, scattered showers are over the NW Caribbean W of 80W.
Expect moderate to fresh winds to prevail over the central
Caribbean through Friday.
Currently, there are three tropical waves, and a subtropical
depression in the Atlantic. See the sections above for details.
A weakening frontal trough is over the central Atlantic from
30N43W to 24N50W. Scattered moderate isolated strong convection
is north of 26N within 90 nm east of the front.
Elsewhere, visible satellite imagery shows a large area of
Saharan dust over the tropical Atlantic from 10N-25N between 30W-
60W, moving W, and encompasses the remnants of Kirk.
The remainder of the basin is under the influence of a surface
ridge, anchored by high pressure centered well north of the area.
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