AXNT20 KNHC 292343
Tropical Weather Discussion
NWS National Hurricane Center Miami FL
0005 UTC Tue Sep 29 2020
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 1800 UTC surface analysis and satellite imagery through
...GULF OF MEXICO GALE WARNING...
A strong cold front moving across the Gulf waters now extends
from the Florida Big Bend SW to 20.5N95W then SE across the
central Bay of Campeche to 18N93W. Scattered moderate isolated
strong convection is along and SE of the front to a line from near
Ft Meyers, Florida to the NE part of the Yucatan Peninsula. The
front will reach the SE Gulf waters early on Wed and the Straits
of Florida by Wed evening. In the wake of the front, strong
northerly winds are occurring west of the front and south of 21N,
and will continue through around sunrise Wed morning. Seas are
forecast to build to 18 ft over the SW Gulf by this evening and
then to 20 ft tonight. These conditions will begin to improve by
Wed morning. Please see the latest High Seas Forecast at
https://www.nhc.noaa.gov/text/MIAHSFAT2.shtml for more details.
A tropical wave over the eastern Atlantic is along 19W-20N from
01N-14N. The wave is moving west at about 10-15 kt. Scattered
showers are noted in the vicinity of this wave.
A tropical wave axis is along 47W from 01N-15N, moving W at
10-15 kt. Scattered moderate isolated strong convection is from
07N-15N between 42W-51W.
A tropical wave axis is along 63W from 10N-19N, moving W at
10-15 kt. Scattered moderate convection is behind the wave from
10N-20N between 55W-63W.
A tropical wave moving across the central Caribbean is currently
located along 74W, moving W at 10 kt. Scattered moderate isolated
strong convection is noted from 14.5N to Hispaniola between 67W
and 73W. This wave will continue moving westward across the basin
through the period accompanied by active weather and enhanced
winds. This feature is expected to become part of a broad low-
pressure area over the western Caribbean in a few days.
The monsoon trough extends from the coast of Africa near 10N14W
to 05N30W. The ITCZ extends from 05N30W to 06N39W. The ITCZ
resumes W of a tropical wave near 05N46W to 03N54W. Besides the
convection mentioned in the tropical wave section, no significant
convection is noted near these boundaries at this time.
Gulf of Mexico...
Refer to the section above for details on the Gale Warning
currently in effect for the SW Gulf.
A surface ridge from the Atlantic extends across South Florida
into the southeastern Gulf. A surface trough is noted southeast
of the cold front from the Yucatan Peninsula to SW Florida, where
most of the active convection is focused. Drier air is moving
into the far northwest Gulf of Mexico behind the cold front. The
most recent scatterometer data depict light to gentle winds over
the southeast Gulf, and gentle to moderate southerly winds ahead
of the front. Fresh to strong northerly winds follow the front,
becoming gale force south of 21N.
Looking ahead, the cold front will continue moving SE across the
basin overnight with strong to near gale force northerly winds
behind it and gale force winds in the region of Veracruz. A
secondary frontal boundary will drop southward to the northern
Gulf early on Fri and reach the far southwestern Gulf by Fri
evening. Strong high pressure will build in behind this front. The
pressure gradient between the front and broad low pressure that
is expected to form over the western Caribbean by the end of the
week is expected to freshen the northeast winds over most of the
southeastern Gulf by the end of the week. These winds may reach
strong speeds on Sat along with building seas.
A tropical wave is moving over the central Caribbean, while
another one is approaching the Lesser Antilles. Please refer to
the Tropical Waves section above for details.
Across the west Caribbean, a 1006 mb low pressure is noted over
northern Colombia with the Pacific monsoon trough extending west
across Panama and Costa Rica. Scattered moderate convection
occurring earlier along the boundary has shifted over land across
Colombia and Panama and the adjacent Caribbean waters south of
10N. To the NW, limited convection is noted. Scatterometer data
depicts light to moderate trade winds across most of the basin
except between 60W- 70W, where moderate to fresh winds prevail.
Moderate to fresh trade winds over the central Caribbean will
increase to fresh to strong speeds tonight. Moderate winds will
continue elsewhere, except for gentle winds over the northwestern
Caribbean. A tropical wave, currently located near 74W, will
continue moving westward across the basin through the period
accompanied by active weather and enhanced winds.
Refer to the section above for details on the tropical waves
moving across the tropical Atlantic.
Surface ridging prevails across the basin, anchored by a 1031 mb
high is centered over the central Atlantic near 39N44W.
Weak high pressure over the western Atlantic is maintaining
gentle to moderate winds across the area. The high pressure will
begin to retreat eastward through Wed in response to a cold front
that will reach the southeastern U.S. coast tonight and move over
the northwest part of the area through Wed. The front will weaken
through the end of the week. Scattered showers and thunderstorms
are expected ahead of the cold front.