AXNT20 KNHC 122348
Tropical Weather Discussion
NWS National Hurricane Center Miami FL
747 PM EDT Thu Sep 12 2019
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
Potential Tropical Cyclone Nine is centered near 23.7N 74.8W at
12/2100 UTC or 200 nm SE of Great Abaco Island moving NW at 7
kt. Estimated minimum central pressure is 1008 mb. Maximum
sustained wind speed is 25 kt with gusts to 35 kt. Scattered
moderate to isolated strong convection is from 22N-27N between
68W-76W. The system is expected to produce total rain
accumulations of 2 to 4 inches through Sunday over the Bahamas
and along the east coast of Florida north of West Palm Beach.
Isolated maximum amounts of 7 inches are possible in the northwest
and central Bahamas. An Air Force Reserve reconnaissance aircraft
is presently over the system. Environmental conditions are
favorable for a tropical depression or tropical storm to form
within the next day or two. The chance of tropical cyclone
formation during the next 48 hours is high. See latest NHC
forecast/advisory under AWIPS/WMO headers MIATCPAT4/WTNT34 KNHC
for more details.
An Atlantic Ocean tropical wave is along 31W, from 19N southward,
moving west at 10-15 knots. Scattered moderate convection is W of
the axis from 13N-16N between 31W-35W. In addition, scattered
moderate convection is near the monsoon trough from 05N-10N
between 30W-35W. Conditions appear conducive for development, and
a tropical depression could form early next week while the system
moves westward over the tropical Atlantic.
An Atlantic Ocean tropical wave is along 42W, from 18N southward,
moving W at 10-15 knots. Scattered showers are within 180 nm of
the wave axis.
An Atlantic Ocean tropical wave is along 56W, from 19N southward,
moving W at 10 knots. Scattered moderate convection is from 14N-
16N between 55W-57W.
A Caribbean Sea tropical wave is along 78W,
from 19N southward, moving W at 15 knots. Numerous moderate to
strong convection is noted mainly along the monsoon trough S of
10N between the coast of Colombia and Costa Rica.
A western Caribbean Sea tropical wave is along 89W, from 17N
southward, moving W at 10 knots. Scattered moderate convection is
within 180 nm of the wave axis.
The monsoon trough extends from Senegal near 14N17W to 09N30 to
08N44W to 15N54W to 14N58W. Besides the convection mentioned in
the tropical wave section, scattered moderate to isolated strong
convection is along the coast of W Africa from 10N-17N between
12W-18W. Scattered moderate to isolated strong convection is also
along the monsoon trough from 06N-10N between 36W-42W.
GULF OF MEXICO...
A surface trough is over the Bay of Campeche from 24N98W to
18N94W. Scattered moderate convection is within 90 nm of the
trough axis. Scattered moderate to isolated strong convection is
inland over the Yucatan Peninsula. Widely scattered moderate
convection is over the SE Gulf and S Florida from 24N-27N between
80W-83W. The remainder of the Gulf of Mexico has 10-15 kt
easterly winds. Of note in the upper levels, a small upper level
low is centered over S Mexico near 20N100W. Upper level diffluence
is over the SW Gulf enhancing convection. Another upper level low
is centered over the NE Gulf near 27N87W. Upper level diffluence
is over the SE Gulf enhancing convection.
High pressure over the southeastern United States will support
moderate to fresh northeast to east winds into the weekend.
Recently developed Potential Tropical Cyclone Nine currently over
the southeastern Bahamas will track northwestward toward the
Florida peninsula through the end of the week. The gradient
between the cyclone and the high pressure will allow for east
winds to increase over the far NE winds Gulf Fri night into Sat
along with building seas. Scattered showers and thunderstorms may
spread westward from the Florida peninsula to the eastern Gulf
from Fri through Sun.
Two tropical waves are over the Caribbean. See above.
The tail end of a surface trough extends from the SE Bahamas to
E Cuba near 20N78W. Widely scattered moderate convection is over
E Cuba. Scattered moderate convection is elsewhere over the NW
Caribbean and W Cuba from 18N-22N between 82W-87W.
High pressure north of the area will maintain moderate trades,
that will at times pulse to fresh to strong in the south central
Caribbean. A tropical wave will cross from the central Caribbean
into the western Caribbean Fri morning, then exit into Central
America Sun. Another tropical wave will enter the tropical N
Atlantic and eastern Caribbean Fri night. A third and stronger
tropical wave will approach the tropical N Atlantic and eastern
Caribbean over the weekend into early next week, expected to bring
widespread showers and thunderstorms, gusty winds and building
See the Special Features, and Tropical Waves, sections above.
A 1021 mb high is centered off the coast of N Carolina near
35N73W. A surface trough is over the central Atlantic from 32N49W
to 24N54W. Scattered moderate convection is from 26N-33N between
46W-51W. Widely scattered moderate convection is also from 19N-
23N between 56W-60W.
Newly developed Potential Tropical Cyclone Nine near 23.7N 74.8W
1008 mb at 5 PM EDT is moving NW at 7 kt. Maximum sustained winds
25 kt gusts 35 kt. Potential Tropical Cyclone Nine will move to
near 24.5N 76.0W Fri morning, to near 25.5N 77.2W Fri afternoon
with maximum sustained winds 30 kt gusts to 40 kt, then intensify
to a tropical cyclone near 26.5N 78.9W late Fri night with maximum
sustained winds 40 kt gusts to 50 kt. Potential Tropical Cyclone
Nine is forecast to reach near 27.5N 80.2W Sat afternoon and move
inland to near 30.0N 82.0W on Sun afternoon and weaken. It is
forecast to move back over water near 31.5N 80.0W by Tue
afternoon. A strong tropical wave may approach the waters S of 22N
early next week.