[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 021040
TWDAT

Tropical Weather Discussion
NWS National Hurricane Center Miami FL
1205 UTC Sat Sep 2 2023

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 31N. The following information is based on satellite
imagery, weather observations, radar and meteorological analysis.

Based on 0600 UTC surface analysis and satellite imagery through
1000 UTC.

...SPECIAL FEATURES...

Gale Warning/Tropical Storm Warning: Post-Tropical Cyclone Idalia
is centered near 31.7N 64.6W at 02/0900 UTC or 40 nm SSE of
Bermuda, moving E at 5 kt. Estimated minimum central pressure is
999 mb. Maximum sustained wind speed is 50 kt with gusts to 60 kt.
Numerous moderate to strong convection is noted north of the low
from 32N to 35N between 60W and 65W. The 12 ft seas extend as far
south as 26N between 61W and 73W. Moderate swell from Idalia is
reaching Florida and the Bahamas. A gale warning is in effect for
the Atlc offshore waters N of 29N between 62W and 68W. The post-
tropical cyclone will move east today. A faster northeastward
motion is forecast to begin on Sunday, and this motion should
continue into Monday. On the forecast track, Idalia will remain
near Bermuda today, and then begin to move away from the island
tonight and Sunday. Little change in strength is forecast during
the next few days. Idalia could transition to a subtropical storm
later today. Swells generated by Idalia will affect the
southeastern U.S. coast and Bermuda during the next couple of
days. These swells are likely to cause life-threatening surf and
rip current conditions. Please consult products from your local
weather office.

Tropical Storm Gert is centered near 27.7N 54.3W at 02/0900 UTC
or 610 nm ESE of Bermuda, moving NE at 2 kt. Estimated minimum
central pressure is 1003 mb. Maximum sustained wind speed is 40
kt with gusts to 50 kt. Numerous moderate to strong convection is
noted south of the low center from 24N to 27N between 52W and 58W.
Seas are peaking at 12 ft and extend 75 nm E of the center. Gert has
moved little during the past several hours. A northward motion is
expected to commence today and continue into Sunday. Little
change in strength is forecast before Gert becomes absorbed by
larger Post-tropical Idalia on Monday. Strong winds and moderate
seas from Gert will move away from the Atlc offshore waters by
tonight as Gert moves farther away.

Newly upgraded Tropical Storm Katia is centered near 22.7N 29.4W
at 02/0900 UTC or 500 nm NW of the Cabo Verde Islands, moving NNW
at 11 kt. Estimated minimum central pressure is 1005 mb. Maximum
sustained wind speed is 35 kt with gusts to 45 kt. Numerous
moderate to scattered strong convection is noted from 22N to 27N
between 26W and 31W. Katia is expected to turn to the northwest
today and this general motion with a decrease in forward speed is
expected through Monday. Weakening is expected to begin by early
Sunday, and the system could degenerate into a remnant low by
Sunday evening. Moderate to rough seas from Katia may impact the
eastern Atlantic high seas Sun night into Mon.

See hurricanes.gov for public advisories on the active systems
and for the latest NHC Tropical Weather Outlook. See
https://www.nhc.noaa.gov/text/MIAHSFAT2.shtml for the latest
High Seas Forecast.

...TROPICAL WAVES...

A strong tropical wave is along 18W from 18N southward, moving W
at 10 to 15 kt. Numerous moderate to scattered strong convection
is noted from 04N to 17N between 17W and 25W.  Environmental
conditions appear conducive for some gradual development of this
system by the middle part of next week, and a tropical depression
is likely to form while it moves westward to west-northwestward at
15 to 20 kt over the eastern and central portions of the tropical
Atlantic. There is a low chance of tropical cyclone formation
within the next 48 hours and high chance within the next 7 days.

A central Caribbean Sea tropical wave is along 73W from 20N
southward, moving W at 10 kt. Scattered moderate convection is
noted near the northern tip of the wave across Haiti and eastern
Jamaica.

...MONSOON TROUGH/ITCZ...

The monsoon trough reaches the Atlantic through the coast of
Guinea near 10N14W to 14N23W, and then from 14N35W to 08N45W. See
the Tropical Waves section for information on convection along the
monsoon trough.

...GULF OF MEXICO...

A surface trough extends across the Gulf from 30N86W to 22N96W.
Scattered moderate to strong convection is noted from the north-
central Gulf to the southern Bay of Campeche from 18N to 29N
between 89W and 90W. Isolated thunderstorms are also noted along
the Florida Panhandle. Winds are moderate or weaker across the
Gulf. Seas are 4 ft or less across the basin.

For the forecast, a weak surface trough with moderate winds over
the central Gulf will drift westward through Sun as high pressure
continues to build over the Gulf waters. Winds and seas could be
higher near thunderstorms associated with the trough. Moderate to
locally fresh winds will pulse at night off the NW Yucatan
Peninsula through Tue night. Otherwise, gentle to moderate winds
and slight seas will persist through Wed across the basin.

...CARIBBEAN SEA...

Please read the TROPICAL WAVES section above for details on the
convection affecting parts of the Caribbean Sea. Numerous strong
convection is noted in the southwest Caribbean along the Eastern
Pacific Monsoon Trough, S of 12N between 75W and 84W. Meanwhile,
thunderstorms persist in the Cuba offshore waters and west of
Jamaica. Scattered thunderstorms are also noted in the Gulf of
Honduras.

Fresh easterly trade winds cover the central Caribbean, except
for strong within 120 nm of the coasts of NW Venezuela and NE
Colombia. Seas in these waters are 6-9 ft. Mainly moderate
easterly breezes and seas of 3-5 ft are evident in the eastern
Caribbean and most of the NW Caribbean.

For the forecast, fresh to strong trades in the central Caribbean
will diminish today with the relaxing pressure gradient. Gentle
to moderate winds with slight to moderate seas will prevail
through the weekend. Fresh winds will return in the central and
eastern Caribbean by early next week and continue through Wed.

...ATLANTIC OCEAN...

Please read the SPECIAL FEATURES section for details about Post-
Tropical Cyclone Idalia, Tropical Storm Gert and Tropical
Storm Katia.

A cold front extends from 30N63W to 24N73W to 28N81W, near the NE
Florida coast. A pre-frontal trough is noted across the Bahamas
from 23N72W to 24N79W. Scattered moderate to isolated strong
convection is within 75 nm S of the trough. Moderate to strong
NE winds are north of the front with gale force winds N of 29N.

Meanwhile, in the central and eastern Atlantic, high pressure
extends across the region. A trough extends from 30N38W to 20N47W.
Scattered thunderstorms are noted along the trough from 24N to 29N
between 38W and 42W. Gentle to moderate winds prevail outside of
the systems described above with slight to moderate seas.

For the forecast W of 55W, Post-Tropical Cyclone Idalia will move
to 31.5N 63.9W this afternoon, 32.1N 62.2W Sun morning, become
extratropical and move to 33.6N 60.2W Sun afternoon, and 35.7N
58.6W Mon morning. Gale force winds and rough to very rough seas
associated with Idalia will impact the north waters through the
weekend. Conditions will improve by Mon night. Meanwhile, Tropical
Storm Gert will move to 28.0N 53.8W this afternoon, 29.2N 53.1W
Sun morning, 30.8N 52.3W Sun afternoon, become post-tropical and
move to 33.4N 51.7W Mon morning, and dissipate Mon afternoon. Gert
will slowly move away from the eastern offshore waters today.
Strong winds and moderate seas will begin to dissipate later today
and improve by tonight.

$$
AReinhart
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