[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 300500
TWDAT

Tropical Weather Discussion
NWS National Hurricane Center Miami FL
0605 UTC Thu Sep 29 2022

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 0000 UTC surface analysis and satellite imagery through
0500 UTC.

...SPECIAL FEATURES...

Hurricane Ian is centered near 30.2N 79.3W at 30/0300 UTC or 160
nm S of Charleston South Carolina moving NNE at 9 kt. Estimated
minimum central pressure is 986 mb. Maximum sustained wind speed
is 70 kt with gusts to 85 kt. Tropical storm force winds extend
up to 360 nm from the center. Peak seas over Atlantic offshore
waters east of NE Florida are 26 ft. 12 ft seas extend up to 300
nm NE of the center. Numerous moderate convection is N of 30N
between 74W and 82W. A weakening outer rainband covers the
offshore waters between 74W and 77W, including the central
Bahamas. On the forecast track, Ian will approach the coast of
northeastern South Carolina mid-day Friday. The center will move
farther inland across the Carolinas Friday night and Saturday. Ian
is expected to maintain intensity before landfall tomorrow, when
it will rapidly weaken over the southeastern United States late
Friday into Saturday. Please read the latest NHC Public Advisory
at https://www.nhc.noaa.gov/text/MIATCPAT4.shtml and Forecast/
Advisory at https://www.nhc.noaa.gov/text/MIATCMAT4.shtml for more
details.

...TROPICAL WAVES...

An eastern Atlantic tropical wave extends along 17W, from 02N to
17N, moving W at 15 kt. Scattered moderate convection is observed
from 05N to 15N, between the coast of Africa and 20W.

A central Atlantic tropical wave extends along 33W, from 07N to
20N, moving W at 10 kt. There is no significant convection
associated with this wave.

...MONSOON TROUGH/ITCZ...

The monsoon trough extends from the coast of Mauritania near
17N16W to 07N34W and from 11N40W to 09N47W. The ITCZ continues
from 09N47W to 11N58W. Convection is isolated and weak along these
boundaries.

GULF OF MEXICO...

The gradient between high pressure over northern Mexico and
Hurricane Ian east of northern Florida is supporting moderate to
fresh northerly flow across the basin. Seas are 6-8 ft on an
abating trend.

For the forecast, the pressure gradient between high pressure
over the Gulf waters and Hurricane Ian located E of Florida
supports an area of fresh northerly winds over the eastern Gulf,
mainly E of 85W, with seas in the 8 to 9 ft range. Fresh NW to N
winds and seas of 8-9 ft are also noted over the SW Gulf,
including the Veracruz area. Winds and seas are forecast to
gradually diminish over the Gulf region overnight. Looking ahead,
a cold front may enter the NE Gulf late Sat or Sun then stall and
dissipate across the area early next week.

CARIBBEAN SEA...

An upper-level trough over the eastern Caribbean is supporting
scattered moderate convection from 11N to 18N, between the Lesser
Antilles and 63W. Similar convection is noted south of
Hispaniola. Otherwise, Hurricane Ian to the north is actually
improving conditions by interrupting the usual pressure gradient.
Winds are gentle to moderate across the basin with slight seas.
The only exception is in the extreme NW basin, where 4-8 ft
northerly swell is propagating through the Yucatan Channel from
the Gulf of Mexico.

For the forecast, large N swell produced from Ian will continue
to spread through the Yucatan Channel through tonight. A surface
trough is forecast to persist over the NW Caribbean through at
least Sun. Moderate to fresh N winds are expected W of the trough
through Fri night. Elsewhere gentle to moderate winds and slight
to moderate seas will persist across the basin.

ATLANTIC OCEAN...

For details on Tropical Storm Ian, centered just offshore
Jacksonville, FL, please read the Special Features section above.
Winds of 20 kt or greater associated with the circulation of Ian
currently extend over the waters to the west of 72W and north of
26N. Seas of 8 ft or greater associated with Ian extend over the
waters west of 72W and north of 27N.

In the central Atlantic, winds are mainly gentle to moderate from
the east with 4 to 6 ft seas. The only exception is a small area
of decreasing fresh winds and abating 6-8 ft seas in the vicinity
of Post-Tropical Depression Eleven near 20N37W. In the eastern
Atlantic, a tighter pressure gradient is supporting moderate to
fresh NE winds with 6-8 ft seas.

For the forecast west of 55W, Hurricane Ian near 30.2N 79.3W 986
mb at 11 PM EDT moving NNE at 9 kt. Maximum sustained winds 70 kt
gusts 85 kt. Ian will move to 31.7N 79.1W Fri morning, move
inland and weaken to a tropical storm near 34.0N 79.6W Fri
evening, weaken as an extratropical cyclone near 36.0N 80.4W Sat
morning, 37.5N 81.0W Sat evening, and dissipate Sun morning.

$$
Flynn
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