[Tropical] Tropical Weather Discussion

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AXNT20 KNHC 301202
TWDAT

Tropical Weather Discussion...UPDATED
NWS National Hurricane Center Miami FL
1205 UTC Fri Sep 30 2022

Updated with the 1200 UTC Intermediate Advisory for Hurricane Ian
AND to add the East Atlantic Gale Warning Special Feature

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
0945 UTC.

...SPECIAL FEATURES...

Hurricane Ian is centered near 31.4N 79.1W at 30/1200 UTC or 91
nm SSE of Charleston South Carolina moving N at 8 kt. Estimated
minimum central pressure is 984 mb. Maximum sustained wind speed
is 75 kt with gusts to 90 kt. 12 ft seas or higher extend over the
forecast waters up to 180SE and 120SW quadrants. Numerous
moderate to strong convection prevails N of 30N between 75W-81W. A
feeding band has developed with scattered moderate convection
extending along 76W and N of 22N. On the forecast track,
the center of Ian will approach and reach the coast of South
Carolina today, and then move farther inland across eastern South
Carolina and central North Carolina tonight and Saturday. Swells generated
by Ian and a nearby frontal system are affecting the east coast
of Florida, Georgia, the Carolinas, and the northwestern Bahamas.
These swells are likely to cause life-threatening surf and rip
current conditions. Please consult products from your local
weather office. Swells will subside along the northern coast of
Cuba and the northeastern coast of the Yucatan peninsula today.

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.

East Atlantic Gale Warning: Meteo-France has issued a Gale Warning
for the Agadir and Tarfaya Zones in the East Atlantic. North winds
of 34-40 kt (Force 8) with gusts are expected through 01/0300 UTC.
Seas are 8-9 ft in N swell. For more information, please see the
latest High Seas Forecast issued by Meteo-France at
http://weather.gmdss.org/II.html

...TROPICAL WAVES...

An eastern Atlantic tropical wave extends along 19W, from 02N to
17N, moving W at 10 to 15 kt. Scattered moderate convection is
observed from 05N to 11N, between the coast of Africa and 25W.

A central Atlantic tropical wave extends along 35W, 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
18N16W to 08N35W, then resumes near 10N41W to 09N47W. The ITCZ
continues from 09N47W to 09N59W. 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 area of moderate to fresh northerly winds
over the NE Gulf, mainly N of 28N and E of 88W, with seas reaching
8 ft will dissipate today. Fresh NW to N winds and seas of 8 ft
are prevail over the SW Gulf, including the Veracruz area. Winds
and seas are forecast to gradually diminish over the Gulf region
this morning. Looking ahead, a cold front may enter the NE Gulf
this weekend, then stall and dissipate across the area early next
week.

CARIBBEAN SEA...

An upper-level trough over the east-central Caribbean is supporting
scattered moderate convection from 11N to 20N between 64W-75W.
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 this morning.
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 tonight. Elsewhere, gentle to
moderate winds and slight to moderate seas will persist across the
basin.

ATLANTIC OCEAN...

For details on Hurricane Ian and the tropical waves across the
basin, please refer to the sections 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 31.4N 79.1W 984
mb at 8 AM EDT, moving N at 8 kt. Maximum sustained winds 75 kt
gusts 90 kt. Ian will move to 32.5N 79.3W this afternoon, move
inland and weaken to a tropical storm near 34.6N 79.9W Sat
morning, weaken as an extratropical cyclone near 36.3N 80.3W Sat
afternoon, and dissipate Sun morning.

$$
ERA/Mahoney
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