[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 230517
TWDAT

Tropical Weather Discussion
NWS National Hurricane Center Miami FL
0605 UTC Fri Sep 23 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 Fiona is centered near 31.9N 68.1W at 23/0300 UTC or
170 nm W of Bermuda moving NNE at 18 kt. Estimated minimum central
pressure is 932 mb. Maximum sustained wind speed is 115 kt with
gusts to 140 kt. Numerous strong convection is within 120 nm of
the center in the E semicircle and 60 nm W semicircle. Scattered
to numerous moderate with isolated strong convection is occurring
elsewhere within 360 nm NE quadrant, 240 nm SE quadrant and 180 nm
W semicircle. Seas of 12 ft or higher are occurring within 240 nm
NE quadrant, 330 nm SE quadrant and 300 nm W semicircle. On the
forecast track, the center of Fiona will pass just to the west of
Bermuda early this morning. Fiona's center will then approach
Nova Scotia late today. Swells generated by Fiona are affecting
the Turks and Caicos Islands, the Bahamas, the southeastern United
States coast, and Bermuda. These swells will continue to spread
northwestward across the western Atlantic toward the mid-Atlantic
and northeast coasts of the United States and Atlantic Canada
today. These swells are likely to cause life-threatening surf and
rip current conditions. Please read the latest High Seas Forecast
issued by the Ocean Prediction Center at website
https://ocean.weather.gov/shtml/NFDHSFAT1.php and the latest NHC
Forecast/Advisory and Public Advisory at www.hurricanes.gov for
more details.

Tropical Storm Gaston is centered near 41.0N 31.0W at 23/0300 UTC
or 180 nm NW of Faial Island in the central Azores, moving E at 10
kt. Estimated minimum central pressure is 999 mb. Maximum
sustained wind speed is 55 kt with gusts to 65 kt. Scattered to
numerous moderate convection is noted within 210 nm of the center
in the NE quadrant, 150 nm SE quadrant and 120 nm NW quadrant. On
the forecast track, the center of Gaston will move near or over
portions of the Azores today through early Saturday. Swells
generated by Gaston are expected to affect portions of the Azores
through Saturday. These swells are likely to cause life-
threatening surf and rip current conditions. Please read the
latest High Seas Forecast issued by the Ocean Prediction Center at
website https://ocean.weather.gov/shtml/NFDHSFAT1.php and the
latest NHC Forecast/Advisory and Public Advisory at
www.hurricanes.gov for more details.

Caribbean Low Pressure Along Tropical Wave: A Caribbean tropical
wave extends its axis along 67W from SW Puerto Rico southward to
southwestern Venezuela, moving W at 10 kt. A 1006 mb low pressure
is analyzed along the wave near 13N67W. Numerous moderate to
strong convection is noted along and within 240 nm W of the wave
axis from 11N-14N between 68W-72W. Locally heavy rainfall and gusty
winds are likely to affect northwestern Venezuela, the ABC island
chain, and northeastern Colombia through today. Interests in
Jamaica and the Cayman Islands should closely monitor the progress
of this system. The low pressure is expected to become a tropical
depression during the next day or two while moving WNW at 10-15
kt across the central Caribbean Sea, and the chance of tropical
cyclone formation is high within the next 48 hours. Expect
increasing winds, seas and squalls for the central Caribbean
through the weekend, and the NW Caribbean Sun night into early
next week.

East Atlantic Low Pressure Along Tropical Wave: An eastern
Atlantic tropical wave extends its axis along 19/20W, moving W at
10 kt. A 1007 mb low pressure is analyzed along the wave axis near
15N19.5W. Scattered moderate and isolated strong convection is
noted with this system from 12N-21N between 16W-22W. A tropical
depression could form by this weekend while the system moves
northward at about 10 kt, parallel to the coast of west Africa.
This system has a medium chance of tropical cyclone formation
within the next 48 hours.

...TROPICAL WAVES...

Please read the Special Features section above for information
about the tropical waves.

...MONSOON TROUGH/ITCZ...

The monsoon trough passes off the west coast of Africa near the
border of Senegal and Mauritania near 16N16.5W to 1007 mb low
pressure near 15N19.5W to 1010 mb low pressure near 10N34W to
09N39W. The ITCZ continues from 09N39W to 07N48W to 08N59W. Aside
from the convection related to the tropical wave described in the
section above, scattered moderate isolated strong convection is
noted in the vicinity of the 1010 mb surface low, from 07N-13N
between 30W-37W. Similar convection is observed from 06N-09N
between 24W-30W. Farther west, scattered moderate convection is
seen north of the ITCZ from 09N-16N between 49W-60W.

GULF OF MEXICO...

A 1013 mb surface high pressure is centered just offshore of SE
Louisiana near 29N89W. This is part of a broad surface ridge that
extends across the northern Gulf of Mexico. Scattered clouds
containing isolated showers are present over the southwestern
portion of the basin. The weather is benign elsewhere. Gentle to
moderate winds prevail across the basin, moderate NE to E over
the west-central Gulf, where seas are 2-4 ft. Seas of 1-3 ft
prevail elsewhere.

For the forecast, a relatively weak pressure gradient across the
Gulf waters will support mainly gentle to locally moderate winds
and slight seas through the weekend. A weak cold front will reach
the NE waters later this morning, then slide east of the area and
dissipate Sat. On Mon, winds and seas could begin to increase
across the Yucatan Channel as a possible tropical cyclone
approaches from the NW Caribbean.

CARIBBEAN SEA...

Please read the Special Features section above for more details
about the eastern Caribbean low pressure along the tropical wave
with a high chance of tropical cyclone formation within the next
48 hours.

The east Pacific monsoon trough is inducing scattered moderate
isolated strong convection mainly inland from the coast over NE
Nicaragua, Honduras and Belize. A recent ASCAT satellite wind data
pass shows that light to gentle winds prevail across the western
and central Caribbean, west of 72W. Seas in this area are 1-2 ft.
Fresh to near-gale force winds and seas of 5-10 ft prevail over
the eastern Caribbean in association with the low pressure along
the tropical wave.

ATLANTIC OCEAN...

Surface ridging prevails across most of the basin, north of 20N
and east of 60W, anchored by a 1024 mb high pressure near 33N38W.
The area of 20 kt or higher winds associated with the circulation
of Major Hurricane Fiona is currently confined to the area north
of 25N between 61W-74W. The area of seas 8 ft or larger covers the
area north of 22N between 60W-80W. Peak seas near the center of
Fiona are near 50 ft in the vicinity of 31N68W. Mostly moderate
winds and 4-6 ft seas prevail across the central Atlantic between
40W-60W. Over the E Atlantic, winds are fresh with 5-7 ft seas. A
line of thunderstorms about 30 nm wide extends from 25N67W to
27.5N65W. Isolated tstorms are also noted from the Straits of
Florida to the NW Bahamas.

For the forecast west of 55W, Major Hurricane Fiona will move to
near 41N62W by this evening. All of the 34-kt and higher winds
are forecast to be north of 31N by late this morning. Seas in
excess of 12 ft will continue to affect waters north of 27N
between 55W-68W this afternoon and tonight before subsiding to
8-11 ft on Sat. A cold front will drop south over the north
waters early today through Sat night, followed by fresh northeast
winds. The front will keep seas in the 8-11 ft range through
tonight or early Sat north of 27N and west of 74W, despite Fiona's
departure. High pressure will build in behind the cold front.

$$
Hagen
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