351
AXNT20 KNHC 251803
TWDAT

Tropical Weather Discussion
NWS National Hurricane Center Miami FL
1805 UTC Wed Sep 25 2024

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 1200 UTC surface analysis and satellite imagery through
1755 UTC.

...SPECIAL FEATURES...

Recently-upgraded Hurricane Helene is centered near 22.0N 86.4W
at 25/1800 UTC or 100 nm NNE of Cozumel Mexico, moving NNW at 9
kt. Estimated minimum central pressure is 980 mb. Maximum
sustained wind speed is 70 kt with gusts to 85 kt. Peak seas are
currently near 29 ft. Seas of 12 ft or greater are occurring
within 180 nm in the E semicircle and 90 nm in the W semicircle.
Numerous strong convection is observed within 100 nm of the
center, while scattered moderate to isolated strong is occurring
within 400 nm to the north and east and 200 nm to the west and
south of the center. Strengthening is forecast, and Helene is
expected to be a major hurricane when it reaches the Florida Big
Bend coast Thursday evening. Weakening is expected after landfall,
but Helene`s fast forward speed will allow strong, damaging
winds, especially in gusts, to penetrate well inland across the
southeastern United States, including over the higher terrain of
the southern Appalachians. A turn toward the north and north-
northeast with an increase in forward speed is expected later
today through Thursday, bringing the center of Helene across the
eastern Gulf of Mexico and to the Florida Big Bend coast by
Thursday evening. After landfall, Helene is expected to slow down
and turn toward the northwest over the southeastern United States
Friday and Saturday. Helene is expected to produce total rain
accumulations of 4 to 8 inches over western Cuba, the Cayman
Islands, and the northeast Yucatan Peninsula, with isolated totals
around 12 inches. This rainfall brings a risk of considerable
flooding. A 24-hour rainfall total of 8.60 inches (218.4 mm) was
recently reported in Embalse Herradura, Pinar del Rio, Cuba, by
the Meteorological Service of Cuba. Over the Southeastern U.S.
into the Southern Appalachians, Helene is expected to produce
total rain accumulations of 5 to 10 inches with isolated totals
around 15 inches. This rainfall will likely result in areas of
considerable flash and urban flooding, with areas of significant
river flooding. Landslides are possible in areas of steep terrain
in the southern Appalachians. Swells generated by Helene will
affect the southern coast of Cuba and the Yucatan Peninsula of
Mexico during the next couple of days. Swells will spread
northward toward the west coast of Florida and the northeastern
Gulf Coast later today and Thursday. These swells are likely to
cause life-threatening surf and rip current conditions. Please
consult products from your local weather office.

Please read the latest HIGH SEAS FORECAST issued by the National
Hurricane Center at website -
https://www.nhc.noaa.gov/text/MIAHSFAT2.shtml and the latest
Helene NHC Forecast Advisory and Public Advisory at
www.hurricanes.gov for more details.

Invest 98L: A broad 1009 mb low pressure is near 13N32W and a
tropical wave is analyzed along the low pres and south of 20N,
moving westward at 10-15 kt. Scattered showers and isolated
thunderstorms are evident from 12N to 19N and between 29W and 39W.
A recent scatterometer satellite data show fresh to locally
strong easterly winds north of the low pressure. Seas in these
waters are 5-8 ft. Environmental conditions appear
favorable for gradual development of this system, and a tropical
depression is likely to form in a few days while it moves westward
to west-northwestward across the eastern and central tropical
Atlantic. There is a medium chance of tropical formation in the
next 48 hours and a high chance of formation in the next seven
days.

Please read the latest Tropical Weather Outlook issued by the National
Hurricane Center at hurricanes.gov

...TROPICAL WAVES...

A central Atlantic tropical wave is along 56W, south of 20N,
moving westward at 10 kt. Scattered moderate convection is
observed from 12N to 20N and between 52W and 65W.

...MONSOON TROUGH/ITCZ...

The monsoon trough reaches the Atlantic through the coast of
Senegal near 15N17W and continues westward to a 1009 mb low pres
(AL98) near 13N32W and then to 11N45W. Scattered showers are noted
from 07N to 15N and east of 23W.

...GULF OF MEXICO...

Please refer to the Special Features section above for details on
Tropical Storm Helene located in the Yucatan Channel.

Aside from Helene, a generally dry airmass dominates the western
half of the Gulf of Mexico, except for a couple of showers west of
95W and south of 25N. Moderate or weaker winds and slight to
moderate seas are found in these waters.

For the forecast, Hurricane Helene is near 21.6N 86.3W at 11 AM EDT,
and is moving north-northwest at 9 kt. Maximum sustained winds
are 70 kt with gusts to 85 kt, and the minimum central pressure is
979 mb. Helene will move to 23.0N 86.4W this evening, 25.7N 85.7W
Thu morning, 29.7N 84.6W Thu evening, move inland and weaken to a
tropical storm near 34.3N 85.0W Fri morning, and weaken to a
tropical depression near 36.6N 86.9W Fri evening. Marine conditions
will gradually improve across the Gulf waters beginning on Fri or
Fri night.

...CARIBBEAN SEA...

Please refer to the Special Features section above for details on
Tropical Storm Helene located in the Yucatan Channel.

Outside of the influence of Helene, moderate to fresh SE trade winds
and moderate seas are occurring in the central Caribbean.
Moderate or weaker winds and slight to moderate seas are found in
the eastern and SW Caribbean.

For the forecast, Hurricane Helene is near 21.6N 86.3W at 11 AM EDT,
and is moving north-northwest at 9 kt. Maximum sustained winds
are 70 kt with gusts to 85 kt, and the minimum central pressure is
979 mb. Helene will move N of area into the Gulf of Mexico near
23.0N 86.4W this evening. Marine conditions will gradually
improve across the NW Caribbean by late Thu or Thu night.

...ATLANTIC OCEAN...

Please refer to the Special Features section above for details on
Tropical Storm Helene located in the Yucatan Channel and Invest
98L in the central Atlantic.

A couple of surface troughs in the north-central Atlantic result
in scattered showers north of 24N and between 47W and 59W. The
remainder of the Atlantic is under the influence of a broad 1022
mb high pressure system centered south of the Azores. The pressure
gradient between this ridge and lower pressures in the deep
tropics support fresh to locally strong NE winds from 19N to 28N
and east of 27W. Seas in these waters are 4-7 ft. Moderate to
locally fresh southerly winds are present south of 10N and east of
40W, along with seas of 4-7 ft. Elsewhere, moderate or weaker
winds and moderate seas are prevalent.

For the forecast W of 55W, Hurricane Helene is near 21.6N 86.3W at
11 AM EDT, and is moving north-northwest at 9 kt. Maximum
sustained winds are 70 kt with gusts to 85 kt, and the minimum
central pressure is 979 mb. Helene will move to 23.0N 86.4W this
evening, 25.7N 85.7W Thu morning, 29.7N 84.6W Thu evening, move
inland and weaken to a tropical storm near 34.3N 85.0W Fri
morning, and weaken to a tropical depression near 36.6N 86.9W Fri
evening. As Helene move across the eastern Gulf of Mexico, expect
increasing winds and building across the waters just E of the
Florida Peninsula.

$$
Delgado