001
AXNT20 KNHC 261803
TWDAT

Tropical Weather Discussion
NWS National Hurricane Center Miami FL
1805 UTC Thu Sep 26 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...

Hurricane Helene is centered near 26.4N 85.0W at 26/1800 UTC or
170 nm SW of Tampa Florida, moving NNE at 14 kt. Estimated minimum
central pressure is 959 mb. Maximum sustained wind speed is 95 kt
with gusts to 115 kt. Seas 12 ft or greater extend up to 240 nm
from the center with peak seas near 35 ft. Numerous moderate to
scattered strong convection is ongoing within about 180 NM of the
center. Additional strengthening is forecast, and Helene is
expected to be a major hurricane when it reaches the Florida Big
Bend coast this 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 significant increase in forward speed
is expected during the next 24 hours. On the forecast track,
Helene will make landfall in the Florida Big Bend region this
evening. After landfall, Helene is expected to turn northwestward
and slow down over the Tennessee Valley on Friday and Saturday.
Hurricane Helene is expected to produce total rain accumulations
of 4 to 8 inches over western Cuba. This rainfall brings a risk of
considerable flooding. Over portions of the Southeastern U.S.
into the Southern Appalachians, Helene is expected to produce
total rain accumulations of 6 to 12 inches, with isolated totals
around 20 inches. This rainfall will likely result in catastrophic
and potentially life- threatening flash and urban flooding, along
with significant river flooding. Numerous significant landslides
are expected in steep terrain across the southern Appalachians.
Swells generated by Helene will affect much of Florida and the
coasts of Georgia and the Carolinas during the next couple of
days. Swells will also continue across portions of Cuba and the
Yucatan Peninsula through tonight. 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 in the Central Atlantic: A 1008 mb low pressure is
near 15N38W and a tropical wave is analyzed along the low pres
and south of 20N, moving westward at 10-15 kt. Scattered moderate
to isolated strong convection is observed from 13N to 19N and
between 35W and 45W. Fresh to strong easterly winds are found
north of the center. The system continues to show signs of
organization. Recent satellite imagery suggests the system does
not yet have a well- defined surface circulation. However,
environmental conditions are expected to be conducive for further
development. A tropical depression is expected to form later today
or tomorrow while the disturbance moves generally westward to
west-northwestward at 10-15 kt. The system is then forecast to
slow down and turn northward late Friday and Saturday. There is a
high chance of tropical cyclone formation in the next 48 hours.

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

...TROPICAL WAVES...

An eastern Atlantic tropical wave is along 20W, south of 20N, moving
westward at 10-15 kt. Scattered moderate to isolated strong
convection is observed from 07N to 18N and east of 27W. A recent
scatterometer satellite pass captured fresh to locally strong
easterly winds north from 15N to 25N and east of 30W. The
strongest winds are associated with the strong thunderstorms. Seas
in these waters are 4-7 ft.

A tropical wave is approaching the Lesser Antilles along 60W,
south of 20N, moving westward at 15 kt. Scattered moderate
convection is present from 11N to 21N and between 57W and 67W,
also impacting the Lesser Antilles and eastern Greater Antilles.

...MONSOON TROUGH/ITCZ...

The monsoon trough reaches the Atlantic through the coast of
Senegal near 15N17W and continues westward to the 1008 mb low
pressure (AL98) near 15N38W and then to 13N44W. Convection near
the monsoon trough is primarily associated with the tropical waves
depicted in the sections above.

A segment of the East Pacific monsoon trough is analyzed over the
far southwest Caribbean, and is aiding in the development of
scattered moderate convection south of 14N, offshore Panama and
Colombia.

...GULF OF MEXICO...

Please refer to the Special Features section above for details on
Hurricane Helene in the eastern Gulf.

Aside from Helene, which dominates the entire eastern half of the
basin, a stationary front extends from Pensacola, Florida to
Brownsville, Texas. The cyclonic circulation of the hurricane is
transporting a dry continental airmass over much of the western
Gulf, especially west of 88W, allowing for generally tranquil
conditions. The pressure gradient supports moderate to fresh
northerly winds and moderate to rough seas north of 25N and west
of 90W, and moderate or weaker winds and moderate seas south of
25N.

For the forecast, Hurricane Helene is near 25.5N 85.5W at 11 AM EDT,
and is moving north-northeast at 12 kt. Maximum sustained winds
are 90 kt with gusts to 110 kt, and the minimum central pressure
is 960 mb. Helene will move to 28.8N 84.3W this evening, move
inland and weaken to a tropical storm near 33.9N 84.5W Fri
morning, weaken as an extratropical cyclone near 36.4N 86.6W Fri
evening, 36.5N 87.5W Sat morning, 36.3N 87.6W Sat evening, and
36.2N 87.2W Sun morning. Helene will dissipate early Mon. Winds
and seas related to Helene will prevail across the eastern Gulf
waters through late Fri. Light to gentle winds and slight seas
will prevail across the basin beginning on Sat through early next
week.

...CARIBBEAN SEA...

Please refer to the Special Features section above for details on
Hurricane Helene in the eastern Gulf of Mexico.

The outer rainbands to the south of the center of Helene are
causing scattered showers and a few thunderstorms over the NW
Caribbean. Heavy rains continue to impact western and central
Cuba. In the last 24 hours, a rain gauge in Acueducto de Mantua,
Cuba has received over 11 inches of rain (286.7 mm) according to
the Cuban Meteorological Service. In the eastern Caribbean, a
robust tropical wave is producing scattered showers and a few
thunderstorms, especially east of 67W. A recent scatterometer
satellite pass captured fresh to near gale- force southerly winds
north of 16N and west of 77W. Seas in these waters are 6-9 ft.
Moderate or weaker winds and slight to moderate seas are prevalent
elsewhere in the basin. However, mariners are advised that gusty
winds and higher seas are likely in associated with the storm
activity in the eastern Caribbean.

For the forecast, Hurricane Helene is near 25.5N 85.5W at 11 AM EDT,
and is moving north-northeast at 12 kt. Maximum sustained winds
are 90 kt with gusts to 110 kt, and the minimum central pressure
is 960 mb. Helene will move to 28.8N 84.3W this evening, move inland
and weaken to a tropical storm near 33.9N 84.5W Fri morning,
weaken as an extratropical cyclone near 36.4N 86.6W Fri evening,
36.5N 87.5W Sat morning, 36.3N 87.6W Sat evening, and 36.2N 87.2W
Sun morning. Helene will dissipate early Mon. Tropical storm
conditions and very rough seas will continue today over the NW
Caribbean as Helen gradually moves away from the area. Gentle to
moderate winds and slight seas will prevail across the area
beginning on Fri night through early next week.

...ATLANTIC OCEAN...

Please refer to the Special Features section above for details on
Hurricane Helene located in the eastern Gulf of Mexico and Invest
98L in the central Atlantic.

A surface trough is analyzed from 31N49W to 26N55W and scattered
showers are evident to the east of this boundary to 47W and north
of 26N. The remainder of the Atlantic is under the influence of a
broad subtropical ridge, maintaining fairly tranquil weather
conditions. Moderate or weaker winds and slight to moderate
prevail over a good portion of the basin.

For the forecast W of 55W, Hurricane Helene is near 25.5N 85.5W at
11 AM EDT, and is moving north-northeast at 12 kt. Maximum
sustained winds are 90 kt with gusts to 110 kt, and the minimum
central pressure is 960 mb. Helene will move to 28.8N 84.3W this
evening, move inland and weaken to a tropical storm near 33.9N
84.5W Fri morning, weaken as an extratropical cyclone near 36.4N
86.6W Fri evening, 36.5N 87.5W Sat morning, 36.3N 87.6W Sat
evening, and 36.2N 87.2W Sun morning. Helene will dissipate early
Mon. Elsewhere, Tropical Storm Issac, well N of the region to the
NE of Bermuda, will continue moving away from the area, but
generate N swell that will propagate into waters N of 28N and E of
65W, producing seas of 6 to 8 ft.

$$
Delgado