[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 301805
TWDAT

Tropical Weather Discussion
NWS National Hurricane Center Miami FL
1805 UTC Thu Sep 30 2021

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
1750 UTC.

...SPECIAL FEATURES...

Hurricane Sam was centered near 22.6N 60.0W at 30/1500 UTC or 315
nm NNE of the Northern Leeward Islands moving NW at 11 kt.
Estimated minimum central pressure is 937 mb. Maximum sustained
wind speed is 125 kt with gusts to 150 kt. Numerous moderate
scattered strong convection is from 20N to 27N between 56W and
63W. Maximum significant wave height near the center is estimated
at 45 ft. On the forecast track, the core of Sam will pass to the
east of Bermuda early Saturday. Some fluctuations in intensity
are expected during the next couple of days, but Sam is forecast
to remain a major hurricane through Saturday, with more significant
weakening anticipated later in the weekend.
Please read the latest NHC Public Advisory at
https://www.nhc.noaa.gov/text/MIATCPAT3.shtml and Forecast/
Advisory at https://www.nhc.noaa.gov/text/MIATCMAT3.shtml for more
details.

Tropical Storm Victor is centered near 9.5N 28.9W at 30/1500 UTC
or 480 nm SW of the Cabo Verde Islands moving WNW at 12 kt.
Estimated minimum central pressure is 1004 mb. Maximum sustained
wind speed is 40 kt with gusts to 50 kt. Numerous moderate
convection is from 04N to 15N between 24W and 33W. Maximum significant
wave height near the center is estimated to be near 17 ft. A
west-northwest to northwest motion over the eastern tropical
Atlantic is expected through the weekend. Gradual strengthening
is forecast, and Victor could be near hurricane strength on
Friday. A weakening trend is expected to begin over the weekend.
Please read the latest High Seas Forecast issued by Meteo-France
at website https://www.weather.gmdss.org/II.html.
Please also read the latest NHC Public Advisory at
https://www.nhc.noaa.gov/text/MIATCPAT5.shtml and Forecast/
Advisory at https://www.nhc.noaa.gov/text/MIATCMAT5.shtml for more
details.

...TROPICAL WAVES...

A tropical wave extends from 06N to 15N with axis near 48W,
moving W near 10 kt. Scattered moderate convection is from 05N to
10N between 42W and 48W.

...MONSOON TROUGH/ITCZ...

The monsoon trough extends from the W coast of Africa near
16N16W and continues to 13N21W, then resumes west of Victor near
07N32W and contiunes to 06N38W. The ITCZ begins near 06N38W and
extends to 05N53W. Aside from the convection associated with
Victor and the tropical wave, scattered moderate convection is
from 05N to 09N between 34W and 42W.

GULF OF MEXICO...

Microwave satellite imagery continue to show moisture inflow from
the Caribbean to the western half of the gulf, which along with
middle level divergent flow continue to support heavy showers and
thunderstorms W of 95W and just to the N of Veracruz, Mexico.
Similar convective activity is along the Texas and SW Louisiana
coastal and offhshore waters. Model guidance indicate the
continuation of shower activity in these regions through the
weekend. Otherwise, a weak surface ridge covers the eastern half
of the basin and provides mainly gentle to moderate E to SE flow
basin-wide, except in the areas of convection where fresh winds
are observed. Seas remains in the 1 to 3 ft range.

For the forecast, a weak ridge of high pressure will persist
north of the Gulf through Fri night, supporting tranquil
conditions. Stronger higher pressure will build across the region
Sat and Sun, allowing winds and seas to increase over the SE Gulf.
Quiescent condition will prevail over the entire Gulf of Mexico
beginning again on Mon.

CARIBBEAN SEA...

An upper level trough extending a base to the south-central
Caribbean continue to support showers and isolated tstms over E
Cuba and portions of Hispaniola. Diffluent flow to the E of the
upper trough support similar convective activity over the SE
Caribbean waters. With a weak pressure gradient across the region,
latest scatterometer data continue to show gentle to moderate
trades basin-wide. Seas are 3 ft or less across most of the
Caribbean Sea, except in the northeast Caribbean passages, where
swell from Hurricane Sam will peak today through tonight.

For the forecast, Hurricane Sam well north-northeast of the
Leeward Islands will continue to generate swells over Atlantic
waters from off the N Leeward Islands to north of the Mona Passage
through Fri. Meanwhile, tranquil trades will prevail over the
Caribbean through Fri. As high pressure builds in behind Hurricane
Sam, winds are expected to become moderate to fresh across the
central and E Caribbean and tropical N Atlantic by Sat through at
least Mon.

ATLANTIC OCEAN...

Hurricane Sam is centered near 22.6N 60.0W at 30/1500 UTC or 320
nm NNE of the Northern Leeward Islands moving NW at 11 kt.
Estimated minimum central pressure is 937 mb. Maximum sustained
wind speed is 125 kt with gusts to 150 kt. Tropical Storm Victor
is centered near 9.5N 28.9W at 30/1500 UTC or 480 nm SW of the
Cabo Verde Islands moving WNW at 12 kt. Estimated minimum central
pressure is 1004 mb. Maximum sustained wind speed is 40 kt with
gusts to 50 kt. Please read the Special Features section above
for details on Hurricane Sam and Tropical Storm Victor.

The Cumbre Vieja volcano on the island of La Palma in the Canary
Islands near 28.6N 17.8W has been erupting since September 19th.
High concentration of volcanic ash is found near the volcano.
Marine and aviation interests should monitor this ongoing
situation by reading the latest Volcanic Ash Advisory issued by
Meteo-France at http://vaac.meteo.fr/volcanoes/la-palma/ for
details.

For the forecast, Sam will move to 24.4N 60.8W this evening,
27.2N 61.7W Fri morning, 30.2N 61.6W Fri evening, and then north
of our waters by Sat morning. Sam will change little in intensity
through Sat. In addition to hurricane conditions northeast of the
Leeward Islands today, expect large swell from Sam to impact the
area northeast of the Bahamas starting Fri and continuing through
the weekend. Meanwhile, a weak pressure pattern will maintain
quiescent conditions through tonight. A weak cold front will move
from the Carolinas to the central Bahamas by Fri and dissipate by
Sat. Stronger high pressure will build in to the area, which will
bring moderate to occasionally fresh winds through Mon.

$$
Ramos
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