[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 010431
TWDAT

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
0400 UTC.

...SPECIAL FEATURES...

Hurricane Sam is centered near 25.0N 61.2W at 01/0300 UTC or 480
nm SSE of Bermuda moving NNW at 14 kt. Estimated minimum central
pressure is 938 mb. Maximum sustained wind speed is 125 kt with
gusts to 150 kt. The eye is 30 nm in diameter. Numerous moderate
scattered strong convection extends outward from the center 150
nm in the N semicircle and 90 nm S semicircle. Scattered
moderate convection is elsewhere within 240 nm N semicircle.
Maximum significant wave height near the center is estimated at
43 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 day or so, but Sam is forecast to
remain a major hurricane into Saturday, with additional
weakening anticipated later in the weekend. 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 NHC Forecast/Advisory and Public Advisory at
www.hurricanes.gov for more details.

Tropical Storm Victor is centered near 10.6N 30.7W at 01/0300
UTC or 510 nm SW of the Cabo Verde Islands moving WNW at 10 kt.
Estimated minimum central pressure is 997 mb. Maximum sustained
wind speed is 50 kt with gusts to 60 kt. Numerous moderate
scattered strong convection is within 180 nm of the center in
the northern semicircle. Scattered moderate convection is within
180 nm SE quadrant. Maximum significant wave height near the
center is estimated to be near 18 ft. A west-northwest to
northwest motion is expected through the weekend. Gradual
strengthening is forecast during the next day or so. However, a
weakening trend is expected to begin over the weekend. Please
read the latest High Seas Forecasts issued by Meteo-France at
website http://weather.gmdss.org/II.html and by the National
Hurricane Center at website
https://www.nhc.noaa.gov/text/MIAHSFAT2.shtml as well as the
latest NHC Forecast/Advisory and Public Advisory at
www.hurricanes.gov for more details.

...TROPICAL WAVES...

A tropical wave axis extends along 51W from 05N to 16N, moving W
at 15-20 kt. Isolated showers and tstorms are noted along and
east of the wave axis from 08N-11N.

...MONSOON TROUGH/ITCZ...

The monsoon trough extends from the W coast of Mauritania near
18N16W to 12N25W, then resumes W of Victor from 08N34W to
06N39W. The ITCZ extends from 06N39W to 06N49W, then resumes W
of a tropical wave from 07N52W to 07N58W. Aside from the
convection associated with Victor and the tropical wave,
scattered moderate to strong convection is noted from 07N-12N,
within 120 nm of the west coast of Africa. Scattered showers are
seen from 05N-11N between 37W-48W.

GULF OF MEXICO...

Ample moisture noted in Total Precipitable Water imagery over
the western Gulf is leading to scattered moderate showers and
isolated tstorms. However, a mid- to upper-level ridge centered
over the SW Gulf of Mexico is acting to suppress the coverage
and intensity of these showers and storms. A recent ASCAT pass
shows mainly moderate E winds across the basin. Seas are 2-4 ft
over the western Gulf and 1-3 ft across the eastern Gulf.

For the forecast, a weak ridge of high pressure will persist
north of the Gulf through tonight, supporting tranquil
conditions. Stronger higher pressure will build across the
region by Sun, allowing winds and seas to increase over the SE
Gulf over the weekend. A weak cold front should move across the
Gulf on Mon and Tue, but with little enhancement of the winds
and seas.

CARIBBEAN SEA...

An upper level trough extending from the W Atlantic to the SW
Caribbean continues to support scattered showers and isolated
tstorms between the Isle of Youth and Puerto Rico, including the
Cayman Islands, Jamaica and Hispaniola. Showers and tstorms are
also noted along the N coast of Venezuela and Colombia. A recent
ASCAT pass shows gentle trades across the basin, with moderate
winds in the south-central Caribbean. Moderate to locally fresh
NE winds are in the Windward Passage. Seas of 2-4 ft prevail
over much of the basin, except 1-2 ft in the NW Caribbean. Swell
from Hurricane Sam is affecting the NE Caribbean passages from
the Mona Passage to the northern Leeward Islands. The swell will
begin to gradually subside later today.

For the forecast, tranquil trades will continue over the
Caribbean through today. As high pressure builds in behind
Hurricane Sam, winds are expected to become moderate to fresh
across the central and E Caribbean beginning Sat and continuing
through mid week.

ATLANTIC OCEAN...

Refer to the section above for details on Hurricane Sam and T.S.
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.

An upper-level trough over the W Atlantic, to the west of
Hurricane Sam, is supporting a weak stationary front along 30N
between 70W-78W, but this front will be dissipating later today.
Scattered showers and isolated tstorms are seen over the central
and NW Bahamas and east of Florida. 1031 mb high pressure over
the Azores dominates the Atlantic to the east of Sam. ASCAT
shows fresh to strong trade winds from 15N-25N between 28W-41W,
and from the Madiera and Canary Islands westward to 28W.

For the forecast, Hurricane Sam will move to near 30N62W this
evening and to near 33N 60.5W Sat morning. Large swell from Sam
will impact the area northeast of the Bahamas today through
Saturday, then gradually subside Saturday night through Sunday.
Seas up to 12 ft will reach as far west as about 72W, and 10 ft
seas will make it to 77W, due to swell from Sam. After that
time, stronger high pressure will build into the area, which
will bring moderate to occasionally fresh winds to the western
Atlantic early next week.

$$
Hagen
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