[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 061747
TWDAT

Tropical Weather Discussion
NWS National Hurricane Center Miami FL
1805 UTC Wed Oct 6 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
1700 UTC.

...TROPICAL WAVES...

An Atlantic Ocean tropical wave is along 25W, from 16N southward,
moving W at 20 kt. Scattered moderate showers are found where the
wave axis intersects the ITCZ, from 01N-05N.

An Atlantic Ocean tropical wave is along 50W, from 18N southward,
moving W at 20 kt. Scattered moderate and isolated strong
convection is noted over a large area along and east of the wave
axis, from 05N-14N between 41W-53W. The convection is being
enhanced by strong upper-level divergence to the east of an
upper-trough. Satellite imagery suggests that dry Saharan Air
accompanies this wave, north of 13N between 55W and 25W.

A Caribbean Sea tropical wave is along 82W, from 17N southward,
moving W near 10-15 kt. Scattered moderate to strong convection
covers the area from 09N-20N between 80W-85W, and from 09N-13N
between 76W-80W. Periods of heavy rainfall are possible over
portions of Nicaragua and Costa Rica through Thursday night.

...MONSOON TROUGH/ITCZ...

The monsoon trough passes through the coastal plains of
Guinea-Bissau near 12N16W to 09N17W. The ITCZ extends from 09N17W
to 05N19W to 08N44W to 07N58W. Aside from the convection mentioned
above, scattered moderate isolated strong convection is noted from
03N-07N between 12W-22W, and from 03N-11N between 32W-41W.

GULF OF MEXICO...

A stationary front extends from Mobile, Alabama to a 1015 mb low
near 29N88W to Veracruz Mexico near 19N96W. Scattered moderate and
isolated strong convection is noted within 270 nm east of the
front and north of 24.5N, especially in the waters off the Big
Bend of Florida. Scattered moderate showers are also near the
front over the western Bay of Campeche south of 21N and west of
93W. A weak high pressure ridge behind the front and across NE Mexico
is promoting gentle to moderate northerly winds behind the front,
except for fresh winds across the Veracruz area, where peak seas
are 5 ft. Elsewhere E of the front, gentle to moderate SE to S
winds prevail, except for fresh within the convection over the NE
Gulf of Mexico. Seas are 1 to 3 ft over the eastern Gulf.

The stationary front will meander through Thu before dissipating.
Weak high pressure to the NW will support moderate to locally
fresh northerly winds over Veracruz adjacent waters through Thu
and fresh to locally strong winds over the NE Gulf through early
this evening. High pressure will build modestly across the basin
during the weekend.

CARIBBEAN SEA...

Strong convection over the western Caribbean Sea is described
above in the tropical waves section. Water vapor imagery shows
much drier air over the eastern half of the basin, especially
between 60W-70W. The latest ASCAT wind data shows strong trade
winds over the central Caribbean from 11N-16N between 72W-78W,
where seas are likely 7 to 9 ft. Moderate to fresh winds prevail
elsewhere north of 10N and east of 85W, where seas are 4 to 6 ft.

High pressure currently NE of Bermuda will continue to support
fresh trade winds across the eastern, central and southwest basin
with locally strong winds along Hispaniola adjacent waters and the
south-central Caribbean. These winds and seas to 8 ft will
diminish Thu evening as the ridge slides ENE and a weaker
pressure gradient establishes across the area. Moderate to locally
fresh trades will dominate these regions Thu night through Sun.

ATLANTIC OCEAN...

A surface trough off the southeast U.S. coast extending from
33N73W to 26N79W is moving slowly NW. Recent buoy and ASCAT wind
data indicate that a weak area of low pressure is developing along
the trough about 150 nm east of the northeastern coast of Florida.
Disorganized scattered moderate showers and isolated tstorms are
noted from 28N-31N between 70W-79W. Upper-level winds are forecast
to remain unfavorable for tropical cyclone development while the
low moves slowly northward and then northeastward off the
southeastern United States coast during the next few days. The
system has a low chance of formation during the next 48 hours.

A 1026 mb high pressure is centered just east of Bermuda. The
gradient between this high pressure and 1009 mb low pressure along
the coast of NW Colombia is producing fresh E winds across the
southeast Bahamas and north of Hispaniola, where seas are 7 to 9
ft. Gentle to moderate winds cover the area north of 25N between
60W and Florida, where seas are 4 to 6 ft. Fresh to locally
strong trade winds will continue south of 25N through Thu.
Moderate to locally fresh winds will then gradually diminish to
gentle to moderate Fri and continue through the weekend.
Northerly swell generated from Sam east of 72W will diminish
through tonight.

Farther east, a surface trough associated with the remnants of
Victor is producing scattered moderate and isolated strong
convection from 23N-27N between 49W-56W. ASCAT data show fresh NE
to E winds within the area of convection. East of 40W, broad
surface ridging prevails. ASCAT shows fresh trade winds across
the tropical Atlantic from 10N-20N, where seas are 6 to 7 ft.
Saharan air is dominating the zone north of 13N between 25W and
the tropical wave along 50W.

The Cumbre Vieja volcano, located on the island of La Palma in
the Canary Islands, has been erupting almost continuously since 19
September. Marine and aviation interests should monitor this
ongoing situation by reading the Volcanic Ash Advisory issued by
Meteo-France at http://vaac.meteo.fr/volcanoes/la-palma/

$$
Hagen
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