[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 140000
TWDAT

Tropical Weather Discussion
NWS National Hurricane Center Miami FL
0005 UTC Thu Oct 14 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 1800 UTC surface analysis and satellite imagery through
2320 UTC.

...SPECIAL FEATURES...

Atlantic Gale Warning: A 1000 mb low pressure is just N of the
area near 31.5N 46.5W. An occluded front extends E from the low
to another low of 1002 mb near 31.5N42W. A cold front extends W
from the 1002 mb low to 29N49W to 31N55W. The morning ASCAT
passes show gale force SW to W winds extending southward to 29N
from the easternmost low. The ASCAT data also show near-gale
force W to NW winds extending southward to 28N from the
westernmost low. Scattered moderate isolated strong convection
with this system is noted north of 25N between 35W-47W. Expect
gale force SW to W winds north of 29N between 36W-47W through
this evening at 14/0000 UTC. As the low moves eastward, expect
the gales to move from west to east within this area. Seas of 11
to 13 ft are expected within the area of gale force winds.
Please read the latest High Seas Forecast issued by the National
Hurricane Center at website
https://www.nhc.noaa.gov/text/MIAHSFAT2.shtml for more details.

...TROPICAL WAVES...

An Atlantic tropical wave axis is along 31W from 03N-18N, moving
W at 10-15 kt. Moderate westerly upper-level winds over the
tropical wave, induced by an upper-level low near 24N23W, are
pushing much of the convection east of the wave axis. Scattered
moderate convection is observed south of Cabo Verde Islands.

Another Atlantic tropical wave axis is along 52W from 04N-17N,
moving W at 10-15 kt. Scattered to numerous moderate with
embedded isolated strong convection is noted where the wave
interacts with the ITCZ from 07N to 10.5N between 48W-54W. The
northern portion of the wave is surrounded by dry Saharan air and
a subsident mid-level ridge axis, suppressing the development of
showers and thunderstorms.

An eastern Caribbean tropical wave axis extends south of 19N67W
to Venezuela. The tropical wave is moving W at 10-15 kt. Isolated
to scattered showers are seen between 60-120 nm E of the wave
axis, mainly N of 15N. Otherwise, mid to upper-level ridging is
providing subsidence, which is suppressing convection.

The western Caribbean tropical wave that had been analyzed along
80W. The tropical wave is moving W at around 10 kt. No deep
convection is noted in association with the wave as it moves into
a dry airmass, except for isolated moderate showers along the
wave south of 11N to Panama, near where the wave intersects the
east Pacific monsoon trough.

...MONSOON TROUGH/ITCZ...

A monsoon trough extends from the coast of Guinea-Bissau near
11N16W to 04N29W. The ITCZ is analyzed from 05N32W to 08N51W to
08N54W, then continues W of a tropical wave from 08N54W to 08N60W.
Isolated moderate convection are along the ITCZ from 03N TO 09N
between 39W to 49W. Scattered moderate and isolated strong
convection is noted along the ITCZ from 06.5N to 10.5N between
37W and 60W.

...GULF OF MEXICO...

A weak ridge extends from northern Georgia to the south-central
Gulf of Mexico and maintains tranquil weather conditions across
most of the basin. The pressure gradient between the ridge and
Tropical Depression Pamela over northern Mexico is resulting in
fresh to locally strong SE to S winds in the west-central Gulf
of Mexico, especially near the coast of southern Texas, where the
latest ASCAT pass shows 20-25 kt winds. SSE winds of 23 kt and
wave heights of 6 ft have recently been occurring at NOAA buoy
42020, located about 60 nm SE of Corpus Christi. Seas of 4 to 6
ft cover the western Gulf. Moderate E winds prevail east of 90W,
with 2 to 3 ft seas.

For the forecast, weak high pressure extending from the eastern
U.S. southwestward to the central Gulf and will influence the
Gulf waters during the next several days. Moderate to fresh
southerly winds are expected over the western Gulf between the
ridge and lower pressure over the Southern Plains and northern
Mexico through Thu. Gentle to moderate breezes will persist
elsewhere through Fri. A cold front will enter the NW Gulf Fri
night with fresh to strong northerly winds following it. The
front will reach from central Florida to the western Bay of
Campeche Sun morning with moderate to fresh N-NE winds across
most of the Gulf.

...CARIBBEAN SEA...

An upper-level low is centered near the NW Bahamas near 25N75W.
An upper-level trough extends SW from the upper-low to northern
Central America. Strong upper-level diffluence to the east of
the upper-trough is inducing numerous strong convection over the
central Caribbean from 12N to 15.5N between 71.5W and 74W.
Scattered moderate and isolated strong convection surrounds that
area, from 09N to 18.5N between 70.5W and 77W. The morning ASCAT
pass indicated a surface trough or possible outflow boundary
within the convection, extending along 74W from 12N to 18N.
Elsewhere, scattered showers and isolated tstorms over the NE
Caribbean are associated with a tropical wave, described in the
section above. The morning ASCAT pass shows gentle wind speeds
over the western Caribbean, west of 77W, where seas are likely 1
to 3 ft. Mainly moderate wind speeds are elsewhere east of 77W,
except for stronger winds likely within the strong thunderstorm
activity. Seas are 3 to 5 ft east of 77W, except higher in the
NE Caribbean passages, due to northerly swell from the Atlantic.
However, this northerly swell will subside tonight.

For the forecast, a vigorous upper level trough from the Bahamas
to the NW Caribbean will support active weather across the central
Caribbean and extreme NE Caribbean through tonight behind two
tropical waves. Northerly swell will subside across the regional
Atlc and Caribbean passages tonight. Low pres NE of the southern
Bahamas will drift E-NE tonight through Thu then accelerate NE
into the weekend. This will weaken the pressure gradient across
the Caribbean basin leading to tranquil marine conditions.

...ATLANTIC OCEAN...

An upper-level low is centered near the NW Bahamas. A weak
surface trough extends from 30N70W to 25N74W. A more potent
surface trough extends from 26N67W to 1009 mb low pressure near
24N70W to 20N71W. ASCAT data shows fresh to strong winds within
180 nm in the NE semicircle of the low pressure center, while
gentle to moderate wind speeds prevail elsewhere across the
western Atlantic, west of 60W. Strong upper-level diffluence to
the east of the upper-low is inducing scattered moderate and
isolated strong convection from 21N-30N between 64W-71W.
Scattered moderate showers and isolated tstorms are occurring
within 60 nm either side of the western/weaker surface trough,
mainly north of 26.5N. Seas of 4 to 6 ft prevail over the western
Atlantic, except up to 8 ft in N swell to the NE of the Virgin
Islands. The N swell across these waters will subside tonight.

The 1010 mb low pressure near 24N70W is forecast to drift
northward through tonight, then accelerate eastward on Thursday.
Development, if any, of this disturbance should be slow to occur
during the next couple of days due to unfavorable upper-level
winds, and there is a low chance of tropical cyclone formation
during the next 48 hours. Regardless of development, this system
will continue to produce very active weather and impact the
regional waters through late Thu. Locally heavy rainfall is
possible over portions of Hispaniola, the Turks and Caicos, and
the southeastern Bahamas during the next day or two.

Farther east, a surface ridge axis extends from 1019 mb high pressure
near 27N27W. Fair weather and light to gentle anticyclonic winds
are within 150 nm either side of the ridge axis. To the south,
fresh trades are noted from 09N to 16N between 30W and 60W, where
seas are mainly 7 to 8 ft. To the north of the ridge, strong to
gale force winds and thunderstorms are occurring, especially from
24N- 31N between 36W-47W, described above in the Special
Features section.

The Cumbre Vieja volcano, on the island of La Palma in the
Canary Islands, has been erupting since 19 September 2021.
Significant volcanic ash is possible near the volcano. 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/

$$
Torres
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