AXNT20 KNHC 261743
Tropical Weather Discussion
NWS National Hurricane Center Miami FL
1805 UTC Tue Oct 26 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
An Atlantic tropical wave is along 27W from 18N southward, moving
W at 10-15 kt. Scattered moderate and isolated strong convection
is evident east of the wave axis from 11N to 14N between 22W and
26W. Similar convection is noted from 05N-06N between 26W-31W.
A Caribbean tropical wave that was analyzed along 64W yesterday is
now along 72W south of 17N, moving W at 15-20 kt. Although the
wave shows up well in total precipitable water imagery, no
significant shower activity is noted at this time.
The western Caribbean tropical wave that was analyzed along 81W at
0600 UTC has dissipated and has been removed from the analysis.
The monsoon trough extends off the coast of Guinea-Bissau near
12N16W to 11N17W to 12N26W. The ITCZ extends from 07N29W to 07N50W
to 09N61W. In addition to the convection described in the
Tropical Waves section, scattered showers are noted from 04N-14N
east of 22W. Scattered moderate and isolated strong convection is
seen from 05N-09N between 34W-48W and from 08N-11N between 55W-
GULF OF MEXICO...
A weak to moderate strength cold front is across the northern Gulf
from Tampa Bay Florida to Lake Charles Louisiana. Moderate NW to
N winds are north of the front over the northeast Gulf of Mexico,
where seas are 2 to 3 ft. No significant precipitation is observed
near the front. Farther south, a surface trough extends from
24N87W to 19N92W, just off the Yucatan Peninsula. Isolated
moderate convection is noted from 22N to 23N between 86W and 89W.
Moderate SE winds and 2 to 3 ft seas are likely occurring in the
far west-central Gulf next the coast of south Texas and NE Mexico.
Gentle winds and 1 to 2 ft seas prevail elsewhere.
For the forecast, fresh to strong southerly winds will develop
across the NW Gulf tonight into Wed ahead of a cold front expected
to push off the Texas coast by midday Wed. The front will reach
from Tallahassee to 25N88W to 19N95W by Thu morning, and from Ft.
Myers Florida to Cancun Mexico Thu night. Strong to near gale
force winds are expected ahead of and behind the front. Seas will
build to 13 ft in the wake of the front, especially over the
north-central and NE Gulf. A squall line containing strong to
severe thunderstorms with very strong wind gusts is expected to
accompany the cold front as it moves from west to east Wed
afternoon through Thu morning. The strongest thunderstorms should
occur over the northwest and north-central Gulf with the line,
Wed afternoon through Wed night. Frequent gusts to gale force are
expected over the north-central and NE Gulf Wed night through Fri
before quickly diminishing early Sat.
Mid to upper-level ridging prevails over the western two-thirds of
the Caribbean Sea, leading to subsidence and mostly dry
conditions, other than a few isolated showers with the typical
trade wind cumulus clouds. Although an upper-level trough extends
from the central Atlantic to the eastern Caribbean Sea, relatively
dry air is limiting shower activity there as well. A 1017 mb
surface high pressure is analyzed over eastern Cuba at 1500 UTC
near 21N78W. As a result of this high pressure, the latest ASCAT
data show light to gentle wind speeds over the NW Caribbean,
except for the Gulf of Honduras, where moderate winds are noted.
Seas are 1 to 3 ft in the NW Caribbean, except up to 4 ft in the
Gulf of Honduras. ASCAT shows fresh trades over the southeast and
south-central Caribbean, mainly south of 15N and east of 77W,
where seas are currently in the 5 to 7 ft range. Gentle to
moderate winds prevail elsewhere, with 2 to 4 ft seas.
For the forecast, the Azores high will continue to extend a ridge
SW to the NE Caribbean and support the continuation of moderate
to fresh winds across the eastern half of the basin with slightly
higher winds in the Gulf of Venezuela through Thu. A cold front
will enter the NW Caribbean Thu night and reach from western Cuba
to the Gulf of Honduras early in the afternoon on Fri. The front
will reach from eastern Cuba to the coast of Nicaragua on Sat
where it will stall before dissipating Sun. Moderate to fresh
northerly winds will follow the front.
West of 60W: A cold front enters the area near 31N76W and extends
to Cape Canaveral Florida and into the eastern Gulf of Mexico.
Another cold front extends from 31N70W to 30N71W, then continues
as a surface trough from 30N71W to the NW Bahamas near 26N77W. An
upper-level trough axis is also over this general area. Upper-
level diffluence to the east of the upper-trough is enhancing
scattered moderate and isolated strong convection north of 26.5N
between 62W-68W. Isolated tstorms are also along the cold front
near 30N-31N and 69W-71W. Strong to near-gale force S to SW winds
are noted within 300 nm east of eastern front/surface trough,
mainly north of 29N. ASCAT shows fresh to strong winds elsewhere
north of 27N and west of 60W. Seas of 8 to 11 ft prevail north of
29N between 65W-73W. 6 to 8 ft seas are elsewhere north of 27.5N
between 62W-80W. Mainly moderate wind speeds prevail through the
Bahamas. A weak surface ridge is oriented over the Greater
Antilles, where gentle wind speeds are occurring. East of the
Bahamas and south of 26N, seas are 3 to 5 ft.
East of 60W: A weak ridge axis extends from 1026 mb high pressure
near 36N20W to near 21N50W, while another ridge extends from
30N57W to 20N66W. This pattern is supporting moderate to fresh
trade winds south of 15N, and gentle winds in the subtropical
latitudes north of 17N. Seas are 6 to 8 ft over the tropical
Atlantic in the area of moderate to fresh trade winds, with a
component of N swell. Seas are 4 to 6 ft elsewhere, except 5 to 7
ft east of 30W.
The Cumbre Vieja volcano, on the island of La Palma in the Canary
Islands, has been erupting since 19 September 2021. Ash cloud
slowly drifting SW. Higher concentration over volcano and western
vicinity. 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/.
For the forecast west of 65W, fresh to strong winds will push
eastward across the northern forecast waters, mainly N of 27N,
through Wed as the two fronts merge and move eastward. The next
cold front is expected to sweep across the region Thu night
through Fri night producing another round of fresh to strong winds
north of the Bahamas. Scattered showers and tstorms will likely
accompany this front.