[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 130003
TWDAT

Tropical Weather Discussion
NWS National Hurricane Center Miami FL
0005 UTC Sat Nov 13 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
2345 UTC.

...MONSOON TROUGH/ITCZ...

The monsoon trough axis passes through the coast of Senegal near
14N17W to 08N22W to 06N30W and to 05N36W, where latest
scatterometer data indicates the ITCZ begins and continues to
07N46W and to the coast of French Guiana near 05N53W. Scattered
moderate to isolated strong convection is noted within 120 nm
south of the trough between 17W-20W and within 120 nm north of
the the trough between 22W-24W. Scattered moderate convection is
within 60 nm either side of the trough between 27W-29W and within
30 nm north of the trough between 34W-36W.

GULF OF MEXICO...

As of 21Z, a weak cold front extends from near Naples, Florida
to 23N87W. A pre-frontal trough is has shifted to east of the
basin from across central Cuba to the north-central Caribbean
Sea. Satellite imagery shows scattered showers over the western
part of the Straits of Florida as well as along western Cuba
and the northeastern tip of the Yucatan Peninsula. Scattered
showers and thunderstorms are developing over the central Gulf
waters from 26N to 28N between 87W-89W. Isolated showers and
thunderstorms are also developing over the interior of the
Yucatan Peninsula.

A 1019 mb high center is over eastern Mexico near 22N98W. Latest
scatterometer data indicates generally gentle north to northeast
winds throughout the basin, except for moderate northeast winds
in the west- central section of the basin. Seas are in the 1-3 ft
range throughout.

For the forecast, the aforementioned cold front will stall over
the southeastern Gulf tonight. A reinforcing front will enter
the basin late tonight followed by strong winds and rough seas
over the northwest and north-central Gulf. The front will merge
with the remnants of the first front and sweep through the basin
Sat. High pressure will build into the northern Gulf Sat night
and Sun, and strengthen into Mon. This will support fresh winds
late this weekend into early next week across portions of the
northwest and southern Gulf, with strong east winds possible
over the Straits of Florida. The high pressure will shift east
of the region through mid-week.

CARIBBEAN SEA...

A trough extends from just west of the Cayman Islands near
19N83W, north- northeastward to across central Cuba and to just
east of South Florida. A few showers and thunderstorms are noted
to the east of the trough to near 79W. Latest ASCAT data shows
moderate to fresh east winds to the southeast of the trough
across the north- central and northeastern Caribbean Sea
sections.

A modest pressure gradient due to the combination of a strong
1033 mb high pressure center located well to the north of the
area and lower pressure that is present over northern South
America is bringing fresh to strong trades to the south-central
Caribbean, with the strongest of the winds occurring within 90
nm of the coast of northwest Colombia. Moderate or weaker trades
are found elsewhere. Seas of 4-7 ft are present over the
southwestern, central and eastern Caribbean Sea, with the highest
seas occurring offshore northwest Colombia. The remainder of the
basin has lower seas of 2-4 ft.

For the forecast, the aforementioned high pressure will shift
east tonight, ahead of a cold front that will move through the
Gulf of Mexico Sat and Sun, then stall from western Cuba to the
Gulf of Honduras by Sun night. Looking ahead, reinforcing high
pressure will build north of the area through mid-week behind
another front moving through the western Atlantic.

ATLANTIC OCEAN...

A rather broad upper-level trough continues to push eastward
across the southeastern United States. This feature supports
a cold front that stretches from New England to across south-
central Florida and into the eastern Gulf of Mexico as of 21Z.
A pre-frontal trough extends from near 31N75W to across the
central Bahamas and to the north-central Caribbean Sea. A jet
stream branch stretches from the eastern Pacific northeastward
rounding the base of the upper-level trough and well north of
31N. Associated upper-level dynamics is sustaining a large area
of numerous showers and thunderstorms west of a line from 31N69W
to 26N71W and to 22N77W. The latest scatterometer satellite data
pass depicts fresh to locally strong southerly winds ahead of the
pre-frontal trough, likely due to the shower and thunderstorm
activity.

Farther east, a cold front enters the area near 31N36W and
continues southwestward to 27N45W, where it transitions to
a stationary front to 25N54W and to north of Puerto Rico near
22N68W. Areas of rain, with embedded scattered showers and
isolated thunderstorms are within 180 nm east of the cold front
north of 29N, and within 120 nm southeast of the cold front
from 28N to 29N. Isolated showers are within 120 nm southeast
of the cold front from 26N to 28N. Similar is along and
within 30-60 nm west of the cold front north of 28N. Satellite-
derived winds show fresh to strong northeast to east winds west
of the frontal boundaries to near 60W and north of 22N. Seas with
these winds are in the 8-11 ft range.

Elsewhere, a weak surface trough is along 36W from 17N to 28N.
It is only producing a few shallow showers near the trough axis.
Moderate or weaker winds remain over the remainder of the basin.
Seas of 5-8 ft are found W of 60W. Outside the seas related to
the above mentioned fronts, north swell is producing seas of
8-10 ft north of 25N and between 35W and 59W. Seas of 4-7 ft are
present over the remainder of the tropical Atlantic.

The Cumbre Vieja volcano, on the island of La Palma in the Canary
Islands, has been erupting since 19 September 2021. Medium
volcanic ash concentration is within vicinity of the volcano,
while lower concentration is further away. 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 W of 65W, the previously-mentioned cold front
that is over the western part of the area will continue to drift
eastward through Sat. Another cold front will move off the
northeast Florida coast late Sat, then merge with first front by
early Sun then stall and weaken from 31N70W to western Cuba.
Looking ahead, a third cold front will move off the northeast
Florida coast late Sun night, eventually overtaking the remnants
of the previous fronts, then drift southeastward and eventually
stall from near 27N65W to western Cuba through mid-week.

$$
Aguirre
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