[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 261723
TWDAT

Tropical Weather Discussion
NWS National Hurricane Center Miami FL
1805 UTC Sat Sep 26 2020

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 32N. The following information is based on satellite
imagery, weather observations, radar and meteorological analysis.

Based on 1200 UTC surface analysis and satellite imagery through
1715 UTC.

...TROPICAL WAVES...

An eastern Atlantic Ocean tropical wave has been added to the
analysis along 23W from 20N southward, moving west at 15 kt.
Scattered moderate convection is within 360 nm E of the wave axis
from 05N-16N.

An Atlantic Ocean tropical wave is along 44W from 16N southward,
moving W at 10-15 kt. Scattered showers are within 90 nm either
side of the wave axis from 09N-11N.

An Atlantic Ocean tropical wave is along 59W from 15N southward,
moving W at 15 kt. Scattered moderate convection is within 180 nm
either side of the wave axis from 05N-11N. An enhancement of
showers and tstorms is possible tonight into Sun near Trinidad
and the SE Caribbean.

...MONSOON TROUGH/ITCZ...

The monsoon trough passes through the west coast of Africa near
18N16W to 18N20W, where there is a break in the monsoon trough.
The monsoon trough resumes at 09N21W to 10N31W to 11N38W. The
ITCZ is from 09N46W to 08N56W. Scattered moderate convection is
south of the monsoon trough from 07N-09N between 31W-37W.
Scattered moderate convection is within 90 nm either side of the
ITCZ.

GULF OF MEXICO...

Upper-level anticyclonic flow covers the Gulf of Mexico. A mid
to upper-level trough is over east Texas. A NE-SW oriented
surface trough stretches from the central Gulf of Mexico near
25N90W to Veracruz Mexico. Scattered moderate and isolated strong
convection is from 19N-26.5N between 88W-97W. Scattered showers
and tstorms are also from 24.5N-27.5N between 84W-88W. ASCAT data
shows mostly gentle wind speeds across the Gulf of Mexico, with
moderate S winds extending offshore near the Mouth of the Rio
Grande River.

For the forecast, a strong cold front will move into the NW Gulf
late Mon afternoon. In the wake of the front, strong northerly
winds are expected in the western half of the basin, with gale
force winds possible west of the front over some areas of the
western Gulf from Mon night through Tue night. High pressure
behind the front will slide eastward across the northern Gulf
through Wed night.

CARIBBEAN SEA...

Scattered showers and isolated tstorms are seen this afternoon in
the NW Caribbean from 20N to the Yucatan Channel between 82W-87W,
including the south coast of western Cuba. Farther south in the
SW Caribbean, scattered to numerous moderate and isolated strong
convection is noted along the monsoon trough from 10N-14N between
76W-84W, including the east coast of Nicaragua. Weak/broad upper-
level cyclonic flow over the south-central Caribbean is resulting
in isolated showers and tstorms across portions of the central
Caribbean. Scattered showers and isolated tstorms are also seen
over portions of the Leeward Islands. A recent ASCAT pass shows
fresh trades over the south-central Caribbean, with moderate
trades elsewhere.

Moderate to fresh trade winds are expected in the central
Caribbean through early Sun, becoming fresh to strong by Wed.
Moderate winds are expected elsewhere across the region.

ATLANTIC OCEAN...

Over the western Atlantic from 24N-32N between 72W-79W, TPW
imagery shows abundant moisture. Upper-level diffluence is in
this area. A surface trough has been added to the map as of
1500 UTC from 31N77W to 27N79.5W. As a result of these features,
scattered moderate and isolated strong convection is occurring
from 24N-29N between 74.5W-78.5W. Scattered moderate to strong
convection is from 29N-32N between 72W-77W. Fresh to strong S to
SW winds are in this convection between 72W and the surface
trough.

A 1017 mb surface low near 25N66W is along a N-S oriented trough
from 20N65W to 28N66W. The low shows up well in the latest ASCAT
data. Strong E winds are north of the low from 27N-29N between
63.5W-66W. Scattered moderate showers are within 120 nm of low.
A small mid to upper-level trough just NE of the Leeward Islands
is giving way to an area of scattered moderate and isolated
strong convection from 19N-23N between 56W-59W. Additional
showers and tstorms are seen from 14N-19N between 54W-58W. A
surface trough extends from 30N48W to 23N51W with isolated
showers. Fresh NE winds are seen from 29.5N-32N between 50W-53W.

A large upper-level low centered near 26N35W is part of a
Tropical Upper-Tropospheric Trough (TUTT) with axis from 31N32W
to 26N35W to 17N43W to Trinidad to the south-central Caribbean.
As a result of the upper-trough, scattered showers and isolated
tstorms cover much of the area from 16N-31N between 25W-38W. A
surface trough is from 18N37W to 09N39W. Scattered showers are
near the trough axis. In the far E Atlantic, strong N to NE winds
are near the Canary Islands and off the coasts of Morocco and
Western Sahara.

For the forecast, moderate to fresh winds are expected northeast
of the Bahamas this weekend as a surface trough moves across the
western Atlantic. A cold front will move east of Florida on Wed,
then begin to weaken as it reaches from near 31N75W to South
Florida Wed night.

$$
Hagen
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