[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 101158
TWDAT

Tropical Weather Discussion
NWS National Hurricane Center Miami FL
1205 UTC Sat Oct 10 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 0600 UTC surface analysis and satellite imagery through
1130 UTC.

...SPECIAL FEATURES...

Tropical Storm Delta is inland near 31.8N 91.8W or about 45 miles
south-southeast of Monroe, Louisiana. Estimated minimum central
pressure has risen to 990 mb. Maximum sustained winds have
diminished to 40 kt with gusts to 50 kt. Satellite imagery shows
decreasing scattered moderate to isolated strong convection
removed to the northeast of the center over central Mississippi
and into western Alabama. Widespread rain areas with embedded
scattered showers and possible isolated thunderstorms are over
northern and central Arkansas and spreading eastward to western
and central Tennessee. A 60 to 75 nm wide band of scattered
showers and associated with Delta extends from south-central
Alabama near 31N87W southwestward to Pensacola and to the Gulf
waters near 28N89W. The west side of this band extends to the
Mobile Bay area. Delta is expected to produce an additional 2 to 5
inches of rain, with isolated storm totals of 10 inches for
northern Louisiana, southeast Arkansas, and western Mississippi,
These rainfall amounts will lead to flash, urban, small stream,
and minor river flooding. Delta will begin a motion toward the
northeast later today and continue through Sun night. On the
forecast track, the center of Delta will move across northeastern
Louisiana this morning, then across northeastern Louisiana this
morning and then across northern Mississippi and into the
Tennessee Valley later today and Sun. Delta is forecast to weaken
to a tropical depression this afternoon over west- central
Mississippi. Please read the latest NHC Public Advisory at
https://www.nhc.noaa.gov/text/MIATCPAT1.shtml and Forecast/
Advisory at https://www.nhc.noaa.gov/text/MIATCMAT1.shtml for more
details.

...TROPICAL WAVES...

A tropical wave has its axis along 37W from 02N-17N, moving
westward at 15-20 kt. Scattered moderate to isolated strong
convection is in an increasing trend in an inverted-V shape
pattern noted across the wave from 09N to 14N between 33W and 40W.
Scattered moderate convection is from 15N to 19N between 35W-
39W. Environmental conditions could be conducive for some slow
development of this system later this weekend or early next week
as it moves westward. Upper-level winds are forecast to become
unfavorable for further development by the middle of next week.
This system has a low chance of tropical cyclone formation within
48 hours and through 5 days.

An eastern Caribbean tropical wave has its axis along 67W and
south of 21N, moving westward at 10-15 kt. Scattered showers and
isolated thunderstorms are increasing from north to 15N to Puerto
Rico and between 65-70W.

A western Caribbean tropical wave has its axis along 79W south
of 20N. It is moving westward at 15 kt. Scattered showers and
isolated thunderstorms are within 180 nm east of the wave from 11N
to 14N and near the northern part of the wave from 17N to 20N
between 77W-79W.

...MONSOON TROUGH/ITCZ...

The monsoon trough axis extends from  enters the Atlantic Ocean
near the border of Senegal and Mauritania near 16N17W and drops
southwestward to 10N23W and to 07N30W, where overnight
scatterometer data indicates that it transitions to the ITCZ
to 07N35W. It resumes west of a tropical wave at 07N40W to 09N50W
and to 09N60W. Scattered moderate convection is within 120 nm
north of the ITCZ between 40W-43W and between 51W-54W. Similar
activity is within 60 nm south of the trough between 25W-27W.

GULF OF MEXICO...

Now that Delta has moved inland and continues to pull farther
away from the area, relatively weak high pressure from the western
Atlantic has settled in over the area. A slackening of the
gradient will allow for winds in the northern Gulf of Mexico to
decrease to below 20 kt by early this afternoon and seas there
will gradually subside to below 8 ft late this afternoon.

Scattered showers and isolated thunderstorms have developed just
north of the Yucatan Channel from 22N to 24N between 85W-86W.

The forecast calls for Delta to continue to move well inland
through late Sun night and dissipate Mon afternoon. In its wake,
weak high pressure will continue to build across the area into
early next week. A weak trough associated with the remnants of
Delta will move across the north-central Gulf Sat and Sat night
and across the eastern Gulf Sun and Sun and Sun night. Swell from
Delta will continue over most of the area through the weekend.

CARIBBEAN SEA...

The only significant shower and thunderstorm activity currently
over the Caribbean Sea are associated with the two tropical waves
over the basin. See the tropical waves section above for details.
An overnight ASCAT pass showed fresh trade winds in the south-
central Caribbean and to the north of eastern Honduras. Gentle to
locally moderate winds cover the remainder of the basin.

The forecast calls for the fresh trade winds over the south-
central Caribbean to pulse to strong speeds at night through Mon.
Gentle to moderate trade winds elsewhere will change little
through the period. Seas will be in the slight range, except for
moderate seas in the south-central Caribbean into next week. The
tropical wave that is presently along 37W may bring higher winds
and building seas to the Atlantic waters east of the Leeward
Islands Tue through Wed night.

ATLANTIC OCEAN...

The southwest periphery of high pressure centered well north of
the area near 37N67W extends south-southwestward toward the
western half of the area. The gradient between the high pressure
and Delta well northwest of the area is allowing for fresh
southeast winds to occur over the northwest waters. These winds
will diminish to moderate speeds Sun as Delta pulls farther to the
northeast.

Scattered showers and thunderstorms are from 21N to 25N between
76W-79W, including the central section of Cuba. Similar activity
moving northwestward is north of 25N between 78W and the Florida
coast. This activity is expected to increase today as very moist
southerly flow between the western Atlantic high pressure and
Delta well to northwest of the area is pulled northward leading to
more shower and thunderstorm activity over far western waters.

A sharp upper-level trough stretches from near 32N53W to near
23N56W. At the surface, a weak cold front extends from a
1015 mb low just north of the area at 33N52W southwest to
27N62W. A trough ahead of it is along a position from 32N51W to
25N51W and to just northeast of Puerto Rico. Scattered moderate to
strong convection is within 180 nm southeast and south of the
surface trough between 56W-62W. Scattered showers and isolated
thunderstorms are from 18N to 22N between 62W-68W and from 19N to
20N between 61W-62W. Another surface trough is over the central
Atlantic from near 28N41W to 21N42W. Scattered showers and
thunderstorms are within 180 nm east of the trough from 22N to
25N. Isolated weak showers moving westward are elsewhere from 12N
to 20N between 45W-61W. A far eastern Atlantic trough extends
from 31N26W to 27N23W as was highlighted by an overnight ASCAT
pass. Over the far eastern part of the area, moderate to fresh
trade winds are from 14N-25N between 40W and the coast of Africa,
while fresh to locally strong northeast winds are from 18N-25N
east of 27W. Generally, gentle to moderate winds under a weak
gradient are over the remainder of the tropical and subtropical
Atlantic between 40W-75W.

As for the forecast, high pressure over the northern and central
waters that extends southwestward toward western half of the area
will begin to shift east-northeast tonight through Mon in
response to a weak trough that will move over the northwest part
of the area. The trough will reach from near 31N74W to the NW
Bahamas and to S Florida on Wed.

$$
Aguirre
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