[Tropical] Tropical Weather Discussion

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AXNT20 KNHC 012327
TWDAT

Tropical Weather Discussion
NWS National Hurricane Center Miami FL
805 PM Sat Aug 01 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 1800 UTC surface analysis and satellite imagery through
2315 UTC.

...SPECIAL FEATURES...

Recently downgraded Tropical Storm Isaias is centered near 25.1N
78.7W at 01/2100 UTC or about 100 nm southeast of Fort
Lauderdale, Florida or 80 nm south of Freeport, Grand Bahama
Island. Isaias is moving NW at 9 kt. The estimated minimum
central pressure is 993 mb. Maximum sustained winds have
diminished to 60 kt with gusts to 75 kt. Recent and current
GOES-16 satellite imagery shows that numerous strong convection
is rapidly increasing within 120 nm of the center in the NE
quadrant. This is occurring after earlier convection had weakened
significantly. Scattered moderate to isolated strong conevection
trails Isaias from 21N to 25N between 75W-76W and from 25N to
27N between 75W-77W. Maximum wave heights generated by the
cyclone are at a peak of 18 ft. Isaias is forecast to continue on
a general northwestward motion with some some decrease in
forward speed is expected for the next day or so, followed by a
north-northwestward motion by late Sun and a turn toward the
north and north-northeast on Mon and Tue with an increase in
forward speed. On the forecast track, the center of Isaias will
approach the southeastern coast of Florida tonight and move near
or along the east coast of Florida Sun and Sun night. On Mon and
Tue, the center of Isaias will move quickly from offshore of the
coast of Georgia into the southern mid-Atlantic states.

Please read the latest NHC Public Advisory at
https://www.nhc.noaa.gov/text/MIATCPAT4.shtml, and the
Forecast/Advisory at
https://www.nhc.noaa.gov/text/MIATCMAT4.shtml, for more details.

Tropical Depression Ten is centered near 19.2N 23.5W at 01/2100
UTC or about 195 nm north of the Cabo Verde Islands. Tropical
Depression Ten is moving NW or 305 degrees at 11 kt. The
estimated minimum central pressure is 1009 mb. Maximum sustained
winds are 25 kt with gusts to 35 kt. Satellite imagery shows that
the depression is devoid of deep convection. The depression is
noted as a poorly defined swirl of broken and mid-level clouds,
with possible isolated showers. The cyclone is moving over
cool waters and while at the same time is surrounded by a dry
atmospheric environment, therefore, deep convection is unlikely
to re-develop. It is forecast to turn west-northwestward and
become a remnant low tonight and dissipate to the north of the
Cabo Verde Islands tonight or on Sun.

Please read the latest NHC Public Advisory at
https://www.nhc.noaa.gov/text/MIATCPAT5.shtml, and the
Forecast/Advisory at
https://www.nhc.noaa.gov/text/MIATCMAT5.shtml, for more details.

...TROPICAL WAVES...

A far eastern Atlantic tropical wave has its axis along 33W from
01N to 16N. It is moving westward at 15-20 kt. Scattered moderate
to isolated strong convection is within 120 nm west of the wave
from 09N to 11N. Scattered moderate convection is behind the wave
along the monsoon trough within 30 nm of 09N32W.

A central Atlantic tropical wave has its axis along 57W south of
21N moving westward 15-20 knots. Since this wave is within close
proximity to an upper-level trough to its northwest, this set-up
under divergence aloft east of the upper-level trough is conducive
for the development of scattered to numerous showers and
thunderstorms along and near the wave. The current observed
activity consists of the scattered moderate to isolated strong
type intensity from 15N to 22N between the wave and 53W and also
from 21N to 24N between 55W-60W. This system is forecast to move
through environmental conditions that favor for it to develop
within the next couple of days. A tropical depression could form
from it early next week. Please monitor the latest Tropical
Weather Outlooks for future updates on this system.

The earlier tropical wave that was south of the Bay of Campeche
has moved further into the eastern Pacific Ocean and is described
in the Eastern Pacific Tropical Weather Discussion.

...MONSOON TROUGH/ITCZ...

The monsoon trough axis extends from the coast of Senegal near
13N17W to 10N30W to 07N44W. Latest scatterometer data indicates
the ITCZ begins near 09N55W and continues to just inland the
coast of Venezuela near 06N54W. Scattered moderate convection
from 07N to 12N between 16W-21W. Otherwise, only rather weak
isolated showers and thunderstorms are observed along and near
the monsoon trough and ITCZ.

GULF OF MEXICO...

Upper-level ridging prevails across the Gulf with a 1015 mb
surface high analyzed near 28N91W. A surface trough is analyzed
just inland the Florida coast from near Naples to just of Tampa
and to near 30N82W. Isolated showers and thunderstorms are
south of 27N and east of 83W. A mid-level trough is pushing
eastward across the southern Plains and approaching the Gulf. As
a result, scattered showers and thunderstorms are along and just
inland the Texas coast and the southwest Louisiana coast. N of
27N between 91W-96W. Light to gentle anticyclonic wind flow is
noted across the basin. Observed wave heights throughout the
basin remain rather low in the 2-3 ft range.

Mainly gentle winds will prevail across the Gulf waters through
the middle of next week as weak high pressure over the northern
Gulf drifts southward.

CARIBBEAN SEA...

A surface trough extends across the northwestern Caribbean from
near 21N80W to along the coast of the border between Honduras
and Nicaragua to 10N83W. Only isolated showers and thunderstorms
are noted from 18N to 21N between 78W-81W. The earlier scattered
moderate convection in the southwestern Caribbean has dissipated.
Otherwise, quick moving showers, in streamer formation, are
moving westward across the Lesser Antilles to across the most of
the eastern Caribbean and waters. Scattered showers and isolated
thunderstorms also moving quickly westward are seen over the
waters near and adjacent to Puerto Rico and the U.S. Virgin
Islands.

Moderate to fresh east-southeast winds are over the eastern
Caribbean, with light to gentle winds in the western basin. Wave
heights range from 3-6 ft, except higher wave heights of up to 7
ft in the central Caribbean where fresh trades are present.

Tropical Storm Isaias is centered near 25.1N 78.7W 993 mb at 5
PM EDT moving NW at 9 kt. Maximum sustained winds 60 kt gusts 75
kt. Isaias will strengthen to a hurricane tonight while moving
away from the region toward the east coast of Florida. Fresh
trade winds will persist over the central Caribbean waters
through the middle of next week. A tropical wave will bring
increasing winds and seas to the Tropical N Atlantic waters
north of 15N and east of 60W tonight through Sun.

ATLANTIC OCEAN

See the special features section for information on Tropical
Storm Isaias and on Tropical Depression Ten.

Upper-level ridging continues across the Atlantic anchored by an
upper-level anticyclone situated near 28N49W. At the surface,
a 1024 mb high center is analyzed near 29N46W, with a ridge
extending west-northwest to near 32N81W. An eastern Atlantic
surface trough is along a position from near 31N31W to 25N32W.
No significant convection is associated with it. The gradient
in place generally supports light to moderate winds across the
area, with the exception of fresh to strong winds over the
waters south of 27N and west of 70W. Wave heights range 5-8 ft
across most of the area, with higher wave heights of 7-12 ft
seas in the SW northern Atlantic outside the tropical storm
force winds associated with Tropical Storm Isaias.

Tropical Storm Isaias is centered near 25.1N 78.7W 993 mb at 5
PM EDT moving NW at 9 kt. Maximum sustained winds 60 kt gusts 75
kt. Isaias will strengthen to a hurricane while it moves near the
east coast of the Florida peninsula to 26.1N 79.4W Sun morning
and to 27.4N 80.1W Sun afternoon. Isaias will weaken to a
tropical storm near 28.8N 80.7W Mon morning, accelerate northward
and move to near 30.7N 80.6W Mon afternoon, then pass to the
north of the area near 33.4N 79.1W Tue morning. Large seas will
remain tonight near and offshore of the Bahamas, then spread
northward across the waters west of 75W through Mon. Winds and
seas will diminish Tue through Thu as Isaias moves away from the
region.

$$
Aguirre
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