[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 010003
TWDAT

Tropical Weather Discussion
NWS National Hurricane Center Miami FL
805 PM Fri Jul 31 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
2345 UTC.

...SPECIAL FEATURES...

Hurricane Isaias is centered near 22.9N 75.9W at 01/00000 UTC or
about 150 nm SSE of Nassau, Bahamas and 270 nm SE of Freeport
Grand Bahama Island. Isaias is moving NW or 315 degrees at 13
kt. The estimated minimum central pressure is 987 mb. The
maximum sustained wind speeds are 70 kt with gusts to 85 kt.
GOES-16 satellite imagery shows scattered moderate to strong
convection within 120 nm of the center in the northern semicircle
and within 60 nm of the center in the SW quadrant. Similar
convection is in an outer band within 45 nm of line from 21N74W
to 22N73W to 24N73W. Scattered moderate to isolated strong
convection is elsewhere from 21N to 25N between 72W-74W. This
convection is impacting the southeastern Bahamas and is gradually
spreading northwestward to over the lower part of the Central
Bahamas. Scatterometer data from this afternoon showed a broad
area of 20-30 kt winds covering the area from 19N-26N between
67W-79W. Latest altimeter data passes highlighted seas to 8 ft as
far north as 28N between 70W-77W. Maximum sea heights are up to
28 ft near the center of Isaias. Isaias is forecast to continue
in a general northwestward motion with some decrease in forward
speed for the next day or so, followed by a turn toward the
north-northwest by late Sun. On this forecast track, the center
of Isaias will be near the central Bahamas tonight, and move near
or over the NW Bahamas Sat and near the east coast of the
Florida peninsula Sat afternoon through Sun.

Please read the latest HIGH SEAS FORECAST issued by the National
Hurricane Center at website-
https://www.nhc.noaa.gov/text/MIAHSFAT2.shtml and the latest
Isaias NHC Forecast/Advisory and Public Advisory at
www.hurricanes.gov for more details.

Tropical Depression Ten in the far eastern Atlantic is centered
near 15.9N 20.0W at 01/0000 UTC or about 230 nm east of the Cabo
Verde Islands moving N or 355 degrees at 8 kt. The estimated
minimum central pressure is 1007 mb. The maximum sustained wind
speeds are 30 kt with gusts to 40 kt. GOES-16 satellite imagery
shows scattered moderate to isolated strong convection within 120
nm of the center in the NW quadrant. Tropical Depression Ten is
forecast to turn toward the northwest tonight, followed by a turn
to the west-northwest and west on Sat and Sat night. On the
forecast track, the center of the depression is expected to pass
north of the northernmost Cabo Verde Islands tonight and Sat. The
depression is forecast to strengthen to a short-lived tropical
storm late tonight near 17.3N 21.0W, with maximum sustained winds
of 35 kt with gusts to 45 kt. Weakening is forecast to begin on
Sat and the system is expected to become a remnant low near
19N26W on Sat night.

Please read the latest Tropical Depression Ten NHC Forecast/Advisory
and Public Advisory at www.hurricanes.gov for more details.

...TROPICAL WAVES...

A far eastern Atlantic tropical wave has its axis along 26W,
from 02N to 18N, moving westward around 10 kt. Scattered moderate
to isolated strong convection is within 120 nm west of the wave
from 09N-11N. Scattered showers and isolated thunderstorms are
within 120 nm east of the wave from 10N to 13N.

A central Atlantic tropical wave has its axis along is along
48W from 02N to 18N, moving westward at 15-20 kt. Scattered
moderate convection is within 120 nm west of the northern part
of the wave from 15N to 18N.

Another central Atlantic tropical wave has its axis along 59W
from 06N to 18N, moving westward at 10-15 kt. There is no
significant convection associated with this wave at this time as
it is being surrounded by a rather dry and stable environment.

...MONSOON TROUGH/ITCZ...

The monsoon trough axis passes through the coastal sections of
Senegal near 16N16W to just south of newly developed Tropical
Depression Ten and continues to 11N130W to 10N40W and to 10N53W,
where latest scatterometer data indicates it transitions to the
ITCZ to just west of the tropical wave that is along 59W.
Scattered moderate convection is within 180 nm south of the
trough between 34W-38W and also between 40W-46W.

GULF OF MEXICO...

Upper-level ridging spans across the Gulf with a weak 1017 mb
surface high pressure center analyzed near 27N89W. A surface
trough is off the Florida west coast along 84W from 24N to 28N.
No shower and thunderstorm activity is noted near this trough. A
surface trough is analyzed over the far western part of the SW
Gulf along a position from 24N98W to just inland the coast of
Mexico at 19N95W. Weakening scattered showers and a few
thunderstorms are seen from 20N to 24N between 92W-97W. Scattered
moderate convection is over the northern Yucatan Peninsula to
along that coast. Some of this activity is weakening with time.
Otherwise, the weak 1017 mb is allowing for generally light to
gentle anticyclonic winds across the basin and rather low seas,
in the range of 2-3 ft are present.

Hurricane Isaias is east of the Gulf basin over the SE Bahamas
near 22.9N 75.9W at 8 PM or about 150 nm SSE of Nassau, Bahamas
and 270 nm SE of Freeport Grand Bahama Island. Isaias is moving
NW or 315 degrees at 13 kt. The estimated minimum central
pressure is 987 mb. The maximum sustained wind speeds are 70 kt
with gusts to 85 kt. Hurricane Isaias will is forecast to be near
the central Bahamas tonight, and move near or over the NW Sat
and near the east coast of the Florida peninsula Sat afternoon
through Sun. Otherwise, mainly gentle winds will continue across
the Gulf waters through early next week as weak high pressure
remains situated over the northern Gulf waters.

CARIBBEAN SEA...

A 1009 mb low is analyzed in the west-central Caribbean near
16N78W with a trough extending northeastward from the low to
eastern Cuba near 20N76W and southwestward from the low to
near 11N82W. A mid to upper-level inverted trough stretches
from just west of Jamaica to near 15N81W and to near 11N82W.
Isolated showers and thunderstorms are noted from 15N to 19N
between 77W-84W. Scattered moderate to isolated strong
convection aided by low pressure over northwestern Colombia
is noted along and to within 60 nm of the Colombia coast between
75W-77W. Moderate to fresh east-southeast winds are occurring
over the northeastern Caribbean as a result of a tighter gradient
there that between Hurricane Isaias and high pressure that
is over the central and western Atlantic. Otherwise, light to
gentle winds are over the western Caribbean. Observed seas range
from 3 to 6 ft with higher seas, up to 8 ft from 15N to 18N
between 64W-80W.

Hurricane Isaias is centered near 22.9N 75.9W at 8 PM or about
150 nm SSE of Nassau, Bahamas and 270 nm SE of Freeport Grand
Bahama Island. Isaias is moving NW or 315 degrees at 13 kt. The
estimated minimum central pressure is 987 mb. The maximum
sustained wind speeds are 70 kt with gusts to 85 kt. Isaias will
continue to pull away from eastern Cuba through tonight and Sat
as it moves across the central Bahamas tonight and the NW Bahamas
Sat. Fresh to strong flow will be south of Hispaniola tonight,
then diminish on Sat. A low pressure trough will bring
increasing winds and seas to the waters north of 15N and east of
60W late Sat night and Sun.

ATLANTIC OCEAN...

See the Special Features section for more information on
Hurricane Isaias and recently formed Tropical Depression Ten.

A trough is analyzed in the central Atlantic along a position
from near 30N54W to 27N57W and to 23N58W. This trough is
supported by a small upper-level low at 29N56W. Isolated
showers are seen within about 90 nm either side of the trough.
High pressure dominates the basin, with high center of 1022 mb
near 32N41W and 29N42W and a 1021 mb high center at 32N53W.
Outside Isaias, the gradient supports generally light to
moderate winds, except for fresh to strong winds south of 26N
between 69W-76W. Seas are in the 5-7 ft range, except for 8-12 ft
seas south of 26N and between 69W-76W.

Hurricane Isaias is centered near 22.9N 75.9W at 8 PM or about
150 nm SSE of Nassau, Bahamas and 270 nm SE of Freeport Grand
Bahama Island. Isaias is moving NW or 315 degrees at 13 kt. The
estimated minimum central pressure is 987 mb. The maximum
sustained wind speeds are 70 kt with gusts to 85 kt. Isaias will
move toward the NW Bahamas near 23.9N 77.2W Sat morning, then
move near the east coast of the Florida peninsula to 25.4N 78.8W
Sat afternoon, 26.8N 79.9W Sun morning, 28.3N 80.4W Sun
afternoon, and weaken to a tropical storm near 30.0N 80.4W Mon
morning. Isaias will then accelerate north of the area to near
32.5N 79.4W by Mon afternoon. Very large seas attributed to
southeast swell are expected over a large portion of the SW North
Atlantic waters near and offshore of the Bahamas tonight into
Sat. Swell associated with Isaias will spread northward across
the waters west of 75W Sat night through Sun night, then move
north of the region early next week.

$$
Aguirre
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