[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 261748
TWDAT

Tropical Weather Discussion
NWS National Hurricane Center Miami FL
1805 UTC Thu Aug 26 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 1200 UTC surface analysis and satellite imagery through
1700 UTC.

...SPECIAL FEATURES...

Tropical Depression Nine formed this morning in the western
Caribbean Sea. As of 1800 UTC, T.D. Nine was centered near 17.5N
79.5W, or about 85 nm SW of Negril, Jamaica, moving NW at 11 kt.
Maximum sustained winds are near 30 kt with gusts to 40 kt.
Minimum central pressure is 1005 mb. Peak seas are 10 ft. Numerous
moderate and scattered strong convection is within 330 nm of the
center in the NE semicircle, including over Jamaica, southeastern
Cuba and the western part of the peninsula in SW Haiti. Scattered
moderate convection is within 300 nm SE to S of the center. On the
forecast track, the depression will pass near or over the Cayman
Islands tonight, the Isle of Youth and western Cuba Friday, and
move over the southeastern and central Gulf of Mexico Friday night
and Saturday. The system is forecast to approach the U.S.
northern Gulf coast on Sunday. Steady strengthening is forecast
during the next few days. The depression is expected to become a
tropical storm tonight, and become a hurricane when it is near
western Cuba or over the southeastern Gulf of Mexico. Additional
strengthening is likely over the Gulf of Mexico and the system
could be near major hurricane strength when it approaches the
northern Gulf coast. Tropical storm conditions are expected in the
Cayman Islands tonight, and are expected to reach the Isle of
Youth and portions of western Cuba on Friday. Heavy rainfall is
expected to produce significant flooding across the Cayman
Islands, western Cuba, the Isle of Youth and the northeastern
Yucatan Peninsula. Please see the latest NHC Public Advisory at
https://www.nhc.noaa.gov/text/MIATCPAT4.shtml and
Forecast/Advisory at https://www.nhc.noaa.gov/text/MIATCMAT4 for
more details. Please refer to the NHC High Seas Forecasts at
https://www.nhc.noaa.gov/text/MIAHSFAT2.shtml for marine impacts.

A trough of low pressure located over the central Atlantic extends
from 25N61W to 1014 mb low pressure near 31N55W to 37N51W.
Scattered moderate and isolated strong convection is noted from
26.5N-33N between 51W-60W. Environmental conditions are forecast
to be generally conducive for development, and a tropical
depression is likely to form this weekend. The system is expected
to move slowly eastward during the next day or two, but a faster
northeastward motion is forecast to begin on Sunday. Please refer
to the latest Tropical Weather Outlook at www.hurricanes.gov for
more details.

A tropical wave located along 40/41W over the central tropical
Atlantic is producing disorganized numerous moderate and scattered
strong convection from 10N-15N between 39W-44W. Environmental
conditions are expected to be conducive for development during the
next few days, and a tropical depression is likely to form over
the weekend while the system moves toward the west-northwest or
northwest at 10 to 15 kt. The disturbance is forecast to turn
northward early next week. The chance of tropical cyclone
formation within 48 hours is medium. Please refer to the latest
Tropical Weather Outlook at www.hurricanes.gov for more details.

...TROPICAL WAVES...

A tropical wave is along 21W S of 18N, moving W at 10 kt.
Isolated showers are seen near where the wave intersects the
monsoon trough.

Please see the Special Features section above for details on the
tropical wave along 40/41W.

The axis of a tropical wave is along 59W from 07N-19N, moving W
at 10 to 15 kt. Isolated showers are seen south of 10N near the
wave axis.

The axis of a tropical wave is along 80W S of 16N, moving W at 10
kt. Numerous moderate and scattered strong convection is seen near
where the wave intersects the east Pacific monsoon trough, from
09N-12N between 79W and the coasts of western Panama, Costa Rica
and SE Nicaragua.

...MONSOON TROUGH/ITCZ...

The monsoon trough enters the Atlantic Ocean near the border of
Senegal and Guinea-Bissau near 12N17W to 14N34W to 12N41W to
08N46W to 07N52W. The ITCZ continues from 07N52W to 09N58W. Aside
from convection noted in the sections above, scattered moderate
isolated strong convection is observed from 10N-12N between 14W-
19W and from 06.5N-09N between 42W-56W.

GULF OF MEXICO...

A surface trough over the northwest Gulf of Mexico is producing
numerous moderate and isolated strong convection from 27N-29.5N
between 91W-96.5W. Another surface trough is located over the
eastern Gulf of Mexico extending from Tampa Bay to the western tip
of Cuba. Scattered moderate convection is noted from 23N-28N
between 82.5W-85W. A recent ASCAT pass shows fresh winds on both
sides of the trough axis over the eastern Gulf of Mexico and the
Yucatan Channel. Gentle winds and mainly fair weather prevail over
the southwest Gulf, except for isolated tstorms noted near the
coast of Veracruz. Seas are currently 1 to 3 ft over the western
Gulf. Seas are 4-6 ft in the Florida Straits, Yucatan Channel and
southeast Gulf, due to the aforementioned surface trough and fresh
winds.

For the forecast, Tropical Depression Nine will strengthen to a
tropical storm in the northwest Caribbean Sea near 18N80W this
evening, cross western Cuba Fri evening, strengthen to a hurricane
over the Gulf of Mexico near 24N86W Sat morning, be near 28N90W
Sun morning as a strong hurricane, and move inland over Louisiana
Mon morning. For more details on Tropical Depression Nine, see the
special features section above.

CARIBBEAN SEA...

Please see the special features section above for details on
Tropical Depression Nine, currently located 85 nm SW of Negril,
Jamaica. Please see the tropical waves section above for details
on the tropical wave along 80W. The eastern Caribbean east of 70W
is free of any significant precipitation areas. Moderate to fresh
trade winds prevail over the area, with 4 to 6 ft seas. Farther
west, the latest ASCAT pass shows strong E to SE winds just south
of Haiti. In the northwest Caribbean, conditions are quiet west of
83W for the moment, except for the Yucatan Channel and just east
of the Yucatan Peninsula, where fresh NE winds and seas of 4 to 6
ft are noted. Scattered moderate showers are seen within 60 nm of
the Yucatan coast from the Belize border to Cozumel.

For the forecast, Tropical Depression Nine will strengthen to a
tropical storm in the northwest Caribbean Sea near 18N80W this
evening, move near or over western Cuba near 22.5N 84W Fri
evening, then strengthen to a hurricane over the Gulf of Mexico
near 24N86W Sat morning. Tropical storm force winds and seas over
12 ft will exit the northwest Caribbean by Sat morning. Moderate
to fresh winds are expected elsewhere through the forecast period,
except for locally strong winds in the south-central Caribbean.

ATLANTIC OCEAN...

Please see the special features section above for details on a
trough of low pressure over the central Atlantic near 31N55W,
which has the potential for tropical cyclone development.

An upper-level trough over Florida and the eastern Gulf of Mexico
is inducing upper-level diffluence to the east of northern
Florida. Numerous moderate and isolated strong convection is noted
east of northern Florida from 27.5N-31N between 74W-81W. A recent
ASCAT pass shows fresh east winds occurring in the same area. Seas
are 5 to 7 ft in this area. Farther south, scattered showers
extend off the north coast of eastern Cuba south of 23N between
74W-80W, associated with the outermost rain bands of T.D. Nine.
Fresh trade winds prevail from the Bahamas to Cuba and westward
through the Florida Straits. Gentle to moderate wind speeds
prevail farther east from 20N-26N between 50W-70W, where seas are
4 to 5 ft. In the northeast portion of the area, a cold front
extends from 31N26W to a 1014 mb low pressure near 29N29W. A
surface trough extends from the low SW to 23N35W. Fresh NE winds
and 6 to 8 ft seas are west of the low and surface trough. A
recent ASCAT pass shows fresh to strong trades in the area from
12N-20N between 37W-51W, where seas are 7 to 10 ft.

For the forecast west of 65W, high pressure located just N of the
forecast region near 34N70W will dominate the western Atlantic
through Mon, supporting mainly moderate E to SE winds. Fresh to
locally strong winds are expected to pulse N of Hispaniola during
the evening hours through Sat night.

$$
Hagen
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