[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 251805
TWDAT

Tropical Weather Discussion
NWS National Hurricane Center Miami FL
1805 UTC Wed Aug 25 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
1705 UTC.

...SPECIAL FEATURES...

A robust tropical wave over the central Caribbean Sea is
producing a large area of disorganized showers and
thunderstorms, mainly south of 17N and between 71W to 78W. A
broad area of low pressure is expected to form over the SW
Caribbean Sea during the next day or so. A recent scatterometer
satellite pass indicate fresh to strong trades over the NE
quadrant of the disturbance. Environmental conditions are
forecast to be conducive for development, and a tropical
depression or tropical storm is likely to form late this week or
over the weekend. The system is expected to move northwestward
over the northwestern Caribbean Sea and near or across the Yucatan
Peninsula of Mexico on Friday and into the Gulf of Mexico this
weekend where conditions are expected to be favorable for
additional development. This system has a medium chance of
development within the next 48 hours. Refer to the National
Hurricane Center Tropical Weather Outlook at www.hurricanes.gov
and the High Seas Forecast at www.hurricanes.gov/marine for more
details.

A 1012 mb low pressure positioned near 26N54N and a surface trough
that extends from 21N55W to a dissipating cold front near 33N49W
results in a large area of showers and thunderstorms, especially
to the NE and SW of the system. Most of the activity is
concentrated from 23N to 34N and between 50W and 58W. Strong to
near-gale SE winds are noted in the latest satellite derived wind
data in the eastern quadrant of the disturbance. Seas of 8-12 ft
are noted from 25N to 30N and between 50W to 53W. Only slow
development of this system is expected during the next day or so
due to unfavorable upper-level winds. Afterwards, environmental
conditions are forecast to become more conducive for development,
and a tropical depression is likely to form late this week or this
weekend while the system turns eastward over the open central
Atlantic. This system has a medium chance of development
within the next 48 hours. Refer to the National Hurricane Center
Tropical Weather Outlook at www.hurricanes.gov and the High Seas
Forecast at www.hurricanes.gov/marine for more details.

Heavy Rainfall in southern Central America: A broad area of low
pressure is expected to form over the SW Caribbean Sea later this
week, resulting in an increase in moisture and unstable conditions
across southern Central America. Heavy rainfall is expected
across eastern Nicaragua, Costa Rica, Panama, and NW Colombia
through early in the weekend. The heaviest precipitation is
forecast to affect southern Costa Rica and western Panama late
this week. These rains could cause significant flooding and
mudslides in some areas. Please, monitor the latest forecasts from
your local or national meteorological service.

...TROPICAL WAVES...

An Atlantic tropical wave has its axis along 34W, south of 19N,
and it is moving W at 10 to 15 kt. A 1008 mb low pressure is along
the wave axis near 11N34W. Scattered moderate to isolate strong
convection is noted in the northern semicircle of the system from
12N to 16N and between 31W and 36W. Fresh to strong NE winds are
noted north of broad center on a recent scatterometer satellite
pass. Some development of this system is possible over the next
several days over the eastern tropical Atlantic. Upper- level
winds are forecast to become less conducive for development by
this weekend. For more details, please see the latest Tropical
Weather Outlook.

Another Atlantic tropical wave has its axis along 54W, south of
19N, and it is moving W at around 15 kt. A few showers are noted
within 200 nm E of the wave from 08N to 10N.

...MONSOON TROUGH/ITCZ...

The monsoon trough enters the Atlantic Ocean through Senegal near
15N17W and continues to 14N29W and to 07N40W. The ITCZ then
extends from 07N41W to 06N47W. Aside from convection noted in the
tropical waves section, scattered moderate isolated strong
convection is observed within 90-120 nm of the coast of Africa
from 04N to 13N. This convective activity is likely ahead of the
next tropical wave approaching the W coast of Africa.

...GULF OF MEXICO...

Weak high pressure over the southern United States maintains
mainly gentle to moderate easterlies across the Gulf of Mexico.
However, moderate to locally fresh trades are noted in the
Florida Straits and NE Gulf based on recent satellite derived wind
data. Moisture in the N Gulf associated with a weak surface
trough, extending from SW Alabama to 27N94W, is interacting with
an upper level trough over the NW Bahamas, resulting in scattered
showers north of 25N and from the W Florida coast to near the
trough axis. Another weak surface trough is noted in the Bay of
Campeche and a few showers are seen near the coast of Veracruz.
The rest of the basin enjoys fairly tranquil weather conditions.
Seas in the SE Gulf and Bay of Campeche are in the 2-4 ft range,
while 1-2 ft are prevalent elsewhere in the region.

For the forecast, a surface trough will move into the eastern Gulf
tonight into Thu morning, bringing fresh NE to E winds.
Otherwise, high pressure pressure will dominate the basin
through Fri, producing mainly gentle to moderate E to SE winds.
Fresh winds will pulse west of the Yucatan Peninsula tonight and
again Thu night. A broad area of low pressure is expected to
form over the southwestern Caribbean Sea over the next day or so.
Environmental conditions are forecast to be conducive for
development, and a tropical depression is likely to form late
this week or this weekend while the system moves northwestward
over the northwestern Caribbean Sea. The disturbance is expected
to move near or across the Yucatan Peninsula of Mexico on
Saturday, and move into the western Gulf of Mexico by Sunday
where conditions could be favorable for additional development to
occur. Expect a large increase in winds and seas Sun and Sun
night over the central and western Gulf.

...CARIBBEAN SEA...

The E Pacific monsoon trough enters the SW Caribbean Sea near the
Nicaragua/Costa Rica border and continues to NW Colombia. The
increase in moisture and instability in the region due to the
interaction between the disturbance discussed in the Special
Features and the monsoon trough is resulting in a large area of
showers and thunderstorms, south of 13N, and from the SE coast of
Nicaragua to NW Colombia. Generally tranquil weather conditions
are observed in the NW and E Caribbean thanks to dry air.

A recent scatterometer satellite pass depicted fresh to strong
trade winds in the central and E Caribbean Sea, mainly between 65W
and 75W. Seas in this area are 5-8 ft. Fresh to locally strong NE
winds were also observed between coast of central Cuba and the
Cayman Islands due to a surface trough that is mostly positioned
over the central Bahamas, but the southern end extends to the NW
Caribbean. Seas in the NW Caribbean and Gulf of Honduras are 3-6
ft. Moderate to locally fresh trades and 5-8 ft seas prevail in
the SW Caribbean.

For the forecast, fresh to locally strong trade winds will dominate
most of the central Caribbean today. A broad area of low pressure
is expected to form over the southwestern Caribbean Sea over the
next day or so from a tropical wave currently located over the
central Caribbean Sea along 74W. Environmental conditions are
forecast to be conducive for development, and a tropical
depression is likely to form late this week or this weekend while
the system moves northwestward over the northwestern Caribbean
Sea. The disturbance is expected to move near or across the
Yucatan Peninsula of Mexico on Saturday, and move into the Gulf of
Mexico by Sunday. Based on the forecast, winds and waves will
likely increase between 78W and the Yucatan Peninsula Fri and Sat.

...ATLANTIC OCEAN...

A sharp and convectively active surface trough extends from the
Bahamas and E Cuba from 28N71W to 19N79W. This system is
interacting with an upper level trough to generate scattered
moderate to isolated strong convection mainly west of the trough
axis to Florida and from 23N to 30N. A recent scatterometer
satellite pass indicate strong to near-gale NE winds from the N
coast of Cuba to 27N and between 72W to the SE coast of Florida.
Seas of 4-7 ft are noted W of 53W. A region of moderate to fresh E
winds is observed NW of the disturbance discussed in the Special
Features, from 15N to 23N and between 28W and 44W. Similar winds
are noted near the coast of Western Sahara. W of 53W, seas are 5-8
ft.

For the forecast W of 65W: A surface trough located over the central and
northwest Bahamas will move into the eastern Gulf of Mexico Thu
morning. Fresh to strong NE winds are expected west of the trough
axis, including the Florida Straits. Otherwise, high pressure
located just N of the forecast region will dominate the SW N
Atlantic through Sat. Fresh to locally strong winds are expected
to pulse N of Hispaniola during the evening hours through Sat
night.

$$
DELGADO
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