[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 252149
TWDAT

Tropical Weather Discussion
NWS National Hurricane Center Miami FL
0005 UTC Mon Jul 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 1800 UTC surface analysis and satellite imagery through
2130 UTC.

...SPECIAL FEATURES...

A 1012 mb low is centered near 30N79W. An Air Force Reserve reconnaissance
aircraft flying over the low pressure found fresh to strong winds
near the center. A recent scatterometer satellite pass showed
mainly fresh winds extending well to the north of the low.
Disorganized shower and thunderstorm activity persists mainly over
the southern part of its circulation. Environmental conditions
are marginally conducive for development, and there is a medium
change a tropical depression could still form later today or
early Monday while the low drifts westward or west-northwestward
toward the northeast coast of Florida. Interests in Florida should
continue to monitor the progress of this system. Please read the
latest Tropical Weather Outlook at hurricanes.gov for more
information.

Heavy rainfall is expected to continue in Southern Central
America, particularly in Panama and Costa Rica and perhaps southern
Nicaragua. High moisture content, persistent monsoon flow, and
favorable conditions aloft will continue to support scattered to
numerous strong convection capable of producing torrential rain
through Monday. Heavy rainfall in these areas could cause
significant flooding and mudslides.

...TROPICAL WAVES...

An Atlantic tropical wave is near 23W/24W from 05N to 20N, moving
westward at 10 kt. Scattered moderate convection is noted from
07N to 09N between 21W and 24W.

An Atlantic tropical wave along 579 south of 12N moving west at
15-20 kt, moving through Guyana and approaching Barbados. There
is reasonable evidence of this wave in Hovmoller diagrams going
back several days. Recent satellite- derived wind data from the
lower levels of the atmosphere hints the wave is restricted to the
deep tropics. Scattered moderate convection is evident from 08N
to 12N between 52W and 60W.

A Caribbean Sea tropical wave is along 73W from central
Hispaniola to northeast Colombia, moving W at 10 kt. The tropical
wave is moving west of an upper level low centered off northern
Haiti. Dry, subsident air in the northerly flow on the west side
of this upper low, along with lingering, dry Saharan air, are
inhibiting any major convection near the tropical wave.

A Caribbean Sea tropical wave is near 82W from western Cuba to
western Panama, moving W at 10 to 15 kt. Convection associated
with this wave is confined to near the monsoon trough, S of 12N
and is described below.

...MONSOON TROUGH/ITCZ...

The monsoon trough enters the Atlantic Ocean along the coast of
Senegal near 13N17W to 11N18W to 08N35W. The ITCZ continues from
08N35W to 08N52W. No significant convection is evident along
these features at this time. The eastern Pacific monsoon trough
extends from off the coast of Colombia near 12N73W to near the
Costa Rica/Panama border near 10N82W. Scattered moderate
convection is noted within 60 nm either side of this monsoon
trough axis, with numerous moderate to heavy rainfall observed
over western Panama at this time.

...GULF OF MEXICO...

A surface trough extends from Cape Sable in southwest Florida to
the central Gulf near 26N90W. Farther west, 1016 mb high pressure
is centered near 28N94W. A few showers are likely ongoing the
trough. Light to gentle winds and slight seas prevail across the
Gulf.

For the forecast, showers and thunderstorms will persist
south of the trough, forecast to drift northward over the next
couple of days as the low pressure located about 130 nm east of
Daytona Beach, Florida, drifts westward or west-northwestward
toward the northeast coast of Florida. At the same time, the
high pressure will move toward SE Louisiana.

...CARIBBEAN SEA...

Refer to the Tropical Waves section above for more information on
convection across the Caribbean Basin.

Overall, a relatively benign pattern continues across the
Caribbean today. There are scattered showers and thunderstorms
over the far southwest Caribbean, south of 12N, from western
Colombia to Costa Rica, to include the coast of Panama, posing a
risk of flooding. A few showers are possible off the coast of
northeast Colombia and northwest Venezuela, as far east as
Curacao. But no significant showers or thunderstorms are noted
elsewhere. Light breezes and slight seas are noted over the
northwest Caribbean, and gentle to moderate trade winds with 2 to
4 ft seas elsewhere. The trade wind flow is lighter than usual,
related in part to a relatively weaker subtropical ridge north of
the area.

For the forecast, the current pattern will continue past mid
week, supporting gentle to moderate trade winds across the basin
through Thu, with the exception of moderate to locally fresh winds
near the coast of Colombia. Winds will increase across the E and
central Caribbean Thu night into Fri as the Atlantic ridge builds
westward in the wake of the low pressure located E of Florida.

ATLANTIC OCEAN...

See the Special Features section for more information on the low
east of Florida and the Tropical Waves section for information on
the wave off the African coast.

Clusters of showers and thunderstorms are noted over the Atlantic
north of Puerto Rico and east of the Bahamas, specifically from
20N to 25N between 62W and 68W. This activity is tied to upper
level divergence between an upper low over the Turks/Caicos
Islands and an upper trough in the northwest flow aloft farther to
the northeast over the central Atlantic. A weak surface trough is
analyzed in this area of convection, from 22N69W to 28N63W.
Another trough is analyzed farther east, from 22N to 28N between
45W and 50W. The troughs are south of a 1028 mb high pressure
near 39N35W. Earlier scatterometer satellite passes indicated
fresh E winds near western trough. This is evidence of a broader
area of fresh winds from 18N to 25N between 55W and 70W between
the trough and the ridge, with seas estimated to be 5 to 7 ft.
Similarly moderate to fresh winds and 5 to 7 ft seas are likely
between the eastern trough and the ridge, from 25N to 30N between
35W and 50W. Aside from fresh to strong winds near the Cape Verde
Islands and off Morocco, this pattern is support generally
moderate trade winds and 4 to 6 ft seas across the basin.

For the forecast for the waters west of 65W, other than what is
described in the Special Features section above regarding the low
pressure off northeast Florida, the area of showers and
thunderstorms will move northward across the waters east of the
Bahamas through Tue.

$$
Christensen
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