[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 291743
TWDAT

Tropical Weather Discussion
NWS National Hurricane Center Miami FL
143 PM EDT Sat Aug 29 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 1200 UTC surface analysis and satellite imagery through
1700 UTC.

...SPECIAL FEATURES...

Atlantic Gale Warning: Meteo France has issued a gale warning for
Agadir, off the coast of Morocco, valid now through 30/0000 UTC.
See http://weather.gmdss.org/II.html for more information.

...TROPICAL WAVES...

An eastern Atlantic tropical wave axis is along 25/26W from
05N-18N, moving W at 5 kt. Scattered moderate convection is
within 120 nm E and 270 nm W of the wave axis from 07N-17N. The
wave will move very slowly W for the next several days. Some
development is possible next week, and there is a medium
chance of tropical cyclone formation in the next 5 days.

A tropical wave located over the central Atlantic, with axis
along 42/43W from 06N-20N is currently in phase with a
surface trough along 44W from 20N-26N. The tropical wave is
moving W at 15-20 kt, while the sfc trough is moving W at 20
kt. Scattered moderate convection is within 210 nm E and 90
nm W of the wave axis from 07N-14N.

A central Atlantic tropical wave axis is along 55/56W south of
19N, moving W at 20 kt. Scattered moderate isolated strong
convection is within 150 nm of the wave axis from 12N-16N. Some
gradual development of this system is possible while it moves W
over the next several days, and it has a low chance of tropical
cyclone formation in the next 2 days. Regardless of development,
this system will likely produce gusty winds and locally heavy
rain across portions of the Windward and Leeward Islands Sunday.

A western Caribbean tropical wave axis is along 83W south of 18N,
moving W at 10-15 kt. Scattered moderate isolated strong
convection is occurring where the wave intersects the east
Pacific monsoon trough, south of 14N between 77W-86W, including
over portions of Nicaragua.

The northern end of a tropical wave is in the SW Gulf of Mexico
from 24N95W extending SSW to Mexico near 18N97W to the Pacific.
The tropical wave is moving W near 10 kt. Low to mid-level
southerly winds to the east of the wave axis are advecting very
moist air into the south-central Gulf of Mexico. Scattered
moderate showers and isolated tstorms are from 21N-25N between
92W-96W.

...MONSOON TROUGH/ITCZ...

The monsoon trough extends from the coast of Mauritania at 20N16W
to the Cape Verde Islands near 16N24W to 13N30W to 13N46W. The
ITCZ extends from 13N46W to 13N53W. The east Pacific monsoon
trough extends from the Gulf of Venezuela near 10N72W to a 1010
mb low near 10N77W to the Costa Rica/Nicaragua border near 11N84W
and west into the eastern Pacific. Aside from the convection
associated with the tropical waves noted above, scattered
moderate isolated strong convection exists south of the monsoon
trough along the W coast of Africa from 08N-15N between 14W-21W.
Scattered showers are seen 30 to 210 nm S of the ITCZ between
46W-53W.

GULF OF MEXICO...

Low to mid-level S-SW winds are advecting very moist air from the
deep tropics, through the south-central Gulf to the NE Gulf and
toward a mid-level trough over the eastern U.S. near the
mid-Atlantic states. The moist air over the Gulf of Mexico shows
up well on TPW imagery. Upper-level diffluence currently over
the NE Gulf of Mexico is fueling numerous moderate isolated
strong convection from 26N-31N between 84W-90W. Strong S-SW
winds at the surface are seen over the NE Gulf with this
activity. Additional convection is over the SW Gulf of Mexico,
mentioned above in the tropical waves section. At the surface,
an E-W ridge extends from the western Atlantic to the central
Gulf along 25N, leading to gentle to moderate anticyclonic
winds in the east-central Gulf. A recent ASCAT pass shows
fresh SE to S winds in the south-central Gulf off the NW coast
of the Yucatan peninsula.

The ridge extending from the western Atlantic into the central
Gulf will persist through early next week. A weak trough will
move from the Yucatan peninsula across the west central Gulf
through Sun. Fresh to locally strong SW winds are expected to
continue through tonight over the north-central and northeast
parts of the Gulf ahead of a cold front moving across the SE
CONUS.

CARIBBEAN SEA...

A mid to upper level trough extends from the central Atlantic
near 24N63W to the Mona Passage to Honduras. This, in combination
with surface ridging extending over the western Atlantic and
northern Caribbean, is producing stable atmospheric conditions
and relatively dry air across much of the basin. Fresh to
locally strong E winds are seen over the western Gulf of
Honduras ahead of the tropical wave along 84W. Fresh to strong
trades are noted in the central Caribbean north of Colombia.
Seas are 4 to 6 ft over most of the basin, with up to 9 ft in
the south central Caribbean. Trade wind convergence into the
active monsoon trough is supporting a line of showers and
tstorms from a 1010 mb low near 10N77W to central Nicaragua.

Fresh trade winds will prevail over the central Caribbean through
Sun, with locally strong winds expected to pulse near the coast
of Colombia at night. Fresh to strong winds are also expected in
the Gulf of Honduras through Sun night in the wake of a tropical
wave moving through that area today. A second tropical wave,
currently along 55/56W, will enter the eastern Caribbean late
tonight or early Sun and reach the central Caribbean late Mon or
Tue. Expect gusty winds and scattered showers with this wave. It
has a low chance of becoming a tropical cyclone during the next
few days.

ATLANTIC OCEAN...

An area of scattered moderate thunderstorms is seen over the
W Atlantic north of 27N between 72W-77W. A surface ridge
extends from a 1019 mb high pressure near 26N71W to South
Florida. Ridging also extends east-northeastward from the
high pressure to a 1023 mb high pressure near 35N34W. A
dissipating stationary front extends from 32N52W to 29N58W.
Scattered showers and isolated tstorms are along and within
120 nm NW of the front. A recent ASCAT pass shows that a
westward moving surface trough, located along 44W from 20N-26N,
has broad cyclonic turning with a large area of fresh NE winds
to the west of the trough, and fresh E winds to the east of
the trough. In the far NE Atlantic, a cold front is from
29.5N10W to the Canary Islands near 29N14W to 30N19W to 32N21W.
Scattered showers are near the front. Strong NE winds are on
both sides of the front and are covering much of the far
eastern Atlantic.

A ridge extending along roughly 25N will persist across the
western Atlantic into early next week. A cold front will move
off the southeastern U.S. coast tonight, then stall and weaken
N of 28N early on Mon before dissipating. Moderate to locally
fresh SW winds may precede the front this weekend over the
waters N of 30N. A large trough, currently located along 44W,
will reach the waters E of 65W by Sun night, crossing 65W by
Mon night. Fresh to locally strong E to SE winds will follow
this system.

$$
Hagen
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