[Tropical] Tropical Weather Discussion

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AXNT20 KNHC 311807
TWDAT

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
1715 UTC.

...SPECIAL FEATURES...

...Heavy rainfall in Central America...

A Central American Gyre is over the eastern North Pacific, with
the broad cyclonic circulation around the gyre encompassing the
discussion waters N of the equator and E of 98W, including
portions of southern Mexico and Central America. Moderate to
strong winds are noted across much of these waters, with seas in
the 6-10 ft range. Numerous moderate and scattered strong
convection is noted across much of these waters, particularly N
of 10N between 87W and 94W. Areas of thunderstorms are impacting
portions of Central America from Nicaragua northwestward to
Southern Mexico and the Gulf of Tehuantepec. The gyre will move
slowly northward, gradually encompassing much of Central America
and southern Mexico within the next 24 hours. Winds around the
gyre will continue to advect abundant moisture into portions of
Central America and southeastern Mexico for the next several
days. This will create a dangerous situation for these areas with
an extended period of active and wet weather, and periods of
heavy rainfall, through the weekend and into next week,
especially over southern Guatemala, El Salvador, southern
Honduras, western Nicaragua, and portions of southern Mexico E of
Veracruz and eastern Oaxaca. This will bring the potential for
life- threatening flash floods and mudslides for locations that
receive the heaviest rainfall, especially in areas of mountainous
terrain. Please refer to products issued by your local weather
service for more details.

Tropical Storm Amanda developed in the eastern north Pacific and
moved inland over Guatemala today. The remnants may rotate
around the larger circulation of the Central American Gyre and
move out over water in the Bay of Campeche. There is a medium
possibility that the remnant circulation of Amanda may develop
into a tropical cyclone in the SW Gulf when it emerges over
water.

...MONSOON TROUGH/ITCZ...

The monsoon trough extends from the coast of Guinea-Bissau 11N15W
04N28W. The ITCZ continues from 04N28W to the coast of Brazil
near 00N47W. Scattered moderate convection is observed from 01N-
011N between the coast of Liberia west to 27W. Scattered showers
and thunderstorms are noted along the coast of Brazil from 02N-
04S east of 50W.

GULF OF MEXICO...

Please read the SPECIAL FEATURES section for more information
about heavy rainfall potential over southern Mexico during the
next few days.

A stationary front extends along the northern Gulf coast from
Panama City Florida to southern Louisiana to Houston Texas. A
Surface trough reaches northward from the far southwest Gulf to
off Brownsville Texas. Numerous thunderstorms are active over
the Bay of Campeche and in the Yucatan peninsula, on the
periphery of the Central American Gyre over the region to the
south. The surface trough and thunderstorm activity are enhanced
by a well developed upper low that is centered over northern
Mexico. Scatterometer pass indicated NE to E winds around 20 to
25 kt over much of the southwest Gulf, east of the trough.
Gentle to light winds persist elsewhere across the Gulf, with 2
to 4 ft seas.

For the forecast, the weak stationary front will dissipate
tonight. Winds and seas may increase over the southwest Gulf
early in the week as a broad area of low pressure, known as a
Central American Gyre, persists over southeast Mexico and
northern Central America.

CARIBBEAN SEA...

Please read the SPECIAL FEATURES section for more information
about heavy rainfall potential over Central America during the
next few days.

The tropical wave in the western Caribbean has been absorbed
into the circulation of the Central American Gyre. Moderate
to fresh winds prevail across the central and western Caribbean
and eastern Caribbean waters and lighter winds west of 79W.
Seas are in the 5-7 ft range over the central Caribbean, and
3-5 ft elsewhere.

Winds and seas will increase in the Gulf of Honduras and off
Yucatan through the end of the week because of the Central
American Gyre. The Bermuda High will rebuild to north of the
basin on Tue, which will lead to the development of fresh to
strong winds in the south-central Caribbean Thu and Thu night.

ATLANTIC OCEAN...

A surface trough reaches from near 28N69W through the southern
Bahamas toward the far eastern tip of Cuba. Scattered tstorm
are active near the northern end of the surface trough from
23N-28N between 66W-71W. A mid to upper level trough is moving
off the Georgia and Carolina coasts into the western Atlantic.
A cold front north of the area is enhancing showers and tstorms
from 28N to 31N between 70W and 78W. Moderate SW winds are active
in this area as well, ahead of the cold front approaching from
the west. A weak 1015 mb low is centered near 32N56W.
Thunderstorm activity near this feature has completely
dissipated over the past six hours. A surface trough extends
south to 25N55W with scattered moderate convection north of 24N
between 49W-54W. Generally light winds persist over open waters
west of 54W.

The cold front will move south of 31N late today and tonight and
extend from just east of Bermuda SW to S Florida by Mon
afternoon, stall along 25N by Tue afternoon, and dissipate by
Wed. NE winds behind the front will increase to moderate to
fresh on Mon and Tue. High pressure building north of the front
will support moderate to fresh trade winds south of 22N on Wed
and Thu.

MTorres
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