Tropical Weather Discussion
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370
AXNT20 KNHC 212332
TWDAT

Tropical Weather Discussion
NWS National Hurricane Center Miami FL
805 PM EDT THU JUL 21 2016

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 1800 UTC surface analysis and satellite imagery through
2315 UTC.

...TROPICAL WAVES...

Tropical wave in the east Tropical Atlantic extends along 26W
from 11N-22N moving west near 15 kt over the past 24 hours. Wave
coincides with a well defied 700 mb trough as depicted in the
global models and within a high amplitude surge of moisture as
seen on the SSMI Total Precipitable Water imagery. No associated
deep convection.

Tropical wave in the east/central Caribbean extends along
71W/72W from over Hispaniola to the Gulf of Venezuela moving
west near 25 kt over the past 24 hours. Wave is trailing a weak
700 mb trough as depicted in the global models and within a
surge of moisture as seen on the SSMI Total Precipitable Water
imagery. No associated deep convection but wave is enhancing
the activity over Hispaniola.

Tropical wave in the west Caribbean extends along 83W/84W from
13N-22N moving west 10 to 15 kt over the past 24 hours. Wave
coincides with a well defined 700 mb trough as depicted in the
global models and within a surge of moisture as seen on the SSMI
Total Precipitable Water imagery. No associated deep convection.

...ITCZ/MONSOON TROUGH...

The monsoon trough extends across Africa into the east Tropical
Atlantic near 14N16W and continues through a newly formed 1012
mb low near 11N22W then along 10N30W to 7N38W where the ITCZ
begins and continues along 8N50W to South America near 8N60W.
Scattered moderate to isolated strong convection is within
120/150 nm south of the monsoon trough between 23W-28W. Clusters
of scattered moderate to isolated strong convection are within
150 nm south of the monsoon trough/ITCZ between 30W-44W.
Clusters of scattered moderate convection are from 7N-13N east
of 23W to the coast of west Africa.

...DISCUSSION...

GULF OF MEXICO...

A large upper ridge anchored over northeast Texas covers the
Gulf of Mexico north of 23N with a ridge axis extending
southeast to Key West, Florida. An inverted upper trough extends
from the west Caribbean across the Yucatan peninsula near Merida
to over Mexico near 23N98W. This is creating a diffluent
environment across the Gulf to generate scattered showers and
isolated thunderstorms within 120 nm of line from 24N85W to over
Mexico near 25N97W. Scattered showers and thunderstorms are
inland and within 90 nm along the coast of the Florida peninsula
and within 60 nm along the north Gulf coast from the Florida
panhandle to the Louisiana/Texas border. Similar activity has
developed over west Cuba with thunderstorms moving across the
Yucatan Channel. A surface ridge remains across  the north Gulf
anchored by a pair of 1021 mb highs near 29N86W and a second
over southwest Louisiana. The surface ridge will persist through
the weekend.

CARIBBEAN SEA...

An inverted upper trough extends from an upper low along the
coast of Nicaragua near 13N83W across Cuba near 21N77W into the
southwest Atlantic to near 23N75W generating clusters of
scattered showers and isolated thunderstorms north of 17N
between 75W-86W. An upper ridge is anchored over Puerto Rico
covering the east Caribbean east of 74W and is providing
difflunce aloft to generate scattered showers and isolated
thunderstorms north of 17N to over Hispaniola and is being
enhanced by the tropical wave moving west across the island this
evening. The last visible satellite images show an area of
Saharan dust has moved into the far east Caribbean east of a
line from Grenada to Puerto Rico leaving skies clear across the
remainder of the Lesser Antilles. The tight pressure gradient
between the west Atlantic surface ridge and the lower pressure
over South America is producing fresh to strong trade winds
across the south-central Caribbean that will continue through
the weekend. The tropical wave in the west Caribbean will move
across the Yucatan Friday afternoon. The east Caribbean tropical
wave will move across the remainder of the Caribbean through
Saturday night.

...HISPANIOLA...

Scattered showers and isolated thunderstorms are north of 17N to
across the island this evening due an diffluent environment
between an upper trough/upper ridge and is being enhanced by a
tropical wave that is currently moving across the island. This
activity will begin to taper off Friday as the wave continues to
move west of the island. The possible afternoon/evening showers
and thunderstorms could return late in the weekend.

ATLANTIC OCEAN...

The upper trough dips south over the the far west Atlantic to
25N between 70W-80W supporting a cold front just north of the
discussion area and a surface trough that extends from 30N67W to
east of the Bahamas near 26N75W. Scattered showers and isolated
thunderstorms are north of 29N between 59W-64W and from 26N-31N
between 71W-76W. The inverted upper trough extends across Cuba
near 21N77W into the southwest Atlantic to near 23N75W
generating clusters of scattered showers and isolated
thunderstorms within 75 nm along the north coast of Hispaniola
and Cuba between 70W-77W. Otherwise, high pressure dominates the
remainder of the Atlantic with a surface ridge extending from a
1027 mb high west of the Azores through 32N46W to 29N68W. The
west Atlantic surface trough will persist through Saturday
night. The surface ridge will begin to build westward across the
west Atlantic late in the weekend.

For additional information please visit
http://www.hurricanes.gov/marine

$$
PAW



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