Tropical Weather Discussion
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000
AXNT20 KNHC 181804
TWDAT

Tropical Weather Discussion
NWS National Hurricane Center Miami FL
204 PM EDT Fri Aug 18 2017

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...

Tropical Storm Harvey is located near 13.1N 61.3W at 18/1500 UTC,
or about 13 nm SSW of St. Vincent, moving west at 18 kt. Reported
minimum central pressure is 1005 mb. Maximum sustained wind speed
is 35 kt with gusts to 45 kt. Harvey will move through the
Windward Islands and into the eastern Caribbean Sea today and move
into the central Caribbean Sea on Saturday. Harvey is expected to
produce additional rainfall totals of 1 to 2 inches with locally
higher amounts across parts of the Leeward and Windward Islands
from Guadeloupe southward to Grenada. These additional rains could
cause life-threatening flash floods and mudslides. Presently,
scattered moderate to strong convection is from 10N-16N between
60W-66W, to include all islands south of Guadeloupe. See the
latest NHC Intermediate Public Advisory under AWIPS/WMO headers
MIATCPAT4/WTNT34 KNHC, and the full Forecast/Advisory under
AWIPS/WMO headers MIATCMAT4/WTNT24 KNHC for more details.

A tropical wave extends from 23N49W to a 1010 mb low near 17N50W
to 10N50W. Scattered moderate to isolated strong convection is
from 16N-20N between 48W-53W. The system continues to show signs
of organization. However, upper-level winds are becoming less
favorable, and the chances for a tropical cyclone to form are
diminishing. The low is expected to move west-northwestward at
about 20 kt during the next few days, and interests in the
northern Leeward Islands should monitor the progress of this
disturbance. This system has a medium chance of becoming a
tropical cyclone within the next two days.

...TROPICAL WAVES...

A tropical wave is in the E Atlantic with axis extending from
20N32W to a 1011 mb near 13N33W to 07N33W. Isolated moderate
convection is from 09N-18N between 27W-37W. This wave is in a very
moist area based on TPW imagery and has a well pronounced 700 mb
trough. Gradual development of this system is possible through the
middle of next week while the wave moves WNW at 20 kt. This
system has a low change of becoming a tropical cyclone within the
next 48 hours.

A tropical wave is in the central Caribbean with axis extending
from the S Bahamas near 23N74W to 16N75W to N Colombia near
10N75W, moving W at 15-20 kt. This wave in a moist area based on
SSMI TPW imagery and has a well pronounced 700 mb trough. Isolated
moderate convection is within 180 nm of the wave axis.

A tropical wave extends from the Bay of Campeche near 20N95W to
the Eastern Pacific near 06N97W. This wave in a moist area based on
SSMI TPW imagery. Isolated moderate convection is within 120 nm
of the wave axis, N of 16N. Scattered moderate to isolated strong
convection is within 120 nm of the wave axis over the Eastern
Pacific.

...ITCZ/MONSOON TROUGH...

The monsoon trough extends from the African coast near 12N16W to
10N20W to 13N30W to a 1011 mb low near 13N33W to 08N40W. Besides
the convection mentioned in the tropical wave and special features
sections, scattered moderate convection is off the coast of W
Africa from 09N-14N between 14W-20W.

...DISCUSSION...

GULF OF MEXICO...

A tropical wave is over the Bay of Campeche. See above. A 1018 mb
high is centered over the north central Gulf of Mexico near
28N90W with mostly fair weather. 5-10 kt anticyclonic winds are
noted around the high. Radar imagery shows scattered moderate
convection over the NE Gulf and N Florida from 27N-31N between
81W-87W. Scattered showers are over the remainder of the E Gulf.
In the upper levels, an upper level low is centered over W Cuba
near 23N81W enhancing showers. A small upper level high is
centered over the NW Gulf near 29N92W. Expect the surface high to
remain quasi-stationary over the Gulf for the next 24 hours.
Expect more airmass thunderstorms Saturday during maximum heating
over Florida, W Cuba, S Mexico, and the Bay of Campeche.

CARIBBEAN SEA...

Tropical Storm Harvey is over the Windward Islands, and a tropical
wave is over the central Caribbean. See above. The eastern extent
of the Pacific monsoon trough is producing scattered moderate
convection over the SW Caribbean, Costa Rica and Panama. Expect
Harvey to move W to the central Caribbean with convection over
the next 48 hours. Expect the tropical wave to move W to the W
Caribbean over the next 48 hours. Also expect continued
convection over the SW Caribbean.

...HISPANIOLA...

Presently fair weather is over Hispaniola. Expect Harvey to
approach E Hispaniola in 24 hours.

ATLANTIC OCEAN...

The Atlantic basin N of 20N is under the influence of the mid-
Atlantic subtropical high near 32N39W with mostly fair weather.
For the tropical Atlantic S of 20N, see the special features and
tropical waves sections above.

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

$$
Formosa




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