Tropical Weather Discussion
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000
AXNT20 KNHC 212335
TWDAT

Tropical Weather Discussion
NWS National Hurricane Center Miami FL
734 PM EDT Sat Oct 21 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 1800 UTC surface analysis and satellite imagery through
2315 UTC.

...TROPICAL WAVES...

A tropical wave is in the central Atlantic with axis extending
from 21N48W to 10N50W, moving W at 20 kt. The wave is embedded in
moderate moisture as seen on SSMI Imagery. There are distinct
surface and 700 mb troughs. Scattered showers are within 120 nm of
the wave axis S of 15N.

A tropical wave is in the western Caribbean with axis extending
from 21N81W to 09N81W, moving W at 15 kt. The wave is embedded in
abundant moisture as seen on SSMI Imagery. There is a well
defined surface trough, and a broad 700 mb trough. Clusters of
scattered moderate to isolated strong convection is from 13N-21N
between 77W-88W.

...ITCZ/MONSOON TROUGH...

The monsoon trough extends from the African coast near 08N13W to
07N20W. The Intertropical Convergence Zone axis extends from
07N20W to 07N40W to 09N61W. Scattered moderate convection is from
07N-11N between 34W-41W.

...DISCUSSION...

GULF OF MEXICO...

A 1028 mb high is centered off the coast of New Jersey near
39N74W producing surface ridging over the N Gulf of Mexico.
Widely scattered moderate convection is over the Yucatan
Peninsula, the Yucatan Channel, W Cuba, and the Straits of
Florida, all moving N from the Caribbean Sea. In addition, radar
imagery shows scattered showers are over the E Gulf and Florida.
In the upper levels, an upper level trough is over Texas and the
W Gulf with axis along 100W. Upper level diffluence E of the axis
is enhancing the showers over the E Gulf of Mexico. An upper
level ridge is over the E Gulf with axis along 79W. Abundant upper
level moisture is over the E Gulf. Expect a cold front to enter
the NW Gulf Sunday night, and a tropical wave to move across the
SE Gulf waters Sunday night. Gale force winds are forecast to
develop behind the cold front Monday.

CARIBBEAN SEA...

A tropical wave is over the W Caribbean. See above. In addition,
the eastern extent of the E Pacific monsoon trough is over Costa
Rica and Panama producing scattered moderate to isolated strong
convection S of 11N. In the upper levels, a large upper level
high is centered over the NW Caribbean near 17N80W with abundant
upper level moisture. Scattered moderate convection is over most
of Cuba. Further E, very strong subsidence is over the E Caribbean
E of 72W, to include Puerto Rico and the Virgin Islands. The
Saharan Airmass Layer Imagery also shows a plume of dry air and
dust over the E Caribbean E of 67W decreasing air quality and
reducing visibility. Expect the tropical wave to move W with
convection. Also expect continued fair weather over Puerto Rico
and the Leeward Islands for the next 24 hours.

...HISPANIOLA...

Presently fair weather is over Hispaniola. Expect within the next
24 hours for the plume of dry air and dust to advect over the
island.

ATLANTIC OCEAN...

A dissipating stationary front is over the W Atlantic from 31N54W
to 24N67W. Scattered showers are within 120 nm of the front. A
1032 mb high is centered over the E Atlantic near 40N18W
producing surface ridging to the E Atlantic. Of note in the upper
levels, an upper level low is over the W Atlantic near 29N66W.
Upper level diffluence E of the low enhancing the showers over
the W Atlantic front. Another upper level low is centered over
the central Atlantic near 23N43W producing scattered showers
within 600 nm E of the center due to upper level diffluence.

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

$$
Formosa




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