Tropical Weather Discussion
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000
AXNT20 KNHC 120004
TWDAT

Tropical Weather Discussion
NWS National Hurricane Center Miami FL
804 PM EDT Fri Aug 11 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.

...SPECIAL FEATURES...

A 1013 mb low is centered N of the Leeward Islands near 22N66W.
Scattered moderate convection is from 21N-24N between 64W-67W.
Dry air aloft and unfavorable upper-level winds have limited
significant development during the past few days. Environmental
conditions, however, are expected to become a little more
conducive for development during the next day or two, and this
system could become a tropical depression over the weekend. The
low is forecast to move generally northwestward through the
weekend and is likely to turn northeastward away from the United
States early next week. The chance for formation during the next
48 hours is medium.

...TROPICAL WAVES...

A tropical wave off the coast of W Africa extends from 17N18W to
09N18W, moving W at 15-20 kt. The wave shows up very well on the
SSMI TPW animation and 700 mb streamline analysis. Scattered
moderate convection is from 12N-14N between 16W-19W. Scattered
showers are within 120 nm of the remainder of the wave axis.

A tropical wave in the central Atlantic extends from 18N40W to
09N40W. It is moving W at 15-20 kt. The wave is in a moist area
as seen by SSMI TPW imagery. The wave has low to moderate vertical
wind shear and has extensive Saharan dry air and dust to the west
of its environment. Scattered showers are within 120 nm of the
wave axis.

A tropical wave in the central Caribbean extends from Hispaniola
at 19N71W to NW Venezuela near 10N72W, moving W at 10-15 kt. The
wave is in a moist area as seen by SSMI TPW imagery. The wave is
in a region of low vertical wind shear. A pronounced 700 mb trough
is over the central Caribbean. Scattered moderate to isolated
strong convection is over Hispaniola from 18N-20N between 70W-75W.
Scattered showers are elsewhere within 120 nm of the wave axis.

...ITCZ/MONSOON TROUGH...

The monsoon trough extends from the African coast near 13N16W to
10N24W to 11N34W to 07N46W. The Intertropical Convergence Zone
axis continues from 07N46W to the South American coast near
06N57W. Aside from convection associated with the tropical waves,
scattered moderate convection is from 07N-12N between 20W-34W.

...DISCUSSION...

GULF OF MEXICO...

A 1020 mb high is centered over the NE Gulf of Mexico near 27N88W.
10 kt anticyclonic surface winds are going around the high. A
1015 mb low is centered over NE Florida near Jacksonville Florida
at 30N81W. A surface trough extends S from the low to near Punta
Gorda Florida at 27N82W. Clusters of scattered moderate convection
are over most of Florida. More scattered moderate convection is
inland over Louisiana, Mississippi, and S Alabama. Further S,
scattered moderate convection is over W Cuba, and the Yucatan
Peninsula. In the upper levels, an upper level high is centered
over N Mexico near 30N100W. NE upper level flow covers the Gulf
of Mexico. Expect over the next 24 hours for the surface high to
remain stationary. Expect the low over NE Florida to lift N. Also
expect convection to persist over the N Gulf and the E Gulf
especially during the afternoon and evening hours.

CARIBBEAN SEA...

A tropical wave is along 71W/72W. Please, see Tropical Waves
section for details. The most recent scatterometer data indicate
fresh to locally strong winds across the south-central Caribbean,
in the Gulf of Honduras, and also across the Windward Passage.
The eastern extent of the E Pacific monsoon trough is producing
scattered moderate convection over the SW Caribbean, Costa Rica,
and Panama, S of 13N. Further N, widely scattered moderate
convection is over E Cuba, Jamaica, Hispaniola, and Puerto Rico.
Scattered moderate convection is also inland over Guatemala, El
Salvador, and Honduras. Of note in the upper levels, an upper
level low is centered over W Honduras near 15N88W enhancing
convection. Expect the tropical wave to move W with convection
and showers. Also expect convection to persist over the SW
Caribbean.

...HISPANIOLA...

A tropical wave is presently moving across Hispaniola. The wave
together with local effects are producing scattered moderate
convection. The tropical wave will move away from the island on
Saturday, however an upper-level trough will continue to produce
scattered showers and convection during the afternoon and evening
hours. Moisture is forecast to diminish across the island on
Sunday.

ATLANTIC OCEAN...

Scattered moderate convection is off the coast of NE Florida N of
27N and W of 76W. Scattered showers are over the N Bahamas. A
1013 mb low is centered N of the Leeward Islands near 22N66W. See
above. A surface trough is over the Central Atlantic from 31N44W
to 24N50W. Scattered showers are within 120 nm of the trough axis.
The remainder of the Atlantic Ocean is under the influence of a
ridge anchored by a 1030 mb high pressure located NE of the
Azores. In the tropics, a 1011 mb low is centered near the Cape
Verde Island at 18N21W. This low is forecast to move move WSW over
the islands with scattered showers over the next 24 hours.
Of note in the upper levels, an upper level low is also located N
of the Leeward Islands near 22N66W, making the system a deep
layered low. The upper level low is enhancing showers and
convection. Another upper level low is centered over the E
Atlantic near 28N41W producing scattered showers within 240 nm of
the center.

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

$$
Formosa




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