[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 270548
TWDAT

Tropical Weather Discussion
NWS National Hurricane Center Miami FL
147 AM EDT Wed Sep 27 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 0000 UTC surface analysis and satellite imagery through
0515 UTC.

...SPECIAL FEATURES...

Tropical Storm Maria is centered near 34.8N 73.0W at 27/0600 UTC
or about 126 nm east of Cape Hatteras North Carolina, moving
north at 4 kt. Minimum central pressure is 976 mb. Maximum
sustained winds are 60 kt with gusts to 75 kt. Maria is a very
large cyclone with tropical storm-force winds extending outward up
to 200 nm from the center. Scattered moderate convection is
within 330 nm of the storm in the eastern semicircle. Stable air
on the western semicircle is resulting in mainly showers within
300 nm west of the center. Buoy data indicates seas of 15 ft
extending nearly 300 nm southeast of the center, with 8 ft seas
about 420 nm south and southeast of the center. See the latest NHC
Forecast/Advisory under AWIPS/WMO headers MIATCMAT5/WTNT25 KNHC
for more details.

Hurricane Lee is centered near 30.0N 55.5W at 27/0300 UTC or
about 495 nm ESE of Bermuda. Lee is moving to the west at 8 kt.
Estimated minimum central pressure is 971 mb. Maximum sustained
winds are 95 kt with gusts to 115 kt. Lee is a small cyclone with
numerous moderate and isolated strong convection confined to
within 90 nm of the center. Lee is forecast to remain a hurricane
the next couple of days as it turns toward the west-northwest by
Wednesday, then turns northeast on Thursday. See the latest NHC
Forecast/Advisory under AWIPS/WMO headers MIATCMAT4/WTNT24 KNHC
for more details.

...TROPICAL WAVES...

A tropical wave is off the coast of Africa with axis extending
along 18W/19W from 04N-13N, moving west at 15 kt. SSMI TPW
imagery shows a very moist area. Surface and 700 mb trough are
also present. Scattered moderate isolated strong convection is E
of the wave axis from 07N-13N between 12W-17W.

A tropical wave extends along 44W/46W from 06N-18N, moving west
at 15 kt. This wave is well defined in 700 mb wind fields. A
fairly dry and stable environment covers the northern portion of
the wave. Scattered showers are south of 13N between 41W-49W.

A tropical wave is in the central Caribbean along 73W, from 10N-
19N, moving west at 10 to 15 kt. The wave is embedded within a
moist area ,and weak 700 mb trough. Isolated moderate convection
is within 90 nm of the wave axis. This convection is also
partially due to upper level diffluence over the region.

...ITCZ/MONSOON TROUGH...

The monsoon trough extends from the coast of Africa near 13N16W
to 10N22W to 09N42W. The Intertropical Convergence Zone extends
from 09N48W to 09N61W. Aside from convection associated with the
tropical waves, isolated moderate convection is from 09N-13N
between 50W-60W.

...DISCUSSION...

GULF OF MEXICO...

Slight surface ridging is over the N Gulf of Mexico, with mostly
5-15 kt E flow over the Gulf. Strongest winds are over the W
Gulf W of 90W. In the upper levels, a large upper level trough is
over the western half of the U.S. with axis along 113W. Upper
level diffluence E of the axis is producing convection over S Texas
and Mexico between 95W-105W. An upper level low is centered over
the NE Gulf of Mexico near 28N83W with strong subsidence. Again
upper level diffluence SE of the center is producing showers and
convection over W Cuba, the Straits of Florida, and the Bahamas.
Expect over the next 24 hours for an increase of showers and
convection over the Yucatan Channel, Yucatan Peninsula, and the
Bay of Campeche.

CARIBBEAN SEA...

A surface trough is over the W Caribbean from 22N87W to 16N88W.
Scattered moderate convection is over the NW Caribbean, Cayman
Islands, and Jamaica, from 17N-22N between 76W-85W. Much of this
convection is also enhanced by upper level diffluence. A tropical
wave is over the central Caribbean. Elsewhere, scattered showers
are over the Leeward and Windward Islands, while Puerto Rico has
fair weather. Lastly, the eastern extent of the E Pacific monsoon
trough is well into the SW Caribbean extending from NE Nicaragua
to N Colombia. Isolated moderate convection is from 11N-16N
between 75W-87W. Expect over the next 24 hours for continued
showers and convection over the W Caribbean and Central America W
of 75W.

...HISPANIOLA...

A tropical wave is presently over Haiti supporting isolated
showers and thunderstorms. The wave will move west of the island
on Wednesday. However, upper level conditions will support
additional mainly afternoon and evening showers and thunderstorms
on Wednesday.

ATLANTIC OCEAN...

Two tropical waves are moving across the basin. Please refer to
the tropical waves section above for details. Tropical Storm
Maria in the western Atlantic and Hurricane Lee in the central
Atlantic are discussed in the special features section above. A
plume of moisture is being pulled northeast across the Bahamas
and surrounding waters by an upper low over the eastern Gulf of
Mexico, and by low level southerly flow well to the south of
Maria. This plume combined with upper level diffluence from the
upper low supports numerous showers and scattered thunderstorms
from 22N-28N, west of 71W. Elsewhere, surface ridging prevails
across much of the remainder of the central and the eastern
Atlantic, anchored by a 1021 mb high centered near 34N42W.

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

$$
Formosa
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