[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 260000
TWDAT

Tropical Weather Discussion
NWS National Hurricane Center Miami FL
800 PM EDT Mon Sep 25 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...

Hurricane Maria is centered near 32.0N 73.0W at 26/0000 UTC or
about 230 nm south-southeast of Cape Hatteras North Carolina,
moving north at 6 kt. Minimum central pressure is 965 mb. Maximum
sustained winds are 70 kt with gusts to 85 kt. Maria is a very
large cyclone with hurricane-force winds extending outward up to
90 nm from the center. Scattered moderate convection extends out
to 240 nm from the center in the northeast semicircle. Dry air is
entraining into the overall circulation with scattered moderate
convection out to 150 nm in the southwest semicircle. The Morehead
City, N.C. WSR-88D indicated narrow bands of scattered showers
approaching the N.C. coast between Cape Lookout and Cape Hatteras
with additional showers over the northern Outer Banks and the
Albemarle Sound. NOAA Buoy 41025 just southeast of Cape Hatteras
recently reported seas to 14 FT. See the latest NHC
Forecast/Advisory under AWIPS/WMO headers MIATCMAT5/WTNT25 KNHC
for more details.

Hurricane Lee is centered near 30.5N 50.6W at 25/2100 UTC or
about 735 nm east of Bermuda. Lee is now moving to the west-
southwest at 7 kt. Estimated minimum central pressure is 983 mb.
Maximum sustained winds are 75 kt with gusts to 90 kt. Lee is a
small cyclone with scattered moderate isolated strong convection
confined to within 60 nm of the center. Lee is forecast to remain
a hurricane and turn toward the west later tonight or Tuesday,
and then move toward the west-northwest by Wednesday. See the
latest NHC Forecast/Advisory under AWIPS/WMO headers
MIATCMAT4/WTNT24 KNHC for more details.

...TROPICAL WAVES...

A tropical wave extends along 34W/35W from 07N to 20N, moving
west at 10 kt. The wave shows up well in GOES high density winds
in the lower to mid levels of the atmosphere. Most of the wave is
embedded within a fairly dry and stable environment per recent
TPW imagery. As such no significant convection is associated with
this tropical wave.

A tropical wave is in the eastern Caribbean along 66W/67W, from
Puerto Rico to north-central Venezuela, moving west at 10 to 15
kt. The wave is situated on the eastern periphery of an upper
level anticyclone over the NW Caribbean in an area dominated by
mid to-upper level northerly flow. No significant convection is
noted at this time.

...ITCZ/MONSOON TROUGH...

The monsoon trough extends from Senegal coast near 15N17W to
10N33W. The Intertropical Convergence Zone extends from 09N35W to
the coast of South America near 06N55W. Scattered moderate
isolated strong convection is from 10N to 15N between 20W and 25W.
Scattered moderate convection was noted from 06N to 09N between
32W and 41W.

...DISCUSSION...

GULF OF MEXICO...

A sharp mid to upper-level trough extends from the Ohio River
Valley through a small cyclone near 28N86W to the Yucatan channel,
supporting scattered showers and thunderstorms over the Straits of
Florida and the Florida Keys. A surface reflection of the upper
level trough extends from near Apalachicola, Florida to 26N87W.
The surface trough located over the far southwest Gulf earlier has
dissipated. Overall, a weak pressure pattern dominated the basin
with light to moderate winds over the Gulf except for fresh winds
along the Texas coast. Little change is expected in overall
conditions. By Tuesday night into Wednesday, easterly flow will
increase slightly into moderate to occasional fresh conditions as
ridging noses in from the lower Mississippi River valley region
into the eastern Gulf waters.

CARIBBEAN SEA...

Scattered showers and thunderstorms remain active across much of
the western Caribbean this evening. This activity is enhanced by
divergence aloft on the southeastern edge of a sharp upper trough
reaching into the far northwest Caribbean, and a broad mid to
upper ridge extending from Nicaragua through the Windward Passage.
Northerly flow aloft over the eastern Caribbean is limiting
convection. Surface ridging over the central Atlantic building in
the wake of the tropical wave in the eastern Caribbean will
support fresh to strong trade winds, which will gradually shift
from the southeast Caribbean to the south central Caribbean
through mid week.

...HISPANIOLA...

Although slightly drier northerly flow aloft associated with a
mid to upper level ridge prevailed over the island today,
scattered strong thunderstorms developed over much of Haiti
this afternoon and have continued into this evening. Low level
moisture remains high with precipitable water values of 2.23"
noted in the Santo Domingo rawindsonde at 1200 UTC today. Scattered
showers and thunderstorms may re-form off the south coast
tonight and early Tuesday, ahead of the tropical wave moving into
the central Caribbean.

ATLANTIC OCEAN...

A tropical wave is moving across the basin. Refer to the section
above for details. Outside the influence of Hurricanes Maria in
the western Atlantic and Lee in the central Atlantic, surface
ridging prevails across much of the remainder of the west-central
Atlantic, anchored by a 1022 mb high centered near 35N58W.

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

$$
Cobb
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