AXNT20 KNHC 272354

Tropical Weather Discussion
NWS National Hurricane Center Miami FL
754 PM EDT TUE SEP 27 2016

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 wave extends from 08N56W to 19N53W moving W at 15 kt. A
1008 mb low is centered along the wave axis near 13N with global
model data indicating 700 mb troughing between 50W-58W on the
southern periphery of a mid-level ridge anchored near 24N49W. 850
mb relative vorticity is also maximized in the vicinity of the
low center. Scattered moderate and isolated strong convection is
from 11N-17N between 50W-57W. Regardless of tropical cyclone
development...near gale to gale force winds are forecast to
develop by 28/0600 UTC as the low approaches Barbados with heavy
rainfall anticipated for the many of the Lesser Antilles. See
latest NWS High Seas Forecast under AWIPS/WMO headers MIAHSFAT2/
FZNT02 KNHC for more details.

Tropical wave extends from 03N25W to 14N24W moving W at 20-25 kt.
The wave coincides with 700 mb troughing between 15W-30W and
largely remains embedded within the Monsoon Trough axis as a low-
amplitude monsoonal gyre centered along the axis near 08N.
Isolated moderate convection is from 04N-11N between 19W-28W.

Tropical wave extends from 10N74W to 19N73W moving W at 10-15 kt.
The wave coincides with subtle 700 mb troughing across the SW
Caribbean Sea generally S of 15N between 75W-80W with 850 mb
relative vorticity model fields indicating maximum values over the
near shore waters of Colombia and across western Colombia itself.
Isolated moderate convection is from 10N-12N between 73W-76W.

The Monsoon Trough extends from the African coast near 14N17W to
07N25W to 07N40W. Scattered moderate and isolated strong
convection is from 10N-15N between 12W-18W. Widely scattered
moderate convection is from 04N-13N between 28W-44W.


A broad middle to upper level trough is noted on water vapor
imagery over much of eastern CONUS dipping its broad base over
the SE CONUS this evening. The troughing supports a cold front
extending from the NE Alabama SW to southeastern Louisiana and
into the Gulf basin near 30N92W. The front meanders SW to 28N95W
then southward to the east-central Mexico coast near Tampico.
While much of the energy aloft supporting the front is over the
CONUS...an upper level anticyclonic circulation is centered over
east-central Mexico providing for an overall diffluent environment
over the western Gulf. Scattered showers and tstms are occurring
primarily S of 27N W of 90W in association with the low-level
convergence in the vicinity of and SE of the front...and maximum
middle to upper level diffluence. The remainder of the basin is
under the influence of NW flow on the eastern periphery of the
upper level ridging with mostly light to gentle anticyclonic
surface winds occurring E of 90W. The front is expected to remain
nearly stationary for the next 24 to 36 hours and begin
progressing eastward by early Thursday across the NE Gulf waters
and SE CONUS. A weak impulse of energy will sweep across the lower
Mississippi River valley on Thursday...however the lingering
stationary front extending from the NE Gulf to the NE Mexico coast
will slowly become diffuse through upcoming weekend into Monday of
next week.

Upper level troughing extends over the western Caribbean between
77W-83W providing an overall unstable environment N of 17N for
Jamaica and most of Cuba. Scattered showers and tstms are
occurring across the NW Caribbean waters and portions of inland
Cuba in association with the base of the upper level troughing.
Farther south across the SW Caribbean...a tropical wave is along
74W moving westward and along with close proximity to the Monsoon
Trough...scattered showers and tstms are occurring S of 15N
between 77W-83W...including portions of Panama. Otherwise...a few
isolated showers and tstms are occurring in the vicinity of Puerto
Rico and across inland portions of Hispaniola...however much of
the eastern and central Caribbean is under mostly clear skies and
fair conditions. Looming to the east of the Lesser Antilles is the
special features tropical wave with 1008 mb low centered along the
wave axis near 13N. The wave is expected to approach the islands
and by Wednesday evening bring rainfall and gusty winds to the
region. Global models indicate the low tracking generally westward
to the central Caribbean and then heading north between 70W-80W
into the SW North Atlc by Monday morning.

A few isolated showers and tstms linger across the island this
evening...however relatively dry air aloft prevails. A tropical
wave is expected to continue moving west of the Windward Passage
region as mostly fair skies and conditions are expected for

A middle to upper level shortwave trough is noted on water vapor
imagery over the Florida peninsula and portions of the far western
SW North Atlc. This shortwave is progressing north-northeastward
as part of a broader middle to upper level trough currently over
much of the eastern CONUS. A weak 1012 mb low is centered near
31N80W with a surface trough extending from the low to 28N79W then
SW to 25N81W. Scattered showers and tstms are occurring S of 29N W
of 76W. Farther east...southwesterly flow aloft prevails providing
an overall diffluent environment to support another area of
scattered showers and tstms occurring N of 26N between 69W-75W.
Otherwise...the remainder of the central and eastern Atlc is under
the influence of a surface ridge anchored by a 1022 mb high
centered near 26N45W. A weakening front extends into the
discussion area near 32N42W then generally westward to 29N54W but
provides little sensible weather at this time.

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