AXNT20 KNHC 270006
Tropical Weather Discussion
NWS National Hurricane Center Miami FL
806 PM EDT MON SEP 26 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
A vigorous tropical wave is in the central Atlantic associated
with a 1008 mb low centered near 10N48W. The wave extends from 05N
to 15N with axis near 48W, moving W at 20-25 kt over the past 24
hours. Abundant moisture at the low and middle levels, and a
diffluent environment aloft support scattered heavy showers and
tstms N of the low center from 10N to 17N between 44W and 53W.
Similar trailing convection is from 11N to 16N between 34W and
44W. Environmental conditions remain conducive for development,
and a tropical depression is likely to form during the next day or
two while the system moves W-NW. Interests in the eastern and
central Caribbean Sea, including the northern coast of South
America, should monitor the progress of this system. Regardless of
development, heavy rains and strong gusty winds, possibly to
tropical storm force, are expected to spread over the Windward
Islands and portions of the southern Lesser Antilles beginning
late Tuesday or Wednesday. The chance of formation of this system
within the next 48 hours is high. Please see the Tropical Weather
Outlook under AWIPS/WMO headers MIATWOAT/ABNT20 KNHC for more
A tropical wave is E of the Cabo Verde Islands extending from
06N to 16N with axis near 18W, moving at 5 kt over the past 24
hours. The wave is in a region of favorable deep layer wind
shear, however CIRA LPW from surface to 850 mb show pockets of dry
air in its environment, which in part is suppressing convection
at the time.
A tropical wave is in the E Caribbean extending from 10N to 19N
with axis near 68W, moving W at 15 kt over the past 24
hours. Unfavorable deep layer wind shear and strong dry air
subsidence from aloft hinder convection at the time.
The Monsoon Trough extends across Africa into the east Tropical
Atlantic near 09N13W to 08N30W to 09N48W to 07N54W. Aside from the
convection associated with the tropical wave discussed in the
special features section, scattered showers are from 06N to 11N
between 21W and 25W and heavy showers are within 90 nm off the
coast of Liberia, Africa.
GULF OF MEXICO...
Generally low pressure dominates across the basin, being the main
feature an elongated surface trough that extends from Texas
adjacent waters near 27N95W to the Bay of Campeche near 19N95W.
Abundant low level moisture advected from the Caribbean by SE to E
flow along with middle to upper level diffluent support scattered
showers S of 26N W of 90W and heavy showers and tstms over the
Yucatan Peninsula and northern Guatemala. At the upper levels, a
broad ridge covers the basin W of 86W while the base of an upper
trough reaches the NW coast of Cuba. Diffluence between these two
upper level features is supporting scattered showers and tstms
across the Florida Peninsula and Gulf waters E of 86W. A weak
frontal boundary will move across the northern Gulf through
Tuesday night. A stronger cold front will push into the north Gulf
An upper trough extends along the Florida Peninsula to a base over
NW Cuba. Diffluent flow between a broad upper ridge covering
great portions of the Gulf of Mexico and this trough support
scattered heavy showers and tstms along Cuba and adjacent waters.
On the other hand, middle level diffluence support heavy showers
and tstms over central Haiti and far west-central Dominican
Republic. A weak tropical wave is moving towards the central
Caribbean tonight. The wave may amplify the convection over
Hispaniola tonight. Fair weather is elsewhere being supported by
unfavorable deep layer wind shear and strong dry air subsidence.
Otherwise, gentle to moderate trades dominate the basin, except
off the Gulf of Venezuela and northern Colombia coastal waters
where fresh to locally strong winds are possible. A vigorous
tropical wave with high potential of becoming a tropical cyclone
within the next two days will generate gale force winds over the
SE Caribbean Wednesday. Regardless of development, this system
will carry heavy rain to affect mainly the Windward Islands Wed to
Middle level diffluence support heavy showers and tstms over
central Haiti and far west-central Dominican Republic. A weak
tropical wave is moving towards the central Caribbean tonight. The
wave may amplify the convection over Hispaniola tonight.
The main feature in the basin is a vigorous tropical wave with
high chances of becoming a tropical cyclone within the next two
days. See special features for more details. A broad area of
diffluent flow aloft with base over NW Cuba support scattered
showers across the Straits of Florida and the SW Atlc W of 70W.
Farther east, a weak stationary front extends from 30N60W to a
1015 mb low from which a surface trough extends SW to 28N70W. Otherwise,
surface ridging dominates elsewhere in the central and eastern
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