Tropical Weather Discussion
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AXNT20 KNHC 180518

Tropical Weather Discussion
NWS National Hurricane Center Miami FL
1218 AM EST Sat Nov 18 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.


The monsoon trough extends from the African coast near 09N13W to
06N26W. The Intertropical Convergence Zone axis extends from
06N26W to 07N36W, then resumes west of a surface trough near
07N39W to 06N46W to the South American coast near 07N58W.
Scattered moderate convection is from 04N-10N E of 24W, and
from 08N-11N between 30W-46W.



A 1023 mb high is centered over North Carolina near 35N77W. A
surface ridge axis extends SW from the high to the central Gulf
of Mexico near 25N90W. 10-15 kt surface winds are over the base
of the ridge axis. Radar imagery shows scattered showers over the
Straits of Florida between 81W-83W. Mostly fair weather is over
the remainder of the Gulf of Mexico. In the upper levels, a large
upper level high is centered over central Mexico near 23N102W
producing northerly upper level flow and strong subsidence over
the entire Gulf of Mexico. The next cold front is expected to
emerge off the Texas and Louisiana coasts Saturday evening with
showers. 25-30 kt N-NE winds will follow in the wake of the front
as it sweeps southeastward.


A surface trough extends from Hispaniola at 20N70W to N Colombia
at 09N75W. Two 1008 mb lows are embedded on the trough axis at
18N73W and 11N75W. Scattered showers and clusters of scattered
moderate convection are within 360 nm E of the trough axis, to
include Puerto Rico. In the upper levels, an upper level trough
is over the NW Caribbean with axis from central Cuba near 22N80W
to the Gulf of Honduras near 16N89W. Upper level diffluence E of
the trough is enhancing the showers and convection over the
central Caribbean Sea. Expect the area of convection to drift E
and persist for the next 48 hours.


Scattered showers and thunderstorms are over the island, and will
continue through the weekend. Convection will likely be heaviest
over E Hispaniola in the afternoon and evening hours during
maximum heating. Localized flooding and life-threatening mud
slides are also possible during this time.


The tail end of a dissipating cold front is over the W Atlantic
from 31N64W to 27N71W. Scattered showers are within 45 nm of the
front. A 1009 mb low is centered over the central Atlantic near
26N59W. A surface trough extends SW from the low to Hispaniola
near 20N70W. Scattered moderate to isolated strong convection is N
of the Leeward Islands from 20N-23N between 60W-68W. Scattered
showers are elsewhere within 120 nm of the trough. A cold front
enters the central Atlantic near 31N40W and extends to 27N46W. A
stationary front continues to the central Atlantic low near
26N59W. Scattered showers are within 120 nm of the frontal system.
A 1018 mb high is centered over the E Atlantic near 27N27W. Of
note in the upper levels, a large upper level trough is over the W
Atlantic supporting the W Atlantic front, and enhancing the
central Atlantic with upper level diffluence. Another upper level
trough is over Morocco.

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