Tropical Weather Discussion
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AXNT20 KNHC 220606

Tropical Weather Discussion
NWS National Hurricane Center Miami FL
206 AM EDT Mon May 22 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
0545 UTC.


A tropical wave is in the central Atlantic with axis extending
from 12N32W to 04N33W, moving west at 10 kt within the last 24
hours. The wave is in a region of unfavorable wind shear and most
of the wave environment is covered by Saharan dry air and dust,
which is hindering convection at the time.

A tropical wave is in the eastern Caribbean with axis extending
from 18N67W to inland Venezuela near 08N68W, moving west at 15-20
kt within the last 24 hours. Similar to the wave in the central
Atlantic, the wave environment is characterized by unfavorable
wind shear, which support the lack of deep convection at the time.


The Monsoon Trough enters the tropical Atlantic near 09N13W and
continues to 06N22W. The ITCZ extends from 06N22W to 06N32W, then
resumes west of a tropical wave at 06N35W to the coast of N
South America near 04N51W. Scattered moderate convection is from
05N-11N between 16W-24W and from 04N-11N between 41W-58W.



Mosaic Doppler Radar and satellite imagery show numerous heavy
showers and tstms are in the north-central and northwest Gulf
ahead of a stationary front that extends across Louisiana and
along the coast of Texas. Moisture inflow from the Caribbean by
SE wind flow and upper level diffluence between a ridge covering
the western Gulf and the trough that support the front support
this convection N of 23N W of 88W. Gusty winds to near 30 kt are
seen per buoy observations near the convective activity over the N
Gulf. A thermal trough is over the Bay of Campeche extending
22N90W to 17N92W lacking convection, however it supports fresh
E-NE winds within 90 nm off the northern Yucatan Peninsula.
Otherwise, scatterometer data show mainly gentle to moderate
return flow in the basin, except for the NE gulf where variable
gentle to light winds are observed. The front will continue to
stall through Monday night when it will transition to a weak cold
front to merge with a stronger cold front that will exit the coast
of Texas early Wednesday morning.


Convection in the SW Caribbean has significantly reduced due in
part to unfavorable wind shear across the region, however upper
level divergence prevails and along shallow moisture support
scattered to isolated showers in the vicinity of the east Pacific
monsoon trough that crosses Costa Rica and Panama to a low over
NW Colombia. The pressure gradient between strong high pressure
in the Atlantic and lower pressure across the southern basin
continue to support fresh to strong winds off the Colombia coast
S of 13N between 70W and 73W. Latest scatterometer data indicate
the presence of moderate trades across the remainder basin.
Otherwise, a tropical wave lacking convection is in the eastern
Caribbean. For further details see the tropical waves section. The
wave will move into the SW Caribbean Monday night and Tuesday
while a new tropical wave enters the eastern basin Wednesday.


Daytime heating, local sea breezes and mountain upslope lifting
will combine with available moisture to produce scattered
showers and isolated thunderstorms mainly during the afternoon
and early evening hours the next two days.


Surface high pressure prevails in the SW N Atlc being anchored by
a 1021 mb high near 30N69W that is forecast to move SE to a
position near 29N63W by Monday night. In the central Atlc, a 1016
mb low is associated with a surface trough that extends from
27N54W to the low near 24N60W to 20N62W. Scattered heavy showers
and tstms are east of the trough from 25N-28N between 52W-56W. A
broad surface ridge covers the remainder central and eastern Atlc
with the center of high pressure being located near 27N32W, which
is forecast to stall through Monday night. A cold front will
enter the north central Atlc waters Monday night. Otherwise,
surface high pressure will dominate elsewhere.

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