Tropical Weather Discussion
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AXNT20 KNHC 201726

Tropical Weather Discussion
NWS National Hurricane Center Miami FL
126 PM EDT Sat May 20 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 1200 UTC surface analysis and satellite imagery through
1715 UTC.


A tropical wave is in the eastern Atlantic with axis extending
from 12N25W to 04N27W, moving west at around 10 kt. Based on
current SAL analysis from UW-CIMSS, african dust surrounds the
wave. As a result, only a few showers are noted near the wave

A tropical wave is approaching the Windward Islands. Its axis
extends from 15N57W to Guyana near 06N58W, moving west at 10-15
kt. A few showers are noted near the wave axis south of 10N,
including parts of northern Guyana. The TPW animation shows a
surge of moisture in the wake of the wave axis.

A tropical wave is reaching the coasts of the Yucatan Peninsula
and Belize, and extends from 20N87W to 12N88W. The wave is moving
west at around 15 kt within the last 24 hours. This system remains
embedded within an area of deep layered moisture as depicted in
the TPW animation.


The Monsoon Trough enters the tropical Atlantic near 08N13W and
continues to 07N19W. The ITCZ extends from 07N19W to 07N25W, then
resumes west of the above mentioned tropical wave from 06N29W to
the coast of Brazil near 02N50W. Isolated moderate convection is
noted from 05N-09N between 18W-23W, and within 120 nm north of the
ITCZ axis between 30W-34W.



High pressure of 1022 mb located near Bermuda extends a ridge
across Florida and the SE CONUS into the Gulf of Mexico. The
pressure gradient between the ridge and lower pressures across
Mexico and the far west Gulf waters supports moderate to fresh E
to SE winds across most of the basin. Once again, areas of fog
were noted over the NW Gulf under the influence of a SE wind
flow. A diffluent pattern aloft is helping to induce some shower
activity over the eastern Gulf, particularly from 25N-27.5N
between 84W-88W. Fresh to locally strong easterly winds will
pulse off the NW coast of the Yucatan Peninsula tonight and Sunday
night in association with a thermal trough. This feature will
develop during the evening hours over the Yucatan Peninsula before
pushing into the SW Gulf each night. The ridge will persist
through Sunday with little change in the weather pattern. A weak
cold front is forecast to move off the Texas coast by Sunday
night. The front will stall and dissipate over the northern Gulf
through Tuesday.


A tropical wave is approachimg the Windward Islands and a second
tropical wave is leaving the basin. Please refer to the TROPICAL
WAVE section above for details. High pressure located near Bermuda
combined with the Colombian/Panamanian low is supporting fresh to
strong trade winds over the east and central Caribbean while
moderate to fresh SE winds prevail across the NW Caribbean. This
weather pattern will persist on Sunday. Patches of low level
moisture, embedded in the trade wind flow, are observed across
the region, with the exception of clusters of strong convection
over the SW Caribbean, mainly S of 10N. This convective activity
is currently affecting parts of Colombia and eastern Panama under
the influence of a monsoonal flow from the eastern Pacific. Upper
diffluence is also helping to induce this convection.


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


High pressure dominates most of the Atlantic Ocean. A 1022 mb
high is located near Bermuda while another high pressure center of
1025 mb is near 28N35W. The latter one will remain nearly stationary
over the next 24 hours. A surface trough extends from 23N58W to
18N63W. A recent scatterometer pass shows moderate to fresh SE
winds on the east side of the trough axis. Scattered showers are
also noted mainly ahead of the trough. This feature is ahead of an
upper-level trough that extends from 31N57W to the Turks and
Caicos Islands. Abundant mid-upper level moisture persists ahead
of this upper-level trough forecast to drift eastward.

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