Tropical Weather Discussion
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AXNT20 KNHC 261748

Tropical Weather Discussion
NWS National Hurricane Center Miami FL
148 PM EDT Fri May 26 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.


Some of the tropical waves were re-located based on a long loop
IR satellite imagery, the Hovmoller Diagram, the TPW animation,
the 700 mb streamlines, visible satellite imagery, and 1200 UTC
surface data. Currently, four tropical waves are between the west
coast of Africa and the Lesser Antilles.

A tropical wave has an axis extending from 12N20W to 02N21W.
Scattered showers and isolated thunderstorms are within about 120
nm E of the wave axis from 07N-09N. Isolated moderate convection
is near the southern end of the wave axis. TPW imagery shows the
wave is situated in an area of deep layer moisture.

A tropical wave is added to the 1200 UTC analysis/surface map
along 34W/35W from 02N-10N. A cluster of moderate to isolated
strong convection is associated with the wave and covers the
waters from 03N-07N between 32W-36W. TPW animation shows the wave
is situated in an area of deep layer moisture south of 10N.

A tropical wave extends from 12N45W to 04N46W. The position of
this wave is based on the above mentioned long loop IR satellite
imagery. At the same time, visible satellite imagery indicates
some cyclonic turning ahead of the wave axis near 09N51W. This is
likely associated with the ITCZ. The TPW data indicate a decent
surge of moisture in association with this wave.

Another tropical wave is approaching the Lesser Antilles and
extends from 16N57W to 08N58W. A weak cyclonic turning is also
noted along the wave axis near 11N. Moisture associated with this
wave is more concentrated on the east side of the wave axis. This
moisture will spread across the Leeward Islands later today and
tonight, and continue to affect the islands on Sunday.

A tropical wave is moving across the SW Caribbean. The wave axis
extends from 15N81W across Costa Rica into the EPAC waters near
05N82W. The wave, combined with the monsoon trough, is producing
clusters of moderate to strong convection over parts of Panama,
Costa Rica and the Atlantic coast of Nicaragua. The wave is well
depicted in the moisture product with the TPW showing a bulge a
moisture near the wave axis.

Another tropical wave is exiting Guatemala and will move across
SE Mexico. Please refer to the Tropical Weather Discussion for
the eastern Pacific Ocean.


The Monsoon Trough enters the tropical Atlantic near 07N11W and
continues to 05N14W. The ITCZ extends from 05N14W to 05N19W to
05N32W to 07N45W to 09N51W to 08N57W. Aside from the convection
associated with the tropical waves, scattered moderate and
isolated strong convection is present from 04N-08N between 10W-



The cold front that was affecting the Gulf of Mexico during the
previous days is now over South Florida and the Florida Keys
generating some shower activity. A 1018 mb high pressure follows
the front and it is located near the Florida Big Bend. This system
extends a ridge aross most of the Gulf region, producing mainly
gentle to moderate winds over the eastern half of the Gulf, and
moderate to fresh winds over the western half. A thermal trough
will develop over the Yucatan Peninsula during the evenings, move
west across the SW Gulf during the overnight hours and dissipate
near 94W by late each morning. A surge of fresh to locally strong
winds will follow the trough. Little change in this weather
pattern is expected over the upcoming weekend.


A tropical wave is over the SW Caribbean. See the Tropical wave
section for more details on this system. Otherwise, high pressure
over the central Atlantic extends a ridge SW across the eastern
Caribbean Sea. The ridge supports fresh to strong easterly winds
across the east and central Caribbean with strong to near gale
force winds near the coast of Colombia. Moderate to fresh ESE
winds are over the western part of the basin, except for S of 11N,
where winds are lighter in the vicinity of the monsoon trough. The
strong winds over the central Caribbean will diminish this
weekend. Pulsing fresh to strong E to SE winds are expected over
the Gulf of Honduras at night through Monday night. Moderate to
locally fresh trades are expected elsewhere. Once again, visible
satellite imagery and Saharan Air layer from UW-CIMSS reveal the
presense of abundant saharan dust across much of the Caribbean
producing dry and hazy conditions.


Mostly dry and hazy conditions will prevail across the island
under the influence of a ridge. Model guidance continue to show
limted moisture across this areaexpected today and tomorrow.
However, patches of low level moisture, embedded in the trade wind
flow, could bring some cloudinees and isolated showers,
particulary late Saturday into Sunday.


A cold front enters the forecast area near 31N71W and continues SW
to south Florida and the Florida Keys. A 120 nm wide band of
showers with embedded thunderstorms is associated with the front,
forecast to stall from Bermuda to the NW Bahamas on Saturday and
gradually dissipate through Sunday. A recent scatterometer pass
shows mainly light to gentle winds behind the front and gentle to
moderate winds ahead of the front. A 1026 mb high pressure located
near 31N52W currently dominates the remainder of the Atlantic
Ocean. A weakening frontal boundary crosses between the Madeira
and the Canary Islands, stretching from 31N16W to 23N30W. A narrow
band of clouds with some showers is associated with the front
forecast to dissipate in about 24 hours. Four tropical waves are
located over the Atlantic between the west coast of Africa and the
Lesser antilles. Please refer to the Tropical Waves section for
more details. African dust is noted across much of the Atlantic Ocean
ahead of the first cold front and mainly from 10N-30N.

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