Tropical Weather Discussion
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AXNT20 KNHC 201716

Tropical Weather Discussion
NWS National Hurricane Center Miami FL
116 PM EDT Sun May 20 2018

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.


An upper-level trough extends across the eastern Gulf of Mexico
and western Caribbean, with diffluent flow aloft prevailing
across the Florida Peninsula and the western Atlantic and
Caribbean, to the east of the upper trough`s axis. This pattern
is drawing deep tropical moisture northward from the SW Caribbean
between 77W and 82W and is supporting scattered to numerous
moderate convection along this corridor. This activity is
expected to continue through early this upcoming week, with heavy
rainfall and flooding possible over the land areas affected.


A tropical wave has an axis that extends from 13N29W to 01N29W,
moving W at around 15 kt. This wave is embedded in a sharp 700 mb
trough and scattered convection south of 3N.

A central Atlantic tropical wave has an axis that extends from
14N56W to 05N57W, moving W at 5 to 10 kt. This wave has slowed
down its forward motion over the past 24 hours and is expected to
become diffuse east of the Caribbean over the next couple of days.
No significant convection is related to this wave at this time.


The monsoon trough passes through the coastal Africa near 14N17W
to 03N27W. The ITCZ extends west of a tropical wave from 02N33W
to 04N51W. Besides the convection associated with the wave,
scattered moderate convection is noted along the ITCZ.



An upper-level trough prevails across the eastern Gulf, with an
axis along 85W. Diffluent flow aloft east of the trough is
bringing tropical moisture over the far east Gulf and western
Atlantic waters affecting the Florida Peninsula and Florida
Straits/Keys. Please refer to the Special Features section above for
more details. A surface trough is embedded within this
convection, extending across central Florida and adjacent waters.
A weak ridge axis extends across the remainder of the basin along
30N producing mainly gentle to moderate winds.

The surface trough is expected move into the eastern Gulf through
Monday. The upper-level trough over the eastern Gulf will remain
nearly stationary through the first half of this upcoming week,
supporting ongoing convection over the eastern Gulf.


An upper-level trough extends over the eastern Gulf of Mexico and
western Caribbean. An overnight scatterometer pass indicated that
a surface trough has developed over the northwest Caribbean, with
axis extending from 23N81W to 19N83W. The combination of upper-
level diffluence on the eastern side of the upper-level trough
and convergence associated with the surface trough is supporting
scattered to numerous moderate convection across the Caribbean
waters between 78W and 83W. Broad high pressure over the
subtropical Atlantic continues to support moderate to fresh
tradewinds over most of the basin, except fresh to strong winds
over the central Caribbean. Wave heights of 8 to 10 ft persist
over the central Caribbean as confirmed by a recent satellite
altimeter pass and current buoy data.

Over the next couple of days, the upper-level trough will remain
in place enhancing shower and thunderstorm activity over the
western Caribbean. The surface ridging pattern over the Atlantic
will persist, keeping a similar wind profile in place across the
basin into the middle of this upcoming week.


Diffluent flow aloft to the east of an upper-level trough
currently over the eastern Gulf of Mexico, combined with a surface
trough extending just offshore of northern Florida is supporting
scattered to numerous moderate convection across Florida, the
Bahamas, and Atlantic waters mainly west of 76W. To the east, high
pressure centered over the central Atlantic spans across the basin.
Surface observations and latest scatterometer data indicate
prevailing fresh to locally strong southeast winds over a portion
of the Bahamas as well as within a few hundred miles north of
Hispaniola. A recent altimeter pass indicates wave heights of 8 to
9 ft over these waters outside of the Bahamas. Moderate to fresh
tradewinds are occurring elsewhere across the central and western
Atlantic south of 27N. Gentle to moderate winds cover the central
Atlantic north of 27N. Moderate to occasionally fresh north to
northeast winds are occurring over the eastern Atlantic.

The overall pattern will change little through the next 24 hours.
Therefore, the chances for heavy rainfall over the Florida
Peninsula, Bahamas, and western Atlantic will continue.

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