Tropical Weather Discussion
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AXNT20 KNHC 231721

Tropical Weather Discussion
NWS National Hurricane Center Miami FL
1805 UTC Wed Jun 23 2021

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 31N. The following information is based on satellite
imagery, weather observations, radar and meteorological analysis.

Based on 1200 UTC surface analysis and satellite imagery through
1630 UTC.


A tropical wave axis is analyzed along 26/27W from 16N southward,
moving W at 10-15 kt. Scattered moderate showers prevail within
120 nm W and 180 nm E of the wave axis from 02N-08N.

An Atlantic Ocean tropical wave axis is along 43W from 12N
southward, moving W at 10 kt. Scattered moderate showers are noted
within 270 nm either side of the wave axis from 04N-08N.

An Atlantic Ocean tropical wave axis has been repositioned
slightly eastward from the previous map, along 55W from 15N
southward, based on evidence from satellite imagery. The tropical
wave is moving W at 5-10 kt. Scattered moderate convection is
noted from 04N-16N between 49W-56W.

A tropical wave has been added to the analysis over the central
Caribbean Sea, along 70W from the Dominican Republic southward to
western Venezuela. The tropical wave is moving W at 10 kt.
Scattered showers and isolated tstorms are seen from 16N-18N
between 69W-72W.


The monsoon trough passes through the coast of Guinea-Bissau near
12N16W to 05N29W. The ITCZ is from 05N29W to 05N40W. Aside from
the convection described in the tropical waves section above,
scattered moderate convection is noted along the ITCZ between
30W-37W. Numerous moderate and scattered strong convection is seen
off the coast of Africa from 02N-10N between 06W-18W.


A cold front extends from the coast of Georgia near 31N81W
westward to the Alabama/Mississippi border near 31N88W and
continues W as a stationary front just inland from the Gulf Coast,
to near New Iberia, Louisiana. The front is being supported by an
upper-level trough that extends along the U.S. east coast, across
northern Florida and into the NE Gulf of Mexico. Scattered showers
and isolated tstorms are seen along the Gulf Coast of Florida,
extending offshore for about 60 nm, from Key West to Pensacola.
Another area of scattered moderate convection is occurring near
the Mouth of the Rio Grande River and extending offshore into the
western Gulf for about 60 nm. A recent ASCAT pass shows fresh SE
winds to the NW of the Yucatan Peninsula, where seas are likely
4-5 ft. Gentle wind speeds are over the eastern Gulf of Mexico,
with seas of 2-3 ft.

High pressure will prevail across the northern Gulf of Mexico. A
diurnally induced trough will develop over the Yucatan each
evening. This will result in a pulsing of fresh E to SE winds each
night NW of the Yucatan peninsula through Thu night.


An upper level low is centered between Jamaica and eastern Cuba.
Isolated moderate thunderstorms are seen between western Cuba and
the Cayman Islands, as well as between Jamaica and far eastern
Cuba. In the SW Caribbean, the monsoon trough is inducing numerous
moderate and scattered strong convection south of 11N between
77W-83W. Another area of scattered moderate and isolated strong
convection is occurring over the SE Caribbean, from 10N-13N
between 60W-67W, due to enhanced moisture in the area in between
two tropical waves. This area includes Trinidad, Grenada and the
NE coast of Venezuela. A recent ASCAT pass shows fresh NE to E
trades in the south-central Caribbean, offshore of Colombia. Fresh
to locally strong E to SE winds are likely occurring in the Gulf
of Honduras. Moderate trades prevail elsewhere. Seas are 5-6 ft in
the central Caribbean and Gulf of Honduras, and 3-4 ft elsewhere,
except 1-2 ft south of Cuba.

A ridge of high pressure north of the area combined with the
Colombian low will continue to support fresh to strong trades over
the south-central Caribbean and the Gulf of Honduras through
tonight. The ridge will shift northward loosening the pressure
gradient with a modest decrease in winds over these areas.


A surface trough is analyzed over the western Atlantic from
31N78W to 28N80W. A line of moderate to strong convection is
along, or just east of the surface trough. Isolated showers and
tstorms are elsewhere from the NW Bahamas northward, and west of
76.5W to the Florida Peninsula. Farther east, an upper-level low
is centered near 28N51W. A surface trough just east of the upper-
low extends along 48W from 31N-24N. Scattered moderate convection
is seen from 25N-30N between 46W-50W. A 1025 mb surface high
pressure near 31N63W extends a surface ridge to southern Florida.
A recent ASCAT pass shows gentle to moderate wind speeds north of
23N and west of 40W, except for moderate to fresh east of northern
Florida, close to the surface trough. Seas are 3-5 ft across the
subtropical Atlantic, except 4-6 ft east of northern Florida.
Moderate to fresh trades are south of 23N and west of 40W, where
seas are 5-6 ft. Fresh N to NE winds prevail near the coast of
Africa, north of 17N and east of 30W, except for strong to near
gale force N winds near the coast of Morocco. Seas are 6-8 ft over
the NE Atlantic.

For the forecast, the surface ridge axis that extends from 31N63W
to 26N80W will start to shift northward tonight. This will push
the surface trough that is currently located off NE Florida
westward into the SE United States by Fri night. Farther
southeast, a tropical wave east of the Lesser Antilles will
interact with an upper level trough, which will enhance
convection with locally higher winds and seas through Fri, east of
the Lesser Antilles. A surface trough will form as a result of
this system, then move north of the Lesser Antilles Friday night.
The trough will continue to move westward across the waters north
of Puerto Rico Sat, and north of Hispaniola Sun.

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