Tropical Weather Discussion
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AXNT20 KNHC 201000

Tropical Weather Discussion
NWS National Hurricane Center Miami FL
600 AM EDT Thu Apr 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 0600 UTC surface analysis and satellite imagery through
1000 UTC.


As of 20/0900 UTC, the center of Subtropical Depression ONE is
near 34.4N 39.3W. The subtropical depression is moving north at
12 kt. The estimated minimum central pressure is 996 mb. The
maximum sustained wind speeds are 30 knots with gusts to 40 knots.
Scattered moderate convection prevails north of 32N between 30W-
43W. Please read the PUBLIC ADVISORIES about Subtropical
Depression ONE under AWIPS/WMO headers MIATCPAT1/WTNT31 KNHC for
more details. FORECAST/ADVISORIES about Subtropical Depression ONE
are issued under the AWIPS/WMO headers MIATCMAT1/WTNT21 KNHC.

A tight pressure gradient will develop over the central Atlantic
behind a cold front that currently extends from 31N47W to 26N52W
to 30N73W. This gradient will support gale-force winds mainly north
of 30N between 49W-54W by 21/0600 UTC. Seas will build to 12-16 ft
by 21/0600 UTC then increasing to 16-22 ft by 21/1200 UTC. These
conditions are expected to continue through 22/0600 UTC. Please
refer to the High Seas Forecast product under the AWIPS/WMO
headers HSFAT2/FZNT02 KNHC for more details.


The Monsoon Trough extends across the western Africa coast from
07N12W to 03N19W. The Intertropical Convergence Zone continues
from 03N19W to 02N36W to the South American coast near 03S42W.
Scattered moderate convection is from 01N-04N between 16W-37W.



Broad surface ridging prevails across the Gulf of Mexico. An
upper-level low is centered over the western Gulf near 22N92W.
Upper-level diffluence to the east of the low is supporting
scattered showers over the Yucatan Peninsula and channel mainly
south of 24N between 84W-90W. A surface trough Scatterometer data
depicts gentle to moderate easterly winds across the basin.
Expect over the next 24 hours for little change over the surface
pattern, while in the upper-levels the low over the western Gulf
will drift east to the south central portion of the basin.


Gentle to moderate tradewinds prevail over most of the Caribbean
Sea with the exception of the central portion of the basin
between 69W-74W where moderate to fresh winds were reported. These
winds are also affecting the Windward Passage. A diffluent flow
prevails across the western Caribbean supporting scattered
showers mainly west of 76W. Scattered moderate convection is
observed over portions of Central America in the proximity of a
surface trough that extends over the EPAC. Portions of Costa Rica
and Panama are affected by this activity, as well as their
adjacent waters south of 12N between 76W-83W. Expect little
change over the next 24 hours.


Abundant cloudiness and isolated showers are over the island at
this time. Expect over the next 24 hours for scattered showers to
advect over the island from the east with the tradewind flow.
Also, expect scattered moderate convection to form due to local


The Subtropical Depression One is over the central Atlantic. A
Gale Warning is in effect over the central Atlantic. Please refer
to the section above for details these features. A broad surface
ridge is over the west Atlantic. A cold front extends from 31N47W
to 26N52W to 30N73W with isolated showers. Further east, a 1016
mb surface high is centered near 25N27W. Scatterometer data
depicts fresh to strong northerly winds mainly north of 27N
between 33W-57W. Another area of fresh easterly winds prevails
across the Bahama Islands south of 24N between 72W-80W. Expect
over the next 24 hours for the Subtropical Depression to move N
while weakening. The gale-force winds will develop over the
central Atlantic in 24 hours.

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