Tropical Weather Discussion
Issued by NWS
AXNT20 KNHC 210521
Tropical Weather Discussion
NWS National Hurricane Center Miami FL
121 AM EDT Fri Apr 21 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 0000 UTC surface analysis and satellite imagery through
The center of T.S. Arlene is located 39.4N 44.2W and is moving
northwest at 24 knots. The estimated minimum central pressure is
993 mb. The maximum sustained wind speeds is 45 knots with gusts
to 55 knots. Scattered moderate convection is observed from 37N-
41N between 32W-47W. Please refer to the public advisory under
the WMO header WTNT31 KNHC and under the AWIPS header MIATCPAT1
for more details.
A tight pressure gradient generated between a broad low pressure
system centered southwest of T.S. Arlene and a high pressure to
the west will support gale-force winds north of 30N between 49W-54W
starting on 04/21 at 0600 UTC and continuing through the evening
hours. Please see the latest High Seas Forecast product under the
WMO header FZNT02 KNHC and under the AWIPS header MIAHSFAT2 for
The Monsoon Trough extends across the western Africa coast from
07N12W to 03N19W. The Intertropical Convergence Zone continues
from 03N19W to the coast of Brazil near 02S43W. Isolated showers
prevail from 04N-04S between 08W-35W.
GULF OF MEXICO...
A mid to upper-level low is centered northwest of the Yucatan
Peninsula near 23N91W. A diffluent flow aloft prevails to the east
of the low supporting scattered light to moderate convection from
20N-27N between 80W-90W. A surface trough accompanies this
convection, extending from the western Caribbean across the
Yucatan Channel to 24N84W. A surface ridge extends across the
basin anchored by a 1022 mb high centered over the west Atlantic.
Scatterometer data depicts gentle to moderate easterly winds
across the northern half of the basin while moderate to fresh
easterlies prevail south of 26N. Expect for the upper-level low to
dissipate in 24 hours. The surface trough is forecast to become a
center of low pressure this weekend over the southeast Gulf. The
low will move over northeast Gulf waters where it will dissipate
The main feature in the basin is a surface trough that extends
from 24N84W to 16N87W. This elongated area of low pressure is
located under a broad area of mid to upper-level diffluent flow
that along with abundant moisture in the region supports
scattered to numerous mainly north of 20N west of 79W. This
shower activity will continue overnight as the trough moves slowly
west towards the Yucatan Peninsula. Latest scatterometer data
depict fresh to locally strong easterly winds in the vicinity of
the trough. An area of fresh trades extends across the central
Caribbean north of 14N, including the Windward Passage. Moderate
trades dominate elsewhere.
Broken to overcast skies persist across the island with possible
isolated showers over the adjacent waters. These conditions are
expected to continue during the next two days.
T.S. Arlene is over central Atlantic waters north of the area.
See the Special Features section above for further details. A
surface ridge extends across the western Atlantic anchored by a
1022 mb high centered near 33N70W. To the east, a cold front
enters the area from 31N42W to 24N46W to 23N54W then dissipates
to 23N59W. A surface trough, previously part of the front, extends
from 24N62W to 28N75W. No convection is associated with these
boundaries. A surface ridge dominates the remainder of the area,
anchored by a 1017 mb high centered near 24N24W. T.S. Arlene is
forecast to dissipate in 24 hours. An area of gale-force winds
will develop today over the central Atlantic. Please refer to the
section above for details.
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