Tropical Weather Discussion
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419
AXNT20 KNHC 181751
TWDAT

Tropical Weather Discussion
NWS National Hurricane Center Miami FL
205 PM EDT THU AUG 18 2016

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.

...SPECIAL FEATURES...

Tropical Storm Fiona is centered near 16.4N 40.5W at 18/1500 UTC
or about 950 nm west of the Cabo Verde Islands moving west-
northwest at 7 kt. Estimated minimum central pressure is 1006
mb. Maximum sustained wind speed is 40 kt with gusts to 50 kt.
Scattered moderate to isolated strong convection is from 16N-20N
between 40W-42W. Please see the latest NHC Intermediate Public
Advisory under AWIPS/WMO headers MIATCPAT1/WTNT31 KNHC and the
full Forecast/Advisory under the AWIPS/WMO headers
MIATCPAT1/WTNT21 KNHC for more details.

...TROPICAL WA

Tropical wave in east Tropical Atlantic is along 26W/27W from
11N-20N moving 10 to 15 kt over the past 24 hours. Wave
coincides with a well defined 700 mb Global models troughing and
is along the leading edge of a surge of moisture as seen on the
SSMI Total Precipitable Water imagery. No associated showers or
deep convection.

Tropical wave in the west Tropical Atlantic extends along 55W
from 9N-15N moving west near 25 kt over the past 24 hours. Wave
coincides with 700 mb Global models troughing south of 16N. Wave
is embedded within an area of dry, stable air and strong
subsidence, thus no associated showers or convection.

Tropical wave in the east Caribbean extends along 68W/69W from
10N-19N moving west 15 to 20 kt over the past 24 hours. Wave
coincides with a weak 700 mb Global models troughing and is
embedded within a high amplitude surge of moisture as seen on
the SSMI Total Precipitable Water imagery. No associated deep
convection is noted. Scattered showers and isolated
thunderstorms are within 75 nm of a line from 14N67W to 17N71W.

Tropical wave in the south Gulf of Mexico extends along 94W
south of 21N across south Mexico into the east Pacific region
moving west 15 to 20 kt over the past 24 hours. Wave coincides
with 700 mb Global models troughing south of 18N and is embedded
within a broad area of moisture as seen on the SSMI Total
Precipitable Water imagery. The energy and activity associated
with this wave is over the east Pacific region.

...ITCZ/MONSOON TROUGH...

The monsoon trough extends across Africa into the east Tropical
Atlantic near 13N16W along 12N24W to 15N33W. The ITCZ begins
near 12N44W and continues along 9N52W into South America near
8N60W. The monsoon trough/ITCZ is disrupted by Tropical Storm
Fiona. Scattered moderate to isolated strong convection is
within a 60 nm radius of 12N19W and from 10N-13N between 26W-
32W. Clusters of scattered moderate convection are within 120 nm
north of the ITCZ between 46W-53W and 56W-60W.

...DISCUSSION...

GULF OF MEXICO...

An upper ridge is anchored inland over Mexico extending a ridge
axis from across south Texas to South Carolina covering the west
Gulf. An elongated upper trough is centered over south Florida
extending an upper trough southwest along 23N91W to over south
Mexico near Veracruz. An area of difflunce aloft is generating
isolated showers and thunderstorms from within 90 nm of a line
from 28N86W to 24N94W. Afternoon scattered showers and isolated
thunderstorms are developing along the north Gulf coast from the
Florida/Alabama border to Freeport Texas, including areas over
southern Louisiana. A surface ridge extends from the west
Atlantic over northeast Florida to a 1021 mb high near 30.5N83W
to east Texas. This surface ridge will shift south and stall
from central Florida to southwest Louisiana/Texas coast this
weekend. The diurnal surface trough will form each evening over
the Yucatan peninsula supporting fresh winds over the east Bay
of Campeche.

CARIBBEAN SEA...

Benign upper features cover the Caribbean this afternoon. The
activity in the east/central Caribbean is associated with the
tropical wave. Please see Tropical Wave section above. The
monsoon trough extends from Colombia near 8N78W across Panama
into the southwest Caribbean near 10N82W continuing across Costa
Rica into the east Pacific region and is generating scattered
showers and isolated thunderstorms south of 10N east of 82W and
south of 11N west of 82W. This is leaving the remainder of the
Caribbean with fair weather this afternoon. The tropical wave
will move through the central Caribbean Thursday and across the
west Caribbean late in the week. Another tropical wave will move
into the east Caribbean Friday. Fresh to strong trade winds will
persist across the central Caribbean through the week into the
weekend and reach near gale force along the northwest coast of
Colombia late night and early morning hours through Friday
night. Fresh to strong trade winds will affect the Gulf of
Honduras tonight.

...HISPANIOLA...

Currently fair weather covers the island this afternoon. However
a tropical wave in the Mona Passage will move across the island
later this afternoon through Thursday increasing showers and
possible thunderstorms. Friday will bring the return of
afternoon/evening showers and thunderstorms to the island.

ATLANTIC OCEAN...

The primary concern for the central Atlantic this afternoon is
Tropical Storm Fiona moving across the central Tropical
Atlantic. Please see the Special Features section above for more
details. The upper low over south Florida extends a trough axis
northeast into the west Atlantic to beyond Bermuda. An upper
ridge is anchored north of the Virgin Islands near 23N65W. At
the surface, a pair of surface troughs extends from 30N68W to
26N69W and 27N64W to 23N65W. The upper ridge/trough is providing
difflunce aloft generate scattered to numerous showers and
isolated thunderstorms from 24N-30N between 60W-68W and
scattered showers from 27N-30N between 68W-72W. The remainder of
the basin is dominated by a surface ridge. The surface ridge is
anchored by a 1021 mb high in the east Atlantic near 28N31W,
then north of the above surface troughs to a 1022 mb high in the
west Atlantic near 32N68W then continues across northeast
Florida into the north Gulf of Mexico. The surface ridge will
persist today, then shift south to along 26N by the weekend. The
surface troughs will gradually shift west through Thursday.

For additional information please visit
http://www.hurricanes.gov/marine

$$
PAW



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