000
AXNT20 KNHC 261749
TWDAT 

Tropical Weather Discussion 
NWS National Hurricane Center Miami FL 
805 PM EDT SAT SEP 24 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 wave along 46W from 4N-17N with a 1010 mb low along the
wave near 9N46W moving west near 20 kt over the past 24 hours.
Wave is beginning to show signs of organization and now has a
high chance of tropical development over the next 48 hours.
Wave coincides with well defined 700 mb low and trough in the
global model and is embedded within an area of moisture with dry
air and Saharan dust to the north. Clusters of scattered
moderate to isolated strong convection is from 9N-15N between
42W-52W. Regardless of development, heavy rains and strong gusty
winds, possibly to tropical storm force, are expected to spread
over the southern Lesser Antilles beginning late Tuesday or
Wednesday. Please see the Tropical Weather Outlook under
AWIPS/WMO headers MIATWOAT/ABNT20 KNHC for more details. 

...TROPICAL WAVES... 

Tropical wave off the coast of Africa was relocated to along 13W-
14W north of 4N to inland over west Africa based on a 24 hour
satellite loop and the wave guidance. Wave is moving west 15 to
20 kt. Wave coincides with a 700 and 800 mb global model low and
trough. Wave remains an area of moisture as seen on the Total
Perceptible Water imagery. No associated deep convection is
noted. 

Tropical wave in the east Caribbean extends along 66W/67W from
10N-19N moving west 15 to 20 kt over the past 24 hours. Wave
coincides with a weak 700 mb global model trough and is embedded
within a weak surge of moisture as seen on the Total Perceptible
Water imagery. Wave is beneath an upper trough partially masking
the satellite signature. No associated deep convection is noted. 

...ITCZ/MONSOON TROUGH... 

The Monsoon Trough extends across Africa into the east Tropical
Atlantic near 10N14W then along 7N19W 11N40W through the 1010 mb
low in the special features section near 9N46W to 7N51W. The
ITCZ is again disrupted by this latest tropical wave. Clusters
of scattered moderate to isolated strong convection are within
250 nm north of the monsoon trough between 18W-22W, within 250
nm south of the monsoon trough between 23W-32W, and within 180
nm north of the monsoon trough between 30W-39W. 

...DISCUSSION...

GULF OF MEXICO...

An upper trough over the upper Mississippi Valley has been
dragging a weakening front across Texas where it is dissipating
as a stationary front along the Texas coast. A surface trough is
just offshore extending from 29N95W to the mouth of the Rio
Grande between Texas and Mexico generating scattered showers and
isolated thunderstorms within 90 nm east of the trough and west
of the trough to the coast of Texas. This front/trough is
beneath an upper ridge that extends from central Mexico over
Texas covering the west Gulf of Mexico while an upper trough
covers the remainder of the Gulf with an upper low centered in
the Big Bend of Florida near 29N84W. The upper low is generating
scattered to numerous showers and isolated thunderstorms from
22N-26N east of 90W through the Straits of Florida and over the
Florida Keys. Isolated showers and possible thunderstorms dot
the remainder of the northeast Gulf north of 26N east of 90W. A
second surface trough is in the southwest Gulf extending from
23N97W to the east Bay of Campeche near 19N93W generating
scattered showers and isolated thunderstorms within 210 nm
northeast of the surface trough with isolated showers and
thunderstorms over the remainder of the southwest Gulf south of
25N west of 91W. A weak frontal boundary will move across the
northern Gulf through Tuesday night. A stronger cold front will
push into the north Gulf Thursday. 

CARIBBEAN SEA...

The upper ridge over the Gulf of Mexico covers the far west
Caribbean west of 79W. Isolated showers and thunderstorms dot
the northwest Caribbean north of 18N west of 75W. An upper low
is centered over the Virgin Islands extending an upper trough
axis southwest to northwest Colombia generating scattered
showers and isolated thunderstorms over the Lesser Antilles
within 90 nm of line from 16N62W to 20N58W including the islands
of Dominica and Guadeloupe. The monsoon trough extends from over
Colombia near 9N75W along 10N80W to across Costa Rica near
10N84W generating scattered showers and isolated thunderstorms
south of 12N to over Panama between 77W-81W. The tropical wave
will continue west and become diffuse west of 75W by Wednesday.
The 1010 low along the tropical wave in the special features is
expected to intensify before reaching the Lesser Antilles
Wednesday night. However showers and thunderstorms will move
over the Lesser Antilles ahead of the trough wave/low as early
as Tuesday night or Wednesday morning. 

...HISPANIOLA...

Currently skies are mostly clear across the island this
afternoon. The upper trough to the east will shift west to over
the island by Wednesday. Afternoon/evening showers and
thunderstorms remain possible through Thursday. 

ATLANTIC OCEAN... 

The upper low over the northeast Gulf extends over the far west
Atlantic with a surface trough extending from over east Georgia
near 32N82W into the west Atlantic to 28N80W. The upper trough
is generating scattered to numerous showers and isolated
thunderstorms within 90/120 nm of a line from 27N74W to the
southeast CONUS coast near the South Carolina/Georgia border and
from 23N-26N west of 79W through the Straits of Florida.
Scattered showers and isolated thunderstorms dot the remainder
of the west Atlantic west of 71W. An upper trough extends over
the northwest Atlantic to 30N then narrows along 26N66W to the
upper low over the Virgin Islands and is supporting a frontal
boundary along the north periphery of the discussion area of the
central into the west Atlantic. Scattered to numerous showers
and isolated thunderstorms are within 90 nm of a line from
29N54W to beyond 32N47W with scattered showers and isolated
thunderstorms from 26N-30N between 53W-59W and from 23N-26N
between 61W-67W. The remainder of the Atlantic east of 60W is
dominated by a surface ridge anchored by a 1028 mb high just
east of the Azores. The central Atlantic cold front will drift
southward to north of 29N through tonight. Winds and Seas will
increase over the west Tropical Atlantic and north of the Virgin
Islands Wednesday and Thursday as the low/tropical wave in the
special features moves into the Caribbean.  

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

$$
PAW