[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 050002
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
805 PM EDT FRI SEP 04 2009

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...METEOROLOGICAL ANALYSIS...WEATHER OBSERVATIONS...AND
RADAR.

BASED ON 1800 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH
2315 UTC.

...SPECIAL FEATURES...

TROPICAL WAVE IS JUST W OF THE CAPE VERDE ISLANDS ALONG 26W S
OF 20N MOVING W AT 20 KT. A 1012 MB LOW IS EMBEDDED ON THE WAVE
AXIS NEAR 14N26W. SATELLITE IMAGERY SHOWS A LARGE CLOUD MASS
FROM 9N-21N BETWEEN 23W-31W. THE WAVE IS ALSO WITHIN A DEEP
LAYER MOISTURE MAXIMUM AS INDICATED BY THE SSMI TOTAL
PRECIPITABLE WATER IMAGERY. SCATTERED MODERATE CONVECTION IS
FROM 15N-18N BETWEEN 25W-28W...AND FROM 9N-12N BETWEEN 27W-30W.
SOME ADDITIONAL DEVELOPMENT OF THIS SYSTEM IS POSSIBLE OVER THE
NEXT COUPLE OF DAYS.

...TROPICAL WAVES...

TROPICAL WAVE IS ALONG 37W S OF 19N MOVING W AT 12 KT. A 1013 MB
LOW IS EMBEDDED ON THE WAVE AXIS NEAR 15N37W. THE WAVE COINCIDES
WITH A DEEP LAYER MOISTURE MAXIMUM OBSERVED IN THE SSMI TOTAL
PRECIPITABLE WATER IMAGERY. SATELLITE IMAGERY SHOWS SAHARAN DUST
TO THE W OF THE WAVE AXIS AND ALSO TO THE NE OF SURFACE LOW.
THIS SAHARAN AIR LAYER IS INHIBITING ANY SIGNIFICANT DEEP
CONVECTION WITH ONLY A SMALL AREA OF ISOLATED MODERATE
CONVECTION FROM 15N-17N BETWEEN 36W-38W.

TROPICAL WAVE IS ALONG 55W S OF 16N MOVING W AT 12 KT. THE
WAVE REMAINS RELATIVELY LOW-AMPLITUDE WITH A WEAKENING 850 MB
VORTICITY SIGNATURE IN THE CIMSS WAVETRAK MODEL GUIDANCE.
SAHARAN DUST REMAINS TO THE E OF THE WAVE AXIS LIMITING
CONVECTION.

...ITCZ...

THE ITCZ AXIS IS CENTERED ALONG 11N15W 14N20W 10N30W 8N40W
89W61W. BESIDES THE CONVECTION MENTIONED IN THE SPECIAL FEATURE
SECTION ABOVE...ISOLATED MODERATE CONVECTION IS 7N-10N BETWEEN
30W-36W.

...DISCUSSION...

GULF OF MEXICO...
A SURFACE TROUGH EXTENDS FROM CENTRAL FLORIDA NEAR 29N80W TO THE
W GULF NEAR 25N95W. SCATTERED MODERATE CONVECTION IS INLAND OVER
CENTRAL AND SOUTHERN FLORIDA. SCATTERED SHOWERS ARE WITHIN 60 NM
OF THE REMAINDER OF THE TROUGH. ELSEWHERE...ISOLATED MODERATE
CONVECTION IS OVER THE SW GULF...W CUBA...AND THE YUCATAN
PENINSULA. THE REMAINDER OF THE GULF HAS SCATTERED HIGH CLOUDS
SKIES WITH LIGHT WINDS. IN THE UPPER LEVELS...AN UPPER LEVEL LOW
IS CENTERED OVER THE E GULF NEAR 24N86W. AN UPPER LEVEL RIDGE IS
OVER THE W GULF W OF 90W. EXPECT...A SURFACE TROUGH TO BE OVER
THE TEXAS COAST WITHIN 24 HOURS WITH SHOWERS. ALSO EXPECT
CONVECTION TO PERSIST OVER THE SAME AREAS MENTIONED ABOVE FOR
THE NEXT 24 HOURS.

CARIBBEAN SEA...
THE REMNANTS OF ERIKA IS NOW A SURFACE TROUGH IN THE VICINITY OF
PUERTO RICO PRODUCING SHOWERS. SCATTERED MODERATE CONVECTION IS
ALSO OVER THE LEEWARD ISLANDS FROM 16N-18N BETWEEN 63W-65W.
ELSEWHERE...A LARGE AREA OF SCATTERED MODERATE TO ISOLATED
STRONG CONVECTION IS OVER THE SW CARIBBEAN S OF 16N BETWEEN
78W-85W. SIMILAR CONVECTION IS MOSTLY INLAND OVER N COLOMBIA AND
NW VENEZUELA FROM 7N-12N BETWEEN 70W-75W. EXPECT...MORE
CONVECTION OVER THE LESSER ANTILLES...THE SW CARIBBEAN...AND
CENTRAL AMERICA OVER THE NEXT 24 HOURS.

ATLANTIC OCEAN...

A SURFACE TROUGH ENTERS THE DISCUSSION AREA NEAR 32N77W AND
EXTENDS SW TO CENTRAL FLORIDA NEAR COCOA BEACH. SCATTERED
SHOWERS ARE OVER THE N BAHAMAS AND THE W ATLANTIC FROM 24N-32N
BETWEEN 77W-80W. ANOTHER SURFACE TROUGH IS OVER THE CENTRAL
ATLANTIC ALONG 29N60W 23N58W. SCATTERED SHOWERS ARE WITHIN 90 NM
OF THE TROUGH AXIS. A 1023 MB HIGH IS ALSO OVER THE CENTRAL
ATLANTIC NEAR 32N51W. IN THE UPPER LEVELS...AN UPPER LEVEL LOW
IS OVER THE CENTRAL ATLANTIC NEAR 25N61W. ANOTHER UPPER LEVEL
LOW IS OVER THE E ATLANTIC NEAR 28N39W. FURTHER S...AN UPPER
LEVEL HIGH IS OVER THE TROPICS NEAR 17N56W. ANOTHER UPPER LEVEL
HIGH IS OVER W AFRICA NEAR 20N14W. EXPECT THE SPECIAL FEATURE
TROPICAL WAVE TO BE THE DOMINATE WEATHER PRODUCER IN THE
ATLANTIC OVER THE NEXT 24 HOURS.

$$
FORMOSA





This weather bulletin was brought to you by:
www.nashvilleweather.net