000
AXNT20 KNHC 181034
TWDAT 

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
805 AM EDT THU SEP 18 2008

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 0600 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 
1015 UTC.

...TROPICAL WAVES...
A TROPICAL WAVE IS NEAR THE CAPE VERDE ISLANDS ALONG 22W/23W S 
OF 18N MOVING W 10 KT. NO DEEP CONVECTION IS ASSOCIATED WITH THE 
WAVE. A LOW LEVEL SWIRL IS SEEN NEAR 17N22W. THE TPW PRODUCT 
FROM CIMSS ALSO INDICATES A BULGE OF MOISTURE E OF 28W. 

A LOW AMPLITUDE TROPICAL WAVE IS ALONG 43W S OF 14N MOVING W 10 
KT. NO DEEP CONVECTION IS ASSOCIATED WITH THE WAVE. ISOLATED 
SHOWERS ARE HOWEVER WITHIN 180 NM OF THE WAVE AXIS. 

A TROPICAL WAVE IS ALONG 70W S OF 19N MOVING W 10-15 KT. 
SCATTERED MODERATE TO STRONG CONVECTION IS ALONG THE COASTS OF 
VENEZUELA AND N COLOMBIA FROM 10N-15N BETWEEN 69W-77W.   

A TROPICAL WAVE IS OVER THE NW CARIBBEAN AND CENTRAL AMERICA 
ALONG 86W/87W S OF 22N MOVING W 10-15 KT. CLUSTERS OF SCATTERED 
MODERATE TO STRONG CONVECTION ARE OVER A LARGE AREA FROM 09N-18N 
BETWEEN 80W-92W. 

...THE ITCZ...
ITCZ AXIS IS CENTERED ALONG 19N17W 10N28W 11N62W. SCATTERED 
MODERATE TO ISOLATED STRONG CONVECTION IS ALONG THE COAST OF 
SOUTH AMERICA FROM 10N-14N BETWEEN 56W-64W. SCATTERED SHOWERS 
ARE OVER A LARGE AREA FROM 4N-13N BETWEEN 20W-45W. 

...DISCUSSION...

GULF OF MEXICO...
A WEAK QUASI-STATIONARY FRONT EXTENDS FROM N FLORIDA TO THE BAY 
OF CAMPECHE ALONG 30N79W 28N84W 27N91W 18N94W. ISOLATED MODERATE 
CONVECTION IS OVER THE W GULF OF MEXICO AND THE BAY OF CAMPECHE 
FROM 17N-26N BETWEEN 91W-97W. 10-15 NLY WINDS ARE N OF THE 
FRONT...WHILE 10 KT ELY WINDS ARE S OF THE FRONT. IN THE UPPER 
LEVELS...AN UPPER LEVEL HIGH IS CENTERED OVER THE BAY OF 
CAMPECHE NEAR 22N98W PRODUCING ANTICYCLONIC FLOW W OF 90W. A 
TROUGH IS OVER THE E GULF OF MEXICO AND FLORIDA E OF 90W. EXPECT 
...THE FRONT TO RETROGRADE SLIGHTLY N THEN DISSIPATE OVER THE 
NEXT 24 HOURS. EXPECT CONTINUED CONVECTION OVER THE W GULF OF 
MEXICO W OF 90W FOR THE NEXT 24 HOURS. ALSO EXPECT AIRMASS 
CONVECTION OVER S FLORIDA AND THE KEYS. 

CARIBBEAN SEA...
TWO TROPICAL WAVES ARE OVER THE CARIBBEAN SEA AND CENTRAL 
AMERICA. SEE ABOVE. FRESH SURFACE EASTERLIES DOMINATE MUCH OF 
THE REMAINDER OF THE CARIBBEAN. IN THE UPPER LEVELS...AN UPPER 
LEVEL HIGH IS OVER HONDURAS NEAR 15N87W. AN UPPER LEVEL LOW IS 
CENTERED N OF THE LEEWARD ISLANDS NEAR 22N64W. DIFFLUENCE E OF 
THE CENTER IS PRODUCING AN IMPRESSIVE AREA OF SCATTERED MODERATE 
TO STRONG CONVECTION OVER THE LEEWARD ISLANDS FROM 14N-20N 
BETWEEN 58W-64W. SIGNIFICANT UPPER LEVEL MOISTURE DOMINATES THE 
ENTIRE CARIBBEAN. EXPECT CONVECTION ASSOCIATED WITH THE TROPICAL 
WAVES OVER THE NEXT 24 HOURS. ALSO EXPECT AIRMASS CONVECTION 
OVER CENTRAL AMERICA.

ATLANTIC OCEAN...
TWO TROPICAL WAVES ARE OVER THE ATLANTIC OCEAN WITH NO 
SIGNIFICANT CONVECTION. SEE ABOVE. A 1014 MB LOW IS OVER THE W 
ATLANTIC NEAR 33N65W, A SURFACE TROUGH EXTENDS SW FROM THE LOW 
TO THE SRN BAHAMAS NEAR 24N73W. SCATTERED SHOWERS ARE WITHIN 120 
NM OF THE TROUGH AXIS. A 1023 MB SURFACE HIGH IS OVER THE 
CENTRAL ATLANTIC NEAR 33N50W. THE TAIL END OF A COLD FRONT IS 
OVER THE E ATLANTIC ALONG 32N16W 26N24W. SCATTERED SHOWERS ARE 
WITHIN 90 NM OF THE FRONT. IN THE UPPER LEVELS...A RIDGE IS OVER 
THE W ATLANTIC N OF 20N BETWEEN 70W-80W. UPPER LEVEL LOWS ARE  
OVER THE CENTRAL ATLANTIC NEAR 27N47W...AND AT 23N40W. A LARGE 
TROUGH IS OVER THE E ATLANTIC N OF 20N AND E OF 30W. TWO UPPER 
LEVEL HIGHS ARE CENTERED OVER THE TROPICAL ATLANTIC AT 15N54W... 
AND AT 12N28W. EXPECT THE TROPICAL WAVES TO PROPAGATE WEST WITH 
SCATTERED SHOWERS OVER THE NEXT 24 HOURS.

$$
FORMOSA