000
AXNT20 KNHC 200530
TWDAT 

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
105 AM EST WED DEC 20 2006

TROPICAL WEATHER DISCUSSION FOR NORTH AMERICA...
CENTRAL AMERICA...THE GULF OF MEXICO...THE CARIBBEAN SEA...
NORTHEASTERN SECTIONS OF SOUTH AMERICA...AND THE 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 0000 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 
0445 UTC.

...THE ITCZ...
ITCZ AXIS IS CENTERED ALONG 7N10W 5N28W 4N43W 3N52W. CLUSTERS OF 
SCATTERED MODERATE/ISOLATED STRONG CONVECTION ARE FROM 2N-7N 
BETWEEN 40W-50W. SCATTERED SHOWERS/THUNDERSTORMS ARE FROM 1N-5N 
BETWEEN 30N-40W. 

...DISCUSSION...
GULF OF MEXICO...
BROAD UPPER RIDGE COVERS THE GULF WITH THE AXIS EXTENDING FROM S 
MEXICO ACROSS THE CENTRAL BAY OF CAMPECHE TO OVER THE SE US NEAR 
32N90W. TROPICAL MOISTURE IS BEING ADVECTED ACROSS MEXICO FROM 
THE E PACIFIC REGION OVER THE W GULF WITH ENOUGH DIFFLUENCE TO 
GENERATE ISOLATED SHOWERS W OF 92W. THE NEXT COLD FRONT IS 
EXPECTED TO MOVE OFF THE TEXAS COAST ON WED NIGHT/THU BRINGING 
MORE ACTIVITY SHOWER ACTIVITY TO THE NW CORNER OF THE GULF THEN 
MOVING EASTWARD. ISOLATED SHOWERS ARE OVER THE FAR SE GULF S OF 
25N E OF 83W THROUGH THE STRAITS OF FLORIDA INCLUDING THE 
FLORIDA KEYS. 
 
CARIBBEAN SEA...
CARIBBEAN IS DOMINATED BY UPPER ZONAL WESTERLY FLOW WITH AN 
UPPER LOW N OF PUERTO RICO AND A SURFACE TROUGH EXTENDING FROM 
16N67W ACROSS THE VIRGIN ISLANDS TO 21N62W. VERY DRY UPPER AIR 
AND MODERATE/STRONG SUBSIDENCE COVERS THE ENTIRE AREA GIVING 
MOST OF THE CARIBBEAN CLEAR SKIES TONIGHT WITH THE EXCEPTION OF 
SCATTERED LOW CLOUDS WITH POSSIBLE ISOLATED SHOWERS OVER THE N 
AND W CARIBBEAN NW OF A LINE FROM THE LEEWARD ISLANDS NEAR 
18N63W ALONG 16N73W TO COSTA RICA NEAR 10N83W. MODERATE/STRONG 
TRADE WINDS ALSO DOMINATE MOST OF THE CARIBBEAN. 

ATLANTIC OCEAN...
UPPER ZONAL WESTERLY FLOW DOMINATES THE W ATLC N OF 26N W OF 58W 
WHILE AN UPPER LOW N OF PUERTO RICO NEAR 23N66W EXTENDS AN UPPER 
TROUGH WSW TO E CUBA NEAR 21N75W. THIS IS GIVING THE AREA FROM 
21N-25N BETWEEN 58W-68W SCATTERED SHOWERS WHILE THE REMAINDER OF 
THE W ATLC IS SHOWER FREE. A SURFACE RIDGE COVERS THE CENTRAL 
AND W ATLC W OF 35W WITH A 1024 MB HIGH LOCATED NEAR 29N57W. 
BROAD UPPER TROUGH COVERS THE REMAINDER OF THE ATLC N OF 17N E 
OF 55W WITH AN UPPER LOW NEAR 31N26W AND A 1016 MB SURFACE LOW 
NEAR 30N30W. SCATTERED SHOWERS/ISOLATED THUNDERSTORMS ARE 
ASSOCIATED WITH THE UPPER LOW N OF 25N FROM 21W-29W. BROAD UPPER 
RIDGE COVERS THE TROPICS CENTERED NEAR 1N43W WITH THE MEAN AXIS 
EXTENDING NNW TO 17N48W. 

$$
WALLACE