000
AXNT20 KNHC 201126
TWDAT 

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
705 AM EST THU DEC 20 2007

TROPICAL WEATHER DISCUSSION FOR NORTH AMERICA...CENTRAL 
AMERICA...THE GULF OF MEXICO...THE CARIBBEAN SEA...NORTHERN 
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 0600 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 
1030 UTC

...THE ITCZ...
ITCZ AXIS IS CENTERED ALONG 7N13W 4N25W 6N35W 4N45W AND INTO 
SOUTH AMERICA NEAR 2N51W. CLUSTERS OF MODERATE TO STRONG 
CONVECTION ARE WITHIN 180 NM N OF THE AXIS AND 100 NM S OF THE 
AXIS BETWEEN 16W-25W. SIMILAR CONVECTION IS WITHIN 82 NM EITHER 
SIDE 31W-38W. WIDESPREAD MODERATE TO STRONG CONVECTION IS FROM 
2N-6N BETWEEN 39W-47W. UPPER DIFFLUENCE IS ENHANCING THIS 
CONVECTIVE ACTIVITY.

DISCUSSION...
GULF OF MEXICO...
A RIDGE OF HIGH PRESSURE CONTINUES TO DOMINATE THE GULF 
RESULTING IN LIGHT TO MODERATE WINDS. CONVECTIVE ACTIVITY 
ASSOCIATED WITH A FRONTAL BOUNDARY OVER TEXAS AND LOUISIANA HAS 
MOVED OUT OF THE NORTHERN GULF REGION AND IS NOW CONFINED TO THE 
CONTINENTAL U.S. ALOFT...A SUBTROPICAL JET WITH CORE WINDS OF 
NEAR 120 KT IS CENTERED OVER THE SOUTHERN UNITED STATES DRAWING 
UPPER-LEVEL MOISTURE ACROSS THE GULF FROM THE E PACIFIC. NEAR 
ZONAL FLOW SOUTH OF THE JET CONTINUES TO MAINTAIN DRY AND STABLE 
CONDITIONS. THE NEXT COLD FRONT IS FORECAST TO ENTER THE REGION 
THIS WEEKEND. STRONG WINDS AND HIGH SEAS WILL BUILD IN THE GULF 
FOLLOWING THE FRONTAL PASSAGE. 

CARIBBEAN SEA...
A WEAK SFC TROUGH CONTINUES TO MOVE ACROSS THE NW CARIBBEAN. AS 
OF 09Z THE TROUGH WAS ANALYZED FROM 21N78W TO17N88W. ASSOCIATED 
LOW CLOUDS WITH EMBEDDED SHOWERS REMAIN OVER THE NW 
CARIBBEAN/GULF OF HONDURAS. ADDITIONAL PATCHES OF LOW-LEVEL 
CLOUDS ARE N OF 18N BETWEEN CUBA AND 82W. SATELLITE IMAGERY 
SHOWS ISOLATED SHALLOW CONVECTION OVER THE VIRGIN ISLANDS AND IN 
THE MONA PASSAGE. ALOFT...STRONG SUBSIDENCE AND DRY STABLE AIR 
DOMINATE THE CENTRAL AND EASTERN CARIBBEAN. MODERATE TO FRESH 
ELY TRADE WINDS WILL CHANGE LITTLE THROUGH SATURDAY.   

ATLANTIC OCEAN...
A COLD FRONT NORTH OF THE REGION IS PRODUCING A BAND OF 
LOW-LEVEL MOISTURE AND POSSIBLE SHOWERS THAT ENTERS THE W ATLC 
NEAR 31N74W AND EXTENDS SW TO 29N79W. THE SUBTROPICAL JET OVER 
THE SOUTHERN U.S. CONTINUES TO ADVECT HIGH CLOUDS/MOISTURE OVER 
THE W ATLC. FARTHER EAST...A COLD FRONT ENTERS THE REGION NEAR 
31N43W AND STRETCHES SW TO 23N67W WHERE IT CONTINUES AS A 
SURFACE TROUGH THROUGH THE BAHAMAS AND CUBA INTO THE CARIBBEAN. 
A BAND OF MAINLY LOW LEVEL CLOUDS WITH ISOLATED SHOWERS/ 
THUNDERSTORMS EXTENDS UP TO 180 NM BEHIND THE FRONT. FAIR 
WEATHER STRATOCUMULUS CLOUDS ARE BEING TRANSPORTED AROUND A 1022 
MB SFC HIGH CENTERED NEAR 30N41W. A FRONTAL BOUNDARY ASSOCIATED 
WITH A DEEP-LAYERED TROUGH OVER THE E ATLC PASSES BETWEEN THE 
CANARY ISLANDS AND THE AFRICAN COAST AND EXTENDS TO 24N17W. THE 
FRONTAL BOUNDARY IS MARKED BY AN ADDITIONAL SURGE OF 
STRATOCUMULUS CLOUDS. IN THE TROPICAL ATLC...UPPER DIFFLUENCE IS 
SUPPORTING CONVECTION ALONG THE ITCZ AND NEAR ZONAL FLOW 
CONTINUES TO TRANSPORT UPPER-LEVEL MOISTURE EASTWARD ACROSS THE 
REGION S OF 14N.

$$
WADDINGTON