000
AXNT20 KNHC 061749
TWDAT 

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL  
105 PM EST SUN DEC 06 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 1200 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH
1645 UTC.

...ITCZ...

THE ITCZ AXIS IS CENTERED ALONG 7N11W 7N22W 4N35W EQ51W. SCATTERED 
MODERATE/ISOLATED STRONG CONVECTION IS FROM 4N-8N BETWEEN 12W-32W.

...DISCUSSION...

GULF OF MEXICO...
A WEAK SURFACE RIDGE IS ACROSS THE GULF OF MEXICO EXTENDING FROM A 
1030 MB HIGH OVER THE ERN OHIO VALLEY. ANTI-CYCLONIC SURFACE FLOW OF 
10-15 KT IS AROUND THE RIDGE REACHING 20 KT IN THE WRN GULF. IN THE 
UPPER LEVELS...SWLY FLOW ALOFT COVERS THE BASIN BETWEEN A BROAD 
UPPER LEVEL TROUGH OVER THE WRN CONUS AND AN UPPER LEVEL RIDGE 
EXTENDING FROM THE E PACIFIC ACROSS THE NW CARIBBEAN. THIS SW FLOW 
IS DRAWING MID/UPPER LEVEL MOISTURE ACROSS MUCH OF THE BASIN NOTED 
IN WATER VAPOR IMAGERY. INCREASING SLY RETURN FLOW ACROSS THE NW 
GULF IS ALSO DRAWING TROPICAL MOISTURE NWD IN THE LOWER ATMOSPHERE. 
THIS ABUNDANCE OF MOISTURE IS SUPPORTING MULTI-LAYER CLOUDS ACROSS 
THE AREA...AS WELL AS ISOLATED SHOWERS ACROSS SE TEXAS AND THE NW 
GULF N OF 20N W OF 93W. EXPECT RETURN FLOW OVER THE WRN GULF TO 
INCREASE WITH CONTINUED MOISTURE ACROSS THE AREA. SHOWER ACTIVITY 
WILL CONTINUE OVER THE NW GULF AND PUSH EWD AS LOW PRESSURE 
CURRENTLY OVER NRN TEXAS SHIFTS E BRINGING A WEAK COLD FRONT TO THE 
NW GULF BY MON. 

CARIBBEAN SEA...
A STATIONARY FRONT DRAPES ACROSS THE NW CARIBBEAN FROM CENTRAL CUBA 
NEAR 22N80W TO BELIZE NEAR 17N88W. NE WINDS UP TO 15 KT ARE NW OF 
THE FRONT. ISOLATED SHOWERS ARE POSSIBLE ALONG THE FRONT AXIS. 
BESIDES MODERATE MOISTURE ASSOCIATED WITH THE FRONT...THE REMAINDER 
OF THE CARIBBEAN IS UNDER THE INFLUENCE OF DRY AIR AND STRONG 
SUBSIDENCE ALOFT SUPPORTING GENERALLY FAIR WEATHER ACROSS THE AREA. 
AN UPPER LEVEL RIDGE COVERS THE WRN CARIBBEAN EXTENDING FROM THE E 
PACIFIC ACROSS NRN CENTRAL AMERICA TO THE CENTRAL BAHAMAS. AN UPPER 
LEVEL TROUGH EXTENDS OVER THE ERN CARIBBEAN FROM THE LEEWARD ISLANDS 
TO NRN COLOMBIA...BUT CONTINUES TO LACK MOISTURE. FRESH TO STRONG 
TRADEWINDS ARE ACROSS THE BASIN WITH STRONGER WINDS NEAR THE COAST 
OF COLOMBIA. EXPECT THE STATIONARY BOUNDARY IN THE NW CARIBBEAN TO 
DISSIPATE TONIGHT.

ATLANTIC OCEAN...
AS OF 1500 UTC...A COLD FRONT EXTENDS ACROSS THE SW N ATLC JUST E OF 
BERMUDA ENTERING THE DISCUSSION AREA NEAR 31N66W ALONG 28N71W 
BECOMING STATIONARY NEAR THE CENTRAL BAHAMAS AT 26N76W. SCATTERED 
SHOWERS/POSSIBLE THUNDERSTORMS ARE WITHIN 100 NM AHEAD OF THE FRONT 
N OF 30N. A SHORTWAVE UPPER LEVEL TROUGH EXTENDING FROM THE 
NORTHEAST UNITED STATES TO NEAR 28N67W SUPPORTS THE FRONT. DIFFLUENT 
FLOW ALOFT BETWEEN THIS TROUGH AND AN UPPER LEVEL RIDGE EXTENDING NE 
FROM HISPANIOLA TO NEAR THE AZORES ISLANDS IS ENHANCING THE SHOWER 
ACTIVITY NEAR THE FRONT. THE UPPER LEVEL RIDGE IS ALSO SUPPORTING A 
WEAK SURFACE RIDGE ACROSS THE REMAINDER OF THE W ATLC ANCHORED BY A 
1025 MB HIGH NEAR 30N46W. IN THE CENTRAL ATLC...A COLD FRONT CLIPS 
THE DISCUSSION AREA ALONG 32N28W 30N36W 32N42W. A PRE-FRONTAL 
SURFACE TROUGH IS ANALYZED AHEAD OF THE FRONT ALONG 30N27W 27N34W 
26N42W. ISOLATED SHOWERS ARE POSSIBLE ALONG BOTH BOUNDARIES. A 
NARROW UPPER LEVEL TROUGH EXTENDING FROM W OF THE CANARY ISLANDS SW 
TO 19N40W TO E OF THE LEEWARD ISLANDS SUPPORTS THE FRONTAL SYSTEM. 
AN UPPER LEVEL WLY JET TO THE S OF THE UPPER TROUGH AXIS IS 
ENHANCING CONVECTION ALONG THE ITCZ. 
 
$$
WALTON