000
AXNT20 KNHC 211146
TWDAT 

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
705 AM EST TUE MAR 21 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...WEATHER OBSERVATIONS... 
RADAR...AND METEOROLOGICAL ANALYSIS.

BASED ON 0600 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 
1115 UTC.

...ITCZ...

THE ITCZ AXIS IS CENTERED ALONG 6N11W 2N24W THEN SHIFTS S OF 
EQUATOR AT 36W AND CROSSES THE COAST OF S AMERICA AT 3S43W. 
SCATTERED MODERATE ISOLATED STRONG CONVECTION IS NOTED WITHIN 60 
NM OF LINE 4N6W 2N21W 3N23W 3N36W 4N40W 1N50W. 

...DISCUSSION...

GULF OF MEXICO...
AN UPPER RIDGE EXTENDS N ALONG 82W FROM AN ANTICYCLONE OVER THE 
NW CARIBBEAN ESTIMATED NEAR 17N85W. AN UPPER TROUGH IS SWINGING 
SE ACROSS E TEXAS. SQUEEZED BETWEEN THE TROUGH AND THE RIDGE IS 
A MOISTURE PLUME THAT ORIGINATED IN THE CENTRAL PACIFIC SEVERAL 
DAYS AGO. THE PLUME NOW CROSSES OLD MEXICO AND THE NW GULF OF 
MEXICO WITHIN 150 NM EITHER SIDE OF LINE 20N105W 26N91W...THEN 
NARROWS AND IS MOVES ACROSS THE FLORIDA PANHANDLE. OTHERWISE... 
DRY UPPER AIR AND SUBSIDENCE IS INDICATED SE OF LINE 21N97W TO 
29N83W. A SURFACE COLD FRONT EXTENDS FROM LOUISIANA TO NE OLD 
MEXICO AT 0300Z. MULTILAYERED CLOUDS AND ISOLATED SHOWERS ARE 
NOTED WITHIN 60 NM SE OF THE FRONT. THE COLD FRONT WILL CONTINUE 
E TO A POSITION FROM SW FLORIDA TO THE CENTRAL BAY OF CAMPECHE 
IN 24 HOURS ACCOMPANIED BY SLIGHTLY COOLER AND DRIER CONDITIONS 
BEHIND THE FRONT.  

CARIBBEAN...
AN UPPER LEVEL ANTICYCLONE IS CENTERED NEAR 16N85W WITH ITS  
ENVELOPE OF ANTICYCLONIC FLOW DOMINATING THE THE NW CARIBBEAN. 
ANOTHER UPPER ANTICYCLONE IS CENTERED OVER VENEZUELA WITH A 
RIDGE EXTENDING NW AND N CRESTING GENTLY OVER THE CARIBBEAN 
ALONG 11N82W 16N72W 18N62W. AN UPPER CYCLONE IS CENTERED NEAR 
5N81W. UPPER DEBRIS MOISTURE IS SPREADING E ACROSS WESTERN CUBA.
A BAND OF UPPER MOISTURE IS NOTED WITHIN 120 NM EITHER SIDE OF 
LINE 10N80W 14N70W 17N62W. OTHERWISE DRY UPPER AIR AND 
SUBSIDENCE IS INDICATED ACROSS THE CARIBBEAN SEA. 

ATLANTIC...
A MID-UPPER RIDGE IS SHIFTING E ACROSS THE DISCUSSION AREA W OF 
75W. THE CENTRAL ATLANTIC IS DOMINATED BY A LONGWAVE TROUGH WITH 
SEVERAL EMBEDDED CYCLONES. AN UPPER TROUGH EXTENDS INTO THE 
SUBTROPICAL ATLC WITH A MEAN AXIS ENTERING THE DISCUSSION AREA 
AT 31N50W AND CONTINUING S TO A BASE NEAR 19N57W. THE UPPER FLOW 
IS ONLY SLIGHTLY CYCLONIC BETWEEN 75W AND 40W. AT THE SURFACE... 
AN INITIAL COLD FRONT IS LOSING IDENTITY ALONG 31N38W 18N65W AND 
IS ACCOMPANIED BY SCATTERED TO BROKEN LOW LEVEL CLOUDS AND 
ISOLATED SHOWERS. A SECONDARY COLD FRONT LIES ALONG 31N43W TO 
22N70W WITH LOCALLY BROKEN STRATOCUMULUS CLOUDS COVERING THE 
AREA NW OF THE FRONT. YET ANOTHER COLD SURGE IS ALONG 32N 
BETWEEN 64W AND 78W...BUT IS PARTIALLY BLOCKED BY A SURFACE HIGH 
PRES 1019 MB AT 28N70W. FARTHER EAST...A MID-UPPER LEVEL RIDGE 
EXTENDS ALONG 15N43W TO BEYOND 32N30W. AN UPPER LEVEL TROUGH 
EXTENDS SW INTO THE DISCUSSION AREA ALONG 32N9W TO A BASE AT 
14N25W. AN UPPER ANTICYCLONE IS OVER AFRICA AT 13N11E WITH A 
RIDGE EXTENDING WSW TO NEAR 5N20W AND IS ENHANCING THE ITCZ E OF 
20W. A BAND OF DRY UPPER AIR IS INDICATED WITHIN 210 NM EITHER 
SIDE OF LINE 20N48W 19N28W 23N10W. AT THE SURFACE...A 1022 MB 
HIGH IS LOCATED NEAR 26N23W.

$$
NELSON