000
AXNT20 KNHC 211754
TWDAT 

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
105 PM 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 1200 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 
1715 UTC.

...ITCZ...

THE ITCZ AXIS IS CENTERED ALONG 6N11W 3N20W 2N30W THEN SHIFTS S 
OF EQUATOR AT 40W TO THE COAST OF S AMERICA AT 2S45W. SCATTERED 
MODERATE/ISOLATED STRONG CONVECTION IS NOTED WITHIN 60 NM ON 
EITHER SIDE OF THE AXIS BETWEEN 20W-31W. WIDELY SCATTERED 
MODERATE CONVECTION IS NOTED WITHIN AROUND 70 NM OF LINE 3N35W 
3N42 1N50W. CLUSTERS OF MODERATE/STRONG CONVECTION ARE FROM THE 
EQUATOR TO THE COAST OF AFRICA BETWEEN THE PRIME MERIDIAN AND 
10 W.  

...DISCUSSION...

GULF OF MEXICO...
WSW UPPER WIND FLOW COVERS THE ENTIRE GULF WITH A SUBTROPICAL 
JET CROSSING THE NORTHERN PORTION OF THE AREA. A MOISTURE PLUME 
IS BEING ADVECTED FROM THE EASTERN PACIFIC ACROSS CENTRAL MEXICO 
AND THE GULF NW OF A LINE 21N97W 25N90W TO CENTRAL FLORIDA. DRY 
UPPER AIR AND SUBSIDENCE IS NOTED SE OF THIS LINE. AS OF 1500 UTC
A SURFACE COLD FRONT EXTENDS FROM NW FLORIDA ACROSS THE CENTRAL 
GULF TO THE COAST OF MEXICO MIDWAY BETWEEN TUXPAN AND VERACRUZ 
THEN CONTINUES AS A STATIONARY FRONT ACROSS THE EASTERN SLOPES 
OF THE SIERRA MADRE MOUNTAINS. A BAND OF BROKEN LOW/MID LEVEL 
CLOUDS AND SCATTERED SHOWERS/TSTMS IS ASSOCIATED WITH THE 
FRONTAL BOUNDARY. THE COLD FRONT WILL CONTINUE SE TO A POSITION 
FROM THE STRAITS OF FLORIDA TO BAY OF CAMPECHE WEDNESDAY 
AFTERNOON ACCOMPANIED BY SLIGHTLY COOLER AND DRIER CONDITIONS 
BEHIND THE FRONT. NEAR GALE CONDITIONS ARE EXPECTED OVER THE 
WESTERN GULF LATE THURSDAY TO FRIDAY.

CARIBBEAN...
A MID/UPPER HIGH IS CENTERED NEAR 16N85W WITH ITS ENVELOPE OF 
ANTICYCLONIC FLOW DOMINATING THE THE NW CARIBBEAN. ANOTHER UPPER 
HIGH IS LOCATED OVER VENEZUELA WITH A RIDGE EXTENDING NW AND N 
CRESTING OVER THE EASTERN CARIBBEAN. A TROUGH LIES BETWEEN THESE 
TWO HIGHS FROM HISPANIOLA SW TO NICARAGUA/COSTA RICA BORDER.   
UPPER DEBRIS MOISTURE IS SPREADING FROM THE EASTERN PACIFIC 
ACROSS PANAMA AND COLOMBIA AND THE SE PORTION OF THE BASIN. 
MODERATE TO STRONG SUBSIDENCE COVERS MOST OF CENTRAL AMERICA AND 
THE REMAINDER OF THE SEA. ATLANTIC RIDGE WILL MAINTAIN MODERATE 
TRADE WINDS ACROSS CARIBBEAN THROUGH WED.

ATLANTIC...
A RIDGE/TROUGH/RIDGE PATTERN COVERS MOST OF THE AREA. A MID TO 
UPPER RIDGE IS OVER THE W ATLANTIC WEST OF 60W. THE CENTRAL 
ATLANTIC IS DOMINATED BY A LONGWAVE TROUGH WITH SEVERAL EMBEDDED 
CYCLONES. ANOTHER MID/UPPER LEVEL RIDGE IS FOUND OVER THE 
EASTERN ATLC BETWEEN 20W-40W...WHILE AN UPPER TROUGH EXTENDS SW 
INTO THE AREA ALONG 32N9W TO A BASE AT THE CAPE VERDE ISLANDS. 
AT THE SURFACE...A COLD FRONT ENTERS THE AREA NEAR 31N40W...THEN 
CONTINUES SW ALONG 27N50W 22N64W. BROKEN LOW LEVEL CLOUDS AND 
ISOLATED SHOWERS ARE RELATED TO THE FRONT. SOUTHEAST OF THE 
FRONT...WITHIN AROUND 200 NM LIES A TROUGH...REMNANTS OF AN OLD 
FRONTAL BOUNDARY. SCATTERED TO BROKEN LOW CLOUDS AND ISOLATED 
SHOWERS ARE ASSOCIATED WITH THE TROUGH. THE TAIL END OF THIS 
TROUGH REACHES NE PUERTO RICO AND THE U.S. VIRGIN ISLANDS. THE 
SAN JUAN DOPPLER RADAR IS DEPICTED ISOLATED TO SCATTERED SHOWERS 
OVER THE AREA. FARTHER EAST...A 1021 MB HIGH IS LOCATED NEAR 
29N26W. THIS FEATURE WILL MOVE MAINLY EAST.

$$
GR