AXNT20 KNHC 191748
TWDAT 

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL 
105 PM EST SAT 19 FEB 2005

TROPICAL WEATHER DISCUSSION FOR NORTH AMERICA...CENTRAL 
AMERICA...GULF OF MEXICO...CARIBBEAN SEA...NORTHEASTERN SECTIONS 
OF SOUTH AMERICA...AND 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...
ITCZ AXIS ALONG 10N1W 1N30W 2N40W 5N60W.  WIDELY SCATTERED 
STRONG CONVECTION WITHIN 100 NM EITHER SIDE OF AXIS FROM 
10W-40W.   
 
...DISCUSSION...
GULF OF MEXICO...
BROAD MIDDLE TO UPPER LEVEL RIDGING REMAINS OVER THE GLFMEX 
WHILE A PERSISTENT UPSTREAM TROUGH LIES ALONG THE W COAST OF THE 
UNITED STATES INTO NW MEXICO.  SUBTROPICAL JET AND ASSOCIATED 
UPPER LEVEL MOISTURE PLUME CUTS ACROSS CENTRAL MEXICO BETWEEN 
PUERTO VALLARTA AND THE S TIP OF THE BAJA PENINSULA THEN UP AND 
OVER THE RIDGE INTO TEXAS AND THE CENTRAL UNITED STATES. S OF 
THE THIS MOISTURE...STRONG SUBSIDENCE COVERS THE ENTIRE GULF OF 
MEXICO CREATING DRY/STABLE CONDITIONS ALOFT. AT THE 
SURFACE...RAPIDLY WEAKENING COLD FRONT LIES OVER THE EXTREME SE 
PORTION OF THE AREA FROM THE W TIP OF CUBA TO JUST N OF THE 
YUCATAN PENINSULA. LATEST VISIBLE SAT IMAGERY INDICATES THE 
FRONT HAS WASHED OUT WITH HIGH PRES OVER THE SE UNITED STATES 
NOW CONTROLLING THE AREA. RESULTING LOW LEVEL FLOW IS NOW 
VEERING WITH RETURN FLOW DEVELOPING OVER THE W GULF.  THE ONLY 
CLOUDS OF NOTE IS A SMALL AREA OF  BROKEN LOW CLOUDS AND WIDELY 
SCATTERED SHOWERS OVER THE CENTRAL GULF FROM 23N-26N BETWEEN 
87W-91W. ADDITIONALLY...LOW CLOUDS AND ISOLATED SHOWERS REMAIN 
ALONG E SLOPES OF THE SIERRA MADRE ORIENTAL MOUNTAINS IN 
MEXICO.  THE PATTERN IS EXPECTED TO REMAIN DRY WITH LIMITED 
SHOWER ACTIVITY THROUGH THE WEEKEND PRIOR TO A COLD FRONT 
APPROACHING THE AREA MONDAY. 

CARIBBEAN...
MID/UPPER LEVEL RIDGE REMAINS ANCHORED OVER THE CARIBBEAN 
EXTENDING FROM THE N COAST OF VENEZUELA TO W CUBA.  STRONG 
SUBSIDENCE ASSOCIATED WITH THIS PATTERN COVERS THE ENTIRE 
CARIBBEAN BASIN WITH LITTLE VERTICAL DEVELOPMENT OF CLOUDS AND 
SHOWER ACTIVITY. IN FACT...THE ONLY ACTIVITY OF NOTE IS 
BROKEN/OVERCAST CLOUDINESS AND WIDELY SCATTERED SHOWERS ALONG 
THE WINDWARD FACING SLOPES OF W PANAMA AND COSTA RICA.  ELY 
TRADES HAVE INCREASED DURING THE LAST 24 HOURS AS A HIGH PRES  
BUILDS SWD OVER THE E GULF AND W ATLC.  LOW LEVEL MOISTURE AND 
SHOWER ACTIVITY IS EXPECTED TO REMAIN SPARSE THROUGH THE WEEKEND 
PRIOR TO THE ARRIVAL OF A DIFFUSE FRONTAL BOUNDARY OVER THE NE 
CARIBBEAN SUN NIGHT INTO MONDAY.  LOW LEVEL MOISTURE POOLING 
ALONG THE BOUNDARY SHOULD PRODUCE A LINE OF SCATTERED SHOWERS AS 
THE WEAKENING BOUNDARY SAGS SWD REACHING THE ABC ISLANDS LATE 
TUE.     

ATLANTIC...
PERSISTENT MIDDLE TO UPPER LEVEL TROUGH REMAINS OVER THE W ATLC 
N OF 30N AND WEST OF 50W RESULTING IN PREDOMINATELY ZONAL FLOW 
AND SUBSIDENCE OVER THE SW N ATLC. ATTENDANT WEAK COLD FRONT 
ENTERS THE CENTRAL ATLC NEAR 32N51W SWD ALONG 24N65W THROUGH THE 
CENTRAL BAHAMAS TO W CUBA.  THE FRONT LACKS UPPER SUPPORT WITH 
ONLY A NARROW CLOUD LINE WITH ISOLATED SHOWERS ALONG THE LEADING 
EDGE. A DEVELOPING SURFACE LOW WELL N OF THE AREA NEAR 39N56W IS 
DRAGGING DOWN A REINFORCING SURGE OF COOL AIR WITH THE LEADING 
EDGE EXTENDING FROM 32N55W TO THE N BAHAMAS. OVER CENTRAL TO E 
ATLC...MIDDLE TO UPPER LEVEL SHORTWAVE TROUGH ALONG 30W IS 
PRODUCING SOME HIGH CLOUDINESS FROM THE CAPE VERDE ISLANDS NWD 
TO 26N.  ELSEWHERE...STRONG SURFACE HIGH PRESSURE N OF THE 
AZORES EXTENDS SWD INTO THE NE PORTION OF THE AREA PRODUCING 
MODERATE TO STRONG NE FLOW.  THE PERSISTENT AREA OF AFRICAN DUST 
OVER THE FAR E TROPICAL ATLC HAS BECOME PARTIALLY OBSCURED BY 
HIGH CLOUDINESS BUT THE HIGHEST CONCENTRATION IS EXPECTED S AND 
E OF THE CAPE VERDE ISLANDS TO THE ITCZ. 

$$
RHOME