000
AXNT20 KNHC 131049
TWDAT 

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
805 AM EDT SAT MAY 13 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 
1045 UTC.

...TROPICAL WAVES...
TROPICAL WAVE ALONG 37W S OF 8N MOVING W 10 KT NOT AS WELL 
DEFINED AS 24 HRS AGO. ISOLATED CONVECTION S OF 4N WITHIN 30 NM 
OF AXIS. 

...ITCZ...
ITCZ AXIS ALONG  6N11W  3N31W  5N37W  6N53W.  CLUSTERS OF 
SCATTERED MODERATE/STRONG CONVECTION WITHIN 180 NM OF AXIS E OF 
29W.  MULTIPLE LAYERS OF CLOUDS W OF 37W WITH ISOLATED 
CONVECTION MAINLY S OF 8N FROM 38W TO 45W. 

...DISCUSSION...
GULF OF MEXICO...
LARGE DEEP LAYERED CYCLONIC VORTEX OVER GREAT LAKES HAS LONGWAVE 
UPPER LEVEL TROUGH DIG SW ACROSS TEXAS AND CENTRAL MEXICO INTO E 
PAC.  WEAK SURFACE TROUGH REFLECTION ALONG NORTH TEXAS BORDER 
DOES NOT APPEAR TO HAVE ENOUGH SUPPORT TO SWEEP SOUTH INTO GULF 
OF MEXICO AS PER GFS SOLUTION. UPPER WIND FLOW NOW QUASI-ZONAL 
BUT MOST MODELS QUICKLY BRING UPPER LEVEL TROUGH OVER GULF BY 
SUN AND E OF FLORIDA BY SUN NIGHT WITH GULF UPPER WIND RETURNING 
BECOMING ZONAL.  WATER VAPOR IMAGES HAVE PLENTY OF WATER AT THE 
UPPER LEVELS OVER SRN HALF OF GULF WHILE NW QUARTER REMAINS 
UNDER DRY SPELL.  LOW PRES CENTER 1004 MB OVER NRN MEXICO AND 
LOW PRES 1007 MB OVER E PAC SUPPLYING HIGH LEVEL MOISTURE OVER 
GULF OF MEXICO.  GFS MAKES THIS MOISTURE AVAILABLE CONGRUENT 
WITH ARRIVAL OF TROUGH IN NW GULF.  CLOUDS AND PRECIPITATION 
INCREASING OVER BAY OF CAMPECHE AND EXPECTED TO INCREASE THROUGH 
SUN.  

HIGH PRES 1014 MB OVER N CENTRAL GULF SLIDES E OF BASIN SUN AND 
SUN NIGHT INTO ATLC BY MON.  

CARIBBEAN SEA...
WEAK TRADEWINDS CONTINUE ACROSS ENTIRE BASIN AS ATLC HIGH PRES 
1016 MB RETREATS E FORCED BY SW N ATLC COLD FRONT.  IN THE UPPER 
LEVELS...CARIBBEAN REMAINS UNDER BROAD RIDGE CENTERED OVER 
PANAMA/COSTA RICA BORDER.  SOUTHEASTERN PERIPHERY OF RIDGE HAS 
PROMPTED SCATTERED SHOWERS/ISOLATED TSTMS INLAND COLOMBIA AS 
EQUATORIAL TROUGH EXTENDS FROM LOW PRES 1009 MB WESTWARD TO LOW 
PRES OVER E PAC.  UPPER TROUGH IN CENTRAL ATLC DIPS SW ACROSS 
TROPICAL ATLC AND EXTREME ERN CARIBBEAN INCLUDING LESSER 
ANTILLES.  DRY UPPER AIR AND MODERATE/STRONG SUBSIDENCE COVERS 
AREA E OF 75W SUPPRESSING ANY SHOWER ACTIVITY.  SCATTERED 
CONVECTION OVER YUCATAN PENINSULA DECREASING AT THIS TIME AS LOW 
PRES OVER MEXICO WEAKENS AND DRIFTS N.  

ATLANTIC OCEAN...
DEEP LAYERED TROUGH PREVIOUSLY OVER SW N ATLC HAS SHIFTED NE 
PULLING UPPER SUPPORT OF WEAK COLD FRONT PRESENTLY FROM 31N71W 
ACROSS NE BAHAMAS TO WRN CUBA.  CLOUDINESS AND ISOLATED 
CONVECTION WITHIN 30 NM OF FRONTAL BOUNDARY WHILE MULTILAYERED 
CANOPY N OF 29N ASSOCIATED WITH UPPER TROUGH.  MODERATE AIR 
MASS CONFLUENCE AT UPPER LEVELS PROMPTING STRONG SUBSIDENCE 
BEHIND FRONTAL BOUNDARY RESULTING IN VERY DRY AIR MASS.  

BROAD DEEP LAYERED TROUGH OVER CENTRAL/EAST ATLC N OF 18N FROM 
44-60W.  ASSOCIATED COLD FRONT APPROACHING AREA ALONG 32N FROM 
35W-45W.  SURFACE HIGH PRES 1016 MB CENTERED AT 25N54W BEING 
FORCED E BY INCOMING COLD FRONT OVER SW N ATLC.  SHOWERS/ 
ISOLATED TSTMS ALONG SURFACE TROUGH FROM 31N29W TO 21N45W.  
BROAD UPPER LEVEL RIDGE AT 12N33W MAINTAINS ANTICYCLONIC FLOW 
ACROSS ENTIRE EAST ATLC WITH FAIRLY ZONAL FLOW E OF 40W. 

$$
WALLY BARNES