000
AXPZ20 KNHC 290321
TWDEP 

TROPICAL WEATHER DISCUSSION      
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
0405 UTC SUN JUL 29 2007

TROPICAL WEATHER DISCUSSION FOR THE EASTERN PACIFIC OCEAN
FROM THE EQUATOR TO 32N...EAST OF 140W. 

BASED ON 0000 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 
0200 UTC.

...TROPICAL WAVES...
TROPICAL WAVE IS ALONG 86W/87W N OF 5N MOVING W NEAR 15 KT. THE 
WAVE IS MOVING OVER CENTRAL AMERICA GENERATING CLUSTERS OF 
MODERATE/ISOLATED STRONG CONVECTION OVER HONDURAS AND EL 
SALVADOR.

TROPICAL WAVE IS ALONG 112W FROM 4N TO 16N MOVING W NEAR 15 KT. 
A 1009 SFC LOW IS EMBEDDED ALONG THE WAVE AXIS NEAR 10N. SHOWERS 
AND THUNDERSTORMS HAVE INCREASED TONIGHT IN ASSOCIATION WITH 
THIS LOW. ANY FURTHER DEVELOPMENT OF THIS SYSTEM IS LIKELY TO BE 
SLOW TO OCCUR AS IT CONTINUES TO MOVE WESTWARD OVER THE OPEN 
OCEAN. SCATTERED MODERATE/ISOLATED STRONG CONVECTION IS FROM 10N 
TO 13N BETWEEN 111W AND 115W ASSOCIATED WITH THE WAVE/LOW.

...ITCZ...
ITCZ AXIS ALONG 8N82W 11N90W 10N110W 7N120W 10N130W 7N140W. 
SCATTERED MODERATE CONVECTION IS WITHIN 45 NM OF 10N106W.     

...DISCUSSION...
ALOFT...A DRY AND STABLE AIR MASS RESULTING IN STRONG SUBSIDENCE 
COVERS MOST OF THE AREA W OF 120W LIMITING THE DEVELOPMENT OF 
SHOWERS AND TSTMS...EVEN ALONG THE ITCZ WHICH IS BASICALLY 
ABSENT OF ANY SIGNIFICANT ACTIVITY W OF 115W. AN UPPER 
ANTICYCLONE IS NEAR 23N115W WITH A RIDGE EXTENDING E OVER 
NORTH-CENTRAL MEXICO. ELY WINDS ON THE SOUTHERN SIDE OF THE 
RIDGE ARE TRANSPORTING A GOOD AMOUNT OF TROPICAL MOISTURE ACROSS 
MEXICO INTO THE EPAC E OF 120W. THESE WINDS ARE ALSO SHEARING 
THE CONVECTION RELATED TO THE AFOREMENTIONED SFC LOW. UPPER 
DIFFLUENT BETWEEN THE RIDGE AND A LARGE UPPER LEVEL LOW OVER 
WESTERN TEXAS IS HELPING TO GENERATE SHOWERS AND TSTMS ALONG THE 
SIERRA MADRE OCCIDENTAL OF MEXICO. A SERIES OF UPPER TROUGHS 
DOMINATE THE NW PORTION. ONE OF THEM IS ALONG 31N122W 25N129W.  

SFC PATTERN REMAINS TRANQUIL WITH HIGH PRES RIDGING ACROSS THE 
REGION TOWARD THE REMNANT LOW PRES OF DALILA. THIS FEATURE IS 
STILL SPINNING NEAR 24N121W AND IS EXPECTED TO FURTHER WEAKEN TO 
AN OPEN TROUGH IN ABOUT 24 HOURS. AN EARLIER QUIKSCAT PASS 
SHOWED WINDS OF 20 KT WITHIN 120 NM OF THE CENTER OF THE LOW. 
BROKEN STRATOCUMULUS CLOUDS AND MODERATE NELY WINDS ARE FOUND 
N OF 20N AND WEST OF 125W.  

$$
GR