000
AXPZ20 KNHC 181603
TWDEP 

TROPICAL WEATHER DISCUSSION     
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
1605 UTC SAT AUG 18 2007

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

BASED ON 1200 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 
1500 UTC.

...TROPICAL WAVES...
TROPICAL WAVE ALONG 84W N OF 8N MOVING W 10-15 KT WITH ISOLATED 
CONVECTION S OF COSTA RICA.

TROPICAL WAVE ALONG 110W N OF 8N MOVING W 10 KT. THE WAVE IS PART OF 
A BROAD AREA OF LOW PRES CENTERED NEAR 18N110W ESTIMATED AT 1007 MB. 
SCATTERED MODERATE CONVECTION WITH A FEW STRONG CELLS WITHIN 150 NM 
OF WAVE AXIS N OF 16N.

TROPICAL WAVE ALONG 133W FROM 6N TO 16N MOVING W 10 KT. THE WAVE 
LACKS SIGNIFICANT CONVECTION AND REMAINS DIFFICULT TO LOCATE. 

...ITCZ...
AXIS IS CENTERED ALONG 9N85W 8N92W 16N102W 18N110W 12N118W 12N128W 
10N140W. AREA OF MODERATE CONVECTION WITHIN 60 NM OF 5N81W. SCATTERED
MODERATE CONVECTION FROM 11N TO 20N BETWEEN 103W AND 115W. 

SCATTERED STRONG CONVECTION WITHIN 90 NM OF 24N109W.

...DISCUSSION...
A BROAD MID LEVEL TROUGH ANCHORED BY LOWS CENTERED NEAR 15N113W AND 
15N123W DOMINATES THE E PAC. FURTHER NORTH A MID LEVEL RIDGE EXTENDS 
ACROSS THE NORTHERN PART OF DISCUSSION AREA. UPPER ANTICYCLONES ARE 
CENTERED NEAR 29N108W AND 25N143W. A WEAKNESS IN THE RIDGE CAUSED BY 
A MID LATITUDE TROUGH N OF THE AREA IS NEAR 28N122W. DRY UPPER LEVEL 
AIR IS NOTED OVER THE DISCUSSION AREA N OF 14N W OF 120W. EVEN S OF 
14N...ITCZ CONVECTION IS ALMOST NON-EXISTENT W OF 120W. A BROAD AREA 
OF LOW PRESSURE CENTERED NEAR 18N110W IS THE PRIMARY SURFACE FEATURE.
IT IS DRAWING SW WINDS AND TROPICAL MOISTURE INTO ITS CIRCULATION AND
DIFFLUENT UPPER LEVEL WINDS ARE ENHANCING CONVECTION IN THE REGION. 
HOWEVER UPPER WINDS ARE PRODUCING JUST ENOUGH UNIDIRECTIONAL SHEAR 
TO PREVENT SIGNIFICANT TROPICAL CYCLONE DEVELOPMENT FROM OCCURRING. 
CONSEQUENTLY LITTLE CHANGE IS EXPECTED OVER THE NEXT 24 HOURS. THE 
MONSOON TROUGH IN PLACE E OF 120W WILL REMAIN FAIRLY ACTIVE BUT NO 
LOW PRESSURE CENTERS ARE EXPECTED TO DEVELOP TO PROVIDE A FOCUS FOR 
ITS VORTICITY.

$$
MUNDELL