000
AXPZ20 KNHC 050321
TWDEP 

TROPICAL WEATHER DISCUSSION      
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
0405 UTC SUN AUG 05 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 
0300 UTC.

...SPECIAL FEATURES...
LOW PRES 1009 MB NEAR 11N111W MOVING W 10 TO 15 KT. ALTHOUGH THE 
LOW PRES AREA REMAINS EMBEDDED WITHIN THE ITCZ THE SYSTEM IS 
FAIRLY WELL ORGANIZED WITH A LOW LEVEL CENTER THAT IS PARTIALLY 
EXPOSED IN THE E SEMICIRCLE. AN AREA OF SCATTERED MODERATE 
CONVECTION IS WITHIN 120 NM OF THE LOW LEVEL CENTER IN THE W 
SEMICIRCLE WITH THE WATER VAPOR IMAGERY INDICATING THAT THIS 
SYSTEM IS CURRENTLY UNDERGOING SOME EASTERLY SHEAR AS IT IS 
SITUATED WELL TO THE S OF A LARGE ANTICYCLONE OVER THE CENTRAL 
CONUS. THE SHEAR MAY RELAX OVER THE NEXT 24 HOURS AND PROVIDE A 
BETTER ENVIRONMENT FOR FURTHER DEVELOPMENT INTO A TROPICAL 
CYCLONE OVER THE NEXT DAY OR SO.

...TROPICAL WAVE...
TROPICAL ALONG 85W/86W N OF 5N AND IS MOVING W 15 KT. THE 
NORTHERN PORTION OF THIS WAVE REMAINS VERY ACTIVE OVER THE 
CARIBBEAN SEA OVER AND HAS BEEN OVER THE PAST SEVERAL DAYS. 
SCATTERED MODERATE TO STRONG CONVECTION IS CONCENTRATED OVER THE 
CARIBBEAN SEA W OF 81W AND EXTENDING OVER HONDURAS...NICARAGUA 
AND AS FAR W AS THE ISTHMUS OF TEHUANTEPEC...THE YUCATAN 
PENINSULA AND BAY OF CAMPECHE. SCATTERED STRONG CONVECTION HAS 
ALSO DEVELOPED ALONG THE WEST COAST OF CENTRAL AMERICA FROM
NICARAGUA TO THE GULF OF TEHUANTEPEC AS WELL WITH WEAKENING
CONVECTION NOTED ALONG THE INTERSECTION OF THE WAVE AXIS AND THE 
ITCZ NEAR THE COAST OF COSTA RICA. 

TROPICAL WAVE ALONG 94W MOVING W 10 TO 15 KT. NO SIGNIFICANT 
CONVECTION ASSOCIATED WITH THE WAVE AXIS. 

TROPICAL WAVE ALONG 111W MOVING W 10 TO 15 KT. A 1009 MB LOW 
PRES IS ALONG THE WAVE AXIS NEAR 11N. SEE SPECIAL FEATURES 
ABOVE.  

TROPICAL WAVE ALONG 123W FROM 7N TO 21N WITH A 1010 MB LOW NEAR 
17N123W MOVING W 10 TO 15 KT. A SMALL AREA OF SCATTERED MODERATE 
CONVECTION REMAINS WITHIN 90 NM OF THE LOW IN THE NW QUADRANT. 
MODERATE UPPER LEVEL SE WINDS IN THE VICINITY OF THE LOW ARE 
KEEPING THE CONVECTION SHEARED FROM THE LOW LEVEL CENTER. 
ALTHOUGH THE SHEAR MAY RELAX OVER THE NEXT DAY OR SO...THE 
SYSTEM IS EXPECTED TO TRACK OVER COOLER WATERS THEREBY LIMITING 
ANY DEVELOPMENT POTENTIAL.

...ITCZ...
ITCZ AXIS IS CENTERED ALONG...8N78W 10N94W 13N108W 16N120W 
10N125W 8N140W. SCATTERED MODERATE WITHIN 120 NM N OF THE ITCZ E 
OF 87W TO THE COAST OF COSTA RICA.

...DISCUSSION...

TWO MID LEVEL RIDGES DOMINATE VIRTUALLY THE ENTIRE AREA THIS 
AFTERNOON. THE FIRST RIDGE REMAINS OVER THE SW CONUS COVERING 
N-CENTRAL MEXICO AND THE EPAC E OF 130W AND THE OTHER JUST W OF 
140W WHICH RIDGES SE INTO OUR REGION TO 25N134W. IN BETWEEN THE 
TWO RIDGES THERE IS A SHEARED UPPER TROUGH THAT ENTERS THE 
REGION NEAR 30N127W AND EXTENDS SWD TO A CYCLONIC CIRCULATION 
NEAR 21N135W. ANOTHER CYCLONIC CIRCULATION MAINLY AT THE MID 
LEVELS IS LOCATED NEAR 22N123W AND IS MOVING NWWD 20 KT 
AROUND THE PERIPHERY OF THE SURFACE LOW NEAR 17N123W. 

DRY AIR ALOFT DOMINATES THE NW CORNER OF THE REGION. MID LEVEL 
EASTERLIES REMAIN S OF 20N SHEARING BOTH AREAS OF LOW PRESSURE 
AS NOTED IN THE SECTIONS ABOVE. THESE WINDS ARE ALSO ADVECTING 
MID TO UPPER LEVELS CLOUD DEBRIS WWD OVER THE EPAC MAINLY E OF 
130W.   

ON THE SURFACE...HIGH PRES RIDGE N OF AREA IS PRODUCING MODERATE 
TRADE WINDS N OF 25N W OF 130W. CROSS EQUATORIAL SLY WINDS TO 20 
KT ARE BETWEEN 100W AND 110W S OF A CONVECTIVE AREA ON THE ITCZ. 

$$
COBB