000
AXPZ20 KNHC 290906
TWDEP 

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
1005 UTC TUE JUL 29 2008

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

BASED ON 0600 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 
0900 UTC.

...TROPICAL WAVES... 
TROPICAL WAVE ALONG 91W/92W N OF 05N MOVING W AT 15 KT. 
CONVECTION IS STRONGEST ALONG THE S EDGE OF THIS TROPICAL WAVE 
WHERE BOTH DEEP TROPICAL MOISTURE AND STRONG UPPER LEVEL 
DIFFLUENCE BETWEEN THE UPPER LEVEL RIDGE AXIS INTENSIFYING OVER 
THE SW CARIBBEAN AND THE CYCLONIC FLOW ALONG THE COAST OF NW 
SOUTH AMERICA CAN BE FOUND. THIS TROPICAL WAVE IS EMBEDDED IN 
THE ITCZ WITH SCATTERED MODERATE ISOLATED STRONG CONVECTION IS 
FOUND WITHIN 300 NM OF S OF THE ITCZ BETWEEN 86W AND 91W. CLOUD
MOTIONS SUGGEST MID LEVEL TURNING NEAR 7.5N89W. THE CENTRAL 
PORTION OF THIS TROPICAL WAVE LIES IN A REGION WITH LOW 
PRECIPITABLE WATER VALUES AND UPPER LEVEL CONFLUENCE BETWEEN THE 
RIDGE OVER THE SW CARIBBEAN AND AN UPPER LEVEL CYCLONE OVER 
JAMAICA AND...AS A RESULT...REMAINS RELATIVELY DEVOID OF 
CONVECTION.

FARTHER W...THERE IS ANOTHER TROPICAL WAVE ALONG 117W BETWEEN 
06N AND 20N MOVING W AT 10-12 KT. THIS TROPICAL WAVE IS ALSO 
EMBEDDED IN THE ITCZ WITH SCATTERED MODERATE CONVECTION WITHIN 
180-240 NM OF THE ITCZ BETWEEN 112W AND 121W. THIS WAVE SHOULD 
MOVE INTO A REGION OF LOWER SEA SURFACE TEMPERATURES OVER THE 
NEXT DAY OR TWO. THIS SHOULD LIMIT THE AVAILABLE ATMOSPHERIC 
MOISTURE...HENCE THE CONVECTION...WITH THE SYSTEM.
  
...ITCZ...

THE ITCZ AXIS LIES ALONG 11N86W TO 06N103W TO 13N114W TO 10N130W 
TO 08N140W. SCATTERED MODERATE ISOLATED STRONG WITHIN 180-240 NM 
OF THE AXIS BETWEEN 112W AND 121W...WITHIN 120 NM N OF THE AXIS 
BETWEEN 97W AND 101W. SCATTERED MODERATE ISOLATED STRONG FROM 
04N TO 10N BETWEEN 86W AND 91W. 

...DISCUSSION...
THE MID TO UPPER LEVEL RIDGE EXTENDING FROM THE ANTICYCLONE OVER 
SRN ARIZONA NEAR 33N111W IS FORECAST TO EXPAND TO THE SW OVER 
THE NEXT FEW DAYS. THE BUILDING RIDGE WILL ALLOW A RATHER LARGE 
CYCLONIC CIRCULATION NEAR 21N116W TO PUSH FURTHER WESTWARD. 
THIS CIRCULATION WILL MOVE IN TANDEM WITH THE TROPICAL WAVE 
CURRENTLY ALONG 117W WEST-NORTHWEST TOWARD COOLER WATERS AT THE
SURFACE AND TOWARD A LARGE AREA OF SUBSIDENCE ASSOCIATED WITH 
THE WEAK INVERTED MID LEVEL TROUGH THAT HAS PERSISTED NEAR 135W. 
EXPECT CONVECTION ASSOCIATED WITH THE WAVE TO DIMINISH OVER THE 
NEXT DAY OR SO AS A RESULT. FARTHER TO THE NORTHWEST...THE 
REMNANT OF GENEVIEVE SHOULD ALSO BE INFLUENCED BY THIS INVERTED 
TROUGH...WITH THE SYSTEM EXPECTED TO LOSE ITS CLOSED SURFACE 
CIRCULATION OVER THE NEXT TWO DAYS AS IT ENCOUNTERS MORE 
VERTICAL SHEAR AND MORE IMPORTANTLY AS IT TRAVERSES OVER COOLER 
WATERS. 

A SURFACE LOW PRESSURE SYSTEM CURRENTLY 1010 MB NEAR 08N97W IS 
EMBEDDED WITHIN THE ITCZ AND SUPPORTS ONLY SCATTERED MODERATE
ISOLATED STRONG CONVECTION WITHIN 120 NM OF THE ITCZ BETWEEN 97W 
AND 101W. THIS LOW PRESSURE SYSTEM IS EXPECTED TO DISSIPATE 
WITHIN 24 HOURS. 

RELATIVELY DRY CONDITIONS AND WEAK UPPER LEVEL CONFLUENCE IS 
LIMITING CONVECTION OVER MUCH OF MEXICO AND NORTHERN CENTRAL 
AMERICA THIS EVENING. WEAKENING SCATTERED MODERATE ISOLATED 
STRONG CONVECTION WHICH FIRED ALONG THE SIERRA MADRE OCCIDENTAL 
IS PUSHING SW AND IS EXPECTED TO IMPACT THE COAST JUST TO THE 
WEST OF ACAPULCO BETWEEN 101W AND 103W OVER THE NEXT FEW HOURS.
ADDITIONAL STORMS ARE MOVING INTO THE GULF OF TEHUANTEPEC.

$$
COBB