000
AXPZ20 KNHC 301556
TWDEP 

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
1605 UTC WED JUL 30 2008

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 
1545 UTC.

...TROPICAL WAVES... 
A TROPICAL WAVE IS N OF 03N ALONG 101W AND HAS MOVED W AT ABOUT 
15 KT OVER THE PAST 24 HOURS. A CYCLONIC SWIRL IS ANALYZED ALONG 
THE WAVE AXIS AT 09N AND IS ACCOMPANIED BY SCATTERED MODERATE 
CONVECTION CONFIRMED BY LIGHTNING DATA...WITHIN 90 NM OF 10N103W 
AT THE MOMENT. THE LOW PRES IS EXPECTED TO DISSIPATE. 

A TROPICAL WAVE ALONG 129W FROM 04N TO 17N HAS BEEN RELOCATED 
SEVERAL TIMES OVER THE PAST FEW DAYS...BUT IS ESTIMATED TO BE 
MOVING W AT 15 KT. THIS WAVE STRETCHES THE ITCZ SLIGHTLY 
NORTHWARD...BUT ONLY SLIGHTLY ENHANCES ITCZ CONVECTION.

...ITCZ...
THE ITCZ AXIS LIES ALONG 07N77W TO 06N90W TO 10N122W TO 10N140W. 
SCATTERED MODERATE AND ISOLATED STRONG CONVECTION NOTED WITHIN 
180 NM EITHER SIDE OF LINE FROM 03N77W TO 08N91W TO 09N140W.

...DISCUSSION...
AN UPPER LEVEL TROUGH LIES ALONG THE NORTHERN PART OF THE 
DISCUSSION AREA WITH ITS MEAN AXIS FROM 34N125W TO 29N140W AND 
INTO AN UPPER CYCLONE AT 25N150W. A SMALL UPPER ANTICYCLONE IS 
CENTERED NEAR 23N133W. A WELL DEFINED UPPER CYCLONE IS CENTERED 
AT 22N121W WITH A TROUGH EXTENDING SW TO 12N130W. THIS CYCLONE 
IS DRIFTING W AND IS ACCOMPANIED BY UPPER LEVEL MOISTURE WITHIN 
ABOUT 600 NM OF ITS CENTER. OTHERWISE THE UPPER LEVELS ARE VERY 
DRY N OF 12N W OF 129W...AND SUPPRESSING CONVECTION. EVEN THE 
REMNANT LOW OF FORMER TROPICAL CYCLONE GENEVIEVE...NEAR 
17.5N136W TOTALLY LACKS CONVECTION. ADDITIONALLY AT THE LOW 
LEVELS A COLD FRONT IS DISSIPATING N OF THE AREA FROM 35N130W TO 
34N140W AND IS ALREADY BRIDGED BY A RIDGE BUILDING SE FROM 
32N141W TO 13N100W.

FURTHER E...AN UPPER ANTICYCLONE IS NOTED OVER NEW MEXICO NEAR 
34N106W WITH ITS ENVELOPE OF ANTICYCLONIC FLOW EXTENDING S OVER 
OLD MEXICO FROM 25N95W TO 30N112W. SCATTERED MODERATE ISOLATED 
STRONG CONVECTION WAS ENHANCED ALONG THE SW PERIPHERY OF THIS 
RIDGE...ROUGHLY WITHIN 120 NM OF THE COAST OF MEXICO FROM 100W 
TO 107W. THIS CONVECTION IS CURRENTLY MOVING SW AWAY FROM SHORE.

A TROPICAL UPPER ANTICYCLONE IS NEAR 12N122W WITH A SHORTWAVE 
RIDGE EXTENDING NE TO A SHARP CREST NEAR 20N112W. ASSOCIATED 
UPPER DIFFLUENCE ENHANCED CONVECTION ALONG A LOW LEVEL TROUGH 
THAT EXTENDS FROM 12N121W TO 20N115W...BUT THE CONVECTION IS 
CURRENTLY WEAKENING. AN UPPER ANTICYCLONE IS NEAR 11N78W WITH 
ITS ENVELOPE OF ANTICYCLONIC FLOW EXTENDING W OVER THE TROPICAL 
PACIFIC TO THE E OF 92W...AND ENHANCING ITCZ CONVECTION IN THE 
SAME AREA WITH THE DEBRIS MOISTURE REMAINING IN THE TROPICS. 
SEPARATING THESE ANTICYCLONES...IS THE W EXTENSION OF AN ATLC 
TROPICAL UPPER TROUGH THAT EXTENDS THROUGH UPPER CYCLONES AT 
24N74W AND 17N88W AND 10N103W TO A BASE AT 01N104W. 

$$
NELSON