000
AXPZ20 KNHC 312219 CCA
TWDEP 

TROPICAL WEATHER DISCUSSION...CORRECTION   
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
2205 UTC SAT JUL 31 2010

CORRECTED FOR AREA DESCRIPTION IN DISCUSSION

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

BASED ON 1800 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 
1930 UTC.

...ITCZ...
THE INTERTROPICAL CONVERGENCE ZONE AXIS LIES FROM 09N84W TO 
11N93W TO 08N101W TO 17N110W TO 11N140W. SCATTERED MODERATE 
CONVECTION IS WITHIN 180 NM S OF THE ITCZ AXIS E OF 90W AND 
ELSEWHERE N OF 05N TO THE COAST BETWEEN 78W AND 84W...WITHIN 120 
NM S OF THE ITCZ AXIS BETWEEN 109W AND 111W...AND WITHIN 120 NM 
N AND 60 NM S OF THE ITCZ AXIS W OF 130W.

...DISCUSSION...

W OF 110W...
AN ANTICYCLONE LIES OVER NW WATERS NEAR 20N127W AND EXTENDS A 
RIDGE TO ITS NE THROUGH 27N125W TO 30N122W AS SWELL AS TO ITS SW 
THROUGH 16N133W TO 15N140W. A REGION OF DRY AIR IN SUBSIDENCE N 
OF 15N W OF 120W IS BLEMISHED BY A DEEP LAYERED LOW NEAR 20N120W 
THAT IS LURING TROPICAL MOISTURE FROM THE ITCZ INTO ITS SOUTHERN 
SIDE AND WRAPPING IT AROUND THE LOW. THE 1009 MB SURFACE 
REFLECTION OF THIS LOW IS SKEWED SOUTHEASTWARD NEAR 17N113W. 
SCATTERED MODERATE CONVECTION LIES WITHIN 60 NM N SEMICIRCLE OF 
THE LOW AS WELL AS OVER THE VAST AREA FROM 09N TO 16N BETWEEN 
113W AND 120W ON THE SW SIDE OF THE LOW WHERE MOISTURE IS 
PLENTIFUL AND UPPER LEVEL WINDS ARE LIGHT. THE UPPER LEVEL RIDGE 
AND LOW ARE EXPECTED TO SHIFT SLIGHTLY TO THE NW OVER THE NEXT 
TWO DAYS. THE SURFACE LOW WILL ALSO FOLLOW SUIT AND SHIFT NW BY 
MON. ELSEWHERE...BROAD UPPER LEVEL DIFFLUENCE S OF THE RIDGE 
AXIS IS ENHANCING SCATTERED MODERATE CONVECTION FOCUSED ALONG 
THE ITCZ W OF 130W.

E OF 110W...
CONVECTION ALONG THE EASTERN EDGE OF THE ITCZ AND INTO PANAMA 
AND SOUTHERN COSTA RICA IS BEING ENHANCED BY UPPER LEVEL 
DIFFLUENCE BETWEEN A RIDGE AXIS THAT EXTENDS THROUGH THE GULF OF 
TEHUANTEPEC SOUTHWESTWARD TO 11N102W AND A 30 KT NORTHEASTERLY 
JET FOUND S OF 06N E OF 100W. A 1009 MB SURFACE LOW LIES NEAR 
10N96W. WHILE THIS LOW MAINTAINS A WELL DEFINED CLOSED 
CIRCULATION EVIDENT ON VISIBLE SATELLITE IMAGERY AND A PARTIAL 
ASCAT PASS AT 1552 UTC...CONVECTION NEAR THIS LOW HAS DIMINISHED 
OVER THE PAST 6 HOURS. THE ASCAT PASS SHOWS 20 KT WINDS RESIDE 
IN THE N QUADRANT OF THE LOW. THIS PASS ONLY CAPTURED WESTERN 
SEMICIRCLE AND N QUADRANT OF THIS LOW. THE LOW IS FORECAST TO 
FINALLY START MOVING NW BY SUN AND GRADUALLY WEAKEN ON MON AS IT 
ENCOUNTERS STRONGER EASTERLY WINDS ALOFT.

$$
SCHAUER