000
AXPZ20 KNHC 100955
TWDEP 

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
1005 UTC FRI JUL 10 2009

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 
0945 UTC.

...SPECIAL FEATURE...

THE OVER CIRCULATION ASSOCIATED WITH A SURFACE LOW PRES THAT 
FORMED AT 10N ALONG A TROPICAL WAVE AXIS THAT CURRENTLY EXTENDS 
FROM 05N TO 16N ALONG 111W HAS CONTINUED TO BECOME BETTER 
ORGANIZED AND HAS BEEN UPGRADED TO TROPICAL DEPRESSION 4E. 
SCATTERED MODERATE ISOLATED STRONG CONVECTION IS OBSERVED IN 
BANDING FEATURES WITHIN ROUGHLY 270 NM NW SEMICIRCLE AND WITHIN 
240 NM OVER THE SE SEMICIRCLE OF THE CENTER. THE SYSTEM IS 
EXPECTED TO CONTINUE MOVING W AT 07 KT AND STRENGTHEN TO A 
TROPICAL STORM IN ABOUT 24 HOURS. SEE THE LATEST NHC FORECAST 
ADVISORY UNDER AWIPS/WMO HEADERS MIATCMEP4/WTPZ24 KNHC FOR 
ADDITIONAL DETAILS. 

...TROPICAL WAVES...
A TROPICAL WAVE N OF 04N ALONG 101W HAS MOVED W AT 15 KT OVER 
THE PAST 24 HOURS. ONLY ISOLATED CONVECTION IS NOTED WITHIN 120 
NM OF THE WAVE AXIS FROM 06N TO 12N.

...ITCZ...
THE ITCZ AXIS MEANDERS FROM 08N TO 10N TO THE E OF THE NEWLY 
FORMED TROPICAL DEPRESSION AT 10N111.5W AND MEANDERS FROM 05N TO 
06N BETWEEN 112W AND 140W. EXCEPT AS MENTIONED ABOVE...SCATTERED 
MODERATE ISOLATED STRONG CONVECTION IS OBSERVED FROM 05N TO 10N 
BETWEEN 91W AND 98W. 

...DISCUSSION...
AN BROAD UPPER LEVEL TROUGH DOMINATES THE SUBTROPICS WITH ITS 
MEAN AXIS ALONG 132W. A NEGATIVE TILT SHORTWAVE UPPER TROUGH IS 
NOTED N OF 12N ALONG 116W. A LARGE ANTICYCLONE CENTERED OVER 
TEXAS HAS A RIDGE EXTENDING W SW TO NEAR 27N126W. THE REMNANT 
SURFACE LOW PRES OF BLANCA IS NEAR 23.5N125W 1008 MB. DEBRIS 
MOISTURE...FROM FORMER CONVECTION AND FROM SOME SHOWERS 
CURRENTLY WELL NW OF THE REMNANT CENTER...IS SPREADING N UNDER 
THE UPPER RIDGE EVENTUALLY CROSSING OVER CALIFORNIA TO THE S OF 
35N.

AN UPPER ANTICYCLONE NEAR 16N107W HAS A RIDGE EXTENDING SW TO A 
CREST NEAR 08N124W...OVER THE NEWLY FORMED TROPICAL DEPRESSION 
4E. THE ASSOCIATED UPPER DIFFLUENCE IS ENHANCING CONVECTION 
AROUND THE DEPRESSION DESCRIBED ABOVE...WITH THE DEBRIS 
MOISTURE  CONCENTRATED UNDER THE RIDGE...ROUGHLY FROM 02N TO 14N 
BETWEEN 109W AND 116W. OTHERWISE THE UPPER LEVELS ARE DRY W OF 
115W.    

BROAD UPPER RIDGING IS NOTED OVER THE TROPICS TO THE E OF 103W 
AND HAS BEEN ENHANCING CONVECTION ALONG THE COASTS OF COLOMBIA 
AND MEXICO WITH THE DEBRIS MOISTURE SPREADING SW CROSSING THE 
EQUATOR TO THE E OF 110W. 

GAP WINDS...FRESH E TRADE WINDS ARE EXPECTED OCCASIONALLY SURGE 
THROUGH THE GULF OF PAPAGAYO SHORTLY AFTER SUNRISE THIS MORNING 
AND TO CONTINUE FOR THE NEXT DAYS. 

$$
NELSON