000
AXPZ20 KNHC 181602
TWDEP 

TROPICAL WEATHER DISCUSSION     
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
1605 UTC SAT AUG 18 2007

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 
1445 UTC.

...TROPICAL WAVES...
TROPICAL WAVE ALONG 84W MOVING W AT 10 KT. SCATTERED MODERATE 
CONVECTION FROM 3N TO 6N BETWEEN 80W AND 84W.  STRONG NE WINDS 
ALOFT MAKES SYSTEM UNLIKELY TO DEVELOP.   

TROPICAL WAVE ALONG 110W N OF 8N HAS EMBEDDED LOW PRES 1006 MB 
AT 18N MOVING NW AT 10 KT.  LARGE CLUSTERS OF STRONG CONVECTION 
WITHIN 90 NM OF LOW PRES CENTER AND BETWEEN CABO SAN LUCAS AND 
MEXICAN MAINLAND COAST.  SCATTERED MODERATE CONVECTION ALONG 
WAVE AXIS.  ADVERSE UPPER LEVEL ENVIRONMENT THAT MIGHT HAVE 
PREVENTED ITS GROWTH SHOULD BECOME LESS ADVERSE WITHIN NEXT 36 
HRS ALLOWING SYSTEM TO DEVELOP SLOWLY.  

TROPICAL WAVE ALONG 133W FROM 6N TO 16N MOVING W AT 15 KT.
SYSTEM SURROUNDED BY VERY DRY AND HOSTILE ENVIRONMENT 
EFFECTIVELY DRYING OUT ANY SIGNIFICANT CONVECTION.  

...ITCZ...
ITCZ AXIS ALONG 9N85W  8N92W  18N107W  12N119W  10N138W 10N140W. 
SCATTERED MODERATE ISOLATED STRONG WITHIN 90 NM S OF AXIS FROM 
96W TO 118W. ISOLATED MODERATE WITHIN 30 NM OF AXIS W OF 132W.  

SCATTERED STRONG WITHIN 90 NM OF 18N112W.  NUMEROUS MODERATE TO 
STRONG WITHIN 120 NM OF 23N109W. 

...DISCUSSION...
UPPER LEVEL LONGWAVE TROUGH FROM 32N130W TO 12N123W MAINTAINS 
VERY DRY ENVIRONMENT N OF 12N W OF 120W DUE TO STRONG SUBSIDING 
AIR MASS.  MID-UPPER LEVEL RIDGE W OF AREA CUT OFF ANY SOURCE OF 
MOISTURE INTO WRN SECTION OF E PAC. 

ANOTHER MID-UPPER LEVEL ANTICYCLONE AT 29N109W DRAWS MOISTURE 
FROM THE GULF OF MEXICO ACROSS CENTRAL AMERICA INTO E PAC TO 
SUPPLY ACTIVE ITCZ E OF 120W.  NE FLOW IN SRN PERIPHERY OF 
ANTICYCLONE STRONG ENOUGH TO SHEAR OFF ORGANIZED DEVELOPMENT 
ALONG TRPCL WAVE AT 110W.  RIDGE SHOULD BE FORCED NE BY INCOMING 
SHORTWAVE NOW AT 32N133W ALLOWING SHEARING WINDS TO DIMINISH.  

REMAINDER OF E PAC E OF RIDGE REMAINS UNDER STRONG ANTICYCLONIC 
WINDS.

LARGE SURFACE HIGH PRES CENTER 1028 MB AT 33N153W HAS RIDGE 
EXTEND SE TO 17N120W WITH MODERATE TRADE WINDS N OF 12N W OF 
130W.  N TO NW WINDS ALONG COAST OF CALIFORNIA ENCROACH INTO E 
PAC ALONG COAST OF BAJA CALIFORNIA WITH LARGE LONG PERIOD SWELLS 
CONTINUING FOR NEXT 48 HRS.  

LOW PRES AT 18N110W TIGHTENS GRADIENT ALONG ITS SRN SEMICIRCLE 
INCREASING WINDS TO 20 KT THROUGH PERIOD. 

$$
WALLY BARNES