000
AXPZ20 KNHC 171622
TWDEP 

TROPICAL WEATHER DISCUSSION     
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
1605 UTC FRI AUG 17 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 107W N OF 6N MOVING W AT 15 KT.  MOIST AND 
WARM SLY FLOW AGAINST MOUNTAIN RANGE PRODUCING NUMEROUS MODERATE 
ISOLATED STRONG CONVECTION WITHIN 180 NM OF MEXICAN COAST FROM 
96W TO 110W.  EMBEDDED LOW PRES 1007 MB AT 16N SHOWS LITTLE 
SIGNS OF CONVECTIVE ORGANIZATION AT THIS TIME...NEVERTHELESS THE 
ADVERSE CONDITIONS AT UPPER LEVELS COULD BECOME LESS UNFAVORABLE 
AND ALLOW SOME SLOW DEVELOPMENT. 

TROPICAL WAVE ALONG 128W FROM 6N TO 17N MOVING W AT 10 KT.  DRY 
AIR MASS AND STRONG UPPER LEVEL WIND HAVE CURTAILED ANY 
DEVELOPMENT OF SYSTEM.  ONLY ISOLATED MODERATE CONVECTION ALONG 
ITCZ NOTED. 

...ITCZ...
ITCZ AXIS ALONG 7N80W  14N95W  15N106W  11N128W  11N140W.  
SCATTERED MODERATE CONVECTION WITHIN 90 NM OF AXIS E OF 85W AND 
WITHIN 120 NM OF AXIS FROM 97W TO 112W.  ISOLATED MODERATE 
CONVECTION WITHIN 30 NM OF AXIS FROM 119W TO 132W.

...DISCUSSION...
BROAD UPPER LEVEL ANTICYCLONE CENTERED 21N140W MAINTAINS VERY 
DRY AIR MASS N OF 13N W OF 125W.  SHARP LONGWAVE UPPER LEVEL 
TROUGH EXTENDING FROM 32N125W TO CYCLONIC VORTEX AT 22N123W THEN 
TO 15N122W EXTENDS DRY SUBSIDING AIR TO N OF 13NB W OF 117W. 
HEALTHY UPPER LEVEL ANTICYCLONE AT 28N107W HAS STRONG NE-E FLOW 
AROUND ITS SRN PERIPHERY TO CURTAIL DEVELOPMENT OF TROPICAL WAVE 
ALONG 107W.  RIDGE ALSO PRODUCING SOME STRONG N WINDS AND 
MODERATE SWELLS ALONG COAST OF CALIFORNIA WHICH ARE ENCROACHING 
ALONG BAJA CALIFORNIA W COAST.

MODERATE TO STRONG E-NE FLOW ALOFT OVER REMAINDER E PAC 
MAINTAINS GOOD FLOW OF MOISTURE INTO ITCZ BUT ADDS GOOD SHEAR 
WIND TO DEVELOPING CONVECTION.  GLOBAL MODELS MAINTAIN FLOW 
WITH LITTLE CHANGE THROUGH FORECAST PERIOD.

HIGH PRES 1028 MB AT 35N153W HAS SURFACE RIDGE EXTEND SE TO 
23N120W.  MODERATE TRADE WINDS FROM 13N TO 22N W OF 135W SHOULD 
DIMINISH BY END OF FORECAST PERIOD.

WEAK LOW PRES 1007 MB 17N117W DRIFTING ALONG WITH TROPICAL WAVE 
HAS INCREASED SW FLOW WITHIN ITS SE QUADRANT.  LITTLE OR IF ANY 
...SLOW DEVELOPMENT EXPECTED.    

$$
WALLY BARNES