000
AXPZ20 KNHC 180948
TWDEP 

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
1005 UTC SAT JUL 18 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 
0900 UTC.

...TROPICAL WAVES...
TROPICAL WAVE FROM 04N-13N ALONG 98W MOVE W 15 TO 20 KT.  
ISOLATED CONVECTION RUNS WELL AHEAD OF AXIS AND N OF ITCZ.  NO 
CYCLONIC ORGANIZATION ASSOCIATED WITH WAVE AS UPPER LEVEL 
ENVIRONMENT IS ADVERSE...BUT AFTER 36 HR IT IS EXPECTED TO ENTER 
MORE FAVORABLE CONDITIONS ALOFT AND INTENSIFICATION IS POSSIBLE. 
 
TROPICAL WAVE FROM 05N TO 15N ALONG 122W MOVE W 15 KT.  
SCATTERED MODERATE CONVECTION ASSOCIATED WITH WAVE AXIS IN SPITE 
OF ADVERSE CONDITIONS ALOFT.  SOME MODEL GUIDANCE CONSIDER WAVE 
HEALTHY ENOUGH TO FORM LOW PRES AFTER 24 HR WHEN UPPER 
ENVIRONMENT IS MORE FAVORABLE.

...ITCZ...
AXIS ALONG 07N78W TO 07N110W TO 10N140W.  SCATTERED MODERATE 
CONVECTION WITHIN 75 NM N OF AXIS E OF 85W. SCATTERED MODERATE 
ISOLATED STRONG CONVECTION WITHIN 240 NM N OF AXIS FROM 101W TO 
108W.  SCATTERED MODERATE CONVECTION WITHIN 120 NM OF AXIS W OF 
132W. 

...DISCUSSION...
UPPER LEVEL ANTICYCLONE AT 15N144W HAS RIDGE EXTENDING INTO E 
PAC TO 130W N OF ITCZ DISPLACING PREVIOUS DEEP LAYER TROUGH IN 
WRN PART OF BASIN.  AIR MASS REMAINS VERY DRY UNDER RIDGE...BUT 
TROUGH HAS WIDE SWATH OF MOISTURE WHICH LEAD TO THE REMNANTS OF 
DOLORES NOW AT 22N130W.  DOWNSTREAM TROUGH FORCED OUT BY RIDGE 
WILL BRING AREA OF DIFFLUENT FLOW RIGHT ON TOP OF UPLIFTING 
MOIST AIR MASS AND CONTRIBUTE TO INTENSIFICATION OF TROPICAL 
WAVE NOW ALONG 122W AND IS EXPECTED TO FORM LOW PRES CENTER.
MODEL GUIDANCE COVERS SITUATION WELL AND DRIVES LOW PRES CENTER 
W ACROSS 140W WITHIN A COUPLE OF DAYS. 

FURTHER DOWNSTREAM...SECOND ANTICYCLONE AT 13N102W BRING NE 
SHEAR TO TROPICAL WAVE ALONG 98W.  WAVE LACKS SIGNIFICANT 
CONVECTION ASSOCIATED WITH AXIS...BUT CONDITIONS IMPROVE ONCE 
AXIS MOVES FURTHER W AWAY FROM RIDGE SHEAR.  POSSIBILITY OF 
BETTER CYCLONIC ORGANIZATION IMPROVES AS WAVE COMES UNDER MORE 
FAVORABLE UPPER ENVIRONMENT.   

ELSEWHERE AT THE SURFACE...
WEAK LOW PRES CENTER...REMNANT OF DOLORES...MEANDER NEAR 22N130W 
...EXPECTED TO SLOWLY TRACK NW OUT OF BASIN PAST THIS FORECAST 
PERIOD...BUT WITH LITTLE OR NO CHANCE OF REINTENSIFICATION AS 
WATER TEMPERATURES HAVE BECOME TOO COLD AND AIR MASS VERY STABLE.

FRESH TO STRONG NE TO E GAP WINDS ACROSS GULF OF PAPAGAYO EXTEND 
WELL INTO E PAC PAST W OF 100W.  CONDITIONS EXPECTED TO LAST 
BEYOND FORECAST PERIOD WITH LITTLE CHANGE. 

CROSS EQUATORIAL SE AND SW SWELLS WITH FRESH S LOW LEVEL WIND 
FLOW RESULT IN SEAS TO 10 FT OVER WATERS S OF 08N W OF GALAPAGOS 
ISLANDS. 

HIGH PRES CENTER 1023 MB JUST N OF AREA PRODUCING FRESH NW WINDS
ALONG BAJA CALIFORNIA W COAST WILL BE SWEPT BY APPROACHING COLD 
FRONT...ALSO N OF AREA...AND WINDS DIMINISH IN 24-36 HR.  

$$
WALLY BARNES