000
AXPZ20 KNHC 121546
TWDEP 

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
1605 UTC FRI SEP 12 2008

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 
1500 UTC.

...TROPICAL WAVES...
TROPICAL WAVE N OF 03N ALONG 89W MOVING W ABOUT 10-15 KT. NO 
SIGNIFICANT CONVECTION IS NOTED IN ASSOCIATION WITH THIS WAVE 
NOR IS THERE A SIGNAL IN THE LOW-LEVEL WIND FIELD S OF CENTRAL 
AMERICA. IT IS POSSIBLE THAT THE OVERWHELMING PRESENCE OF IKE TO 
THE N IS MAKING IT TO DIFFICULT TO TRACK THIS FEATURE.

...ITCZ...
ITCZ AXIS IS CENTERED ALONG 09N78W TO 06N86W TO 09N105W TO 
07N119W TO 12N130W TO 11N140W. ISOLATED MODERATE CONVECTION E OF 
105W WITHIN 90 NM OF THE AXIS.

...DISCUSSION...

A SMALL LOW-LEVEL CYCLONIC CIRCULATION EMBEDDED WITHIN THE ITCZ 
YESTERDAY NEAR 13N130W HAS VIRTUALLY DISSIPATED OVER THE LAST 12 
HOURS. A LACK OF SUSTAINED LOW-LEVEL CONVERGENCE IN ADDITION TO 
HOSTILE NE TO E VERTICAL WIND SHEAR LIKELY CONTRIBUTED TO ITS 
DEMISE. THE REMNANTS...A SKELETAL LOW-LEVEL CIRCULATION...SHOULD 
CONTINUE PROPAGATING WITHIN THE ITCZ FOR THE NEXT DAY OR TWO AND 
BECOME INDISTINGUISHABLE.

TO THE E...AN ANOMALOUS LOW-LEVEL WESTERLY FLOW REMAINS IN PLACE 
GENERALLY S OF 20N E OF 120W...AS HAS BEEN THE CASE FOR MOST OF 
THE LAST WEEK OF AUGUST AND NOW THE FIRST 10 DAYS OF SEPTEMBER. 
THIS PATTERN SUPPORTS A MONSOON TROUGH-TYPE FEATURE...DISPLACED 
N OF ITS CLIMATOLOGICAL POSITION...FROM CENTRAL AMERICA 
NORTHWEST THROUGH MUCH OF SOUTHERN MEXICO. WITH THE REGION OF 
CYCLONIC SHEAR OVER LAND AND WITH STRONG EASTERLY SHEAR STILL 
DOMINATING THE MAIN DEVELOPMENT REGION OF THE EASTERN NORTH 
PACIFIC...ONLY A FEW WEAK TROPICAL CYCLONES HAVE FORMED IN THE 
EAST PACIFIC THE PAST FEW WEEKS...ALL FARTHER NORTHWEST THAN 
NORMAL. MODELS SHOW FORECAST THE WESTERLY LOW-LEVEL FLOW TO 
WEAKEN BETWEEN 110-120W AS HIGH PRESSURE OVER THE NE PACIFIC 
BUILDS INTO THE REGION EARLY THIS WEEKEND. 

FINALLY...LONG PERIOD SOUTHWEST SWELL ARRIVING FROM THE 
SOUTHERN HEMISPHERE CONTINUES TO ENGULF MUCH OF THE TROPICAL 
EAST PACIFIC WATERS...EXCEPT W OF 120W WHERE SOUTHEAST SWELL 
PREVAILS. MODEL GUIDANCE INDICATES THAT WAVE HEIGHTS S OF 20N 
AND ARE NOW GENERALLY RUNNING BETWEEN 6 AND 8 FT AND SHOULD 
CONTINUE AT THESE LEVELS INTO THE WEEKEND. ADDITIONAL SOUTHWEST 
SWELL SHOULD REACH THE SOUTHERN WATERS LATE THIS WEEKEND...WITH 
HIGHEST WAVE HEIGHTS OVER THE SOUTH CENTRAL WATERS.


$$
KIMBERLAIN