000
AXPZ20 KNHC 122132
TWDEP 

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
2205 UTC FRI SEP 12 2008

TROPICAL WEATHER DISCUSSION FOR THE EASTERN PACIFIC OCEAN FROM 
THE EQUATOR TO 32N...EAST OF 140W. 

BASED ON 1800 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 
2100 UTC.

...TROPICAL WAVES...
A TROPICAL WAVE N OF 03N ALONG 90W IS 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 08N78W TO 06N94W TO 06N110W THEN 
FROM 13N119W TO 10N140W. SCATTERED MODERATE CONVECTION WITHIN 
200 NM S OF AXIS BETWEEN 77W TO 89W. ISOLATED CONVECTION WITHIN 
90 NM EITHER SIDE OF AXIS BETWEEN 136W AND 140W.

...DISCUSSION...

DEEP CONVECTION SURROUNDING A SMALL LOW-LEVEL CYCLONIC 
CIRCULATION EMBEDDED WITHIN THE WESTERN END OF 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...NOW A SKELETAL LOW-LEVEL CIRCULATION 
...SHOULD CONTINUE DRIFTING SW WITHIN THE ITCZ FOR THE NEXT DAY 
OR TWO AND EVENTUALLY BECOME INDISTINGUISHABLE.

ELSEWHERE...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...FEW TROPICAL CYCLONES HAVE BEEN FORMING 
IN THE EAST PACIFIC THE PAST FEW WEEKS. THOSE WHICH HAVE FORMED 
HAVE DONE SO MUCH FARTHER NORTHWEST THAN NORMAL...WHILE 
SUFFERING THE EFFECTS
OF A SUSTAINED EASTERLY SHEAR. MODELS FORECAST THIS WESTERLY 
LOW-LEVEL FLOW TO WEAKEN BETWEEN 110-120W EARLY THIS WEEKEND IN 
RESPONSE TO HIGH PRESSURE BUILDING OVER THE NE PACIFIC INTO THE 
REGION.

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