000
AXPZ20 KNHC 230304
TWDEP 

TROPICAL WEATHER DISCUSSION 
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
0405 UTC FRI OCT 23 2009

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

BASED ON 0000 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 
0315 UTC.

...TROPICAL LOW...
THE SOUTHERN EXTENT OF AN ATLANTIC AND CARIBBEAN UPPER TROUGH 
TERMINATES OVER THE E PACIFIC NEAR 10N86W WHERE A BROAD AREA OF 
LOW PRESSURE IS ANALYZED ON THE SURFACE AT AN ESTIMATED 1005 MB. 
ALTHOUGH CYCLONIC ROTATION IS NOTED...CONVECTION REMAINS 
UNORGANIZED AND IS CURRENT DECREASING.   

...ITCZ...
THE INTERTROPICAL CONVERGENCE ZONE AXIS EXTENDS ALONG 10N.
SCATTERED MODERATE AND ISOLATED STRONG CONVECTION IS NOTED FROM 
09N TO 11N E OF 92W AND ALSO FROM 09N TO 13N W OF 113W.

...DISCUSSION...
AN UPPER LEVEL ANTICYCLONE IS CENTERED AT 32N141W WITH A RIDGE 
EXTENDING SE TO A SHARP CREST AT 26N127W. A TROPICAL 
ANTICYCLONE IS CENTERED W OF THE AREA AT 07N151W WITH A RIDGE 
EXTENDING E INTO THE AREA OVER THE ITCZ TO A CREST AT 11N119W... 
AND ENHANCING CONVECTION ALONG THE ITCZ AS DESCRIBED ABOVE.  
SOME OF THE DEBRIS MOISTURE IS ADVECTED S ACROSS THE EQUATOR 
BETWEEN 133W AND 145W. A THIRD ANTICYCLONE IS OVER THE BAY OF 
CAMPECHE AT 20N95W WITH A RIDGE EXTENDING SW TO A CREST AT 
13N109W...RESULTING IN A BROAD UPPER RIDGE OVER THE TROPICAL 
PACIFIC BETWEEN 91W AND 109W.

THE DISCUSSION AREA BETWEEN THESE ANTICYCLONES IS DOMINATED BY 
THE SOUTHERN EXTENSION OF A LONG WAVE TROUGH THAT DISSECTS 
CENTRAL N AMERICA AND EXTENDING INTO THE DISCUSSION AREA ALONG 
32N103W TO 15N115W WITH THE TROUGH CONTINUING W TO 20N131W AND 
INTO AN UPPER CYCLONE AT 19N143W. A THIN BAND OF UPPER MOISTURE 
IS NOTED FROM 27N TO 29N BETWEEN 111W AND 130W...OTHERWISE VERY 
DRY UPPER AIR IS INDICATED N OF 17N W OF 110W AND OVER OLD 
MEXICO N OF 23N. 

AT THE LOW LEVELS HIGH PRES IS CENTERED AT 32N136W WITH A RIDGE 
EXTENDING SE TO NEAR 13N117W. THE GRADIENT NE OF THE RIDGE IS 
SUPPORTING NORTHERLY WINDS TO 20 KT WHILE THE GRADIENT SW OF THE 
RIDGE IS SUPPORTING NE TRADES TO 20 KT. N AND NW SWELLS ARE 
MIXING OVER THE SUBTROPICAL WATERS. SOUTHERLY SWELLS ARE 
CROSSING THE EQUATOR AND MIXING WITH THE NORTHERLY SWELLS 
BETWEEN 10N AND 20N.  

$$
NELSON