000
AXPZ20 KNHC 222146
TWDEP 

TROPICAL WEATHER DISCUSSION 
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
2205 UTC THU OCT 22 2009

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 
2130 UTC.

...TROPICAL LOW...
THE SOUTHERN EXTENT OF AN ATLANTIC AND CARIBBEAN UPPER TROUGH 
TERMINATES OVER THE E PACIFIC NEAR 10N88W. THIS RESULTS IN A 
BROAD AREA OF LOW PRESSURE NOW ANALYZED ON THE SURFACE AS A LOW 
PRES NEAR 09N87W...AT AN ESTIMATED 1008 MB. ALTHOUGH CYCLONIC 
ROTATION IS NOTED...CONVECTION REMAINS UNORGANIZED THIS 
AFTERNOON...AND IS DESCRIBED WITH OTHER ITCZ ASSOCIATED 
CONVECTION.   

...ITCZ...
THE INTERTROPICAL CONVERGENCE ZONE AXIS EXTENDS FROM 09N80W TO 
09N98W TO 13N105W TO 12N120W TO 08N140W. SCATTERED MODERATE AND 
ISOLATED STRONG CONVECTION IS WITHIN 150 NM LINE FROM 07N83W TO 
11N93W AND ALSO FROM 09N TO 13N BETWEEN 98W AND 135W.

...DISCUSSION...
AN UPPER LEVEL ANTICYCLONE IS CENTERED AT 32N140W WITH A RIDGE 
EXTENDING SE TO A SHARP CREST AT 26N126W. A TROPICAL 
ANTICYCLONE IS CENTERED W OF THE AREA AT 06N145W WITH A RIDGE 
EXTENDING E INTO THE AREA OVER THE ITCZ TO A CREST AT 11N115W... 
AND ENHANCING CONVECTION ALONG THE ITCZ BETWEEN 117W AND 144W. 
SOME OF THE DEBRIS MOISTURE IS ADVECTED S ACROSS THE EQUATOR 
BETWEEN 130W AND 143W. A THIRD ANTICYCLONE IS OVER THE BAY OF 
CAMPECHE AT 20N94W WITH A RIDGE EXTENDING SW TO A CREST AT 
13N111W...RESULTING IN A BROAD UPPER RIDGE OVER THE TROPICAL 
PACIFIC BETWEEN 95W AND 114W.

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 15N113W WITH THE TROUGH CONTINUING W TO 20N130W AND 
INTO AN UPPER CYCLONE AT 19N142W. A THIN BAND OF UPPER MOISTURE 
IS NOTED FROM 28N TO 31N BETWEEN 130W AND 113W...OTHERWISE VERY 
DRY UPPER AIR IS INDICATED N OF 16N W OF 110W AND OVER OLD 
MEXICO N OF 22N. 

AT THE LOW LEVELS HIGH PRES IS CENTERED AT 32N136W WITH A RIDGE 
EXTENDING SE TO NEAR 13N118W. 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