000
AXPZ20 KNHC 212144
TWDEP 

TROPICAL WEATHER DISCUSSION 
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
2205 UTC WED OCT 21 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.

...ITCZ...

INTERTROPICAL CONVERGENCE ZONE AXIS EXTENDS FROM 10N84W TO 
10N100W TO 15N111W TO 07N140W. SCATTERED STRONG CONVECTION IS 
NOTED WITHIN 120 NM OF 08N130W. SCATTERED MODERATE ISOLATED 
STRONG CONVECTION IS OBSERVED ALONG THE THE ITCZ FROM 06N TO 11N 
BETWEEN 82W AND 107W AND ALSO IN A CLUSTER WITHIN 120 NM OF 
14N111W...AND ELSEWHERE FROM 05N TO 11N BETWEEN 122W AND 136W, 

...DISCUSSION...

AN UPPER LEVEL RIDGE HAS COLLAPSING SE OVER THE NW PORTION OF 
THE DISCUSSION AREA GENERALLY COVERING THE AREA N OF 25N W OF 
120W. AN UPPER LEVEL ANTICYCLONE IS CENTERED OVER THE DEEP 
TROPICS NEAR 09N125W WITH A RIDGE EXTENDING NW TO A CREST AT 
21N133W WITH THE RIDGE CONTINUING BEING ERODED BY AN UPPER 
TROUGH DESCRIBED BELOW. THE STRONG ITCZ CONVECTION DESCRIBED 
ABOVE IS DIRECTLY UNDER THIS UPPER RIDGE AND THE DEBRIS MOISTURE 
IS CONFINED IN THE ERA FROM 05N TO 11N BETWEEN 123W AND 133W.    

THE UPPER LEVEL ANTICYCLONE ASSOCIATED WITH TROPICAL CYCLONE 
RICK HAS MOVED OVER OLD MEXICO NEAR 23N101W AND IS RAPIDLY 
LOSING IDENTITY. DEBRIS MOISTURE FROM THE REMNANTS OF RICK ARE
SPREADING NE ACROSS MOST OF NE OLD MEXICO N OF 19N AND THE S 
CENTRAL CONUS AND THE NW GULF OF MEXICO.

BETWEEN THESE ANTICYCLONES IS THE SOUTHERN EXTENSION OF A LONG 
WAVE TROUGH THAT DISSECTS CENTRAL N AMERICA AND EXTENDS INTO THE 
DISCUSSION AREA ALONG 32N107W TO A BASE NEAR 14N120W. VERY DRY 
UPPER AIR IS INDICATED N OF 12N W OF 115W AND N OF 18N BETWEEN 
115W AND 106W. 

AN UPPER TROUGH EXTENDS SW ACROSS THE NW CARIBBEAN TO NEAR 
11N85W. BROAD UPPER RIDGING DOMINATES THE TROPICS ELSEWHERE S OF 
10N E OF 115W ENHANCING ITCZ CONVECTION. THE RESULTANT DEBRIS 
MOISTURE IS SPREADING S TOWARDS THE EQUATOR BUT SEEMS TO 
EVAPORATE ALONG 05N.

AT THE LOW LEVELS HIGH PRES IS CENTERED AT 32N135W WITH A RIDGE 
EXTENDING ESE TO NEAR 17N115W. THE GRADIENT E OF THE RIDGE HAS 
INCREASED THE NORTHERLY FLOW TO 20 KT WHILE THE GRADIENT SW OF 
THE RIDGE IS ALSO 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