000
AXPZ20 KNHC 202136
TWDEP 

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
2205 UTC WED OCT 20 2010

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 
2115 UTC.

...ITCZ...
AXIS FROM 08N85W TO 08N119W TO 10N129W TO 09N140W. SCATTERED 
MODERATE ISOLATED STRONG CONVECTION WAS NOTED E OF LINE FROM 
02N79W TO 07N84W. SCATTERED MODERATE ISOLATED STRONG CONVECTION 
IS OBSERVED FROM 09N TO 11N BETWEEN 139W AND 144W.

...DISCUSSION...
A DEEP LAYERED UPPER TROUGH IS APPROACHING THE NW CORNER OF THE 
DISCUSSION AREA FROM 32N142W TO 23N150W WITH A LOW LEVEL PRE 
FRONTAL TROUGH ENHANCING SCATTERED CONVECTION FROM 32N138W TO 
27N141W. THE ASSOCIATED COLD FRONT EXTENDING FROM 32N141W TO 
27N146W. SOUTHWESTERLY SURFACE WINDS AT 15 TO 20 KT AND SEAS TO 
8 FT WILL PRECEDE THE FRONT BY ABOUT 150 NM. WINDS WILL VEER TO 
N AT 20 KT WITH SEAS BUILDING TO 11 FT IN NW SWELL W OF THE 
FRONT TILL IT NEARLY STALLS AND GRADUALLY DISSIPATES FROM 
32N128W TO 28N133W ON FRI. 

AN UPPER LEVEL ANTICYCLONE IS CENTERED NEAR 13N117W WITH AN 
UPPER RIDGE EXTENDING NW TO A CREST AT 33N135W. UPPER DIFFLUENCE 
IS ENHANCING CONVECTION ALONG THE ITCZ BETWEEN 128W AND 136W 
WITH THE RESULTANT MOISTURE ADVECTED N AND NE WITHIN 120 NM 
EITHER SIDE OF A LINE FROM 11N132W TO 17N128W THEN NARROWS TO 
NEAR 19N115W WHERE THIS MOISTURE PLUME EVAPORATES. CONSIDERABLE 
DEBRIS MOISTURE...ORIGINATING FROM THE ITCZ CONVECTION BETWEEN 
137W AND 145W...IS ADVECTED N MERGING WITH A WELL ESTABLISHED 
TROPICAL PLUME...ORIGINATING IN THE CENTRAL PACIFIC...WITH THE 
COMBINED MOISTURE PLUME CONTINUING N AROUND THE W PERIPHERY OF 
THE UPPER RIDGE...ALL WITHIN 360 NM EITHER SIDE OF A LINE FROM 
14N146W TO 28N135W THEN TURNING E AND NARROWING TO NEAR 25N117W 
WHERE THE MOISTURE SEEMS TO COMPLETELY EVAPORATE. 

A MID TO UPPER LEVEL CYCLONE IS CENTERED AT 32N116W WITH AN 
UPPER TROUGH EXTENDING SE TO A BASE AT 19N106W. UPPER DEBRIS 
MOISTURE IS ROTATING CYCLONICALLY WITHIN 240 NM OF THE CENTER 
WITH SOME MOISTURE SPREADING N OVER CALIFORNIA AND ARIZONA AND 
AS FAR E AS SW NEW MEXICO. AN UPPER LEVEL ANTICYCLONE IS 
ESTIMATED AT 18N105W WITH A RIDGE EXTENDING N OVER OLD MEXICO TO 
A CREST OVER W TEXAS AT 32N103W WITH UPPER MOISTURE SPREADING N 
ALONG RIDGE CREST. OTHERWISE...THE UPPER LEVELS ARE VERY DRY W 
OF 95W AND SUPPRESSING CONVECTION ALONG THE THE ITCZ.

AN UPPER TROUGH IS SWEEPING THROUGH EASTERN N AMERICA AND 
EXTENDS S ACROSS THE GULF OF MEXICO FROM 32N88W TO A BASE OVER 
THE GULF OF TEHUANTEPEC AT 17N96W. AN UPPER ANTICYCLONE CENTERED 
OVER THE N CENTRAL CARIBBEAN RIDGES W ACROSS CENTRAL AMERICA TO 
A SHARP CREST OVER THE TROPICAL PACIFIC AT 10N102W. THE 
ASSOCIATED UPPER DIFFLUENCE IS ENHANCING SIGNIFICANT CONVECTION 
OVER A SURFACE LOW PRESSURE SYSTEM...SHOWING SIGNS OF TROPICAL 
CYCLONE DEVELOPMENT...IN THE NW CARIBBEAN BUT THE DEBRIS 
MOISTURE IS ADVECTED NE FURTHER AWAY FROM THE DISCUSSION AREA. 
CONVECTION IS ENHANCED OVER THE SW CARIBBEAN...OVER W COLOMBIA 
AND WITHIN 120 OF THE PACIFIC COAST OF CENTRAL AMERICA. THE 
UPPER DEBRIS MOISTURE FROM THESE CONVECTIVE AREAS IS SPREADING W 
OVER THE DISCUSSION BUT SEEMS TO EVAPORATE BEFORE REACHING 
ALONG 90W.

ELSEWHERE AT THE SURFACE...1020 MB HIGH PRES CENTERED AT 27N131W 
HAS A RIDGE EXTENDING SE TO 20N110W. NW WINDS AT 15 TO 20 KT ARE 
NOTED ALONG THE MEXICAN COAST NEAR 20N107W. NE TRADES AT 15 TO 
20 KT ARE NOTED S OF THE RIDGE AND N OF THE ITCZ IN THE AREA 
FROM 10N TO 14N W OF 135W. SOUTHWESTERLY MONSOON FLOW IS 
EXPECTED TO INCREASE TO 15 TO 20 KT OVER THE WATERS FROM 02N TO 
07N E OF 100W THROUGH FRI WITH SEAS INCREASING TO 8 FT IN SW 
CROSS EQUATORIAL SWELL THAT WILL COVER MOST OF THE PACIFIC 
WATERS FROM 08N TO THE EQUATOR BETWEEN CENTRAL AMERICA AND 140W. 

$$
NELSON