000
AXPZ20 KNHC 200318
TWDEP 

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
0405 UTC WED SEP 20 2006

TROPICAL WEATHER DISCUSSION FOR THE EASTERN PACIFIC OCEAN FROM 
THE EQUATOR TO 32N...EAST OF 140W. THE FOLLOWING INFORMATION IS 
BASED ON SATELLITE IMAGERY...WEATHER OBSERVATIONS...RADAR...AND 
METEOROLOGICAL ANALYSIS.

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

...TROPICAL LOWS...

THE REMNANT LOW OF TROPICAL CYCLONE MIRIAM IS NEAR 23.5N115W 
1010 MB MOVING N 10 KT AND FORECAST TO DISSIPATE BY 24 HOURS.
A FEW THUNDERSTORMS FLARED OVER THE NW QUADRANT AROUND SUNSET. 
 
LOW PRES NEAR 15N102.5W 1009 MB LIES UNDER AN UPPER RIDGE WITH 
UPPER DIFFLUENCE ENHANCING LATE AFTERNOON CONVECTION WITHIN 150 
NM OVER THE W SEMICIRCLE. THIS CONVECTION HAS ALMOST COMPLETELY 
DISSIPATED SINCE SUNSET. ANOTHER SURFACE LOW TO THE E HAS LOST 
IDENTITY AND IS DROPPED FROM THE 0000 UTC ANALYSIS.

...ITCZ...

ITCZ AXIS IS CENTERED ALONG 9N85W 10N99W 7N110W 9N136W 7N140W. 
SCATTERED MODERATE ISOLATED STRONG CONVECTION WITHIN 90 NM 
EITHER SIDE OF LINE 4N77W 7N90W 7N118W. 

...DISCUSSION...

AN UPPER CYCLONE OVER THE NW CONUS NEAR 46N120W TRAILS A 
SHORTWAVE TROUGH INTO THE DISCUSSION AREA FROM 32N119W TO A BASE 
AT 21N131W. AN UPPER ANTICYCLONE IS CENTERED AT 24.5N102W WITH A 
RIDGE EXTENDING W TO CREST NEAR 21N125W. ITS ENVELOPE OF UPPER 
ANTICYCLONIC FLOW DOMINATES THE DISCUSSION AREA N OF 10N BETWEEN 
92W AND 112W. AN INVERTED UPPER TROUGH LIES ALONG 16N125W 2N138W 
AND IS SHIFTING W WITH TIME. 

DRY UPPER AIR IS INDICATED OVER THE DISCUSSION AREA NW OF LINE 
10N137W 20N126W 30N114W.

A LARGE UPPER ANTICYCLONE IS OVER S AMERICA NEAR 11S63W WITH A 
RIDGE EXTENDING NW ACROSS THE EQUATOR AT 71W WITH ITS CREST 
MERGING WITH THE NE FLOW ASSOCIATED WITH THE MEXICAN 
ANTICYCLONE.

ELSEWHERE AT THE SURFACE A RIDGE EXTENDS ALONG 32N138W 17N118W. 

$$
NELSON