000
AXPZ20 KNHC 181554
TWDEP 

TROPICAL WEATHER DISCUSSION     
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
1605 UTC MON DEC 18 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 1200 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 
1545 UTC.

...ITCZ...

THE ITCZ AXIS IS CENTERED ALONG 6N77W 9N109W 7N140W. SCATTERED 
MODERATE ISOLATED STRONG WITHIN 150 NM EITHER SIDE OF LINE 
12N107W 6N120W 6N140W. 

...DISCUSSION...

THE SUBTROPICS IS DOMINATED BY A RIGOROUS SHORTWAVE TROUGH WITH 
ITS AXIS ALONG 32N117W 22N124W TO BASE AT 14N134W. A BAND OF DRY 
UPPER AIR IS INDICATED WITHIN 240 NM EITHER SIDE OF LINE 30N120W 
23N128W 28N138W. JUST W OF THE AREA AN UPPER ANTICYCLONE IS NEAR 
20N150W WITH A RIDGE EXTENDING N TO A SHARP AND UNSTABLE CREST 
AT 29N144W. THIS RIDGE WILL LIKELY SOON COLLAPSE SE INTO THE W 
PORTION OF THE DISCUSSION AREA AS ANOTHER STRONG SHORTWAVE 
CURRENTLY ALONG 150W RACES EASTWARD.     

THE TROPICS IS DOMINATED BY AN UPPER ANTICYCLONE ESTIMATED NEAR 
8N112W WITH A RIDGE EXTENDING W OVER THE ITCZ TO BEYOND 8N142W 
ENHANCING ITCZ CONVECTION. A RIDGE ALSO EXTENDS NE TO A CREST 
NEAR 14N105W AND ENHANCES CONVECTION UNDER THE CREST. THE 
RESULTANT DEBRIS MOISTURE IS ADVECTED NE INTO THE SW FLOW 
ASSOCIATED WITH THE TROUGH TO THE N...WITH THE PLUME CONTINUING 
OVER THE CONUS DESERT SW. TRANSVERSE CLOUDS BANDING...POSSIBLY 
PRODUCING CLEAR AIR TURBULENCE...IS NOTED WITH 60 NM EITHER SIDE 
OF LINE 18N126W 25N110W. 

AN UPPER LEVEL ANTICYCLONE IS OVER GUATEMALA NEAR 15N90W WITH A 
RIDGE EXTENDING SW TO 6N98W. AN UPPER LEVEL CYCLONE IS OBSERVED 
NEAR 6N102W WITH A TROUGH EXTENDING S ACROSS THE EQUATOR AT 
104W. THE UPPER LEVELS ARE DRY OVER THE TROPICS E OF 103W. 

LOW LEVELS...HIGH PRES IS CENTERED NEAR 33N135W 1027 MB RIDGING 
SE TO NEAR 20N108W THROUGH A WEAK FRONTAL TROUGH THAT LIES ALONG 
25N109W 18N130W 17N140W.

GAP WINDS...NLY WIND TO 20 KT PRESENTLY IN GULF OF TEHUANTEPEC 
EXPECTED TO LAST FOR ABOUT 18 HOURS. ENE WINDS TO 20 KT SEAS TO 
8 FT IN THE GULF OF PAPAGAYO EXPECTED TO CONTINUE FOR 48 HOURS.

$$
NELSON