000
AXPZ20 KNHC 200417
TWDEP 

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
0405 UTC THU DEC 20 2007

TROPICAL WEATHER DISCUSSION FOR THE EASTERN PACIFIC OCEAN
FROM THE EQUATOR TO 32N...EAST OF 140W. 

BASED ON 0000 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 
0300 UTC.
 
...ITCZ...
INTERTROPICAL CONVERGENCE ZONE ALONG 8N79W 7N88W 8N100W 7N115W 
10N130W 8N140W.  SCATTERED MODERATE WITHIN 120 NM N OF AXIS FROM 
102W-110W.

...DISCUSSION...
MID-LATITUDE UPPER LEVEL RIDGE HAS AXIS ALONG CENTRAL AMERICA 
WITH 125 KT JET CORE RIDING OVER ITS CREST ACROSS ERN TEXAS. 
JTST BRINGS PLENTY OF TRPCL MOISTURE INTO NRN MEXICO AND SRN 
CENTRAL PLAINS IN CONUS...BUT OTHERWISE VERY DRY S OF 24N E OF 
113W.  

MID-UPPER CYCLONIC VORTEX AT 24N130W HAS UPPER LEVEL TROUGH 
EXTEND SE TO SECOND CYCLONE WHIRL AT 4N108W.  DEFORMATION ZONE 
IN MIDST OF TROUGH HAS SUFFICIENT UPPER DIFFLUENCE TO BRING LOW 
LEVEL TRPCL MOISTURE TO HIGHER LEVELS AND FEED SWATH ADVECTING 
NE IN JTST.  MID-UPPER LEVEL RIDGE WITH WEAK 60 KT JET CORE OVER 
ITS CREST N OF 24N JUST WEST OF 140W ALSO BRINGS MOISTURE INTO E 
PAC SCENE BUT WITH LITTLE OR NO UPLIFT MECHANISM SINCE 1026 MB 
SURFACE HIGH PRES RIDGE AT 26N129W DOMINATE ENTIRE E PAC WATERS.

AT THE SURFACE...WELL ANCHORED HIGH PRES CENTER MENTIONED ABOVE 
DIVERTS WEAK FRONTAL TROUGH JUST N OF 30N PREVENTING ANY FURTHER 
SOUTHWARD INTRUSION BUT ALLOWING NW FLOW OVER GULF OF CALIFORNIA 
N OF 25N TO INCREASE FOR SHORT PERIOD OF TIME.  

NE TRADES REMAIN AT CLIMATOLOGICAL MEAN FROM 10N-20N W OF 120W.  
GULF OF TEHUANTEPEC EVENT WINDS DOWN WITHIN 12-24 HRS AS DOES 
GULF OF PAPAGAYO GAP WINDS. 

$$
WALLY BARNES