000
AXPZ20 KNHC 172151
TWDEP 

TROPICAL WEATHER DISCUSSION     
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
2205 UTC SUN DEC 17 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 1800 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 
2145 UTC.

...ITCZ...

THE ITCZ AXIS IS CENTERED ALONG 7N78W 6N90W 7N100W 7N120W 
6N140W. SCATTERED MODERATE ISOLATED STRONG FROM 4N TO 8N WEST OF 
123W.

...DISCUSSION...
AN UPPER LEVEL TROUGH EXTENDS OVER THE NW PORTION OF THE AREA. A 
100-130 KT JET STREAM IS JUST AHEAD OF THE TROUGH ALONG 25N126W 
30N120W...ENTERING THE SW U.S. THROUGH SOUTHERN CALIFORNIA. 
MID/UPPER LEVEL TROUGH EXTENDS FROM W-CENTRAL MEXICO SWWD INTO 
THE PACIFIC NEAR 10N105W. A SUBTROPICAL JETSTREAM IS NOTED E OF 
THE TROUGH FROM 8N105W TO THE MEXICAN COAST NEAR 18N100W THEN 
EWD INTO THE GULF OF MEXICO...WITH WINDS TO NEAR 60 KT. THESE 
WINDS ARE ADVECTING ABUNDANT UPPER LEVEL MOISTURE THROUGH 
SOUTH-CENTRAL MEXICO INTO THE GULF OF MEXICO. MODERATE TO STRONG 
SUBSIDENCE WITH DRY AIR AT THE MID/UPPER LEVELS OF THE 
ATMOSPHERE IS OVER THE NW PORTION OF THE AREA AND ACROSS 
NORTHERN MEXICO. IN BETWEEN THESE TROUGHS THERE IS A RIDGE. 
ANOTHER UPPER LEVEL RIDGE COVERS THE E PACIFIC E OF 100W... 
SUPPRESSING CONVECTION ALONG THE ITCZ IN THIS REGION.  

AT THE SURFACE...
A 1033 MB SFC HIGH PRES IS CENTERED NEAR 34N138W RIDGING SE TO 
NEAR 23N113W. A DYING COLD FRONT ENTERS THE AREA NEAR 30N112W 
AND EXTENDS SW AND W ALONG 23N120W 19N130W 18N140W. A NARROW 
BAND OF MAINLY LOW CLOUDS IS ASSOCIATED WITH THE FRONT. BROKEN 
COLD AIR STRATOCUMULUS CLOUDS ARE JUST BEHIND THE FRONTAL 
BOUNDARY COVERING THE NW CORNER OF THE DISCUSSION AREA. A 1010 
MB SFC LOW PRES IS ALONG THE ITCZ NEAR 7N118W. ISOLATED MODERATE 
CONVECTION IS RELATED TO THIS LOW WHICH IS MOVING WWD AT 10-15 
KT. A SFC TROUGH EXTENDS FROM 14N103W TO 5N106W GENERATING 
SCATTERED SHOWERS AND ISOLATED TSTMS FROM 8N-13N BETWEEN 100W 
AND 105W.

GAP WINDS...NLY WIND TO 20 KT PRESENTLY IN GULF OF TEHUANTEPEC 
EXPECTED TO LAST FOR ABOUT 36 HOURS. ENE WINDS TO 20 KT IN THE 
GULF OF PAPAGAYO EXPECTED TO SPREAD W AND INCREASE TO 20 TO 25 
KT MON THEN BEGIN TO WEAKEN TUE.

$$
GR