000
AXPZ20 KNHC 201608
TWDEP 

TROPICAL WEATHER DISCUSSION  
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
1605 UTC TUE JAN 20 2009

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

BASED ON 1200 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 
1515 UTC.

...ITCZ...
AXIS ALONG 03N77W TO 06N90W TO 05N100W TO 07N115W TO 05N135W TO 
05N140W.  ISOLATED MODERATE CONVECTION WITHIN 45 NM OF AXIS FROM 
100W-116W.

...DISCUSSION...
NEGATIVELY TILTED UPPER LEVEL DEEP LAYER TROUGH EXTENDS FROM 
32N128W TO 11N118W WITH VERY DRY AIR MASS W OF AXIS LIFTING NE 
AS BROAD MID-UPPER LEVEL RIDGE BLOCKS FURTHER EASTWARD 
INTRUSION.  RIDGE COVERS REMAINDER OF BASIN E OF TROUGH AXIS 
EXCEPT CONVECTIVE DEBRIS EMANATING FROM ITCZ ENHANCED TSTMS 
CAUSED BY DIFFLUENCE ALOFT BETWEEN RIDGE AND TROUGH.

LOW PRES 1015 MB AT 21N129W AND ASSOCIATED SURFACE TROUGH DRIFT 
NE WITH MODERATE TO STRONG NE WIND ON W SIDE SQUEEZED BY PRES 
GRADIENT.  COLD FRONT EXTENDS FROM 32N124W TO 18N140W.  SWATH OF 
MODERATE TO STRONG NE WINDS WITHIN 120 NM OF FRONTAL BOUNDARY.  

SURGE OF HIGH PRES OVER GULF OF MEXICO BEHIND HEALTHY COLD FRONT 
BRINGS COLD AIR ACROSS ISTHMUS OF TEHUANTEPEC AND SHORT LIVED 
GALE FORCE WINDS EXPECTED WITHIN 18 HRS...BUT GONE WITHIN 48 
HRS.  GULF OF PAPAGAYO STRONG NE WINDS EXPECTED TO CONTINUE 
UNABATED THROUGH FORECAST PERIOD.      

$$
WALLY BARNES