000
AXPZ20 KNHC 151616
TWDEP 

TROPICAL WEATHER DISCUSSION 
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
1605 UTC THU JAN 15 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 05N77W TO 07N86W TO 05N100W TO 07N120W TO 09N136W.  
SCATTERED MODERATE CONVECTION WITHIN 30 NM N OF AXIS E OF 88W.

...DISCUSSION...
NARROW LARGE AMPLITUDE UPPER LEVEL TROUGH ALONG 137W SUPPORTS 
STRONG COLD FRONT ABOUT TO CROSS 140W INTO E PAC.  WELL ANCHORED 
MID-UPPER LEVEL RIDGE AXIS ALONG 126W HOLDS TO ITS POSITION 
SHIFTING TROUGH AND ATTENDANT COLD FRONT NE.  MODERATE DIFFLUENT 
WIND FLOW ALOFT BETWEEN THESE TWO FEATURES PRODUCING SCATTERED 
CONVECTION ALONG WEAK SURFACE TROUGH BETWEEN 135W-140W.  

ELSEWHERE AT THE SURFACE...
GULF OF TEHUANTEPEC EXISTING GALE EXPECTED TO INTENSIFY TO STORM 
WITHIN 24 HRS AS SECOND SURGE OF COLD AIR MASS CROSSES THE 
ISTHMUS FROM GULF OF MEXICO.  EVENT EXPECTED TO LAST BEYOND END 
OF FORECAST PERIOD. 

GULF OF PAPAGAYO NE WINDS EXPECTED TO INCREASE TO JUST BELOW 
GALE FORCE FRI AS ARCTIC AIR MASS ENTERS NW CARIBBEAN.  POSSIBLE 
OCCASIONAL GUST TO GALE FORCE COULD OCCUR AS DEEPENING LOW PRES 
OVER COLOMBIA IS ENHANCING NE TRADE WINDS OVER SW CARIBBEAN.  

LARGE LONG PERIOD...16-20 SECONDS...NW SWELLS ENTERING E PAC 
FROM LOW PRES 980 MB WELL N OF FORECAST WATERS.  S WINDS 
ASSOCIATED WITH ATTENDANT COLD FRONT AFFECT EXTREME NW CORNER OF 
BASIN...BUT SWELL REACH N OF 08N W OF 130W BY END OF FORECAST 
PERIOD.  

WEAK SURFACE TROUGH FROM 130W-135W S OF 15N PRODUCING SCATTERED 
CONVECTION AND MODERATE NE TRADES AS UPPER LEVEL DIFFLUENCE 
ENHANCES CONVECTION.  

$$
WALLY BARNES