000
AXPZ20 KNHC 200400
TWDEP 

TROPICAL WEATHER DISCUSSION    
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
0405 UTC WED JAN 20 2010

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...
AXIS ALONG 00N80W TO 06N88W TO 04N101W TO 09N120W TO 06N140W. 
SCATTERED MODERATE CONVECTION WITHIN 60 NM N AND 90 NM S OF 
AXIS W OF 110W.

...DISCUSSION...
LONG WAVE DEEP LAYER TROUGH WITH AXIS FROM GUATEMALA TO SMALL 
UPPER LEVEL CYCLONE AT 01N121W HAS VERY DRY AIR MASS CONVERGING 
ALONG AND WITHIN 10-12 DEG W OF ITS AXIS KEEPING LARGE REGION OF 
BASIN UNDER LOW LEVEL STRATIFIED CLOUDS.  DRYNESS EXTEND SE OF 
AXIS WITH MODERATE TO STRONG SUBSIDENCE TO CURTAIL CONVECTION 
EVEN ALONG ITCZ E OF 105W AND WEAK SURFACE TROUGH ALONG 93W. 

VERY LARGE UPSTREAM RIDGE CENTERED WITH ANTICYCLONE AT 14N155W 
MOVING E BRINGS EVEN DRIER STABLE AIR MASS INTO E PAC JUST N OF 
ITCZ W OF ABOVE TROUGH.  DEEP LAYER CYCLONE WELL N OF REGION 
PACKS 200 KT JETSTREAM MOVING JUST N OF RIDGE INTO NW CORNER OF 
E PAC ALONG WITH ASSOCIATED COLD FRONT AS DISCUSSED BELOW.   

ELSEWHERE AT THE SURFACE...
HIGH PRES CENTER 1015 MB AT 21N115W FORCED E BY APPROACHING COLD 
FRONT EXTENDING FROM 31N116W TO 25N130W.  TRADE WINDS W OF 130W 
FROM 08N-14N DIMINISH AS RIDGE PULLS AWAY AND PRES GRADIENT 
RELAXES.  GALE FORCE WINDS E OF COLD FRONT DIMINISH AS MAIN 
ENERGY SOURCE PULLS NE OF AREA ALTHOUGH NEAR GALE WINDS REMAIN W 
OF BOUNDARY FOR ANOTHER 12-24 HRS.  SECOND AND MUCH STRONGER 
COLD FRONT ASSOCIATED WITH GOOD UPPER LEVEL TROUGH SUPPORT MOVES 
INTO BASIN WITHIN 6 HRS WITH GALE FORCE WINDS BEHIND FRONT AND 
SWEEPS THROUGH E PAC N OF 25N THROUGH THU... PRODUCING 
ADDITIONAL GALE FORCE WINDS E OF FRONTAL BOUNDARY LATE THU.  

STRONG E WINDS CONTINUE THROUGH GULF OF PAPAGAYO EXPECTED TO 
DIMINISH BELOW 20 KT BY THU.

MODERATE TO STRONG N WIND ACROSS GULF OF PANAMA DIMINISH BELOW 
20 KT LATE WED.

FOR ADDITIONAL INFORMATION PLEASE VISIT 
HTTP://WWW.HURRICANES.GOV/MARINE

$$
WALLY BARNES