000
AXPZ20 KNHC 290257
TWDEP 

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
0405 UTC FRI OCT 29 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 FROM 11N86W TO 08N100W TO LOW PRES 1012 MB AT 14N121W TO 
09N134W TO 09N140W.  SCATTERED MODERATE WITHIN 150 NM OF AXIS E 
OF 95W AND FROM 124W TO 135W.  ISOLATED MODERATE WITHIN 90 NM OF 
AXIS FROM 95W TO 115W. 

...DISCUSSION...
LARGE AMPLITUDE UPPER LEVEL TROUGH EXTEND FROM 32N133W TO 
22N140W IN LINE WITH SURFACE COLD FRONT.  FLOW ALOFT ADVECTS 
PLENTY OF MOISTURE RIDING ON 115 KT JET CORE INTO BASIN WITH 
SCATTERED SHOWERS FAR NW CORNER OF FORECAST AREA BEHIND FRONT.  
ONLY FRESH BREEZE BEHIND FRONT...BUT NW SWELL CURRENTLY TO 12 FT 
SPREAD SE QUICKLY.  FRONT WEAKENS AS ITS SUPPORTING UPPER LEVEL 
TROUGH SHIFT NE WITH WINDS DIMINISHING TO MODERATE OR LESS.  
FRONT DISSIPATES BY SAT.

SURFACE LOW PRES 1010 MB EMBEDDED IN ITCZ NEAR 14N121W DRIFT W. 
SCATTERED MODERATE CONVECTION ON N SIDE OF LOW PRES WITH FRESH 
TO STRONG NE BREEZE SQUEEZED BETWEEN LOW PRES AND SURFACE HIGH 
PRES 1018 MB AT 26N123W FORCED S BY APPROACHING COLD FRONT 
TIGHTENING PRES GRADIENT THROUGH SAT. 

MODEL GUIDANCE ALSO SPRINGS WEAK LOW PRES OFF W COAST OF COSTA 
RICA WITH FAVORABLE UPPER LEVEL CONDITIONS.  AMOUNT OF MOISTURE 
VORTICITY AND UPPER ENVIRONMENT MAKES THIS SOLUTION POSSIBLE. 

GAP WINDS...
PRESENT FRESH N BREEZE ACROSS GULF OF TEHUANTEPEC MARK ONSET OF 
NEXT GALE FORCE EVENT AS COLD FRONT OVER GULF OF MEXICO FORCE 
WINDS ACROSS CHIVELAS PASS.  WINDS EXPECTED TO INCREASE TO GALE 
FORCE TONIGHT THROUGH END OF PERIOD REACHING AS HIGH AS 40 KT.  
MODEL GUIDANCE HAS KEPT GOOD HANDLE ON EVENT WITH ALL MODELS ON 
BOARD.  MAIN DIFFERENCE IN THEM IS TIME OF ENDING.

$$
WALLY BARNES