000
AXPZ20 KNHC 282211
TWDEP 

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
2205 UTC THU OCT 28 2010

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

BASED ON 1800 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY
THROUGH 2100 UTC.

...ITCZ...
AXIS FROM 10N85W TO 10N91W TO 09N99W TO LOW PRES 1012 MB AT 
14N121W TO 09N135W TO 09N140W.  SCATTERED MODERATE CONVECTION 
WITHIN 150 NM OF AXIS E OF 100W.  ISOLATED MODERATE WITHIN
90 NM OF AXIS W OF 100W.

...DISCUSSION...
LARGE AMPLITUDE UPPER LEVEL TROUGH EXTEND FROM 32N134W TO 
23N140W IN LINE WITH SURFACE COLD FRONT.  FLOW ALOFT ADVECTS 
PLENTY OF MOISTURE INTO BASIN WITH SCATTERED SHOWERS FAR NW 
CORNER OF FORECAST AREA BEHIND FRONT.  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.

SURFACE LOW PRES 1012 MB EMBEDDED IN ITCZ NEAR 14N121W DRIFT W. 
SCATTERED MODERATE CONVECTION ON W SIDE OF LOW PRES SKEWED INTO 
ITS SW QUADRANT JUST N OF ITCZ.  MODEL GUIDANCE AGREES ON FRESH 
BREEZE ON SOUTHEASTERN SIDE OF CENTER WORKING ITS WAY N BY SAT 
AS SURFACE HIGH PRES 1018 MB AT 27N124W FORCED S BY APPROACHING 
COLD FRONT SQUEEZES PRES GRADIENT THROUGH SAT. 

MODEL GUIDANCE ALSO SPRINGS WEAK LOW PRES OFF W COAST OF COSTA 
RICA WITH FAVORABLE UPPER LEVEL CONDITIONS...BUT COMPLEXITY OF 
SURFACE PATTERN INDICATES POSSIBLE DELAY IN FORMATION. 

GAP WINDS...
FRESH N BREEZE ACROSS GULF OF TEHUANTEPEC MARK THE 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