000
AXPZ20 KNHC 280329
TWDEP 

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
0405 UTC THU OCT 28 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 09N84W TO 1010 MB LOW PRES AT 10N92W TO 09N102W TO 
13N113W TO 08N130W TO 08N140W. SCATTERED MODERATE CONVECTION 
WITHIN 90 NM OF AXIS E OF 97W.

...DISCUSSION...
LARGE AMPLITUDE DEEP LAYER POSITIVE TILT TROUGH ENTERS 
CROSSES 140W EASTWARD EXTEND FROM 32N139W TO 10N129W AND CONNECT 
TO CYCLONIC VORTEX AT 06N126W.  THIN SWATH OF TROPICAL MOISTURE 
ROUNDS TROUGH BASE AND ADVECTS N ON 55 KT JET CORE BUT TRAPPED 
BETWEEN TWO LARGE AREAS OF DRY SUBSIDING AIR MASSES.  STILL...IT 
MAY REACH FAST MOVING COLD FRONT NOW ENTERING NW CORNER OF BASIN 
AND SUPPLY ENERGY TO ITS BOUNDARY.  

DOWNSTREAM ANTICYCLONIC GYRE AND RIDGE ARE BEING SQUEEZED BY 
ABOVE MENTIONED VORTEX AND ANOTHER TROUGH OVER SOUTHERN GULF OF 
CALIFORNIA.  MAIN FEATURE IN RIDGE IS SMALL AREA OF DIVERGENT 
FLOW ALOFT JUST NE OF SURFACE TROUGH AND EMBEDDED LOW PRES 1010 
MB WHICH SEEM TO ENHANCE CONVECTION W OF TROUGH.  WEAK RIDGE 
OVER ISTHMUS OF TEHUANTEPEC BRINGS TROPICAL MOISTURE FROM SOUTH 
AMERICA ALONG ITCZ AND TO WEAK LOW PRES 1010 MB AT 10N92W.  
SCATTERED MODERATE ISOLATED TSTMS ACTIVE ALONG THAT STRETCH OF 
ITCZ WITH DRY AIR MASS CURTAILING ANY OTHER SIGNIFICANT 
DEVELOPMENT.  

ELSEWHERE AT THE SURFACE...
STRONG PACIFIC COLD FRONT ASSOCIATED WITH DEEP UPPER TROUGH 
EXTENDS FROM 32N135W TO 28N140W MOVE TO ALONG 32N130W TO 26N136W 
TO 25N140W THU WITH FRESH NW BREEZE...FOLLOWED BY NEW TRAIN OF 
LARGE LONG PERIOD NW SWELLS...UP TO 15 FT AS PER LATEST NWW3 
MODEL GUIDANCE.

WEAK LOW PRES AT 11N120W 1010 MB DO NOT SEEM TO BE ABLE TO 
DEVELOP IN SPITE OF UPPER LEVEL DIVERGENT FLOW ENHANCING ITS 
CONVECTION AS WATERS REMAIN COOL AND SURROUNDING ENVIRONMENT 
DRY.  FRESH MONSOONAL SW FLOW BRINGS WARM MOIST AIR TO COASTS OF 
COLOMBIA...PANAMA AND COSTA RICA...BUT EVENTUALLY WEAKENS AS LOW 
PRES WEAKENS AND DRIFTS NW.

GAP WINDS...
ONSET OF NEXT GALE EVENT THROUGH GULF OF TEHUANTEPEC EXPECTED 
THU NIGHT AS N WINDS SURGE ACROSS ISTHMUS FORCED BY COLD FRONT 
ACROSS GULF OF MEXICO.  GALE FORCE N WINDS BEGIN WITHIN 90 NM 
FROM GULF COAST...EXPANDING TO WITHIN 30 NM OF LINE FROM 16N95W 
TO 14N96W BY 48 HOURS WITH SEAS PEAKING AT 13 FT.

$$
WALLY BARNES