000
AXPZ20 KNHC 301550
TWDEP 

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
1605 UTC SAT OCT 30 2010

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 1545 UTC.

...ITCZ...

THE INTERTROPICAL CONVERGENCE ZONE WAS ANALYZED FROM 10N81W TO 
08N90W TO 11N108W THROUGH EMBEDDED CYCLONIC SWIRLS AT 11N113W 
AND 11N118W BOTH ESTIMATED AT 1011 MB. THE ITCZ CONTINUES W TO 
11N127W TO 08N140W. SCATTERED MODERATE ISOLATED STRONG 
CONVECTION IS NOTED WITHIN 60 NM EITHER SIDE OF A LINE FROM 
05N77W TO 09N85W AND ALSO WITH THE AREA FROM 07N TO 14N BETWEEN 
92W AND 116W.

...DISCUSSION...

AN UPPER TROUGH DOMINATES THE NW PORTION WITH ITS MEAN AXIS 
ENTERING THE AREA AT 32N124W AND EXTENDING SW TO AN EMBEDDED 
UPPER CYCLONE AT 26N137W...WITH THE TROUGH THEN CONTINUING S 
BECOMING SLIGHTLY NEGATIVE TILT TO A BASE OVER THE ITCZ AT 
10N135W. UPPER MOISTURE IS ROTATING CYCLONICALLY THROUGH THE  
UPPER TROUGH OVER THE DISCUSSION AREA N OF 30N WITH ONLY FAINT 
EVIDENCE OF THE MOISTURE REACHING THE UPPER LEVELS OVER EXTREME 
SOUTHERN CALIFORNIA AT THE MOMENT. THE UPPER LEVELS APPEAR DRY 
ELSEWHERE W OF A LINE FROM 30N120W TO 15N135W. AN ASSOCIATED 
SURFACE COLD FRONT EXTENDS FROM 32N116W TO 24N125W THEN BEGINS 
TO WASH OUT TO NEAR 24N140W. SURFACE WINDS HAVE DIMINISHED BELOW 
20 KT EITHER SIDE OF THE SURFACE FRONT...BUT SEAS OF 8 TO 12 
FT...PRIMARILY IN NW SWELL...ARE REPORTED FROM THE NORTHERN BAJA 
CALIFORNIA PENINSULA TO 15N140W. THESE NW SWELLS EXPECTED TO 
CONTINUE TO SPREAD SE ACROSS THE AREA. 

AN UPPER ANTICYCLONE IS NOTED OVER THE TROPICAL PACIFIC AT 
10N128W WITH A RIDGE AMPLIFYING N TO NEAR 27N110W. A BROAD LOW 
LEVEL TROUGH EXTENDS ROUGHLY FROM 11N131W TO 20N122W. A FEW 
CONVECTIVE CLUSTERS WERE ENHANCED EARLIER WITHIN 180 NM OF 
13N125W. THE DEBRIS MOISTURE IS SPREADING N ALONG THE W 
PERIPHERY OF THE UPPER RIDGE ROUGHLY ALONG 16N127W TO 26N122W 
WITH THE MOISTURE PLUME BECOMING VERY NARROW AS IT CONTINUES N 
ACROSS S CENTRAL ARIZONA. 

AN UPPER CYCLONE IS OBSERVED OVER OLD MEXICO AT 25N105W WITH 
VERY DRY UPPER AIR INDICATED FROM 17N TO 30N BETWEEN 100W AND 
115W.

A UPPER CYCLONE IS NEAR 12N120W WITH A TROUGH EXTENDING S TO 
ANOTHER CYCLONE OVER THE EQUATOR AT 114W. AN UPPER LEVEL 
ANTICYCLONE IS CENTERED OVER THE NW GULF OF MEXICO NEAR 27N93W 
WITH AN UPPER RIDGE EXTENDING SW TO A CREST OVER THE TROPICAL 
PACIFIC AT 13N114W. ITS ENVELOPE OF ANTICYCLONIC FLOW EXTENDS S 
OVER THE PACIFIC N OF 12N BETWEEN 94W AND 117W. CONVECTION IS 
ENHANCED OVER THE PACIFIC FROM 07N TO 14N BETWEEN 92W AND 116W 
WITH THE MOISTURE SPREADING N TO ALONG 17N WHERE IT EVAPORATES. 

AN UPPER TROUGH EXTENDS SW ACROSS THE NW CARIBBEAN AND ACROSS 
CENTRAL AMERICA INTO THE PACIFIC NEAR 10N92W. A TROPICAL RIDGE 
EXTENDS W ACROSS NORTHERN COLOMBIA TO A CREST NEAR 10N86W. 
CONVECTION IS ENHANCED ALONG THE COASTS OF COLOMBIA...PANAMA AND 
COSTA RICA.

ELSEWHERE AT THE SURFACE...SOUTHERLY WINDS AT 15 TO 20 KT IN THE 
FAR NORTHERN GULF OF CALIFORNIA SHOULD DIMINISH BELOW 20 KT THIS 
AFTERNOON. THE PRES GRADIENT WILL TIGHTEN BETWEEN A BUILDING 
RIDGE OVER THE SUBTROPICAL PACIFIC AND A THERMAL TROUGH OVER NW 
OLD MEXICO AND SOUTHERN CALIFORNIA RESULTING IN NW WINDS OF 15 
TO 20 KT IN THE GULF OF CALIFORNIA BEGINNING LATE SUN.

GAP WINDS...
MINIMAL GALE FORCE NORTHERLY WINDS IN AND DOWNSTREAM OF THE GULF 
OF TEHUANTEPEC SHOULD DIMINISH BELOW GALE FORCE THIS AFTERNOON 
AND FURTHER DIMINISH BELOW 20 KT AFTER SUNRISE MON. EASTERLY 
WINDS AT 15 TO 20 KT ARE SURGING ACROSS THE GULF OF PAPAGAYO 
AND EXPECTED TO PERSIST THROUGH SUNRISE SUN THEN DIMINISH.

$$
NELSON