000
AXPZ20 KNHC 280301
TWDEP 

TROPICAL WEATHER DISCUSSION
NWS NATIONAL HURRICANE CENTER MIAMI FL
0405 UTC FRI OCT 28 2011

TROPICAL WEATHER DISCUSSION FOR THE EASTERN PACIFIC OCEAN FROM 
THE EQUATOR TO 32N...EAST OF 140W. THE FOLLOWING INFORMATION IS 
BASED ON SATELLITE IMAGERY...WEATHER OBSERVATIONS...RADAR...AND 
METEOROLOGICAL ANALYSIS.

BASED ON 0000 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 
0230 UTC.

...ITCZ/MONSOON TROUGH...

THE MONSOON TROUGH EXTENDS E TO W FROM 10N80W TO 08N97W TO  
12N126W WHERE LOW LEVEL WINDS INDICATE THE ITCZ AXIS BEGINS AND 
CONTINUES W TO BEYOND 14N140W. A FEW SMALL CLUSTERS OF TSTMS 
WILL CONTINUE TO FLARE FOR THE NEXT FEW ALONG THE PACIFIC COASTS 
OF PANAMA AND COSTA RICA AND NICARAGUA. SCATTERED MODERATE 
ISOLATED STRONG CONVECTION IS WEAKENING WITHIN 60 NM EITHER SIDE 
OF A LINE FROM 09N112W TO 09N133W AND ALSO WITHIN 45 NM OF 
13N128W...AND WITHIN 15 NM OF 19N133W.

...DISCUSSION...

UPPER CYCLONES HAVE CUT OFF NEAR 26N136W AND 19N133W WITH AN 
UPPER TROUGH EXTENDING S TO BASE OVER THE DEEP TROPICAL PACIFIC 
AT 07N130W. AN UPPER ANTICYCLONE IS OVER THE E PACIFIC NEAR 
18N107W WITH AN UPPER RIDGE EXTENDING SW TO A CREST AT 13N118W
AND A RIDGE IS ALSO AMPLIFYING NW TO A CREST NEAR 31N128W.
UPPER DIFFLUENCE E OF THIS UPPER TROUGH AXIS IS ENHANCING 
CONVECTION ALONG THE ITCZ AND ALONG THE W EXTENSION OF THE 
MONSOON TROUGH AS PREVIOUSLY DESCRIBED. THE DEBRIS MOISTURE IS 
ADVECTED NE ALONG THE NW PERIPHERY OF THE RIDGE...ROUGHLY WITHIN 
480 NM EITHER SIDE OF A LINE FROM 09N128W TO 27N121W. VERY DRY 
UPPER AIR IS SPREADING SE THROUGH THE UPPER TROUGH ACROSS 
SOUTHERN CALIFORNIA AND THE N PORTIONS OF THE BAJA CALIFORNIA 
PENINSULA. DRY UPPER AIR IS ALSO NOTED OVER THE ENTIRE AREA TO 
THE S OF 23N E OF 112W.

ELSEWHERE AT THE SURFACE...A RIDGE EXTENDS FROM 33N140W TO 
19N112W. NW WINDS AT 15 TO 20 KT ARE EXPECTED TO CONTINUE OVER 
THE GULF OF CALIFORNIA THROUGH LATE SAT THEN DIMINISH SOME SAT 
EVENING.  
 
GAP WINDS...A STRONG COLD FRONT WILL MOVE THROUGH THE SW GULF OF 
MEXICO ON FRI RESULTING IN A STRONG SURGE OF NORTHERLY WINDS TO 
FUNNEL THROUGH THE CHIVELA PASS AT 20 TO 25 KT LATE FRI 
AFTERNOON. THESE WINDS WILL RAPIDLY INCREASE TO GALE FORCE LATE 
FRI NIGHT AND CONTINUE THROUGH MID DAY SAT BEFORE DIMINISHING 
BELOW GALE FORCE LATE SUN AFTERNOON.

$$
NELSON