000
AXPZ20 KNHC 260953
TWDEP 

TROPICAL WEATHER DISCUSSION
NWS NATIONAL HURRICANE CENTER MIAMI FL
1005 UTC FRI AUG 26 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 0600 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 
0945 UTC.

...ITCZ/MONSOON TROUGH...
THE MONSOON TROUGH AXIS EXTENDS THROUGH INTERIOR CENTRAL AMERICA 
FROM 10N80W TO 10N92W...THEN CONTINUES W OVER THE PACIFIC INTO A 
1005 MB LOW PRES NEAR 18N112W...THEN THE TROUGH TURNS SW TO 
12N121W TO 14N134W TO 10N140W WHERE LOW LEVEL WINDS SUGGEST THE 
ITCZ BEGINS. SCATTERED MODERATE ISOLATED STRONG CONVECTION IS 
NOTED WITHIN 60 NM EITHER SIDE OF A LINE FROM 06N84W TO 10N87W 
AND ANOTHER LINE EXTENDING FROM 07N96W TO 16N99W...AND A THIRD 
LINE FROM 16N104W TO 10N117W.

...DISCUSSION...
AN UPPER TOUGH DOMINATES THE NE PACIFIC E OF 160W WITH A 
VIGOROUS SHORTWAVE TROUGH MOVING THROUGH THE LONG WAVE PATTERN 
BETWEEN 120W AND 130W. THE SHORT WAVE TROUGH MEAN AXIS EXTENDS 
INTO THE DISCUSSION AREA FROM 32N130W TO A BASE AT 20N136W. 
SOME UPPER MOISTURE IS SWINGING E THROUGH THE TROUGH WITHIN 60 
NM OF LINE FROM 30N132W TO 36N129W. AN UPPER ANTICYCLONE IS OVER 
WESTERN NEW MEXICO WITH AN UPPER RIDGE EXTENDING SW TO 24N125W 
AND IS BLOCKING THE EASTWARD ADVANCE OF THE UPPER TROUGH WHICH 
SHOULD FILL IN ABOUT 24 HOURS. CONVECTION HAS BEEN ENHANCED ALONG
THE SIERRA MADRE OCCIDENTAL...AND IS CURRENTLY SCATTERED 
ISOLATED STRONG WITHIN 30 NM OF MEXICAN COAST FROM 20N TO 24N.
THE DEBRIS MOISTURE IS NOW SPREADING W ACROSS THE GULF OF 
CALIFORNIA AND THE BAJA CALIFORNIA PENINSULA TO OVER THE PACIFIC 
TO THE N OF 20N E OF 119W. IMMEDIATELY TO THE SW...AN UPPER 
ANTICYCLONE CENTERED NEAR THE HAWAIIAN ISLANDS HAS AN UPPER 
RIDGE EXTENDING E TO A SHARP CREST AT 19N130W. DRY UPPER AIR IS 
INDICATED ELSEWHERE N OF 15N W OF 120W. 

AN UPPER TROUGH DISSECTS THE GULF OF MEXICO FROM NE TO SW AND 
CONTINUES SW OVER CENTRAL OLD MEXICO AND THE E PACIFIC THROUGH 
UPPER CYCLONES AT 20N105W AND 18N114W AND 09N123W. ANOTHER UPPER 
CYCLONE IS NOTED NEAR 11N87W. AN UPPER RIDGE...ORIENTATED FROM 
NE TO SW...IS NOTED OVER THE TROPICS...EXTENDING THROUGH UPPER 
ANTICYCLONES AT 17N87W AND 13N107W AND 09N115W. SCATTERED 
MODERATE ISOLATED STRONG CONVECTION IS OBSERVED WITHIN 90 NM OF 
COAST FROM 87W TO 96W. THE UPPER FLOW IS GENERALLY NE OVER THE 
TROPICS TO THE S OF 17N BETWEEN 109W AND 80W...AND IS ADVECTING 
DEBRIS MOISTURE S TO ALONG THE EQUATOR BETWEEN 80W AND 120W.    

AT THE SURFACE...WEAK RIDGING DOMINATES THE SUBTROPICS W OF 
120W. A 1005 MB SURFACE LOW PRES IS AT 18N112W BUT IS SURROUNDED 
BY ONLY 15 KT WINDS WITHIN 180 NM OF CENTER. SCATTERED MODERATE 
ISOLATED STRONG CONVECTION IS CURRENTLY OBSERVED WITHIN 30 NM 
17.5N114W. MONSOONAL SOUTHWESTERLY FLOW CONTINUES OVER THE AREA 
E OF A LINE FROM 05N135W TO 20N105W. SW SURFACE WINDS AT 20-25 
KT ARE OBSERVED WITHIN 240 NM E OF LINE FROM 07N127W TO 15N111W 
WITH SEAS OF 8 TO 12 FT IN SW SWELL. SW WINDS AT 20 KT ARE ALSO 
OBSERVED WITHIN THE AREA FROM 07N TO 10N BETWEEN 86W AND 98W 
WITH SEAS OF 9 TO 11 FT IN SW SWELL. 

$$
NELSON