000
AXPZ20 KNHC 131520
TWDEP 

TROPICAL WEATHER DISCUSSION  
NWS NATIONAL HURRICANE CENTER MIAMI FL
1605 UTC SAT AUG 13 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 1200 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH
1500 UTC.

...SPECIAL FEATURES...

A 1008 MB LOW IS LOCATED NEAR 12N122W 1008 MB. WITHIN 240 NM NW 
AND 90 NM SE SEMICIRCLES OF THE LOW WINDS ARE 20 TO 25 KT WITH 
SEAS 8 TO 10 FT. SCATTERED TO NUMEROUS STRONG CONVECTION IS 
LOCATED WITHIN 120 NM OVER THE W SEMICIRCLE. THE LOW IS FORECAST 
TO TRACK W AND HAS A HIGH CHANCE OF DEVELOPING INTO A TROPICAL 
CYCLONE OVER THE NEXT TWO DAYS.

...ITCZ/MONSOON TROUGH...

MONSOON TROUGH EXTENDS FROM 09N85W TO 12N92W TO 10N108W TO LOW 
PRES 12N122W TO 10N133W. ITCZ AXIS FROM 10N133W TO 09N140W. 
SCATTERED MODERATE TO STRONG CONVECTION IS LOCATED WITHIN 
120-180 NM OF THE MONSOON TROUGH BETWEEN 88W AND 97W AND WITHIN 
120 NM S OF THE AXIS E OF 88W. SCATTERED MODERATE ISOLATED 
STRONG CONVECTION IS LOCATED FROM 06N TO 09N BETWEEN 109W AND 
112W. 

...DISCUSSION...

W OF 105W...
AN UPPER LEVEL ANTICYCLONIC CIRCULATION IS CENTERED IN THE 
VICINITY OF 20N142W WITH A RIDGE AXIS EXTENDING NE THROUGH 
32N125W. MODERATE TO STRONG SOUTHWESTERLY WINDS ALOFT ARE 
LOCATED N OF THE RIDGE N OF 25N W OF 130W WITH SPEEDS ESTIMATED 
AT 50 TO 60 KT. WATER VAPOR IMAGERY INDICATES STRONG SUBSIDENCE 
FROM 13N TO 25N W OF 128W. A MIDDLE/UPPER LEVEL CYCLONIC 
CIRCULATION IS CENTERED NEAR 28N120W WITH A SHARP TROUGH AXIS 
EXTENDING SW TO NEAR 20N128W. MOVING DOWNSTREAM BROAD RIDGING 
ALOFT IS LOCATED N OF 18N E OF 115W INTO MEXICO. A SMALL 
MIDDLE/UPPER LEVEL CYCLONIC CIRCULATION IS CENTERED NEAR 17N118W 
AND IS MOVING NW ABOUT 10 KT. AT THE SURFACE A 1024 MB HIGH IS 
POSITIONED AT 35N135W WITH A RIDGE AXIS EXTENDING SE FROM THE 
HIGH TO NEAR 20N115W. A SURFACE TROUGH IS LOCATED ALONG 136W 
FROM 17N TO 22N.  

E OF 105W...
LIGHT TO MODERATE EASTERLY FLOW ALOFT IS LOCATED FROM THE 
EQUATOR INTO MEXICO BETWEEN 90W AND 105W WITH SATELLITE CLOUD 
DRIFT WINDS INDICATING SPEEDS UP TO 25 KT. FROM 03N TO 08N 
BETWEEN 95W AND 104W S TO SW WINDS ARE 20 KT WITH SEAS 10 FT IN 
SW SWELL. ELSEWHERE S OF 15N E OF 105W WINDS ARE LESS THAN 20 KT 
WITH SEAS 8 TO 11 FT IN SW SWELL.

$$
CAB