000
AXPZ20 KNHC 202151
TWDEP 

TROPICAL WEATHER DISCUSSION
NWS NATIONAL HURRICANE CENTER MIAMI FL
2205 UTC MON AUG 20 2012

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 1800 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 
2100 UTC.

...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH...
MONSOON TROUGH AXIS FROM 08N83W TO 07N89W TO 16N102W TO 07N122W. 
ITCZ EXTENDS FROM LOW PRES 1012 MB AT 13N12W TO 11N133W TO 
BEYOND 10N140W.  SCATTERED MODERATE CONVECTION S OF AXIS TO 04N 
E OF 90W.  SCATTERED MODERATE ISOLATED STRONG CONVECTION WITHIN 
120 NM OF AXIS FROM 97W TO 106W.  ISOLATED MODERATE CONVECTION 
WITHIN 90 NM S OF AXIS FROM 113W TO 120W.

...DISCUSSION...
BROAD UPPER LEVEL ANTICYCLONE OVER SW ARIZONA BRINGS ABUNDANT 
MOISTURE INTO E PAC N OF 15N E OF 118W.  SURFACE LOW PRES 1010 
MB...REMNANTS OF HECTOR...TOO WEAK TO TAKE ADVANTAGE DUE TO THE 
STABILIZING EFFECT OF COOLER SEA TEMPERATURES.  A SECOND SURFACE 
LOW PRES 1010 MB AT 19N108W DOES PROMPT SCATTERED MODERATE TO 
STRONG CONVECTION BUT IS UNDER MODERATE EASTERLY WIND SHEAR AND 
LOSING A BATTLE TO STAY OVER WARM WATERS AS IT DRIFT FURTHER W. 
UPPER LEVEL CYCLONE OVER BELIZE CONTRIBUTES MORE MOIST AIR MASS 
UNTO E PAC FROM 10N-15N E OF 110W...JUST ALONG MONSOON TROUGH 
AXIS WITH SCATTERED MODERATE ISOLATED STRONG CONVECTION WITHIN 
120 NM OF TROUGH AXIS.  ELSEWHERE...BASIN REMAINS VERY DRY W OF 
125W AND N OF 10N W OF 118W.  MODEL GUIDANCE CHANGE VERY LITTLE 
IN THIS SCENARIO THROUGH THE NEXT TWO DAYS.  

...ELSEWHERE AT THE LOWER LEVELS...
HIGH PRES CENTER 1022 MB AT 30N143W HAS RIDGE EXTEND SE TO 
18N118W.  BOTH THE AFOREMENTIONED SURFACE LOW PRES CENTERS AND A 
THIRD ONE EMBEDDED IN ITCZ AT 13N128W AT ALL ARE EXPECTED TO 
DISSIPATE WITHIN NEXT TWO DAYS LEAVING BASIN WITH NO SIGNIFICANT 
FEATURES FOR NEXT DAY OR SO.   

STRONG SE WINDS OVER S PAC PROMPT CROSS EQUATORIAL SWELLS 8-9 FT 
PROPAGATING N AND W INTO E PAC S OF 06N W OF 96W.  

$$
WALLY BARNES