000
AXPZ20 KNHC 210245
TWDEP 

TROPICAL WEATHER DISCUSSION 
NWS NATIONAL HURRICANE CENTER MIAMI FL
0405 UTC WED AUG 21 2013

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.
                                    
...SPECIAL FEATURES...

1007 MB LOW PRES IS EMBEDDED IN THE MONSOON TROUGH AND IS 
CENTERED NEAR 14.5N110W. SCATTERED MODERATE CONVECTION IS WITHIN 
120 NM IN THE NW QUADRANT OF THE LOW. THE MAJORITY OF THE MODEL 
GUIDANCE TAKES THE LOW IN A NORTHWARD MOTION DURING THE NEXT 24 
TO 48 HOURS. AT THE VERY LEAST...ASSOCIATED WINDS ARE FORECAST 
TO INCREASE TO 20 TO 25 KT WITH RESULTANT SEAS OF 8 TO 10 FT 
THROUGH TONIGHT...GRADUALLY INCREASING TO 30 KT AND 12 FT 
THROUGH THU. THIS LOW HAS THE POTENTIAL TO BECOME A TROPICAL 
CYCLONE DURING THE NEXT 48 HOURS.

...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH...          

THE MONSOON TROUGH EXTENDS FROM 08N79W TO LOW PRES NEAR 14.5110W 
TO LOW PRES NEAR 16N123W TO 11N140W. NO ITCZ AXIS IS PRESENT. 
SCATTERED MODERATE TO STRONG CONVECTION IS WITHIN 180 NM S OF 
THE MONSOON TROUGH BETWEEN 101W AND 109W. SCATTERED MODERATE 
WITHIN 120 NM N OF THE MONSOON TROUGH BETWEEN 113W AND 118W... 
BETWEEN 119W AND 125W...WITHIN 180 NM S OF THE MONSOON TROUGH 
BETWEEN 112W AND 119W...AND WITHIN 120 NM EITHER SIDE OF THE 
MONSOON TROUGH BETWEEN 127W AND 133W.

...DISCUSSION...

A LARGE AND BROAD UPPER LEVEL ANTICYCLONIC CIRCULATION IS OVER 
THE NW PORTION OF THE DISCUSSION WATERS CENTERED OVER 21N138W. 
VERY DRY AND STABLE AIR IS NOTED ACROSS THE MAJORITY OF THE 
WATERS N OF 14N W OF 128W. 

THIS DRY AIR CONTINUES EASTWARD ACROSS THE WATERS N OF 20N 
BETWEEN 120W AND 128W UNDER AN UPPER TROUGH WHICH EXTENDS FROM 
32N123W TO 22N124W TO 17N127W. THIS TROUGH IS CONTRIBUTING TO 
THE NORTHWARD ADVECTION OF CONVECTIVE DEBRIS FROM ALONG THE 
MONSOON TROUGH E OF 120W TOWARD BAJA CALIFORNIA AND NW MEXICO.

THE UPPER TROUGH IS ALSO BRINGING STRONG SW SHEAR OVER THE 
WESTERN SURFACE LOW WHICH IS EMBEDDED IN THE MONSOON TROUGH NEAR 
14.5N120W AT 1008 MB. WINDS ON THE S SIDE OF THE LOW ARE 
FORECAST TO GRADUALLY INCREASE TO 20 TO 25 KT WITH SEAS BUILDING 
TO 8 TO 10 FT THROUGH WED...HOLDING STEADY THROUGH THU WITH 
LIMITED MOVEMENT OF THE LOW.

1024 MB SURFACE HIGH PRES IS CENTERED WELL N OF THE AREA NEAR 
42N135W WITH A RIDGE AXIS EXTENDING SOUTHWARD THROUGH 33N142W 
THEN SE TO NEAR 24N123W. A MAINLY LOOSE PRES GRADIENT EXTENDS 
ACROSS THE MAJORITY OF THE WATERS WITH LIGHT TO MODERATE WINDS 
AT THE SURFACE...EXCEPT FOR MODERATE TO FRESH SW FLOW S OF THE 
MONSOON TROUGH.
 
$$
LEWITSKY