000
AXPZ20 KNHC 310236
TWDEP 

TROPICAL WEATHER DISCUSSION
NWS NATIONAL HURRICANE CENTER MIAMI FL
0405 UTC WED AUG 31 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 
0300 UTC.

...SPECIAL FEATURES...
A BROAD AREA OF LOW PRESSURE...ANALYZED 1004 MB NEAR 16.5N102W 
ON THE 0000 UTC SURFACE MAP...IS PRODUCING NUMEROUS SHOWERS AND 
THUNDERSTORMS ALONG THE SOUTHWEST COAST OF MEXICO AND THE 
ADJACENT WATERS. THIS DISTURBANCE HAS THE POTENTIAL TO BECOME A 
TROPICAL DEPRESSION AS IT MOVES SLOWLY TOWARD THE WEST-NORTHWEST 
HUGGING THE SOUTHWEST COAST OF MEXICO DURING THE NEXT 48 HOURS. 
LOCALLY HEAVY RAINS ARE POSSIBLE OVER COASTAL SECTIONS OF THE 
MEXICAN STATES OF GUERRERO...MICHOACAN...AND COLIMA THROUGH 
THURSDAY IN ASSOCIATION WITH THIS SYSTEM. CURRENTLY...NUMEROUS 
MODERATE TO ISOLATED STRONG CONVECTION IS OCCURRING N OF 17N 
BETWEEN 102W AND 105W. SCATTERED MODERATE CONVECTION IS N OF 16N 
BETWEEN 99W AND 102W. 

...ITCZ/MONSOON TROUGH...
THE MONSOON TROUGH IS ALONG 10N86W TO THE DEVELOPING 1004 MB 
SURFACE LOW AT 17N102W TO 14N115W TO 16N125W TO 11N140W. 
CONVECTION ASSOCIATED WITH LOW PRES IS DESCRIBED IN THE SPECIAL 
FEATURES. SCATTERED MODERATE CONVECTION FROM 09N TO 12N BETWEEN 
121W AND 129W. SIMILAR CONVECTION IS NE OF LINE FROM 14N93W TO 
16N95W. 

...DISCUSSION...
AN UPPER-LEVEL ANTICYCLONE CENTERED OVER WEST TEXAS HAS A RIDGE 
EXTENDING SW ACROSS THE NORTHERN BAJA CALIFORNIA PENINSULA TO 
NEAR 20N124W. S OF THIS RIDGE THERE IS A TROUGH STRETCHING FROM 
NE MEXICO TO AN UPPER LEVEL CYCLONE AT 22N109W. ANOTHER 
ANTICYCLONIC CIRCULATION IS NOTED NEAR 17N 134W WITH A RIDGE 
EXTENDING NW TO BEYOND 32N144W. STRONG SUBSIDENCE ACCOMPANIES 
THIS SYSTEM AS EVIDENT IN RECENT WATER VAPOR IMAGERY. AN UPPER 
LEVEL ANTICYCLONE IS OVER THE NW CARIBBEAN AND YUCATAN PENINSULA 
RESULTING IN NORTHEASTERLY UPPER LEVEL FLOW DOMINATING MOST OF 
TROPICS E OF 115W.

AT THE SURFACE...A RIDGE DOMINATES THE NW CORNER OF THE FORECAST 
AREA. N TO NE WINDS OF 20 KT ARE ASSOCIATED WITH THIS RIDGE 
COVERING THE AREA N OF 27N BETWEEN 122W AND 132W. THESE WINDS 
WERE INDICATED BY AN EARLIER ASCAT PASS.

LONG-PERIOD CROSS EQUATORIAL SOUTHWESTERLY SWELLS...WAVE PERIODS 
BETWEEN 20 AND 22 SECONDS...DOMINATE MOST OF THE REGIONAL WATERS 
RAISING SEAS TO 11 FT MAINLY S OF 10N BETWEEN 100W AND 130W. 
THIS SWELL EVENT IS FORECAST TO REACH THE COAST OF MEXICO... 
INCLUDING BAJA CALIFORNIA THIS WED. 

$$
GR