000
AXPZ20 KNHC 260924
TWDEP 

TROPICAL WEATHER DISCUSSION
NWS NATIONAL HURRICANE CENTER MIAMI FL
1005 UTC SUN AUG 26 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 0600 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 
0900 UTC.

...SPECIAL FEATURE...

SURFACE LOW PRESSURE IS ANALYZED ALONG THE MONSOON TROUGH AXIS 
NEAR 12N101W WITH AN ESTIMATED PRESSURE OF 1007 MB...MOVING WEST 
AT 07 KT. SCATTERED MODERATE CONVECTION FROM 120 NM TO 180 NM N 
OF LOW. CONTINUED DEVELOPMENT IS POSSIBLE DURING THE NEXT COUPLE 
OF DAYS AND TROPICAL CYCLONE FORMATION IS POSSIBLE.

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

THE MONSOON TROUGH EXTENDS FROM 09N90W ALONG THE W COAST OF 
CENTRAL AMERICA TO 15N93W TO LOW PRES NEAR 12N101W 1007 MB TO 
13N107W TO 10N114W TO 10N140W. SCATTERED MODERATE ISOLATED 
STRONG CONVECTION FROM 08N TO 10N BETWEEN 89W AND 94W...FROM 09N 
TO 12N BETWEEN 104W AND 111W...AND FROM 09N TO 12N BETWEEN 119W 
AND 129W.

...DISCUSSION...

AN UPPER LEVEL ANTICYCLONE HAS SHIFTED SW OVER THE PAST 24 HOURS 
TO A POSITION W OF THE AREA AT 16N152W WITH A RIDGE NE INTO THE 
AREA CRESTING AT 29N133W. A SECOND UPPER ANTICYCLONE IS OVER THE 
GULF OF CALIFORNIA AT 27N112W WITH A RIDGE W TO A SHARP CREST AT 
25N123W...AND A RIDGE ALSO EXTENDS ENE TO A CREST OVER TEXAS AT 
29N98W. CONVECTION WAS ENHANCED EARLIER UNDER THIS RIDGE ALONG 
AND JUST INLAND THE MEXICAN COAST FROM 20N TO 27N. THE DEBRIS 
MOISTURE HAS FANNED OUT OVER THE AREA FROM 16N TO 28N BETWEEN 
104W AND 113W. 

AN UPPER CYCLONE NEAR 48N133W HAS DRAGGED AN UPPER TROUGH S INTO 
THE DISCUSSION AREA ALONG 32N125W INTO A WELL DEFINED UPPER 
CYCLONE AT 18N129W WHICH IS SHIFTING W WITH TIME. THE UPPER 
TROUGH THEN CONTINUES SW INTO ANOTHER UPPER CYCLONE FILLING NEAR 
14N140W AND IT PROGRESSES WESTWARD. THIS UPPER TROUGH SEPARATES 
THE SUBTROPICAL ANTICYCLONIC FLOW OVER THE W AND E PORTIONS OF 
THE DISCUSSION AREA. THE UPPER LEVELS APPEAR VERY DRY N OF 14N W 
OF 113W.

AN UPPER TROUGH EXTENDS S ALONG THE EASTERN SEABOARD OF THE 
CONUS...THEN DISSECTS THE GULF OF MEXICO THROUGH AN UPPER 
CYCLONE AT 23N88W TO ANOTHER UPPER CYCLONE OVER CENTRAL MEXICO 
AT 19N102W...WITH EVIDENCE OF THE UPPER TROUGH CONTINUING S 
ALONG 102W TO BEYOND THE EQUATOR. SIGNIFICANT CONVECTION 
CONTINUES TO BE ENHANCED OVER LAND AROUND THE CYCLONE AT 19N102W 
WITH SOME OF THE CONVECTION SPREADING OFF THE MEXICAN COAST NEAR 
103W.

THE UPPER LEVELS OF THE DEEP TROPICS TO E OF 100W IS SLIGHTLY 
COMPLEX WITH AN UPPER CYCLONE OVER THE SW CARIBBEAN AT 14N82W 
AND ANOTHER OVER THE PACIFIC AT 07N94W. A SMALL UPPER 
ANTICYCLONE IS NOTED BETWEEN THE CYCLONES OVER NICARAGUA AT 
13N86W WHERE A FEW TSTMS ARE NOW DISSIPATING. THE STRONG
NORTHEASTERLY UPPER FLOW OBSERVED OVER THE ENTIRE AREA S OF 09N 
APPEARS TO BE WEAKENING...BUT CONTINUES TO ADVECT MONSOON TROUGH 
DEBRIS MOISTURE SW TO ALONG ABOUT 04N WHERE THE MOISTURE 
EVAPORATES IN DRY UPPER AIR THAT EXTENDS N ACROSS THE EQUATOR.
 
ELSEWHERE AT THE LOW LEVELS...A WEAK 1011 MB SURFACE LOW IS 
ANALYZED NEAR 15N114W WITH ONLY A COUPLE OF TSTMS OBSERVED AT 
18N115W. A BROAD RIDGE DOMINATES THE SUBTROPICS ELSEWHERE W OF 
120W WITH SURFACE WINDS GENERALLY 20 KT OR LESS. SOUTHWESTERLY 
MONSOON FLOW AT 20 TO 25 KT IS NOTED IN SCATTEROMETER DATA IN 
THE AREA FROM 03N TO 09N BETWEEN 100W AND 110W...WITH SEAS TO 8 
FT IN LONG PERIOD CROSS EQUATORIAL SWELLS THAT ARE CURRENTLY 
OBSERVED IN THE WATERS S OF 04N BETWEEN 92W AND 111W. THESE 
SWELLS ARE EXPECTED TO PROPAGATE N TO ALONG 11N BETWEEN 95W AND 
120W ON MON.

$$
NELSON/MUNDELL