000
AXPZ20 KNHC 270330
TWDEP 

TROPICAL WEATHER DISCUSSION
NWS NATIONAL HURRICANE CENTER MIAMI FL
0405 UTC MON AUG 27 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 0000 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 
0215 UTC.

...SPECIAL FEATURE...

A SURFACE LOW PRESSURE IS ANALYZED ALONG THE MONSOON TROUGH AXIS 
NEAR 13N102.5W WITH AN ESTIMATED PRESSURE OF 1007 MB...MOVING 
WNW AT 8 KT. THIS SYSTEM FORMED A COUPLE OF DAYS AGO ALONG THE 
MONSOON TROUGH SOUTH OF THE GULF OF TEHUANTEPEC AS A TROPICAL 
WAVE MIGRATED INTO THE AREA AND INTERACTED WITH THE MONSOON 
TROUGH. SHOWERS AND THUNDERSTORMS IN ASSOCIATION WITH THIS AREA 
OF LOW PRESSURE CONTINUE TO SHOW SIGNS OF ORGANIZATION. 
SCATTERED MODERATE TO ISOLATED STRONG CONVECTION IS NOTED  
WITHIN 180 NM NW AND S QUADRANTS OF LOW CENTER. ENVIRONMENTAL 
CONDITIONS ARE CONDUCIVE FOR ADDITIONAL DEVELOPMENT DURING THE 
NEXT COUPLE OF DAYS. CURRENTLY...THIS SYSTEM HAS A MEDIUM CHANCE 
OF BECOMING A TROPICAL CYCLONE DURING THE NEXT 48 HOURS.

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

MONSOON TROUGH AXIS EXTENDS FROM 08N78W TO 12N89W THEN RESUMES 
AT 15N101W TO 1007 MB LOW PRES AT 13N102.5W TO 1010 MB LOW PRES 
AT 11N126W TO 09N140. SCATTERED MODERATE CONVECTION IS FROM 07N 
TO 11N BETWEEN 109W AND 121W AND FROM 11N TO 15N BETWEEN 109W 
AND 112W. 

...DISCUSSION...

AN UPPER ANTICYCLONE REMAINS ANCHORED NEAR 27N115W WITH A RIDGE 
EXTENDING ACROSS THE N WATERS TO NEAR 22N135W. ANOTHER RIDGE 
EXTENDS SE FROM THE SAME ANTICYCLONE TO NEAR 18N107W AND IS 
HELPING TO INDUCE ISOLATED SHOWER/TSTM ACTIVITY S OF BAJA 
CALIFORNIA PARTICULARLY FROM 18N TO 22N E OF 112W. MODERATE TO 
STRONG SUBSIDENCE AND IMPLIED DRY AIR MASS CAN BE FOUND N OF 16N 
W OF 120W. A DIFFLUENT PATTERN ALOFT IS SUPPORTING THE AREAS OF 
CONVECTION ASSOCIATED WITH THE LOW PRES NEAR 13N102.5 AND ALONG 
THE MONSOON TROUGH. 

SCATTEROMETER DATA PROVIDED OBSERVATIONS OF FRESH TO STRONG S TO 
SW FLOW SOUTH OF THE MONSOON TROUGH...COVERING ROUGHLY THE 
REGION FROM 04N TO 11N BETWEEN 104W AND 122W. 

MODEL CONSENSUS BETWEEN THE GFS...ECMWF...AND UKMET SHOWS THAT 
THE LOW PRES NEAR 13N102.5W WILL DEEPEN GRADUALLY OVER THE NEXT 
COUPLE OF DAYS AS IT MOVES NORTHWESTWARD AT 5 T0 10 KT. MODELS 
ALSO INDICATE WINDS REACHING 20 TO 25 KT ON THE SE SIDE OF THE 
LOW...AND WITH SEAS BUILDING TO AROUND 10 FT.  

FURTHER WEST... A DISSIPATING SURFACE LOW...ANALYZED 1009 MB ON 
THE 0000 UTC SURFACE MAP...IS NOTED NEAR 14.5N114.5W. THE LOW 
PRES PREVIOUSLY LOCATED NEAR 18N115W HAS DISSIPATED. ANOTHER  
WEAK 1010 MB LOW PRES IS ALONG THE MONSOON TROUGH NEAR 11N126W. 

LONG PERIOD CROSS EQUATORIAL SWELLS ARE CURRENTLY OBSERVED IN 
THE WATERS S OF 11N BETWEEN 95W AND 120W. THESE SWELLS ARE 
EXPECTED TO PROPAGATE N AND COMBINE WITH FRESH SWELLS GENERATED 
S OF THE DEEPENING LOW.

NLY WINDS OF 20 KT ARE BLOWING ACROSS THE GULF OF TEHUANTEPEC 
DUE TO THE PRESENCE OF A RIDGE ALONG THE WESTERN PORTION OF THE 
GULF OF MEXICO. THIS WEATHER PATTERN IS EXPECTED TO PERSIST AT 
LEAST THROUGH TUE MORNING AS PRES GRADIENT TIGHTENS BETWEEN THE 
RIDGE AND TROPICAL CYCLONE ISAAC MOVING ACROSS THE EASTERN PART 
OF THE SAME GULF.

$$
GR