000
AXPZ20 KNHC 110244
TWDEP 

TROPICAL WEATHER DISCUSSION 
NWS NATIONAL HURRICANE CENTER MIAMI FL 
0405 UTC SUN AUG 11 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 
0130 UTC.

...SPECIAL FEATURES...   
A BROAD AND ELONGATED LOW PRESSURE SYSTEM REMAINS EMBEDDED 
WITHIN THE MONSOON TROUGH... WITH A MEAN CENTER NEAR 13N119.5W 
AND ANALYZED AT 1007 MB...DRIFTING W. THE LATEST VISIBLE 
SATELLITE IMAGERY THIS EVENING SHOWS A FEW LOW LEVEL CYCLONIC 
CLOUD SWIRLS ROTATING CYCLONICALLY ABOUT THE MEAN CENTER...WITH 
DRY AIR AND LITTLE TO NO SIGNIFICANT CONVECTION WITHIN 270 NM 
ACROSS THE NORTHEASTERN SEMICIRCLE. ACTIVE CONVECTION DESCRIBED 
BELOW CONTINUES WELL TO THE SW OF THE MEAN CENTER...WHERE FRESH 
NE WINDS ARE CONVERGING WITH S TO SW WINDS OCCURRING THE TO S OF 
THE MONSOON TROUGH. THIS SYSTEM REMAINS OVER WARM SEA SURFACE 
TEMPERATURES...AND IS EMBEDDED WITHIN AN AREA OF ABUNDANT 
TROPICAL MOISTURE...BUT AT PRESENT IS POORLY ORGANIZED. THIS 
SYSTEM IS EXPECTED TO BECOME GRADUALLY BETTER ORGANIZED OVER THE 
NEXT FEW DAYS AS IT SHIFTS W...AND HAS MODERATE POTENTIAL TO 
DEVELOP INTO A TROPICAL CYCLONE OVER THE NEXT 48 HOURS...AND A 
HIGH CHANCE WITHIN THE NEXT FIVE DAYS. 
                       
...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH... 
MONSOON TROUGH AXIS EXTENDS FROM COLOMBIA NEAR 09N74W TO 11N81W 
TO 08N91W TO 07N98W TO 13N106W...WHERE IT FRACTURES. THE TROUGH 
RESUMES FROM NEAR 17N113W TO BROAD LOW PRES AT 13N119.5W TO 
13N130W TO WEAK LOW PRES NEAR 11N135W TO 10N140W.  SCATTERED 
MODERATE ISOLATED STRONG CONVECTION IS NOTED WITHIN 150 NM S OF 
TROUGH E OF 94W. SCATTERED MODERATE ISOLATED STRONG CONVECTION 
NOTED FROM 09N TO 14N BETWEEN 120W AND 127W. SCATTERED MODERATE 
TO STRONG CONVECTION IS NOTED WITHIN 120 NM EITHER SIDE OF 
TROUGH BETWEEN 130W AND 138W.

...DISCUSSION... 
WATER VAPOR IMAGERY SHOWS AN ELONGATED UPPER LEVEL ANTICYCLONE 
NEAR 22.5N123W WITH A RIDGE STRETCHING SW TO 10N140W...AND NE TO 
ACROSS SRN BAJA CALIFORNIA TO A SECOND ANTICYCLONE OVER NW 
MEXICO. BROAD UPPER SW TO W FLOW IS SEEN N OF THE ANTICYCLONE 
AND ASSOCIATED RIDGES...PRODUCING VERY DRY AND STABLE CONDITIONS 
WITHIN THE RIDGE AND TO ITS NW. E TO NELY WINDS ALOFT GENERALLY 
PREVAIL ACROSS THE REMAINDER OF THE AREA S AND SE OF THE 
RIDGE...PRODUCING A GENERALLY LIGHTLY SHEARED ENVIRONMENT.

AT THE SURFACE...A 1021 MB HIGH IS ANALYZED AT 28N131W WITH A 
RIDGE EXTENDING SE TO 20N114W. THE WEAK PRES GRADIENT BETWEEN 
THE HIGH AND PERSISTENT LOW PRES ALONG THE SIERRA MADRES 
OCCIDENTALES IS PRODUCING NNW WINDS NEAR 20 KT ALONG AND 
OFFSHORE OF THE W COAST OF BAJA CALIFORNIA TO ABOUT 116W...WHERE 
WAVE MODEL GUIDANCE AND SHIP OBSERVATIONS  SUGGEST PEAK SEAS ARE 
5-6 FT. A WEAKENING COLD FRONT HAS STALLED ACROSS THE NW CORNER 
OF THE AREA FROM 30N133W TO 28.5N140W WHERE IT THEN CURVES W AND 
NW FROM THERE. ONLY ISOLATED SHOWERS ARE WITHIN ABOUT 30-60 NM 
OF THE FRONT. THE HIGH IS FORECAST TO DISSIPATE OVER THE NEXT 24 
HOURS AS ANOTHER HIGH OF 1021 MB N OF THE AREA AT 36N141W MOVES 
SE TO NEAR 32N138W. THE PRES GRADIENT BETWEEN THE HIGH AND THE 
MONSOON TROUGH TO THE S IS MODEST AT BEST...AND IS AIDING IN 
PRODUCING SMALL AREAS OF FRESH NE TRADES TO THE N AND NW OF TWO 
LOW PRES CENTERS EMBEDDED ALONG THE MONSOON TROUGH...BOTH 
MENTIONED ABOVE WITH CONVECTION. THESE LOWS WILL SHIFT WWD OVER 
THE NEXT FEW DAYS...WITH FRESH NE TRADES PERSISTING ACROSS THE N 
AND NW PORTIONS AS THEY SHIFT WWD. 

E OF 110W...LIGHT TO MODERATE MONSOONAL FLOW DOMINATES THE 
REGION...WITH SMALL TO MODERATE CLUSTERS OF CONVECTION OCCURRING 
ALONG AND JUST SOUTH OF THE TROUGH. A WEAK TROPICAL WAVE IS 
SUGGESTED BY GLOBAL MODEL OUTPUT AND SATELLITE IMAGERY MOVING 
ACROSS CENTRAL AMERICA ALONG ABOUT 86W...AND WILL LIKELY INDUCE 
ADDITIONAL CONVECTION NEAR THE TROUGH TONIGHT AND SUNDAY AS IT 
SHIFTS W 10 KT. 
 
$$ 
STRIPLING