000 AXPZ20 KNHC 122221 TWDEP TROPICAL WEATHER DISCUSSION NWS NATIONAL HURRICANE CENTER MIAMI FL 2205 UTC MON AUG 12 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 1800 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 2115 UTC. ...SPECIAL FEATURE... SATELLITE IMAGERY THIS AFTERNOON SHOWED A COMPLEX CYCLONIC CIRCULATION ASSOCIATED WITH A TROPICAL LOW PRES SYSTEM...WITH A MEAN CENTER NEAR 13N127.5W AND ANALYZED AT 1009 MB. SEVERAL LOW LEVEL CYCLONIC SWIRLS CAN BE SEEN IN VISIBLE IMAGERY THIS AFTERNOON ROTATING CYCLONICALLY. SIGNIFICANT CONVECTION ASSOCIATED WITH THIS FEATURE CONTINUES TO OCCUR ACROSS THE SW QUADRANT OF THE LOW...WHERE THE BEST MOISTURE AND LLVL CONVERGENCE AREA OCCURRING. AS MENTIONED BELOW...AN INVERTED MID TO UPPER TROUGH APPROACHING THIS CIRCULATION THE PAST FEW DAYS HAS NEARLY CAUGHT UP TO THE LOW...AND CONTINUES TO MAINTAIN DRY AND STABLE CONDITIONS ACROSS THE E SEMICIRCLE OF THE LOW OUT TO NEARLY 500 NM...DUE TO UPPER CONVERGENCE. THERE REMAINS AN OPPORTUNITY FOR THE LOW TO BECOME BETTER ORGANIZED OVER THE NEXT FEW DAYS...AND IT HAS A HIGH CHANCE OF INTENSIFYING INTO A TROPICAL CYCLONE OVER THE NEXT 48 HOURS AS IT TRACKS IN A GENERALLY WESTWARD MOTION. ...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH... MONSOON TROUGH AXIS EXTENDS FROM CARIBBEAN LOW PRES NEAR 11.5N77W 1010 MB TO 11N89W TO 10N100W TO LOW PRES NEAR 08.5N111W 1010 MB TO 10N114W WHERE IT REMAINS FRACTURED. TROUGH RESUMES AT 16.5N123W TO COMPLEX LOW PRES NEAR 13N127.5W 1009 MB TO 10N133W TO 13N140W. SCATTERED MODERATE TO STRONG CONVECTION NOTED FROM TROUGH S TO 07N E OF 88W. SCATTERED MODERATE TO STRONG CONVECTION NOTED WITHIN 45 NM EITHER SIDE OF TROUGH W OF 135W. SCATTERED TO NUMEROUS STRONG CONVECTION NOTED WITHIN 75 NM EITHER SIDE OF LINE FROM 12N98.5W TO 14.5N100W TO 16N97W. SCATTERED MODERATE CONVECTION NOTED FROM 15N TO 23N BETWEEN 107W AND 110W AND ASSOCIATED WITH STATIONARY TROUGH FROM 26N111W TO 17N110W. ...DISCUSSION... AN UPPER LEVEL ANTICYCLONE IS NOTED OVER FAR N CENTRAL MEXICO AT 30N106W WITH A RIDGE STRETCHING SW TO 20N138W... THROUGH A COL REGION...THEN CONTINUES SW TO ANOTHER ANTICYCLONE NEAR 14.5N146W. BROAD UPPER LEVEL SW TO W FLOW PREVAILS TO THE N AND NW OF THE RIDGE...WITH SATELLITE WATER VAPOR IMAGERY SHOWING MODERATE TO STRONG SUBSIDENCE ALLOWING FOR DRY AND STABLE ATMOSPHERIC CONDITIONS THERE. E TO NE WINDS ALOFT GENERALLY PREVAIL ACROSS THE REMAINDER OF THE AREA S AND SE OF THE RIDGE...CONTINUING TO PRODUCE A GENERALLY LIGHTLY SHEARED ENVIRONMENT. THE TROPICAL LOW DESCRIBED ABOVE IN SPECIAL FEATURES IS OBSERVED TO THE S OF THE AFOREMENTIONED RIDGE. AN INVERTED MID TO UPPER TROUGH TO THE E OF THIS TROPICAL LOW HAS BEEN MOVING WWD THE PAST SEVERAL DAYS...GRADUALLY GETTING CLOSER TO THE LOW...AND IS ABOUT TO MERGE WITH THE MID LEVEL CIRCULATION ASSOCIATED WITH THIS LOW. THE UPPER ANTICYCLONE OVER N MEXICO IS AIDING IN PRODUCING A GENERAL NE TO E UPPER FLOW ACROSS PORTIONS OF THE AREA SE OF THE RIDGE AND E OF 120W. SATELLITE DERIVED WINDS INDICATED AN INVERTED MID LEVEL TROUGH OVER THE FAR EASTERN PART OF THE AREA TO THE S OF THE UPPER ANTICYCLONE...ROUGHLY 19N107W TO 14N106W. A SECOND SIMILAR MID/UPPER INVERTED TROUGH IS MOVING WSW OFF THE S TIP OF BAJA CALIFORNIA. INSTABILITY CREATED BY THESE FEATURES OVER AN ABUNDANT POOL OF TROPICAL MOISTURE...AND A SURFACE TROUGH OFF THE S TIP OF BAJA CALIFORNIA HAVE CONTINUED TO PRODUCE SCATTERED MODERATE CONVECTION THROUGHOUT THE DAY PRESENTLY DESCRIBED ABOVE. THIS AREA OF WEATHER SHOULD CONTINUE TO TRANSLATE SLOWLY WESTWARD THIS EVENING AND TONIGHT. AT THE SURFACE...A WEAK 1023 MB HIGH IS ANALYZED NEAR 31N137W WITH A RIDGE EXTENDING SE TO NEAR 23N114W. THE WEAK PRES GRADIENT BETWEEN THE HIGH AND PERSISTENT LOW PRES ALONG THE SIERRA MADRES OCCIDENTALES HAS BEEN PRODUCING NNW WINDS 15-20 KT ALONG AND OFFSHORE OF THE W COAST OF BAJA CALIFORNIA TO ABOUT 117W...WHERE WAVE MODEL GUIDANCE AND A FEW SHIP OBSERVATIONS FROM THE PAST 24 HOURS INDICATED PEAK SEAS ARE 5-6 FT. THESE CONDITIONS ARE FORECAST TO GENERALLY PREVAIL OVER THE NEXT 24-48 HOURS...WITH BRIEF PULSING OF WINDS TO AROUND 20 KT WITH HIGHER GUSTS AND SEAS BRIEFLY 6-7 FT EXPECTED EACH OF THE NEXT FEW EVENINGS. THE HIGH IS FORECAST TO WEAKEN SLIGHTLY AS IT SHIFTS SLOWLY E DURING THE NEXT 24-48 HOURS. THE PRES GRADIENT BETWEEN THE HIGH AND THE MONSOON TROUGH CONTINUES TO SUPPORT NE WINDS OF 20-25 KT WITH SEAS PRESENTLY TO 9 FT TO THE NW AND N OF THE TROPICAL LOW NEAR 13N127.5W. THESE MARINE CONDITIONS ARE LIKELY TO PERSIST OVER THE NEXT 48 HOURS AS THE LOW BEGINS TO ACCELERATE TO THE W AT 15 TO 20 KT THE NEXT FEW DAYS. $$ STRIPLING