000 AXPZ20 KNHC 190225 TWDEP TROPICAL WEATHER DISCUSSION NWS NATIONAL HURRICANE CENTER MIAMI FL 0405 UTC TUE JUN 19 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 0200 UTC. ...SPECIAL FEATURES... THUNDERSTORM ACTIVITY HAS INCREASED THIS EVENING NEAR THE CENTER OF LOW PRESSURE LOCATED NEAR 17.5N107.5W...WHICH IS DRIFTING SLOWLY E. VISIBLE SATELLITE IMAGERY FROM LATE THIS AFTERNOON SUGGESTED THAT THE LOW LEVEL CIRCULATION IN SOMEWHAT ELONGATED NW TO SE. SCATTERED TO NUMEROUS MODERATE TO STRONG CONVECTION WAS OCCURRING WITHIN 180 NM ACROSS THE SE QUADRANT OF THE LOW WHILE SCATTERED MODERATE ISOLATED STRONG CONVECTION WAS NOTED ELSEWHERE WITHIN 270 NM ACROSS THE S SEMICIRCLE. A NARROW BAND OF SCATTERED MODERATE TO STRONG CONVECTION 60 NM WIDE STRETCHED ACROSS THE NE QUADRANT...AND NEAR THE MEXICAN COASTLINE. MODERATE N TO NE VERTICAL WIND SHEAR OF 10-20 KT WAS AFFECTING CONVECTION ASSOCIATED WITH THIS SYSTEM EARLY THIS EVENING....BUT IS EXPECTED TO DIMINISH OVERNIGHT AND TUESDAY...WHICH MAY ALLOW FOR IMPROVED ORGANIZATION. THE LOW REMAINS EMBEDDED IN THE NE PORTION OF THE MONSOON TROUGH...WITH STRONG SW TO S WINDS CONTINUING ACROSS A BROAD AREA SE OF THE LOW AND THE TROUGH. ENVIRONMENTAL CONDITIONS ARE FAVORABLE FOR ADDITIONAL DEVELOPMENT OF THIS SYSTEM. THIS SYSTEM HAS A HIGH CHANCE...70 PERCENT...OF BECOMING A TROPICAL CYCLONE DURING THE NEXT 48 HOURS. REGARDLESS OF DEVELOPMENT...PERIODS OF HEAVY RAINFALL AND THE THREAT FOR FLASH FLOODS AND MUDSLIDES WILL CONTINUE ACROSS COASTAL PORTIONS OF SOUTHWESTERN AND SOUTH-CENTRAL MEXICO... GENERALLY FROM NEAR ACAPULCO TO PUERTO VALLARTA...FOR THE NEXT COUPLE OF DAYS. ...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH... MONSOON TROUGH EXTENDS FROM LOW PRES 1007 MB OVER W CARIBBEAN NEAR 16.5N83W THEN MEANDERS W AND NW ACROSS CENTRAL AMERICA AND S COASTAL PORTIONS OF SE MEXICO TO NEAR 17N98W...WHERE IT REMAINS FRACTURED FROM RECENT DAYS INTERACTION WITH CARLOTTA... THEN RESUMES AGAIN FROM LOW PRES 1006 MB NEAR 17.5N107.5W TO SECOND LOW PRES 1010 MB NEAR 13.5N117.5W TO 04N133W TO BEYOND 04N140W. SCATTERED MODERATE TO STRONG CONVECTION NOTED WITHIN 150 NM S OF TROUGH BETWEEN 85W AND 98W. SCATTERED MODERATE ISOLATED STRONG CONVECTION NOTED WITHIN 210 NM S AND SE OF TROUGH FROM 109W TO 135W. ...DISCUSSION... ALOFT...A MIDDLE TO UPPER LEVEL CUT OFF LOW IS NEAR 25N134W AND SHIFTING W. A SURFACE LOW UNDERNEATH THIS CIRCULATION YESTERDAY HAS WEAKENED TO AN INVERTED TROUGH FROM 30N129W TO 20N133W. UPPER RIDGING GENERALLY PREVAILS E OF THIS LOW...BETWEEN 100W AND 128W...CENTERED ON A PRIMARY UPPER ANTICYCLONE NEAR 23N115W. THE RIDGE EXTENDS SW...GENERALLY ALONG THE MONSOON TROUGH AXIS...WHERE DEEP CONVECTION IS AIDING IN MAINTAINING UPPER DIVERGENCE. THE RIDGE ALSO EXTENDS SE ALONG THE SW MEXICAN COAST AND CENTRAL AMERICA...TO THE FAR SW CARIBBEAN. AT THE SURFACE...A HIGH PRES RIDGE CENTERED ON A MEAN 1034 MB HIGH NEAR 40N149W EXTENDS E TO THE COAST OF N CALIFORNIA. A VERY TIGHT PRES GRADIENT CONTINUES BETWEEN THE SURFACE TROUGH MENTIONED ABOVE...AND THIS HIGH...YIELDING STRONG NELY WINDS ACROSS NW PORTIONS OF THE DISCUSSION AREA...WITH A 1548 UTC WINDSAT PASS SUGGESTING WINDS TO 30 KT N OF 28N ACROSS THIS AREA. MORNING ALTIMETER PASSES ALSO MEASURED AN ELONGATED AREA OF 12-14 FT SEAS THERE. GLOBAL MODELS INDICATE THAT THE TROUGH WILL DRIFT WWD WHILE THE HIGH PRES WILL WEAKEN WEAKEN AND SHIFT SW...RESULTING IN A GRADUAL DECREASE IN WINDS AND SEAS ACROSS THE NW WATERS OVER THE NEXT 48 HOURS. AS MENTIONED ABOVE...SW WINDS OF 20-25 KT ARE NOTED IN A LARGE AREA SE OF LOW PRES CENTER NEAR 17.5N107.5W...AND ALONG AND SE OF THE MONSOON TROUGH THERE...COVERING ROUGHLY FROM 12N TO 15N BETWEEN 110W AND 118W. THE SW FLOW EXTENDS FARTHER E AND BECOMES WLY ALONG THE PACIFIC COAST OF MEXICO TO OFFSHORE OF THE GULF OF TEHUANTEPEC. THIS FLOW IS BRINGING ABUNDANT TROPICAL MOISTURE ACROSS THESE AREAS...PROVIDING THE POTENTIAL FOR PERIODS OF LOCALLY HEAVY RAIN AND THE THREAT FOR FLASH FLOODS AND MUDSLIDES...PARTICULARLY OVER MOUNTAINOUS AND STEEP TERRAIN. THIS PATTERN IS EXPECTED TO REMAIN IN PLACE FOR THE NEXT FEW DAYS AND WILL MAINTAIN A WET WEATHER PATTERN ACROSS CENTRAL AMERICA AND SOUTHERN MEXICO. $$ STRIPLING