000 AXPZ20 KNHC 131601 TWDEP TROPICAL WEATHER DISCUSSION NWS NATIONAL HURRICANE CENTER MIAMI FL 1605 UTC SAT OCT 13 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 1200 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 1500 UTC. ...SPECIAL FEATURE... 1007 MB LOW PRES CENTERED ALONG THE MONSOON TROUGH NEAR 15N111W LOOKS A LITTLE BETTER ORGANIZED THIS MORNING. CONVECTION CONTINUES TO GROW IN COVERAGE AND INTENSITY WITHIN 210 NM ON THE WESTERN SEMICIRCLE OF THE LOW LEVEL CENTER. THE SYSTEM IS STILL BEING AFFECTED BY MODERATE EAST SHEAR ALOFT...ON THE SOUTHERN EDGE OF AN UPPER ANTICYCLONE CENTERED OVER THE COAST OF CENTRAL MEXICO. THE SHEAR WILL SLACKEN AS THE LOW PRES DRIFTS FURTHER WEST ALLOWING CONVECTION TO DEVELOP FURTHER AND THE LOW TO DEEPEN...POSSIBLY FORMING INTO A TROPICAL CYCLONE. GLOBAL MODELS SHOW THE LOW REACHING 115W TONIGHT THEN STARTING A NORTHWARD TURN. THIS WILL KEEP THE LOW PRES ON THE EDGE OF WARMER WATER AND HELP MAINTAIN THE SYSTEM THROUGH EARLY NEXT WEEK. BY TUE...INCREASING SW SHEAR ALOFT BETWEEN THE UPPER ANTICYCLONE AND AN UPPER TROUGH NEAR 23N118W...ALONG WITH COOLER WATER TEMPS OFF CENTRAL BAJA WILL START TO WEAKEN THE SYSTEM. ASIDE FROM THE CONVECTION...LATEST OBSERVATIONS ARE SHOWING WINDS STARTING TO INCREASE AROUND THE LOW LEVEL CENTER. A JASON 1 PASS FROM AROUND 11 UTC JUST TO THE WEST OF THE LOW LEVEL CENTER IN THE MAIN AREA OF CONVECTION INDICATED WINDS TO 25 KT WITH 9 FT SEAS. AN EARLIER ASCAT PASS FROM AROUND 07 UTC SHOWED WINDS TO 25 KT IN A BROAD SWATH OF SW WINDS CONVERGING INTO THE CENTER. ...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH... MONSOON TROUGH FROM 10N85W TO LOW PRES 1010 MB NEAR 07N91W TO LOW PRES 1007 MB NEAR 15N111W TO LOW PRES 1012 MB NEAR 11N131W TO 08N140W. SCATTERED MODERATE N OF 05N BETWEEN 80W AND 85W. SCATTERED MODERATE ISOLATED STRONG CONVECTION WITHIN 120 NM W QUADRANT OF LOW NEAR 07N91W. NUMEROUS MODERATE SCATTERED STRONG WITHIN 240 NM W SEMICIRCLE OF LOW NEAR 15N111W. SCATTERED MODERATE WITHIN 60 NM N OF TROUGH AXIS BETWEEN 120W AND 130W. SCATTERED MODERATE FROM 06N TO 09N BETWEEN 125W AND 135W. ...DISCUSSION... AN UPPER LEVEL SHORT WAVE TROUGH EXTENDS FROM SOUTHERN CALIFORNIA TO 23N130W...DRIFTING SE WHERE IT IS EXPECTED TO CUTOFF AND STALL NEAR 25N120W BY EARLY SUN AS A MID TO UPPER LEVEL RIDGE BUILDS ALONG 135W N OF 25N. THE SHORT WAVE TROUGH WAS PROVIDING SUPPORT TO A WEAK COLD FRONT MOVING INTO THE NW PORTION OF THE DISCUSSION AREA YESTERDAY...BUT HAS SINCE STALLED AND STARTED TO DISSIPATED AS THE UPPER SUPPORT SHIFTED EAST. A TIGHT PRES GRADIENT BETWEEN THE 1024 MB HIGH PRES NEAR 31N129W AND LOW PRES OVER NW MEXICO IS RESULTING IN FRESH TO STRONG N TO NW FLOW OFF THE COAST OF NORTHERN BAJA...AS NOTED IN A 0730 UTC SCATTEROMETER PASS...AND CORROBORATED BY SHIP PDAN AT 15 UTC. SIMILARLY FRESH TO LOCALLY STRONG NW FLOW WILL PERSIST IN THE CENTRAL PORTION OF THE GULF OF CALIFORNIA THROUGH TODAY...BEFORE DIMINISHING OVERNIGHT. THE HIGH PRES WILL MERGE WITH HIGH PRES BEHIND THE DYING FRONT AND REORGANIZE A LITTLE FARTHER TO THE N TO ALONG 30N BY TONIGHT. FRESH TO STRONG TRADE WINDS BETWEEN THE SUBTROPICAL RIDGE AND A WEAK 1012 MB LOW ALONG THE MONSOON TROUGH NEAR 11N131W...BUT WILL DIMINISH LATER TODAY AS THE HIGH PRES SHIFTS FURTHER N. MEANWHILE RESIDUAL NW SWELL ALONG WITH FRESH NE TRADES WILL MAINTAIN COMBINED SEAS 8 TO 10 FT MAINLY FROM ROUGHLY 10N TO 20N W OF 125W...GRADUALLY SUBSIDING WITH DECREASING COVERAGE THROUGH 48 HOURS. PERSISTENT STRONG HIGH PRES OVER THE GULF OF MEXICO CONTINUES TO ALLOW FRESH TO STRONG GAP WIND FLOW TO PULSE THROUGH THE GULF OF TEHUANTEPEC...PRIMARILY DURING OVERNIGHT AND EARLY MORNING HOURS. $$ CHRISTENSEN