000 AXPZ20 KNHC 132203 TWDEP TROPICAL WEATHER DISCUSSION NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL 2205 UTC WED AUG 13 2008 TROPICAL WEATHER DISCUSSION FOR THE EASTERN PACIFIC OCEAN FROM THE EQUATOR TO 32N...EAST OF 140W. BASED ON 1800 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 2100 UTC. ...SPECIAL FEATURE... TROPICAL STORM ISELLE IS LOCATED AT 16.6N 106.7W AT 2100 UTC WITH MAXIMUM SUSTAINED WINDS AT 35 KT WITH GUSTS TO 45 KT. ISELLE HAS A CENTRAL PRESSURE OF 1003 MB AND IS MOVING W NW OR 285 DEGREES AT 09 KT. NUMEROUS MODERATE TO ISOLATED STRONG CONVECTION CAN BE FOUND WITHIN 120 NM W SEMICIRCLE AND SCATTERED MODERATE CONVECTION CAN BE FOUND ELSEWHERE WITHIN 240 NM SW SEMICIRCLE. ISELLE IS FORECAST TO MOVE W NW OVER THE NEXT 48 HOURS. SEE THE LATEST NHC FORECAST/ADVISORY UNDER AWIPS/WMO HEADER MIATCMEP5/WTPZ24 KNHC FOR MORE DETAILS. ...TROPICAL LOWS... THE REMNANT LOW OF HERNAN IS CENTERED NEAR 17N137W AND ITS CENTRAL PRESSURE IS ESTIMATED AT 1012 MB. THERE IS NO DEEP CONVECTION ASSOCIATED WITH THIS LOW AND IT IS FORECAST TO MOVE W SW FOR THE NEXT FEW DAYS. A LOW PRESSURE SYSTEM IS ANALYZED NEAR 14N118W AND ITS CENTRAL PRESSURE IS ESTIMATED AT 1010 MB. SCATTERED MODERATE AND ISOLATED STRONG CONVECTION CAN BE FOUND WITHIN 210 NM W QUADRANT. THIS SYSTEM WILL MOVE W NW OVER THE NEXT 48 HOURS. ...TROPICAL WAVES... A TROPICAL WAVE IS ALONG 96W AT THE MOMENT AND HAS BEEN MOVING W AT ABOUT 20 KT THE PAST 24 HOURS. ISOLATED MODERATE CONVECTION CAN BE FOUND WITHIN 150 NM OF THE WAVE AXIS PRIMARILY S OF 08N AND N OF 12N. A TROPICAL WAVE IS ALONG 85W AND HAS BEEN MOVING W AT ABOUT 18 KT THE PAST 24 HOURS. ISOLATED MODERATE CONVECTION CAN BE FOUND S OF THE WAVE FROM 00N TO 05N AND SCATTERED MODERATE TO STRONG CONVECTION CAN BE FOUND E OF THE TROPICAL WAVE OVER E HONDURAS...NICARAGUA...AND COSTA RICA. ...ITCZ... THE ITCZ AXIS IS ALONG 09N84W TO 11N100W TO 13N120W TO 14N130W 10N140W. SCATTERED MODERATE CONVECTION CAN BE FOUND WITHIN 150 NM OF AXIS BETWEEN 99W AND 112W. ISOLATED MODERATE CAN ALSO BE FOUND ELSEWHERE WITHIN 420 NM S OF AXIS 91W AND 125W. ...DISCUSSION... THE LONGWAVE UPPER TROUGH CURRENTLY OVER THE FAR NW WATERS WILL LIFT NE OVER THE NEXT TWO DAYS AND TAKE THE UPPER LOW CURRENTLY NEAR 25N120W N WITH IT...BUT LEAVE SOME ENERGY BEHIND ALONG 136W. THIS ENERGY ALONG WITH THE W MOVING INVERTED MID LEVEL TROUGH CURRENTLY CENTERED NEAR 111W S OF 20N WILL WORK TOGETHER TO SUSTAIN THE INVERTED TROUGH ALONG 135W. THIS TROUGHING WILL HELP STEER THE LOW PRESSURE SYSTEM CURRENTLY NEAR 14N118W N OF W THE NEXT FEW DAYS. A REGION OF WEAK UPPER LEVEL DIFFLUENCE TO THE W OF THE LOW NEAR 14N118W WILL CONTINUE TO TRACK W SW WITH THE SYSTEM OVER THE NEXT 48 HOURS AND SUPPORT CONVECTION. MEANWHILE...RIDGING BETWEEN THE TROUGH OVER NW WATERS AND THE REMNANT LOW OF HERNAN WILL BE FORCED S...ALSO PUSHING THE THE HERNAN REMNANT LOW PRESSURE SYSTEM S OF W OVER THE NEXT FEW DAYS. DEEP TROPICAL MOISTURE ON THE E SIDE OF TROPICAL STORM ISELLE WILL SURGE N THROUGH THE GULF OF CALIFORNIA...HELPING TO FUEL AFTERNOON THUNDERSTORMS OVER THE SIERRA MADRE OCCIDENTAL THU AND FRI. IN ADDITION...THE TROPICAL WAVES ALONG 96W AND 85W WILL CONTINUE ON THEIR W TRACK...WITH THEIR MID LEVEL SHORTWAVE SYSTEMS EXPECTED TO TRACK ALONG THE NORTHERN EDGE OF THESE WAVES THROUGH CENTRAL AMERICA...ALLOWING MORE TROPICAL MOISTURE TO BE ADVECTED N AND INCREASING THE POTENTIAL FOR PRECIPITATION ALONG THE N EDGE OF THE WAVES...ESPECIALLY WITH AFTERNOON HEATING OVER LAND. E FLOW ON THE SOUTHERN EDGE OF THE MID TO UPPER LEVEL ANTICYCLONE SHOULD PROPEL DEBRIS MOISTURE W TO THE COAST FROM SOUTHERN/CENTRAL MEXICO. $$ SCHAUER CLARK