000 AXPZ20 KNHC 111552 TWDEP TROPICAL WEATHER DISCUSSION NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL 1605 UTC THU SEP 11 2008 TROPICAL WEATHER DISCUSSION FOR THE EASTERN PACIFIC OCEAN FROM THE EQUATOR TO 32N...EAST OF 140W. BASED ON 1200 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 1515 UTC. ...SPECIAL FEATURES... TROPICAL DEPRESSION LOWELL CENTERED NEAR 23.3N 110.1W OR ABOUT 30 MILES NNW OF CABO SAN LUCAS MEXICO AT 11/1500 UTC MOVING ENE OR 065 DEG AT 7 KT. ESTIMATED MINIMUM CENTRAL PRESSURE IS 1001 MB. MAXIMUM SUSTAINED WINDS 25 KT WITH GUSTS TO 35 KT. LOWELL IS RECURVING INTO AN INCREASING MID-LATITUDE WESTERLY FLOW PRESENT OVER THE WESTERN STATES AND NORTHWESTERN MEXICO AHEAD OF A HIGH AMPLITUDE MID- TO UPPER-LEVEL TROUGH. THE INCREASED WESTERLY FLOW OVER LOWELL IN THIS ENVIRONMENT HAS LEAD TO STRONG SOUTHWESTERLY SHEAR...WHICH IN TURN HAS RESULTED IN A CONTORTED AND RATHER ELONGATED CLOUD PATTERN. SATELLITE IMAGERY INDICATES THAT THE BULK OF THE DEEP CONVECTIVE CLOUDS NOW LIE WELL DOWNWIND OF THE LOW-LEVEL CENTER...WITH NUMEROUS MODERATE/NUMEROUS STRONG NOTED WITHIN 240 NM OF THE NE QUADRANT. WEAKENING LOWELL IS FORECAST ON A NE TRACK THROUGH THE SOUTHERN GULF OF CALIFORNIA TODAY BEFORE DISSIPATING OVER NW MAINLAND MEXICO LATER TONIGHT. PLEASE REFER TO THE LATEST NHC PUBLIC ADVISORY UNDER AWIPS HEADER MIATCPEP3 OR WMO HEADER WTPZ33 KNHC AND THE FULL FORECAST ADVISORY UNDER AWIPS HEADER MIATCMEP3 OR WMO HEADER WTPZ23 KNHC FOR MORE DETAILS. ...ITCZ... ITCZ AXIS IS CENTERED ALONG 11N86W TO 07N94W TO 10N103W TO 06N113W TO 13N126W TO 10N140W. ISOLATED MODERATE WITHIN 300 NM S OF THE AXIS E OF 92W. SCATTERED MODERATE WITHIN 120 NM ON EITHER SIDE OF THE AXIS BETWEEN 128W AND 134W. ISOLATED MODERATE WITHIN 120 NM SOUTH OF THE AXIS WEST OF 137W. ...DISCUSSION... THE WESTERN END OF THE ITCZ DIVES SOUTHWEST FROM TROPICAL DEPRESSION LOWELL...EXTENDING THROUGH 15N120W ON ITS WAY TO 08N140W. A WEAK LOW-LEVEL CYCLONIC CIRCULATION PERSISTS WITHIN THE ITCZ NEAR 13N130W...HAVING DRIFTED SLIGHTLY NORTHWEST SINCE THIS TIME YESTERDAY. DESPITE HOSTILE EASTERLY SHEAR ON THE ORDER OF 20 KT...NUMEROUS MODERATE ISOLATED STRONG CONVECTION IS OBSERVED WITHIN 90 NM OF THE NW QUADRANT. IN THE END...THE STRONG SHEAR SHOULD PROVE TO BE A STRONG INHIBITING FACTOR FOR ANY FUTURE DEVELOPMENT...AND PERHAPS THIS IS A REASON WHY NO GLOBAL MODEL IS FORECASTING TROPICAL CYCLONE DEVELOPMENT FROM THIS AREA OVER THE NEXT FEW DAYS. TO THE E...AN ANOMALOUS LOW-LEVEL WESTERLY FLOW REMAINS IN PLACE MOSTLY S OF 20N E OF 120W...AS HAS BEEN THE CASE FOR MOST OF THE LAST WEEK OF AUGUST AND NOW THE FIRST 10 DAYS OF SEPTEMBER. THIS PATTERN SUPPORTS A MONSOON TROUGH-TYPE FEATURE...DISPLACED N OF ITS CLIMATOLOGICAL POSITION...FROM CENTRAL AMERICA NORTHWEST THROUGH MUCH OF SOUTHERN MEXICO TO NEAR TROPICAL DEPRESSION LOWELL. WITH THE REGION OF CYCLONIC SHEAR OVER LAND AND WITH STRONG EASTERLY SHEAR DOMINATING THE MAIN DEVELOPMENT REGION OF THE EASTERN NORTH PACIFIC...ONLY A FEW WEAK TROPICAL CYCLONES HAVE FORMED IN THE EAST PACIFIC THE PAST FEW WEEKS...ALL FARTHER NORTHWEST THAN NORMAL. MODELS SHOW LITTLE CHANGE TO THE WESTERLY LOW-LEVEL EXCEPT TO CURB IT TO THE WEST AS HIGH PRESSURE OVER THE NE PACIFIC BUILDS INTO THE REGION BETWEEN 110-120W BY EARLY THIS WEEKEND. ELSEWHERE...LONG PERIOD SOUTHWEST SWELL ARRIVING FROM THE SOUTHERN HEMISPHERE CONTINUES TO ENGULF MUCH OF THE TROPICAL EAST PACIFIC WATERS...EXCEPT OVER THE W OF 120W WHERE SOUTHEAST SWELL PREVAILS. MODEL GUIDANCE INDICATES THAT WAVE HEIGHTS HAVE PEAKED YESTERDAY AROUND 7 TO 9 FT OVER THE WATERS S OF 20N AND ARE NOW GENERALLY RUNNING BETWEEN 6 AND 8 FT. ADDITIONAL SOUTHWEST SWELL SHOULD REACH THE SOUTHERN WATERS THIS WEEKEND... WITH HIGHEST WAVE HEIGHTS OVER THE SOUTH CENTRAL WATERS. $$ KIMBERLAIN