000 WTPZ41 KNHC 301454 TCDEP1 TROPICAL DEPRESSION SIX-E DISCUSSION NUMBER 1 NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL EP062009 800 AM PDT THU JUL 30 2009 CONVECTIVE BANDING FEATURES HAVE CONTINUED TO IMPROVE AROUND THE AREA OF DISTURBED WEATHER LOCATED OVER THE OPEN WATERS OF THE PACIFIC OCEAN WELL TO THE EAST-SOUTHEAST OF HAWAII. SATELLITE INTENSITY ESTIMATES FROM TAFB AND SAB HAVE INCREASED TO 2.0...AND THE SYSTEM IS BEING UPGRADED TO TROPICAL DEPRESSION SIX-E. THE CENTER POSITION IS A LITTLE DIFFICULT TO DETERMINE...BUT A 1116 UTC AMSU PASS INDICATES THAT IT IS PROBABLY NOT ANY FARTHER SOUTH THAN ABOUT 12N. THE DEPRESSION IS LOCATED ON THE SOUTHERN PERIPHERY OF A MID-LEVEL RIDGE WHICH EXTENDS FROM NORTHWESTERN MEXICO WEST-SOUTHWESTWARD ACROSS THE EASTERN PACIFIC...AND THE RESULTANT MOTION IS A QUICK 275/16. GLOBAL MODEL GUIDANCE INDICATES THAT AN ANTICYCLONE WILL BREAK OFF THE WESTERN END OF THE RIDGE AND MOVE WESTWARD...KEEPING THE DEPRESSION ON A GENERAL WESTWARD COURSE SOUTH OF THE HAWAIIAN ISLANDS DURING THE FORECAST PERIOD. THE DEPRESSION IS EXPECTED TO WEAKEN BY DAYS 4 AND 5...AND THE SYSTEM SHOULD BE SHALLOW ENOUGH AT THAT TIME TO BE STEERED WESTWARD BY THE LOW-LEVEL FLOW. UPPER-LEVEL WINDS ARE EXPECTED TO REMAIN FAVORABLE FOR STRENGTHENING FOR ONLY THE FIRST 36-48 HOURS...AFTER WHICH TIME SOUTHWESTERLY TO WEST-SOUTHWESTERLY SHEAR IS EXPECTED TO STEADILY INCREASE AS SHOWN BY THE SHIPS MODEL. THEREFORE...THE OFFICIAL FORECAST INDICATES MODEST STRENGTHENING THROUGH 36 HOURS THEN STEADY WEAKENING THEREAFTER. THIS SCENARIO AGREES WITH THE SHIPS GUIDANCE AND IS A COMPROMISE BETWEEN GFDL AND THE HWRF MODELS. THIS DEPRESSION WILL BE CROSSING 140W SOON...AND ADDITIONAL INFORMATION WILL BE PROVIDED BY THE CENTRAL PACIFIC HURRICANE CENTER IN HONOLULU HAWAII. FORECAST POSITIONS AND MAX WINDS INITIAL 30/1500Z 12.0N 139.7W 30 KT 12HR VT 31/0000Z 12.1N 141.9W 35 KT 24HR VT 31/1200Z 12.3N 144.9W 40 KT 36HR VT 01/0000Z 12.6N 147.7W 50 KT 48HR VT 01/1200Z 13.1N 150.6W 45 KT 72HR VT 02/1200Z 14.0N 156.0W 35 KT 96HR VT 03/1200Z 15.0N 161.0W 30 KT 120HR VT 04/1200Z 15.5N 166.0W 25 KT $$ FORECASTER BERG