000 WTPZ44 KNHC 100837 TCDEP4 TROPICAL DEPRESSION NINE-E DISCUSSION NUMBER 3 NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL EP092009 200 AM PDT MON AUG 10 2009 INFRARED SATELLITE IMAGERY INDICATES THAT THE CLOUD PATTERN ASSOCIATED WITH THE CYCLONE HAS NOT CHANGED SIGNIFICANTLY. THE CENTER APPEARS TO BE LOCATED ON THE NORTHWEST SIDE OF A SMALL AND AMORPHOUS MASS OF DEEP CONVECTION...WITH A SHARP WESTERN EDGE. DVORAK T-NUMBERS REMAIN THE SAME AS 6 HOURS AGO...2.0 AND 2.5 FROM SAB AND TAFB...RESPECTIVELY. ON THIS BASIS...THE INTENSITY IS BEING HELD AT 30 KT. THE INITIAL MOTION ESTIMATE IS 280/7...A BIT SLOWER THAN BEFORE. THE DEPRESSION IS BEING STEERED BY A SUBTROPICAL RIDGE EXTENDING FROM THE SOUTHERN UNITED STATES WEST-SOUTHWESTWARD INTO THE TROPICAL EAST PACIFIC. MODEL GUIDANCE...TIGHTLY CLUSTERED THROUGH ABOUT 48 HOURS...SHOWS THIS FEATURE BUILDING WESTWARD OVER THE NEXT FEW DAYS...WHICH SHOULD KEEP THE CYCLONE ON A COURSE JUST NORTH OF DUE WEST. WHILE THE MAJORITY OF THE TRACK GUIDANCE FAVORS A CONTINUED WESTERLY OR WEST-NORTHWESTERLY MOTION BEYOND 48 HOURS... SOME MODELS...SUCH AS THE NOGAPS AND ECMWF...SUGGEST A POSSIBLE INTERACTION WITH ANOTHER SYSTEM DEVELOPING CLOSE TO 140W. THE OFFICIAL FORECAST PLACES LITTLE WEIGHT ON THIS SCENARIO FOR THE TIME BEING AND ESSENTIALLY REPRESENTS AN UPDATE OF THE PREVIOUS ADVISORY. WATER VAPOR IMAGERY AND CLOUD-TRACKED WINDS INDICATE MODEST WESTERLY FLOW ALOFT IMPACTING THE CYCLONE. GLOBAL MODELS INDICATE THE RESULTING SHEAR IS ASSOCIATED WITH AN UPPER-LEVEL TROUGH ALONG 125W. THE INTENSITY GUIDANCE INDICATES LITTLE TO NO STRENGTHENING...WITH THE SHEAR FORECAST TO INCREASE IN THE SHORT-TERM. THE UPPER TROUGH IS FORECAST TO GRADUALLY SHIFT WESTWARD AND DEGENERATE INTO A SHEAR AXIS IN THE NEXT 2-3 DAYS...ALLOWING A NARROW WINDOW OF OPPORTUNITY FOR INTENSIFICATION. HOWEVER...SEA SURFACE TEMPERATURES BEGIN TO GRADUALLY COOL ALONG THE FORECAST TRACK AROUND THIS TIME...AND THE MODELS INDICATE THAT SHEAR MAY AGAIN INCREASE TOWARD THE END OF THE PERIOD. THE OFFICIAL WIND SPEED FORECAST IS SLIGHTLY LOWER COMPARED TO THE PREVIOUS ADVISORY...AND IS IN CLOSE AGREEMENT WITH THE INTENSITY MODEL CONSENSUS. FORECAST POSITIONS AND MAX WINDS INITIAL 10/0900Z 14.9N 122.1W 30 KT 12HR VT 10/1800Z 15.1N 123.3W 35 KT 24HR VT 11/0600Z 15.5N 125.0W 35 KT 36HR VT 11/1800Z 16.0N 126.7W 35 KT 48HR VT 12/0600Z 16.4N 128.5W 40 KT 72HR VT 13/0600Z 16.7N 132.3W 45 KT 96HR VT 14/0600Z 17.0N 136.0W 45 KT 120HR VT 15/0600Z 17.0N 140.0W 40 KT $$ FORECASTER KIMBERLAIN/PASCH