000 WTPZ44 KNHC 272042 TCDEP4 TROPICAL DEPRESSION NINE-E DISCUSSION NUMBER 1 NWS NATIONAL HURRICANE CENTER MIAMI FL EP092012 200 PM PDT MON AUG 27 2012 SATELLITE IMAGES SHOW THAT THE LOW PRESSURE SYSTEM LOCATED A FEW HUNDRED MILES SOUTH-SOUTHWEST OF MANZANILLO MEXICO HAS DEVELOPED ORGANIZED DEEP CONVECTION DURING THE LAST SEVERAL HOURS. IN ADDITION...RECENT MICROWAVE DATA INDICATE THAT THE LOW-LEVEL CENTER HAS BECOME WELL DEFINED. THEREFORE...THE LOW IS NOW CLASSIFIED AS A TROPICAL DEPRESSION...THE NINTH OF THE EAST PACIFIC SEASON. THE INITIAL INTENSITY IS 30 KT...THOUGH SOME ESTIMATES SUGGEST IT COULD BE A LITTLE STRONGER. THE DEPRESSION IS FORECAST TO GAIN STRENGTH DURING THE NEXT 3 TO 4 DAYS AS ENVIRONMENTAL CONDITIONS ARE EXPECTED TO BE FAVORABLE. AFTER DAY 4...THE CYCLONE IS EXPECTED TO MOVE OVER COOLER WATERS...AND THAT SHOULD END THE STRENGTHENING TREND. THE OFFICIAL FORECAST IS IN THE MIDDLE OF THE INTENSITY GUIDANCE ENVELOPE...IN CLOSEST AGREEMENT WITH LGEM. THE DEPRESSION IS MOVING WEST-NORTHWESTWARD AT ABOUT 11 KT ON THE SOUTH SIDE OF A MID-LEVEL RIDGE CENTERED OVER THE SOUTHWESTERN U.S. THIS GENERAL MOTION SHOULD CONTINUE FOR ANOTHER DAY OR TWO AS THE RIDGE REMAINS THE PRIMARY STEERING FEATURE. AFTER THAT...THE GLOBAL MODELS SHOW THE RIDGE WEAKENING DUE TO THE COMBINED INFLUENCES OF ATLANTIC TROPICAL STORM ISAAC MOVING OVER THE SOUTH-CENTRAL U.S. AND A TROUGH MOVING TOWARD CALIFORNIA. THIS STEERING PATTERN SHOULD CAUSE THE CYCLONE TO SLOW DOWN AND TURN NORTHWESTWARD. THE RIDGE COULD REBUILD TO THE NORTHEAST OF THE SYSTEM BY THE END OF THE FORECAST PERIOD CAUSING IT TO TURN BACK TO THE WEST-NORTHWEST. THE OFFICIAL FORECAST IS NEAR THE CONSENSUS AIDS...TVCA AND TV15...AND KEEPS THE CENTER OF THE CYCLONE WELL OFFSHORE OF THE COAST OF MEXICO. FORECAST POSITIONS AND MAX WINDS INIT 27/2100Z 15.1N 107.0W 30 KT 35 MPH 12H 28/0600Z 15.6N 108.7W 40 KT 45 MPH 24H 28/1800Z 16.2N 110.6W 45 KT 50 MPH 36H 29/0600Z 16.6N 111.6W 50 KT 60 MPH 48H 29/1800Z 17.4N 112.2W 55 KT 65 MPH 72H 30/1800Z 19.0N 112.7W 60 KT 70 MPH 96H 31/1800Z 20.4N 113.7W 60 KT 70 MPH 120H 01/1800Z 22.0N 117.5W 55 KT 65 MPH $$ FORECASTER CANGIALOSI