000 WTPZ42 KNHC 182040 TCDEP2 TROPICAL DEPRESSION TWELVE-E DISCUSSION NUMBER 2 NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL EP122007 200 PM PDT TUE SEP 18 2007 SATELLITE IMAGERY INDICATES THAT TROPICAL DEPRESSION TWELVE-E IS GETTING BETTER ORGANIZED...WITH A BAND OF CURVED CONVECTION FORMING NEAR THE CENTER. SATELLITE INTENSITY ESTIMATES ARE 30 KT FROM TAFB AND SAB...SO THAT IS THE INITIAL INTENSITY FOR THIS ADVISORY. HOWEVER...THE ORGANIZATION HAS IMPROVED SINCE THE ESTIMATES WERE MADE...AND THERE IS A CHANCE THIS INTENSITY IS A LITTLE CONSERVATIVE. WHILE THE SYSTEM REMAINS UNDER LIGHT NORTHWESTERLY VERTICAL SHEAR...THE CIRRUS OUTFLOW IS IMPROVING EVEN IN THE NORTHWEST QUADRANT. THE INITIAL MOTION IS 295/10. THE DEPRESSION REMAINS ON THE SOUTH SIDE OF OF A MID-LEVEL RIDGE EXTENDING WESTWARD FROM NORTHERN MEXICO. THE DYNAMICAL MODELS FORECAST THIS RIDGE TO BREAK DURING THE NEXT THREE DAYS AS A LARGE DEEP-LAYER LOW MOVES SOUTHWARD OVER CALIFORNIA. THIS SHOULD ALLOW THE DEPRESSION TO TURN NORTHWARD AND THEN NORTHEASTWARD BY THE END OF THE FORECAST PERIOD. HOWEVER... THE LOW DOES NOT MOVE FAR ENOUGH SOUTH FOR ACCELERATION AFTER RECURVATURE...WITH THE GFDL SHOWING LITTLE MOTION AND THE HWRF MODEL SHOWING A SLOW EASTWARD MOTION. THE FORECAST TRACK AGAIN CALLS FOR RECURVATURE AND DECELERATION DURING THE FORECAST PERIOD. IT IS SIMILAR TO THE PREVIOUS FORECAST FOR THE FIRST 72 HR AND THEN SHIFTED A LITTLE TO THE NORTHWEST THEREAFTER. THE LARGE-SCALE MODELS FORECAST THE CURRENT LIGHT SHEAR TO CONTINUE FOR 48-72 HR...FOLLOWED BY A SIGNIFICANT INCREASE IN THE SHEAR. THIS...COMBINED WITH DRY AIR SEEN IN WATER VAPOR IMAGERY NORTHWEST OF THE CYCLONE AND MOTION OVER COOLER WATER AT ABOUT 72 HR... SUGGESTS GRADUAL STRENGTHENING THROUGH 72 HR FOLLOWED BY WEAKENING. NONE OF THE GUIDANCE CURRENTLY FORECASTS THE DEPRESSION TO BECOME A HURRICANE...SO THE INTENSITY FORECAST WILL FOLLOW THAT IN CALLING FOR A PEAK INTENSITY OF 55 KT. FORECAST POSITIONS AND MAX WINDS INITIAL 18/2100Z 13.8N 108.4W 30 KT 12HR VT 19/0600Z 14.5N 110.1W 35 KT 24HR VT 19/1800Z 15.4N 112.2W 40 KT 36HR VT 20/0600Z 16.2N 113.7W 45 KT 48HR VT 20/1800Z 17.1N 114.6W 50 KT 72HR VT 21/1800Z 19.0N 115.0W 55 KT 96HR VT 22/1800Z 20.5N 114.5W 45 KT 120HR VT 23/1800Z 21.5N 113.5W 30 KT $$ FORECASTER BEVEN