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#453399 (Received by flhurricane at: 10:43 PM 25.Aug.2011) TCDAT5 TROPICAL DEPRESSION TEN DISCUSSION NUMBER 4 NWS NATIONAL HURRICANE CENTER MIAMI FL AL102011 1100 PM EDT THU AUG 25 2011 DESPITE THE PERSISTENCE OF A LARGE AREA OF DEEP CONVECTION...THE LOW-LEVEL CENTER STILL APPEARS TO BE DISPLACED ABOUT A DEGREE TO THE EAST OF THE EDGE OF THE COLDER CLOUD TOPS. THIS STRUCTURE IS CONSISTENT WITH THE NORTHEASTERLY SHEAR OF ABOUT 20 KT SHOWN OVER THE DEPRESSION BY THE SHIPS MODEL AND THE UW-CIMSS SATELLITE ANALYSES. GIVEN THE RELATIVELY DISORGANIZED STRUCTURE OF THE CYCLONE...THE INITIAL INTENSITY IS HELD AT 30 KT FOR THIS ADVISORY IN AGREEMENT WITH A BLEND OF DVORAK FINAL-T AND CI NUMBERS FROM TAFB AND SAB. THE ENVIRONMENTAL CONDITIONS NEVER BECOME ESPECIALLY CONDUCIVE FOR MUCH INTENSIFICATION...HOWEVER THERE IS A SMALL WINDOW OF OPPORTUNITY FOR GRADUAL STRENGTHENING AS THE SHEAR DECREASES OVER THE NEXT DAY OR TWO. BY 48 HOURS THE CYCLONE WILL BE MOVING OVER WATERS NEAR OR BELOW 26C...WHICH SHOULD HALT ANY INTENSIFICATION. WESTERLY SHEAR IS EXPECTED TO INCREASE BY 72 HOURS...AND SHOULD LEAD TO STEADY WEAKENING TO A REMNANT LOW BY THE END OF THE PERIOD. THE NHC INTENSITY FORECAST IS UNCHANGED FROM THE PREVIOUS ADVISORY AND IS CLOSE TO A BLEND OF THE SHIPS AND LGEM THROUGH 48 HOURS AND LIES BELOW THE INTENSITY CONSENSUS LATE IN THE PERIOD. GIVEN THE DIFFICULTY IN LOCATING THE CENTER...THE INITIAL MOTION ESTIMATE IS A RATHER UNCERTAIN 295/8. THE DEPRESSION IS STILL MOVING GENERALLY TOWARD THE WEST-NORTHWEST TO THE SOUTH OF A WEAKENING MID-LEVEL RIDGE. AS THE RIDGE WEAKENS AND A MID- TO UPPER-LEVEL TROUGH AMPLIFIES NORTH OF THE CYCLONE...A TURN TOWARD THE NORTHWEST IS EXPECTED FROM 24 TO 72 HOURS. BEYOND THAT TIME...THE CYCLONE SHOULD TURN BACK TOWARD THE WEST-NORTHWEST AS THE TROUGH LIFTS OUT AND THE WEAKENING CYCLONE COMES UNDER THE INFLUENCE OF THE LOW-LEVEL SUBTROPICAL RIDGE. THE NEW NHC TRACK FORECAST IS CLOSE TO THE PREVIOUS ONE AND THE TVCA MULTI-MODEL CONSENSUS THROUGH 96 HOURS...AND IS SLOWER THAN MOST OF THE GUIDANCE AT DAY 5. FORECAST POSITIONS AND MAX WINDS INIT 26/0300Z 14.1N 33.1W 30 KT 35 MPH 12H 26/1200Z 14.7N 34.0W 30 KT 35 MPH 24H 27/0000Z 15.5N 34.9W 35 KT 40 MPH 36H 27/1200Z 16.4N 35.7W 40 KT 45 MPH 48H 28/0000Z 17.4N 36.4W 45 KT 50 MPH 72H 29/0000Z 19.5N 38.0W 40 KT 45 MPH 96H 30/0000Z 20.5N 40.5W 30 KT 35 MPH 120H 31/0000Z 21.5N 43.5W 25 KT 30 MPH...POST-TROP/REMNT LOW $$ FORECASTER BRENNAN |