000 WTNT45 KNHC 040246 TCDAT5 TROPICAL STORM EMILY DISCUSSION NUMBER 10 NWS NATIONAL HURRICANE CENTER MIAMI FL AL052011 1100 PM EDT WED AUG 03 2011 EMILY HAS MOVED LITTLE OVER THE LAST SEVERAL HOURS...AS MULTIPLE FIXES FROM THE AIR FORCE RESERVE HURRICANE HUNTER AIRCRAFT BETWEEN 21Z AND 00Z WERE ALL ESSENTIALLY IN THE SAME LOCATION. DATA FROM THE AIRCRAFT SHOWED LITTLE CHANGE IN THE INTENSITY...WHICH REMAINS 45 KT FOR THIS ADVISORY. THE SLOW MOTION APPEARS TO HAVE ALLOWED THE LOW-LEVEL CENTER TO COME IN CLOSER PROXIMITY TO THE DEEP CONVECTION...WHICH HAS EXPANDED WESTWARD OVER THE PAST FEW HOURS. HOWEVER...THE CIRCULATION SHOULD BECOME SOMEWHAT DISRUPTED BY LAND INTERACTION WITHIN 24 TO 36 HOURS...SO SLIGHT WEAKENING IS INDICATED DURING THAT PERIOD. BEYOND 36 HOURS...GRADUAL STRENGTHENING IS SHOWN...BUT THE OFFICIAL FORECAST REMAINS A LITTLE BELOW THE INTENSITY CONSENSUS...AND WELL BELOW THE MORE AGGRESSIVE GFDL AND HWRF MODELS...GIVEN THE UNCERTAINTY IN THE STRUCTURE OF EMILY AFTER IT TRAVERSES THE HIGH TERRAIN OF WESTERN HISPANIOLA AND EASTERN CUBA. THE INITIAL MOTION ESTIMATE IS VERY SLOW...TOWARD THE WEST OR 280 DEGREES AT 4 KNOTS USING A LONG-TERM AVERAGE...ALTHOUGH THE SHORT TERM MOTION IS EVEN SLOWER. THE GUIDANCE IS INSISTENT ON TURNING EMILY TOWARD THE WEST-NORTHWEST AND NORTHWEST WITH AN INCREASE IN FORWARD SPEED OVER THE NEXT 24 HOURS OR SO...BUT THE OFFICIAL FORECAST IS TO THE LEFT OF AND SLOWER THAN MOST OF THE DYNAMICAL MODELS THROUGH THAT TIME DUE TO THE SLOW INITIAL MOTION. AFTER 36 HOURS...EMILY SHOULD CONTINUE NORTHWESTWARD AND EVENTUALLY TURN NORTHWARD INTO A WEAKNESS IN THE SUBTROPICAL RIDGE EAST OF THE FLORIDA PENINSULA. THE GUIDANCE CONTINUES TO HAVE RUN TO RUN CONSISTENCY ISSUES WITH BOTH THE DETAILS OF THE STEERING FEATURES AND THE STRUCTURE OF THE CYCLONE IN THE MODEL FIELDS. OVERALL... THE LATEST ROUND OF GUIDANCE HAS SHIFTED FARTHER TO THE LEFT...AND THE OFFICIAL FORECAST HAS BEEN NUDGED IN THAT DIRECTION FROM 36 TO 72 HOURS...BUT STILL LIES TO THE EAST OF THE MULTI-MODEL CONSENSUS AT THOSE TIMES. BY DAYS 4 AND 5...EMILY SHOULD ACCELERATE QUICKLY NORTHEASTWARD INTO THE MID-LATITUDE WESTERLIES...AND THE NEW FORECAST AT THOSE TIMES IS ESSENTIALLY AN UPDATE OF THE PREVIOUS NHC FORECAST. THE UNCERTAINTY IN THE TRACK FORECAST CONTINUES TO BE LARGER THAN NORMAL GIVEN THE CURRENT SLOW MOTION...THE POTENTIAL STRUCTURAL CHANGES OF THE CYCLONE DUE TO ITS INTERACTION WITH LAND IN THE NEXT 24 TO 36 HOURS...AND THE LACK OF CONSISTENCY IN THE TRACK GUIDANCE FROM RUN TO RUN. IF A NORTHWARD COMPONENT OF MOTION DOES NOT BEGIN SOON...OR THE TRACK GUIDANCE SHIFTS FARTHER TO THE LEFT IN FUTURE CYCLES...THE THREAT TO FLORIDA AND THE SOUTHEASTERN UNITED STATES WILL INCREASE. FORECAST POSITIONS AND MAX WINDS INIT 04/0300Z 17.1N 71.0W 45 KT 50 MPH 12H 04/1200Z 17.9N 72.9W 45 KT 50 MPH 24H 05/0000Z 20.0N 74.8W 40 KT 45 MPH 36H 05/1200Z 22.1N 76.4W 40 KT 45 MPH 48H 06/0000Z 23.8N 77.4W 45 KT 50 MPH 72H 07/0000Z 27.0N 79.0W 55 KT 65 MPH 96H 08/0000Z 31.5N 76.0W 65 KT 75 MPH 120H 09/0000Z 35.0N 69.0W 65 KT 75 MPH $$ FORECASTER BRENNAN