000 WTNT43 KNHC 232033 TCDAT3 TROPICAL DEPRESSION EIGHTEEN DISCUSSION NUMBER 1 NWS NATIONAL HURRICANE CENTER MIAMI FL AL182011 500 PM EDT SUN OCT 23 2011 THE HURRICANE HUNTER AIRCRAFT INVESTIGATING THE LOW PRESSURE AREA OVER THE WESTERN CARIBBEAN SEA HAS FOUND A WELL-DEFINED CENTER AND SATELLITE IMAGERY INDICATES THAT THE DISTURBANCE HAS ACQUIRED JUST ENOUGH CONVECTIVE ORGANIZATION FOR THE SYSTEM TO BE CLASSIFIED AS A TROPICAL DEPRESSION. THE INITIAL WIND SPEED IS SET AT 30 KT... BASED ON A FEW BELIEVABLE 27 TO 28 KT SFMR WIND MEASUREMENTS. THE DEPRESSION IS OVER WARM WATER BUT IN AN AREA OF MODERATE SOUTHEASTERLY VERTICAL SHEAR WITH DRY AIR TO THE NORTH AND WEST. THE ENVIRONMENT DURING THE NEXT COUPLE OF DAYS IS NOT FORECAST TO BE CONDUCIVE FOR SIGNIFICANT STRENGTHENING...BUT SHOULD NOT BE HOSTILE ENOUGH TO PREVENT THE SYSTEM FROM BECOMING A TROPICAL STORM. THE OFFICIAL FORECAST IS JUST SLIGHTLY ABOVE THE STATISTICAL/DYNAMICAL SHIPS AND LGEM GUIDANCE. THE INITIAL MOTION ESTIMATE IS A SOMEWHAT UNCERTAIN 335/5. THE CYCLONE IS FORECAST TO TURN WESTWARD DURING THE NEXT DAY OR TWO TO THE SOUTH OF A MID-LEVEL RIDGE OVER THE EASTERN GULF OF MEXICO. THE UNCERTAINTY IN THE TRACK FORECAST INCREASES GREATLY IN THE 3 TO 5 DAY TIME FRAME. THE GFS AND NOGAPS MODELS MOVE THE SYSTEM INLAND OVER CENTRAL AMERICA IN A FEW DAYS. CONVERSELY...THE HWRF...ECMWF...AND UKMET MODELS TAKE THE CYCLONE INTO THE SOUTHEASTERN GULF OF MEXICO IN THE LATTER PART OF THE FORECAST PERIOD IN RESPONSE TO AN EASTWARD SHIFT OF THE ABOVEMENTIONED RIDGE. THE OFFICIAL FORECAST LIES BETWEEN THESE TWO EXTREMES... AND IS CLOSE TO THE GFDL TRACK. FORECAST POSITIONS AND MAX WINDS INIT 23/2100Z 15.9N 81.9W 30 KT 35 MPH 12H 24/0600Z 16.4N 82.2W 35 KT 40 MPH 24H 24/1800Z 16.8N 82.9W 40 KT 45 MPH 36H 25/0600Z 17.0N 83.5W 45 KT 50 MPH 48H 25/1800Z 17.1N 84.3W 50 KT 60 MPH 72H 26/1800Z 17.3N 86.0W 50 KT 60 MPH 96H 27/1800Z 17.7N 87.0W 50 KT 60 MPH 120H 28/1800Z 19.0N 88.0W 50 KT 60 MPH $$ FORECASTER BROWN