000 WTNT43 KNHC 230249 TCDAT3 TROPICAL STORM BONNIE DISCUSSION NUMBER 3 NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL AL032010 1100 PM EDT THU JUL 22 2010 AN AIR FORCE RESERVE HURRICANE HUNTER AIRCRAFT EARLIER FOUND 1500 FT FLIGHT-LEVEL WINDS OF 43 KT IN THE NORTHEASTERN QUADRANT...AND BELIEVABLE SFMR WINDS OF 35-39 KT. BASED ON THIS TROPICAL DEPRESSION THREE WAS UPGRADED TO TROPICAL STORM BONNIE. SATELLITE IMAGERY SINCE THAT TIME SUGGESTS LITTLE CHANGE IN STRENGTH...WITH SOUTHERLY VERTICAL WIND SHEAR DISPLACING THE CONVECTION TO THE NORTH OF THE LOW-LEVEL CENTER. THE NEXT AIRCRAFT IS SCHEDULED TO REACH BOONIE AROUND 06Z. THE CENTER HAS BEEN WOBBLING NORTHWESTWARD DURING THE PAST SEVERAL HOURS...WITH THE INITIAL MOTION A SOMEWHAT UNCERTAIN 305/12. BONNIE IS ON THE EAST SIDE OF A LARGE MID/UPPER-LEVEL LOW OVER THE EASTERN GULF OF MEXICO AND SOUTH OF A DEEP-LAYER RIDGE OVER THE SOUTHEASTERN UNITED STATES. AS THE UPPER LOW MOVES WESTWARD... BONNIE SHOULD TURN WEST-NORTHWESTWARD IN RESPONSE TO THE FLOW AROUND THE RIDGE...WITH THE TRACK GUIDANCE MODELS IN GOOD AGREEMENT ON THIS SCENARIO THROUGH 72 HR. THIS MOTION SHOULD BRING THE CENTER ACROSS THE FLORIDA PENINSULA OR KEYS ON FRIDAY...AND NEAR OR OVER THE NORTHERN GULF COAST IN 60-72 HR. AFTER THAT...THE CYCLONE IS EXPECTED TO MOVE NORTHWARD AROUND THE WESTERN END OF THE RIDGE. THE NEW FORECAST TRACK HAS BEEN SHIFTED NORTHWARD DURING THE FIRST 72 HR BASED ON THE CURRENT POSITION AND MOTION. HOWEVER...IT LIES SOUTH OF THE MODEL CONSENSUS THROUGH THE FIRST 48 HR AND SOME ADDITIONAL NORTHWARD ADJUSTMENT MAY BE NECESSARY LATER. IN ADDITION TO THE SOUTHERLY SHEAR...BONNIE IS CURRENTLY IN AN AREA OF UPPER-LEVEL CONFLUENCE ON THE EASTERN SIDE OF THE GULF UPPER LOW. THIS IS A LESS THAN IDEAL ENVIRONMENT FOR STRENGTHENING...AND THE INTENSITY GUIDANCE FORECASTS ONLY MODEST INTENSIFICATION BEFORE BONNIE REACHES FLORIDA. THE FORECAST HAS BECOME MORE PROBLEMATIC OVER THE GULF OF MEXICO. THE SHIPS AND LGEM MODELS...PERHAPS RESPONDING TO SOME DECREASE IN THE SHEAR...NOW FORECAST BONNIE TO PEAK NEAR 60 KT OVER THE GULF. ON THE OTHER HAND...THE GFDL...GFDN...AND HWRF DO NOT FORECAST SIGNIFICANT STRENGTHENING... AND NEITHER DO THE GLOBAL MODELS. SINCE THE LARGE UPPER LOW IS FORECAST TO DOMINATE THE NORTHERN GULF THROUGH 48 HR...THE INTENSITY FORECAST WILL LEAN IN FAVOR OF THE DYNAMICAL MODELS. THE NEW INTENSITY FORECAST IS THE SAME AS THE PREVIOUS FORECAST. FORECAST POSITIONS AND MAX WINDS INITIAL 23/0300Z 23.4N 76.5W 35 KT 12HR VT 23/1200Z 24.4N 78.7W 40 KT 24HR VT 24/0000Z 25.4N 81.9W 45 KT 36HR VT 24/1200Z 26.5N 84.9W 45 KT 48HR VT 25/0000Z 27.6N 87.5W 45 KT 72HR VT 26/0000Z 30.0N 91.0W 40 KT...INLAND 96HR VT 27/0000Z 33.0N 93.0W 25 KT...INLAND 120HR VT 28/0000Z 35.5N 92.5W 20 KT...POST-TROP/REMNT LOW $$ FORECASTER BEVEN