|
|
|||||||
000 WTNT42 KNHC 100844 TCDAT2 TROPICAL STORM BONNIE DISCUSSION NUMBER 9 NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL 5 AM EDT TUE AUG 10 2004 IN SATELLITE IMAGERY...BONNIE REMAINS A RATHER UNIMPRESSIVE TROPICAL CYCLONE...WITH A SMALL CDO...CENTRAL DENSE OVERCAST...AND BANDING THAT IS LIMITED BUT INCREASING. THE CENTRAL CONVECTION HAS BEEN RATHER PERSISTENT THOUGH...AND DATA FROM A RECONNAISSANCE AIRCRAFT CURRENTLY INVESTIGATING BONNIE SHOWS THAT THE CYCLONE IS MAINTAINING ITS ORGANIZATION AND STRENGTH. THE CREW REPORTED A TEN MILE WIDE EYE...ALMOST UNHEARD OF IN A SYSTEM OF THIS INTENSITY. THE PEAK FLIGHT-LEVEL WINDS WERE 49 KT...AND A DROPSONDE IN THE SOUTHEAST QUADRANT REPORTED SURFACE WINDS OF 43 KT. BASED ON THESE DATA...THE INITIAL INTENSITY ESTIMATE IS HELD AT 45 KT FOR THIS ADVISORY. SMALL TROPICAL CYCLONES SUCH AS BONNIE ARE PRONE TO RAPID CHANGES IN INTENSITY...EITHER UP OR DOWN. THERE ARE A COUPLE OF FACTORS THAT WOULD ARGUE FOR SUBSTANTIAL STRENGTHENING OVER THE NEXT DAY OR TWO. FIRST...ALTHOUGH BONNIE IS CURRENTLY EXPERIENCING SOME NORTHERLY SHEAR...IT SHOULD BE MOVING UNDER LIGHT ANTICYCLONIC FLOW IN THE CENTRAL GULF LATER TODAY. SECOND...THE FORECAST TRACK TAKES BONNIE OVER OR VERY NEAR A POOL OF DEEP WARM WATER IN THE NORTH-CENTRAL GULF. A MITIGATING FACTOR WOULD BE THE RELATIVELY DRY AIR IN THE NORTHWESTERN GULF. THE LAST TWO RUNS OF BOTH THE GFDL AND SHIPS MODELS MAKE BONNIE A HURRICANE PRIOR TO LANDFALL. THE GFS DOES NOT SHOW INTENSIFICATION...BUT IN FACT BARELY ACKNOWLEDGES BONNIE'S EXISTENCE DUE TO THE CYCLONE'S SMALL SIZE. THE OFFICIAL FORECAST IS ADJUSTED UPWARD FROM THE PREVIOUS ADVISORY...AND CALLS FOR BONNIE TO REACH HURRICANE STRENGTH WITHIN 48 HOURS. HOWEVER...IT IS STILL BELOW THE SHIPS GUIDANCE...AND IS CONSIDERABLY BELOW THE GFDL GUIDANCE...... http://www.srh.noaa.gov/data/NHC/TCDAT2.0408100845 |