|
Show Selection: |
| #9637 (Received by flhurricane at: 11:18 PM 22.Sep.2004) TCDAT3 TROPICAL STORM LISA DISCUSSION NUMBER 15 NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL 11 PM EDT WED SEP 22 2004 METEOSAT-8 IMAGERY DURING THE PAST FEW HOURS INDICATES THAT THE LOW LEVEL CENTER OF LISA COMPLETELY SEPARATED FROM THE DEEP CONVECTION. DURING THE PAST FEW HOURS...THE WELL-DEFINED LOW LEVEL CIRCULATION HAS BEEN DRIFTING...AND IS NOW NEARLY STATIONARY. FURTHER...THIS LOW LEVEL CENTER TUCKED UNDER CONVECTION ASSOCIATED WITH THE BROAD CIRCULATION OF THE TROPICAL DISTURBANCE APPROACHING FROM THE EAST. IN FACT...NEW CONVECTION IS NOW FORMING NEAR THIS LOW LEVEL CENTER...AND THE CONVECTIVE BANDS ARRIVING FROM THE EAST ALSO SEEM BE WRAPPING AROUND THE CENTER OF LISA. THEREFORE...THE MERGER OF THE TWO SYSTEMS APPEARS TO BE IN PROGRESS. WHILE IT IS STILL POSSIBLE THAT THE MERGED SYSTEM COULD BECOME FOCUSED ELSEWHERE WITHIN THE BROAD EAST-WEST ORIENTED CIRCULATION...WE WILL FOR NOW ASSUME THAT THIS WILL NOT OCCUR AND WILL MAINTAIN THE EXISTING LISA CIRCULATION AS THE DOMINANT ENTITY. NOW THAT THE DISTURBANCE MOVING IN FROM THE EAST HAS JUST ABOUT COME INTO PHASE WITH THE CENTER OF LISA...WITH SOME UNCERTAINTY WE EXPECT A GENERAL WESTWARD MOTION TO BEGIN WITHIN THE NEXT FEW HOURS AND THEN CONTINUE THROUGH ABOUT 36 HOURS. NOT SURPRISINGLY...THE MODELS ARE HANDLING THIS MERGER/INTERACTION IN A VARIETY OF WAYS AND IT IS DIFFICULT TO FOLLOW A MODEL CONSENSUS...ESPECIALLY DURING THE FIRST TWO DAYS OF THE FORECAST. THE MODELS DO GENERALLY AGREE...HOWEVER...ON AN EVENTUAL TURN TO THE NORTHWEST INTO A WEAKNESS IN THE NARROW SUBTROPICAL RIDGE TO THE NORTH...FOLLOWED BY A STRONG UPPER-LEVEL TROUGH OVER THE CENTRAL ATLANTIC THAT SHOULD INDUCE A NORTH-NORTHWESTWARD MOTION BY DAYS 4 AND 5. THE OFFICIAL FORECAST IS SIMILAR TO THE PREVIOUS ADVISORY BEYOND ABOUT 48 HOURS. LACKING ANY REASON TO CHANGE THE CURRENT INTENSITY...IT WILL BE HELD AT 45 KNOTS. NORTHERLY SHEAR IS CURRENTLY IMPACTING LISA...BUT SHIPS INDICATES THIS SHEAR SHOULD ABATE IN ABOUT 36 HOURS...WHICH MAY ALLOW FOR SOME GRADUAL STRENGTHENING. THE OFFICIAL FORECAST CLOSELY FOLLOWS SHIPS AND BRINGS LISA TO HURRICANE INTENSITY BY 72 HOURS. FORECASTER KNABB/AVILA FORECAST POSITIONS AND MAX WINDS INITIAL 23/0300Z 13.2N 41.2W 45 KT 12HR VT 23/1200Z 13.2N 41.8W 45 KT 24HR VT 24/0000Z 13.3N 42.4W 45 KT 36HR VT 24/1200Z 13.5N 43.2W 50 KT 48HR VT 25/0000Z 14.0N 44.2W 55 KT 72HR VT 26/0000Z 16.0N 45.5W 65 KT 96HR VT 27/0000Z 18.5N 47.0W 70 KT 120HR VT 28/0000Z 21.0N 48.0W 70 KT |
