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| #152910 (Received by flhurricane at: 4:34 PM 28.Sep.2007) TCDAT2 TROPICAL STORM KAREN DISCUSSION NUMBER 16 NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL AL122007 500 PM EDT FRI SEP 28 2007 NOT SURPRISINGLY...THIS AFTERNOON...KAREN IS ATTEMPTING TO MAKE A COMEBACK. DEEP CONVECTION IS DEVELOPING JUST TO THE NORTHEAST OF THE CENTER. A 1328Z ASCAT OVERPASS HAPPENED TO CAPTURE THE MAJORITY OF THE SYSTEM AND INDICATED 30 KT WINDS OVER THE NORTHEAST QUADRANT. HOWEVER...THIS PARTICULAR PASS WAS A FEW HOURS BEFORE THE CONVECTIVE CANOPY BEGAN TO EXPAND AND INTENSIFY. THE DVORAK SATELLITE CURRENT INTENSITY ESTIMATES HAVE INCREASED TO 35 KT AND THE INITIAL INTENSITY REMAINS AT 35 KT. THE OFFICIAL INTENSITY FORECAST IS SIMILAR TO THE PREVIOUS PACKAGE AND IS A BLEND OF THE SHIPS AND THE LGEM...INDICATING WEAKENING UNDER STRONG UPPER LEVEL SOUTHWESTERLY FLOW DURING THE NEXT 24 HOURS...THEN LITTLE CHANGE THROUGH DAY 5...DUE TO AN UNFAVORABLE UPPER WIND ENVIRONMENT. INITIAL MOTION IS ESTIMATED AT 310/10. THE UNPREDICTED TEMPORARY NORTHWARD MOTION COULD BE DUE TO A COMBINATION OF SLIGHT STRENGTHENING OF THE LOW- LEVEL RIDGE BETWEEN TROPICAL DEPRESSION 14 AND KAREN AND SOUTHERLY FLOW WITH A TROUGH WEST OF THE CYCLONE. CONSEQUENTLY...IT IS UNCLEAR IF OR WHEN THE SYSTEM WILL RETURN TO ITS PREVIOUS NORTHWESTWARD MOTION THAT THE DYNAMICAL MODELS CONTINUE TO SUGGEST. THEREFORE...BASED ON A BLEND OF THE LARGE-SCALE MODELS AND THE GFDL...THE OFFICIAL FORECAST SHOWS A TURN BACK MORE TO THE NORTHWEST DURING THE NEXT 12 HOURS. THE MODELS HAVE SPLIT INTO TWO POSSIBLE SCENARIOS AGAIN...WITH THE GFS AND THE HWRF INDICATING MORE OF A NORTHWARD MOTION AT THE END OF THE FORECAST PERIOD IN RESPONSE TO AN APPROACHING MID-LATITUDE TROUGH FROM THE NORTHWEST. THE OTHER CLUSTER CONSISTS OF THE UKMET...ECMWF...AND NOGAPS WHICH REFLECTS A TURN MORE TOWARD THE WEST-NORTHWEST. BASED ON THE CONSTANT INCONSISTENCIES FROM ONE MODEL RUN TO THE OTHER...THE OFFICIAL FORECAST IS BASED ON A DYNAMICAL MODEL CONSENSUS AND IS ADJUSTED TO THE RIGHT OF THE PREVIOUS FORECAST DUE TO THIS MORNING'S NORTHWARD JOG. FORECAST POSITIONS AND MAX WINDS INITIAL 28/2100Z 16.4N 49.9W 35 KT 12HR VT 29/0600Z 17.1N 50.9W 35 KT 24HR VT 29/1800Z 18.2N 52.4W 30 KT 36HR VT 30/0600Z 19.2N 53.7W 30 KT 48HR VT 30/1800Z 20.3N 55.0W 30 KT 72HR VT 01/1800Z 22.5N 57.5W 30 KT 96HR VT 02/1800Z 24.0N 59.5W 30 KT 120HR VT 03/1800Z 25.5N 61.5W 30 KT $$ FORECASTER ROBERTS |
