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| #34616 (Received by flhurricane at: 4:52 AM 22.Jul.2005) TCDAT1 TROPICAL STORM FRANKLIN DISCUSSION NUMBER 4 NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL 5 AM EDT FRI JUL 22 2005 WHILE THE CONVECTIVE TOPS ARE COOLING AS THE DIURNAL MAXIMUM APPROACHES...FRANKLIN HAS A SOMEWHAT RAGGED APPEARANCE IN SATELLITE IMAGERY THIS MORNING. THE CENTRAL CONVECTION IS POORLY ORGANIZED...WITH THE STRONGEST CLUSTER EAST OF THE CENTER. SURFACE REPORTS FROM GREAT ABACO HAVE NOT YET SHOWN THE TIGHT CENTER REPORTED BY THE RECONNAISSANCE AIRCRAFT YESTERDAY AFTERNOON. THE INITIAL INTENSITY WILL REMAIN 40 KT...WHICH IS A LITTLE ABOVE THE SATELLITE INTENSITY ESTIMATES OF 35 KT FROM ALL AGENCIES. A NEW RECONNAISSANCE AIRCRAFT SHOULD REACH FRANKLIN AROUND 12Z. THE INITIAL MOTION IS 305-310 AT 10 KT. FRANKLIN IS HEADING FOR A WEAKNESS IN THE SUBTROPICAL RIDGE EAST OF FLORIDA AS A DEEP LAYER TROUGH AND ASSOCIATED FRONTAL SYSTEM MOVE SOUTHEASTWARD FROM THE CENTRAL AND EASTERN UNITED STATES. THE DYNAMICAL MODEL GUIDANCE RESPOND TO THIS PATTERN BY RECURVING FRANKLIN TO THE NORTHEAST AND ACCELERATING IT OUT TO SEA. THIS INCLUDES BOTH THE GFS AND UKMET...WHICH WERE CALLING FOR THE STORM TO STALL IN EARLIER RUNS. HOWEVER...THE BAMM AND BAMD STILL CALL FOR FRANKLIN TO TURN WESTWARD AFTER 36 HR...WHILE THE NHC98 CALLS FOR A 5-DAY LOOP NEAR THE NORTHERN BAHAMAS. THESE SCENARIOS ARE POSSIBLE IF FRANKLIN MISSES CONNECTING WITH THE ONCOMING TROUGH. THE OFFICIAL FORECAST WILL COMPROMISE BETWEEN THESE EXTREMES...CALLLING FOR FRANKLIN TO RECURVE NORTHEASTWARD AT A SIGNIFICANTLY FASTER FORWARD SPEED THAN THE PREVIOUS FORECAST...BUT AT A SIGNIFICANTLY SLOWER FORWARD SPEED THEN THE DYNAMICAL MODELS. FRANKLIN IS CURRENTLY LOCATED UNDER AN UPPER-LEVEL CYCLONIC SHEAR AXIS...WITH WESTERLY UPPER-LEVEL WEST OF THE AXIS TRYING TO PUSH THE AXIS ACROSS THE CENTER AND PRODUCE SHEAR. THIS SHOULD AT LEAST SLOW INTENSIFICATION IN THE SHORT TERM. IN THE LONGER TERM...HOW FAST FRANKLIN MOVES OFF TO THE NORTHEAST WILL DETERMINE HOW FAVORABLE CONDITIONS ARE FOR STRENGTHENING. A FASTER MOTION WOULD PLACE THE STORM EAST OF THE ONCOMING UPPER-LEVEL TROUGH...WHICH WOULD ALLOW MORE STRENGTHENING. A SLOWER MOTION WOULD ALLOW THE TROUGH TO RUN OVER THE STORM AND EXPOSE IT TO NORTHERLY SHEAR. THE GFDL...WHICH NOW RACES THE STORM OFF TO THE NORTHEAST...NEVER STRENGTHENS IT ABOVE 60 KT...AND THE OTHER INTENSITY GUIDANCE DOES NOT STRENGTHEN IT MUCH ABOVE 65 KT. THE INTENSITY FORECAST IS AN UPDATE OF THE PREVIOUS FORECAST AND A COMPROMISE BETWEEN THE GFDL AND SHIPS MODELS. FORECASTER BEVEN FORECAST POSITIONS AND MAX WINDS INITIAL 22/0900Z 26.7N 77.3W 40 KT 12HR VT 22/1800Z 27.6N 77.7W 45 KT 24HR VT 23/0600Z 29.0N 77.6W 50 KT 36HR VT 23/1800Z 29.9N 76.8W 55 KT 48HR VT 24/0600Z 30.5N 75.5W 55 KT 72HR VT 25/0600Z 31.5N 73.0W 60 KT 96HR VT 26/0600Z 32.5N 69.0W 60 KT 120HR VT 27/0600Z 34.0N 64.0W 60 KT |
