|
Show Selection: |
| #34668 (Received by flhurricane at: 11:03 AM 22.Jul.2005) TCDAT1 TROPICAL STORM FRANKLIN DISCUSSION NUMBER 5 NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL 11 AM EDT FRI JUL 22 2005 THE OVERALL CONVECTIVE APPEARANCE OF FRANKLIN HAS IMPROVED THIS MORNING AND THE SHEAR ON THE WEST SIDE HAS LESSENED. THIS HAS ALLOWED FOR CONVECTION TO DEVELOP ON THE WEST SIDE OF THE CIRCULATION AND FOR THE CLOUD PATTERN TO BECOME MORE CIRCULAR. THE SURFACE WIND FIELD HAS ALSO BECOME BETTER DEFINED AS NOTED BY A 1046Z QUIKSCAT OVERPASS AND SURFACE OBS FROM THE BAHAMAS AND FLORIDA. AIR FORCE RECON FOUND 49 KT FLIGHT-LEVEL WINDS IN THE SOUTHEAST QUADRANT... WHICH EQUALS ABOUT A 39-KT SURFACE WIND. HOWEVER...THE ONBOARD METEOROLOGIST ESTIMATED SURFACE WINDS OF 55-60 IN THE SAME AREA. THEREFORE...THE INITIAL INTENSITY IS BEING CONSERVATIVELY INCREASED TO 45 KT...BUT IT COULD BE A LITTLE HIGHER. THE INITIAL MOTION IS AN UNCERTAIN 330/02 KT. THE FIRST TWO RECON POSITIONS HAVE COME IN EAST OF THE PREVIOUS ADVISORY POSITIONS... AND THE MOST RECENT FIX CAME IN ABOUT 15 MILES NORTHEAST OF THE FIRST ONE. SATELLITE IMAGERY AND RADAR DATA FROM MIAMI AND MELBOURNE INDICATE LITTLE OVERALL NET MOTION...OTHER PERHAPS A SLOW NORTHWESTWARD DRIFT. UPPER-AIR DATA AT 06Z AND 12Z INDICATE THAT FRANKLIN APPEARS TO BE LOCATED ON THE SOUTH SIDE OF OR WITHIN A FAIRLY STOUT MID- TO UPPER-LEVEL RIDGE. AS RESULT...THERE MAY BE SOME SLOW ERRATIC MOTION TO THE NORTHWEST OR NORTH FOR THE NEXT 24 HOURS OR SO UNTIL A SHORTWAVE TROUGH OVER THE EASTERN OHIO AND TENNESSEE VALLEYS MOVES EASTWARD TO THE U.S. EAST COAST AND WEAKENS THE RIDGE AXIS TO THE NORTH OF FRANKLIN. THAT MAY ALLOW FOR MORE SIGNIFICANT NORTHWARD AT THAT TIME AND...IF THE RIDGE WEAKENS AS THE GLOBAL MODELS ARE FORECASTING...THEN THE CYCLONE WOULD MOVE THROUGH THE RIDGE AND RECURVE TO THE NORTHEAST. HOWEVER...FRANKLIN IS A VERY SMALL TROPICAL CYCLONE AND IT WOULD NOT TAKE MUCH RIDGE TO THE NORTH TO KEEP THE CYCLONE FROM RECURVING OUT TO SEA AND TURN TOWARD THE WEST. THIS ALTERNATE SCENARIO IS SUGGESTED BY THE STATISTICAL-DYNAMICAL MODELS NHC98 AND A9UK...WHICH MAKE A SMALL LOOP NORTH OF THE NORTHWESTERN BAHAMAS AND THEN TURN FRANKLIN BACK TO THE SOUTHWEST AFTER 96 HOURS. THE DEEP AND MEDIUM BAM MODELS HAVE ALSO PERSISTED WITH THEIR PREVIOUS SOLUTIONS OF SLOW NORTHWESTWARD MOTION THROUGH 36-48 HOURS...AND THEN TURNING THE CYCLONE WEST-SOUTHWESTWARD ACROSS SOUTH-CENTRAL FLORIDA IN 72-96 HOURS. THE SHEAR ACROSS FRANKLIN HAS STEADILY WEAKEND THIS MORNING...AND THE VARIOUS MODELS FORECAST THIS TO CONTINUE FOR AT LEAST THE NEXT 36-48 HOURS. THIS SHOULD ALLOW FOR AT LEAST SOME MODEST STRENGTHENING TO OCCUR AS PER THE SHIPS AND GFDL MODELS. IF FRANKLIN REMAINS STATIONARY EAST OF FLORIDA AND DOES NOT RECURVE AS FORECAST...THEN THE INTENSITIES AFTER 48 HOURS WOULD LIKELY BE HIGHER THAN INDICATED. FORECASTER STEWART FORECAST POSITIONS AND MAX WINDS INITIAL 22/1500Z 26.8N 77.0W 45 KT 12HR VT 23/0000Z 27.7N 77.5W 50 KT 24HR VT 23/1200Z 29.0N 77.5W 55 KT 36HR VT 24/0000Z 29.9N 76.0W 60 KT 48HR VT 24/1200Z 30.4N 74.4W 60 KT 72HR VT 25/1200Z 31.3N 71.5W 60 KT 96HR VT 26/1200Z 32.5N 68.0W 60 KT 120HR VT 27/1200Z 34.0N 62.5W 60 KT |
