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| #39062 (Received by flhurricane at: 10:43 AM 12.Aug.2005) TCDAT4 TROPICAL STORM IRENE DISCUSSION NUMBER 32 NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL 11 AM EDT FRI AUG 12 2005 THE CLOUD PATTERN HAS DEFINITELY BECOME BETTER ORGANIZED SINCE YESTERDAY. THERE IS A LOW-LEVEL CENTER EMBEDDED WITHIN THE DEEP CONVECTION AND A WELL-DEFINED UPPER-LEVEL OUTFLOW. MICROWAVE DATA SHOW A CONVECTIVE RING ASSOCIATED WITH THE CENTER OF IRENE. T-NUMBERS FROM ALL AGENCIES HAVE REACHED 3.5 ON THE DVORAK SCALE SO THE INITIAL INTENSITY HAS BEEN INCREASED TO 55 KNOTS. HOWEVER...A MORE ACCURATE MEASUREMENT OF THE INTENSITY AND STRUCTURE OF IRENE WILL BE KNOWN WHEN AN AIR FORCE PLANE REACHES THE CYCLONE LATER TODAY. THIS IS THE FIRST FLIGHT INTO IRENE. THE SHEAR AHEAD OF IRENE IS FORECAST TO BE LOW..AND THAT SHOULD LEAD TO ADDITIONAL STRENGTHENING. HOWEVER...THE CYCLONE WILL MOVE OVER A POCKET OF RELATIVELY COOL WATERS LEFT BY FRANKLIN AND HARVEY. SO INTENSIFICATION BEYOND CATEGORY ONE HURRICANE STRENGTH IS NOT ANTICIPATED. THIS IS CONSISTENT WITH THE SHIPS AND THE GFDL MODELS. IRENE IS MOVING TOWARD THE NORTHWEST OR 305 DEGREES AT 11 KNOTS AROUND A STRONG MID-LEVEL SUBTROPICAL RIDGE. AS THE RIDGE MOVES EASTWARD...IRENE SHOULD TURN MORE TOWARD THE NORTH-NORTHWEST AND NORTH INTO AN AREA OF LIGHT STEERING CURRENTS. THIS WOULD RESULT IN A SIGNIFICANT DECREASE IN FORWARD SPEED BEYOND 3 DAYS AND IN FACT...IRENE COULD BEGIN MEANDERING. THIS IS CONSISTENT WITH MANY OF THE GLOBAL MODELS WHICH SHOW BASICALLY VERY WEAK STEERING FLOW NEAR THE 3 TO 5 DAY FORECAST POSITION OF IRENE. EVENTUALLY...A WESTERLY STEERING FLOW SHOULD BECOME ESTABLISHED WHICH SHOULD TURN THE CYCLONE AWAY FROM THE US COAST. THAT IS STILL TOO FAR IN THE FUTURE TO BE CERTAIN. FORECASTER AVILA FORECAST POSITIONS AND MAX WINDS INITIAL 12/1500Z 28.3N 66.8W 55 KT 12HR VT 13/0000Z 29.2N 68.1W 65 KT 24HR VT 13/1200Z 30.0N 69.3W 75 KT 36HR VT 14/0000Z 31.0N 70.0W 75 KT 48HR VT 14/1200Z 32.0N 71.0W 75 KT 72HR VT 15/1200Z 34.0N 72.0W 75 KT 96HR VT 16/1200Z 35.0N 72.0W 75 KT 120HR VT 17/1200Z 36.5N 71.5W 75 KT |
