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#40078 (Received by flhurricane at: 5:31 PM 16.Aug.2005) TCDAT4 HURRICANE IRENE DISCUSSION NUMBER 49 NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL 5 PM EDT TUE AUG 16 2005 THE EYE BECAME BETTER DEFINED AND ITS EMBEDDED DISTANCE WITHIN THE COLD CLOUD TOPS WAS LARGE ENOUGH TO YIELD A T NUMBER OF 5.0 AT 18Z...CORRESPONDING TO 90 KNOTS. SINCE THEN...THE CLOUD TOPS HAVE WARMED SOMEWHAT AND THE EYE BECAME LESS DISTINCT. THEREFORE THE ADVISORY INTENSITY IS SET AT 85 KNOTS. IRENE'S CONTINUED EASTWARD TRACK HAS KEPT THE HURRICANE MOSTLY SHELTERED FROM THE STRONG BELT OF UPPER-LEVEL WESTERLIES THAT LIE NORTH OF ABOUT 38N LATITUDE. IT IS STILL EXPECTED THAT IRENE WILL BE IMPACTED BY MUCH STRONGER SHEAR ASSOCIATED WITH THESE WESTERLIES WITHIN 12-24 HOURS...AND THIS SHOULD CAUSE WEAKENING. THE SHIPS GUIDANCE LOOKS SUSPECT... SINCE IT KEEPS IRENE AT HURRICANE STRENGTH THROUGH 48 HOURS...BY WHICH TIME THE SHEAR IS FORECAST TO INCREASE TO 37 KNOTS WITH A SEA SURFACE TEMPERATURE OF 15 DEG C. THE OFFICIAL FORECAST SHOWS A MORE RAPID RATE OF WEAKENING THAN SHIPS...BUT MAINTAINS A VIGOROUS EXTRATROPICAL STORM OUT TO 72 HOURS. BEYOND THAT TIME...THE SYSTEM IS LIKELY TO BECOME ABSOREBED BY...OR MERGE WITH...ANOTHER BAROCLINIC CYCLONE. IRENE HAS CONTINUED ITS UNEXPECTEDLY PROLONGED EASTWARD TRACK. HOWEVER...A MID-TROPOSPHERIC TROUGH NEAR JAMES BAY WILL SOON BE APPROACHING THE LONGITUDE OF THE HURRICANE. THIS SHOULD INTRODUCE A SOUTHWESTERLY COMPONENT TO THE STEERING FLOW...AND INDUCE A LEFTWARD TURN IN LESS THAN 24 HOURS. HOWEVER BECAUSE OF THE CONTINUED EASTWARD MOTION...THE OFFICIAL FORECAST TRACK IS SHIFTED A LITTLE MORE TO THE EAST OF THE PREVIOUS NHC TRACK. THE OFFICIAL TRACK FORECAST IS IN GOOD AGREEMENT WITH THE DYNAMICAL MODEL CONSENSUS. BY 72 HOURS...THERE IS A CONSIDERABLE SPREAD IN THE INDIVIDUAL MODELS. THEREFORE THERE IS LOW CONFIDENCE IN THE LOCATION AT THAT FORECAST TIME. BY THEN...HOWEVER...IRENE'S EXTRATROPICAL REMNANT MAY NO LONGER HAVE RETAINED ITS IDENTITY. FORECASTER PASCH FORECAST POSITIONS AND MAX WINDS INITIAL 16/2100Z 36.5N 61.6W 85 KT 12HR VT 17/0600Z 37.2N 60.1W 80 KT 24HR VT 17/1800Z 38.8N 57.3W 70 KT 36HR VT 18/0600Z 42.0N 52.5W 60 KT...BECOMING EXTRATROPICAL 48HR VT 18/1800Z 47.0N 46.0W 50 KT...EXTRATROPICAL 72HR VT 19/1800Z 56.0N 40.0W 50 KT...EXTRATROPICAL 96HR VT 20/1800Z...ABSORBED |