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#38454 (Received by flhurricane at: 10:37 PM 08.Aug.2005) TCDAT4 TROPICAL DEPRESSION IRENE DISCUSSION NUMBER 18 NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL 11 PM EDT MON AUG 08 2005 IRENE CONTINUES TO LOOK INSIGNIFICANT ON SATELLITE IMAGES...AND SHOWS NO INDICATIONS OF RESTRENGTHENING ANY TIME SOON. THE LOW-CLOUD CENTER IS NEAR THE WESTERN EDGE OF A SMALL AREA OF DEEP CONVECTION...AND THERE ARE NO OBVIOUS BANDING FEATURES. THE DEPRESSION IS BEING SHEARED BY WESTERLY FLOW ASSOCIATED WITH THE MID-ATLANTIC UPPER-LEVEL TROUGH. ALSO...DROPSONDE DATA FROM A SAHARAN AIR LAYER RESEARCH MISSION WITH THE NOAA G-IV JET CONFIRM THAT IRENE IS IN AN ENVIRONMENT OF VERY DRY MID- TO UPPER- TROPOSPHERIC AIR. AS THE CYCLONE MOVES FARTHER TO THE WEST- NORTHWEST OVER THE NEXT COUPLE OF DAYS...IT IS LIKELY TO ENTER A WEAKER WIND SHEAR ENVIRONMENT SINCE THE UPPER FLOW IS EXPECTED TO BECOME MORE SOUTHEASTERLY. SOME RESTRENGTHENING IS THEREFORE SHOWN IN THE FORECAST. INITIAL MOTION IS 285/11. IRENE IS EXPECTED TO EVENTUALLY TURN MORE NORTHWARD LATER IN THE FORECAST PERIOD...IN RESPONSE TO A WEAKNESS IN THE SUBTROPICAL RIDGE NEAR BERMUDA. HOWEVER THERE ARE SIGNIFICANT DIFFERENCES OF OPINION AMONG THE GLOBAL MODELS AS TO THE CONFIGURATION OF THE SUBTROPICAL RIDGE OVER THE WESTERN ATLANTIC AT DAYS 4-5. BY THAT TIME IT DOES APPEAR THAT THE STEERING CURRENTS WILL BECOME QUITE WEAK...SO THE FORWARD SPEED IS FORECAST TO SLOW CONSIDERABLY LATE IN THE PERIOD. THE OFFICIAL FORECAST FOR THIS ADVISORY IS SIMILAR TO THE PREVIOUS ONE THROUGH DAY 3 AND SHIFTED A LITTLE TO THE EAST AFTERWARDS...BUT NOT AS FAR EAST AS THE DYNAMICAL CONSENSUS. FORECASTER PASCH FORECAST POSITIONS AND MAX WINDS INITIAL 09/0300Z 22.6N 52.7W 30 KT 12HR VT 09/1200Z 23.0N 54.4W 30 KT 24HR VT 10/0000Z 23.7N 56.7W 35 KT 36HR VT 10/1200Z 24.5N 59.0W 35 KT 48HR VT 11/0000Z 25.5N 61.2W 40 KT 72HR VT 12/0000Z 28.0N 64.5W 40 KT 96HR VT 13/0000Z 30.0N 65.0W 45 KT 120HR VT 14/0000Z 32.0N 65.0W 45 KT |