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| #218767 (Received by flhurricane at: 10:55 AM 26.Sep.2008) TCDAT1 TROPICAL STORM KYLE DISCUSSION NUMBER 4 NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL AL112008 1100 AM EDT FRI SEP 26 2008 KYLE IS SHOWING A CLASSIC SHEAR PATTERN IN SATELLITE IMAGERY THIS MORNING...WITH THE LOW-LEVEL CENTER PARTLY EXPOSED TO THE WEST OF THE CONVECTION BY 15-20 KT OF WESTERLY VERTICAL WIND SHEAR. SATELLITE INTENSITY ESTIMATES FROM TAFB AND SAB ARE 45 KT...WHILE RECENT QUIKSCAT DATA INDICATES BELIEVABLE WINDS OF 45 KT. BASED ON THIS AND CONTINUITY FROM THE PREVIOUS ADVISORY...THE INITIAL INTENSITY REMAINS 50 KT. THE INITIAL MOTION IS A SOMEWHAT WOBBLY 340/11...SLIGHTLY TO THE LEFT OF THE PREVIOUS ADVISORY. OTHER THAN THAT...THERE IS LITTLE CHANGE TO THE FORECAST PHILOSOPHY FROM THE PREVIOUS ADVISORY. KYLE IS ON THE SOUTHWEST SIDE OF A BUILDING RIDGE OVER THE CENTRAL ATLANTIC...AND SOON SHOULD PASS BETWEEN THE RIDGE AND A DEEP-LAYER LOW PRESSURE AREA OVER THE EASTERN UNITED STATES. THIS PATTERN SHOULD STEER KYLE GENERALLY NORTHWARD FOR THE NEXT 24-36 HR. AFTER THAT...KYLE MAY TURN MORE TOWARD THE NORTH-NORTHEAST AS IT APPROACHES THE MAIN BRANCH OF THE WESTERLIES AND THE NORTHERN END OF THE ATLANTIC RIDGE. SOME UNCERTAINTY EXISTS AS TO HOW FAST THE NORTHERN END OF THE RIDGE MAY WEAKEN AND HOW SOON KYLE MAY ACQUIRE AN EASTWARD COMPONENT OF MOTION...AS SOME OF THE GFS ENSEMBLES SHOW A STRONGER RIDGE AND A MORE NORTHWARD MOTION THAN THE OPERATIONAL MODEL. HOWEVER...THE MODEL CONSENSUS HAS CHANGED LITTLE SINCE THE PREVIOUS PACKAGE...WITH THE CENTER OF THE GUIDANCE ENVELOPE OVER NORTHEASTERN NEW ENGLAND AND THE CANADIAN MARITIME PROVINCES. THE NEW FORECAST TRACK IS SIMILAR TO...BUT A LITTLE SLOWER THAN THE PREVIOUS FORECAST AND IS NEAR THE CENTER OF THE GUIDANCE ENVELOPE. THE INTENSITY FORECAST IS PROBLEMATIC. THE CURRENT SHEAR MAY DECREASE SOMEWHAT OVER THE NEXT 24 HOURS...WHICH WOULD ALLOW KYLE TO GRADUALLY INTENSIFY. AFTER THAT...KYLE IS FORECAST TO ENCOUNTER STRONG...BUT DIVERGENT...UPPER-LEVEL SOUTHWESTERLY FLOW....WITH THE RESULTING SHEAR TRYING TO WEAKEN THE CYCLONE AND THE DIVERGENCE TRYING TO STRENGTHEN IT. WHICH OF THESE INFLUENCES WILL BE THE STRONGEST IS UNCLEAR AT THIS TIME. THE INTENSITY FORECAST CALLS FOR KYLE TO SLOWLY INTENSIFY DURING THE FIRST 48 HR IN AGREEMENT WITH MOST GUIDANCE...BECOMING A HURRICANE IN ABOUT 36 HR. AFTER 48 HR...KYLE IS EXPECTED TO MOVE NORTH OF THE GULF STREAM INTO VERY COLD WATER. WHILE THIS AND THE EXPECTED ONSET OF EXTRATROPICAL TRANSITION SHOULD CAUSE KYLE TO WEAKEN...IT MAY STILL BE OF HURRICANE STRENGTH WHEN THE CENTER REACHES NEW ENGLAND OR THE MARITIMES. AFTER LANDFALL...KYLE SHOULD WEAKEN AND BECOME EXTRATROPICAL...EVENTUALLY BEING ABSORBED IN A FRONTAL SYSTEM. INTERESTS IN EASTERN NEW ENGLAND AND THE CANADIAN MARITIMES SHOULD CLOSELY MONITOR THE PROGRESS OF KYLE. FORECAST POSITIONS AND MAX WINDS INITIAL 26/1500Z 26.4N 68.8W 50 KT 12HR VT 27/0000Z 28.6N 69.4W 55 KT 24HR VT 27/1200Z 31.7N 69.9W 60 KT 36HR VT 28/0000Z 35.5N 69.8W 65 KT 48HR VT 28/1200Z 39.5N 68.7W 70 KT 72HR VT 29/1200Z 46.5N 66.0W 50 KT...INLAND EXTRATROPICAL 96HR VT 30/1200Z 52.0N 62.0W 40 KT...INLAND EXTRATROPICAL 120HR VT 01/1200Z...ABSORBED BY FRONTAL SYSTEM $$ FORECASTER BEVEN |
