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| #218922 (Received by flhurricane at: 4:58 AM 27.Sep.2008) TCDAT1 TROPICAL STORM KYLE DISCUSSION NUMBER 7 NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL AL112008 500 AM EDT SAT SEP 27 2008 AIR FORCE RECON REPORTS INDICATE LITTLE CHANGE IN THE STRENGTH AND STRUCTURE OF KYLE DURING THE PAST 6 HOURS. THERE WERE TWO REPORTS OF 70 KT AT 850 MB FLIGHT-LEVEL IN THE NORTHEAST QUADRANT...WHICH WOULD TYPICALLY CORRESPOND TO ABOUT 55 KT SURFACE WINDS. SFMR WINDS IN THAT SAME AREA ALSO ONLY SUPPORT ABOUT 55 KT. HOWEVER...THE MAXIMUM FLIGHT-LEVEL WINDS OCCURRED ABOUT 30 NMI NORTHWEST OF THE MOST INTENSE CONVECTION...SO IT IS POSSIBLE THAT STRONGER WINDS MAY HAVE BEEN MISSED ALONG THE NORTHEAST FLIGHT LEG. THE HIGHER LATITUDE AND INCREASING PRESSURE GRADIENT TO THE EAST ALSO SUPPORTS KEEPING THE INTENSITY A LITTLE HIGHER THAN WHAT THE STANDARD PRESSURE-WIND RELATIONSHIP FOR A 996 MB PRESSURE WOULD SUPPORT. KYLE HAS MADE A SHORT TERM JOG TO THE NORTHWEST...OR 330 DEGREES AS A MID- TO UPPER-LEVEL SHORTWAVE TROUGH HAS PASSED TO THE NORTHWEST OF THE CYCLONE. HOWEVER...A 9-HOUR AVERAGE MOTION YIELDS 345/14... AND THAT IS WHAT WAS USED FOR THIS ADVISORY. KYLE REMAINS WEDGED BETWEEN A LARGE DEEP-LAYER RIDGE TO THE EAST AND A DEEP-LAYER BUT WEAKENING LOW TO THE WEST OVER WESTERN NORTH CAROLINA. THE COMBINED SOUTHERLY TO SOUTH-SOUTHEASTERLY FLOW BETWEEN THESE TWO SYSTEMS IS EXPECTED TO GRADUALLY ACCELERATE KYLE NORTHWARD TODAY AND THEN NORTH-NORTHEASTWARD ON SUNDAY. ALTHOUGH THE GLOBAL MODELS REMAIN TIGHTLY CLUSTERED...THE VARIOUS SURFACE TRACKS HAVE SHIFTED SLIGHTLY WESTWARD DUE TO THE RIDGE TO THE EAST BEING STRONGER THAN THE MODELS HAVE BEEN FORECASTING OVER THE PAST 24 HOURS. HOWEVER... SOME UNCERTAINTY STILL REMAINS ON THE EXACT TIME AND LOCATION OF RECURVATURE OF KYLE TO THE NORTHEAST. IF THE EXPECTED TURN TOWARD THE NORTH-NORTHEAST IS DELAYED BY JUST 6 HOURS ...THEN KYLE WOULD PASS CLOSER TO CAPE COD THAN INDICATED BY THE OFFICIAL FORECAST. WATER VAPOR IMAGERY INDICATES THE RIDGE TO THE EAST OF KYLE CONTINUES TO AMPLIFY NORTHWARD OVER THE NORTHEASTERN U.S. AND THE CANADIAN MARITIMES REGION. IF THIS TREND CONTINUES IN CONTRAST TO WHAT THE MODELS ARE FORECASTING...THEN SUBSEQUENT FORECAST TRACKS WILL HAVE TO BE SHIFTED WESTWARD AND CLOSER TO EASTERN NEW ENGLAND. AS A RESULT...WATCHES OR WARNINGS MAY BE REQUIRED FOR PORTIONS OF THE COASTAL NEW ENGLAND AND CANADIAN MARITIMES REGION LATER THIS MORNING. THE OVERALL CONVECTIVE PATTERN HAS IMPROVED...EVEN THOUGH CLOUD TOPS HAVE WARMED. ONE MID- TO UPPER-LEVEL SHORTWAVE THAT PASSED TO THE NORTHWEST OF KYLE LATE YESTERDAY ALLOWED THE CYCLONE TO BRIEFLY INTENSIFY. ANOTHER SHORTWAVE TROUGH LOCATED ALONG 30N LATITUDE IS LIFTING NORTHWARD AS NOTED IN WATER VAPOR IMAGERY. ONCE THIS SYSTEM PASSES TO THE NORTHWEST OF KYLE AND RELIEVES PRESSURE ON THE WEST SIDE OF THE CYCLONE...AN INTENSIFICATION PHASE SHOULD RESUME AND KYLE IS EXPECTED BECOME A CATEGORY 1 HURRICANE LATER TODAY. THE OFFICIAL INTENSITY FORECAST IS ONLY SLIGHTLY HIGHER THAN THE PREVIOUS FORECAST...AND IS A BLEND OF THE ICON...SHIPS...AND THE GFDL MODELS. FORECAST POSITIONS AND MAX WINDS INITIAL 27/0900Z 30.5N 69.4W 60 KT 12HR VT 27/1800Z 33.0N 69.7W 65 KT 24HR VT 28/0600Z 36.8N 69.4W 70 KT 36HR VT 28/1800Z 41.0N 68.4W 70 KT 48HR VT 29/0600Z 44.9N 66.7W 60 KT...BECOMING EXTRATROPICAL 72HR VT 30/0600Z 50.5N 64.0W 40 KT...EXTRATROPICAL INLAND 96HR VT 01/0600Z...ABSORBED BY FRONTAL SYSTEM $$ FORECASTER STEWART |
