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| #218715 (Received by flhurricane at: 5:05 AM 26.Sep.2008) TCDAT1 TROPICAL STORM KYLE DISCUSSION NUMBER 3 NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL AL112008 500 AM EDT FRI SEP 26 2008 AN AIR FORCE RESERVE RECON AIRCRAFT FOUND 850 MB SLIGHT-LEVEL WINDS OF 63 KT IN THE NORTHEAST QUADRANT...WHICH IS ROUGHLY EQUAL TO A 47-KT SURFACE WIND. HOWEVER...SFMR SURFACE WINDS OF 50 AND 53 KT WERE MEASURED BENEATH THE MAXIMUM FLIGHT-LEVEL WINDS...SO A BLEND OF THESE VALUES YIELDS AN AVERAGE SURFACE WIND SPEED ESTIMATE OF 50 KT. THIS WIND SPEED ESTIMATE IS ALSO CONSISTENT WITH THE PRESSURE-WIND RELATIONSHIP ASSOCIATED WITH THE 997 MB CENTRAL PRESSURE THAT WAS MEASURED BY A DROPSONDE. RECENT AIRCRAFT AND SATELLITE FIXES INDICATE THE MOTION IS NOW 350/10 KT. AS HIGH PRESSURE/RIDGING CONTINUES TO BUILD TO THE NORTHEAST OF KYLE...THE CYCLONE IS EXPECTED TO TURN MORE TOWARD THE NORTH-NORTHWEST OVER THE NEXT 24-36 HOURS. AFTER THAT...A TURN BACK TOWARD THE NORTH WITH EVENTUAL RECURVATURE TO THE NORTHEAST IS FORECAST BY ALL OF THE GLOBAL MODELS. HOWEVER...THE FORECAST TRACK IS NOT AS STRAIGHTFORWARD AS THAT. ALTHOUGH THE MODELS ARE TIGHTLY CLUSTERED THROUGH 72 HOURS...THERE REMAINS ENOUGH UNCERTAINTY IN EXACTLY WHEN AND WHERE THE POINT OF RECURVATURE WILL OCCUR. 00Z UPPER-AIR HEIGHT DATA FROM BERMUDA WAS IN ERROR TO DUE A BAD BASELINE...BUT THE 00Z MODELS APPEAR TO HAVE FILTERED OUT THIS ERRONEOUS MASS FIELD DATA. HOWEVER...THE WIND DATA WAS GOOD...AND THE BACKING WIND FLOW FROM SOUTH TO SOUTHEAST INDICATES THAT RIDGING COMING IN FROM THE NORTHEAST IS A LITTLE STRONGER THAN THE MODELS HAVE BEEN FORECASTING. ALSO...ALL OF THE GLOBAL AND REGIONAL MODELS ARE FORECASTING AN OMEGA BLOCKING PATTERN TO DEVELOP OVER THE CENTRAL ATLANTIC BETWEEN THE LOW CURRENTLY OVER SOUTHEASTERN U.S. AND A MUCH LARGER LOW FORECAST TO DEVELOP WEST OF THE AZORES. SINCE OMEGA BLOCKS ARE GENERALLY STABLE PATTERNS...THE MODELS MAY BE BREAKING DOWN THE NORTHERN PORTION OF THE RIDGE SOUTH OF NOVA SCOTIA TOO QUICKLY...WHICH WOULD RESULT IN PREMATURE RECURVATURE BY THE MODELS. AS A RESULT...THE OFFICIAL TRACK FORECAST HAS BEEN SHIFTED TO THE WEST OF THE PREVIOUS TRACK...AND IS CLOSE TO THE NHC MODEL CONSENSUS. SUBSEQUENT FORECAST TRACKS MAY ALSO HAVE TO BE SHIFTED A LITTLE FARTHER WEST AND CLOSER TO THE U.S. CAPE COD AREA SIMILAR TO THE 00Z GFS...GFDL...HWRF...NOGAPS...AND CANADIAN MODEL RUNS. ONLY THE UKMET AND ECMWF KEEP KYLE WELL TO THE EAST OF THE NORTHEASTERN U.S. SHEARED DEEP CONVECTION WITH CLOUD TOPS COLDER THAN -80C IN THE NORTHEAST QUADRANT HAVE STARTED TO DEVELOP CLOSER TO THE LOW-LEVEL CENTER. ONCE KYLE TURNS MORE TOWARD THE NORTH-NORTHWEST...THE VERTICAL CIRCULATIONS ARE EXPECTED TO BECOME VERTICALLY STACKED AND MORE ALIGNED WITH THE DEEP LAYER FLOW. THIS SHOULD ALLOW FOR STEADY INTENSIFICATION TO OCCUR OVER RELATIVELY WARM WATER UNTIL KYLE REACHES THE NORTH WALL OF THE GULFSTREAM IN ABOUT 48 HOURS. ALTHOUGH MUCH COOLER WATER LIES NORTH OF GULFSTREAM...THE FAST FORWARD SPEED OF THE CYCLONE SHOULD INHIBIT ANY SIGNIFICANT DECREASE IN INTENSITY UNTIL LANDFALL OCCURS. THE OFFICIAL INTENSITY FORECAST IS SIMILAR TO THE PREVIOUS FORECAST...AND IS CLOSE TO THE SHIPS AND GFDL MODELS...BUT NOT AS STRONG AS THE HWRF MODEL. INTERESTS IN EASTERN NEW ENGLAND AND THE CANADIAN MARITIMES SHOULD CLOSELY MONITOR THE PROGRESS OF KYLE. FORECAST POSITIONS AND MAX WINDS INITIAL 26/0900Z 25.6N 68.3W 50 KT 12HR VT 26/1800Z 27.5N 68.8W 55 KT 24HR VT 27/0600Z 30.5N 69.5W 60 KT 36HR VT 27/1800Z 34.0N 69.8W 65 KT 48HR VT 28/0600Z 38.5N 69.0W 70 KT 72HR VT 29/0600Z 45.7N 66.3W 60 KT...EXTRATROPICAL INLAND 96HR VT 30/0600Z 51.0N 61.0W 50 KT...EXTRATROPICAL INLAND 120HR VT 01/0600Z...ABSORBED BY FRONTAL SYSTEM $$ FORECASTER STEWART |
