000
WTNT41 KNHC 270856
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