Tropical Storm KYLE

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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
 
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