TWA FLT 524, A BOEING 727-231, WAS EXECUTING AN ILS RWY 22 APCH TO LAGUARDIA AIRPORT WHEN IT ENCOUNTERED LOW LEVEL WINDSHEAR ON FINAL APCH. THE APCH WAS CONDUCTED IN IMC. THE CREW REPORTED THAT THEY BROKE OUT AND OBSERVED THE RWY CENTERLINE LIGHTS AT 100FT ABOVE DECISION HEIGHT. THE APCH WAS STABILISHED UNTIL 50-100FT AGL WHEN THE NOSE SWUNG RAPIDLY TO THE RT TO 242DEG AND A HIGH RATE OF DESCENT DEVELOPED. THE CAPTAIN APPLIED LEFT RUDDER AND FULL POWER BUT WASUNABLE TO ARREST THE DESCENT. FLT 524 TOUCHED DOWN NR THE INTXN OF RWYS 22 AND 13, BOUNCED, RETURNED TO THE RWY SURFACE AND ROLLED OUT ON THE RWY. THE NUMBER 7 AND 8 LEADING SLATS AND THEIR ACTUATORS WERE DMGD. THE RT TIP ALSO EXHIBITED MINOR DMG. THE WIND HAD CHGD FROM 230 DEG/06 KTS WHEN FLT 524 WAS AT THE OUTER MARKER TO 330 DEG/21 KTS GUSTING TO 48KTSSHORTLY AFTER TOUCHDOWN. THE CREW MONITORED THEIR WX RADAR DRG THE APCH AND NOTED A TSTM TO THE RIGHT. AN ACFT AT THE RWY 13 RUNUP PAD REPORTED THAT HEAVY RAIN AND A GUST FRONT HIT JUST PRIOR TO TWA'S TOUCHDOWN.