AS THE PLT WAS TAXIING TO TAKEOFF, THE TOWER ADZD HIM THAT WIND SHEAR ADVISORIES WERE IN EFFECT. AT APRX 1359, HE WAS CLRD FOR TAKEOFF ON RWY 31. AT THAT TIME, THE WIND WAS FROM 280 DEG AT 18 KTS. DRG TAKEOFF, THE ACFT WAS CLIMBING THRU ABOUT 300 TO 500 FT, WHEN THE PLT DECLARED AN EMERGENCY. HE WAS CLRD TO LAND ON ANY RWY. HE TURNED BACK TO THE ARPT & ATMTD TO LAND IN THE OPPOSITE DIRECTION. THE PLT SAID HE MADE A DSCNDG TURN, BUT COULD NOT GET ALIGNED WITH THE RWY. HE STATED THAT THE DSCNDG TURN 'SEEMED TO GO WELL UNTIL BETWEEN 50 & 25 FT AGL, THEN THE PLANE DARTED LEFT & DOWN UNTIL IMPACT.' SUBSEQUENTLY, THE ACFT IMPACTED THE GND IN A LEVEL ATTITUDE APRX 100 FT LEFT OF RWY 13, NEAR THE APCH END. AFTER THE ACDNT, THE PLT RPRTD HE THOUGHT HE HAD LOST RUDDER CTL DRG THE CLIMB-OUT & ELECTED TO LAND ON THE CLOSEST RWY. HOWEVER, AN EXAM OF THE ACFT AFTER THE ACDNT REVEALED THAT ALL FLT CONTROL SYSTEMS, INCLUDING THE RUDDER CONTROL, WERE OPERATING NORMALLY. THE PLT RPRTD THE WIND WAS FROM 280 DEG AT 16 GUSTING 30 KTS.