Delta B763 at Buenos Aires on Jan 21st 2014, turbulence rips off slat

A Delta Airlines Boeing 767-300, registration N191DN performing flight DL-101 (dep Jan 20th) from Atlanta,GA (USA) to Buenos Aires Ezeiza,BA (Argentina), was on approach to Buenos Aires when the aircraft encountered severe turbulence prompting the crew to initiate a go around at about 4500 feet MSL. A slat departed the aircraft's right hand wing. The crew diverted to Montevideo (Uruguay) for a safe landing on runway 06 about 30 minutes later.

Passengers reported seeing sparks, possibly lightning, and a part flying off the right hand wing.

Metars Buenos Aires:

AEZ 211200Z 16003KT 2900 -TSRA BR SCT030 FEW050CB OVC100 20/20 Q1005

SAEZ 211100Z 22023G35KT 190V260 2900 TSRA FEW005 FEW040CB SCT030 BKN050 20/20 Q1003

SAEZ 211100Z 22023G35KT 190V260 2900 TSRA FEW005 FEW040CB SCT03 0 BKN050 20/20 Q1003

SAEZ 211043Z 25032G48KT 210V280 2900 TSRA FEW003 SCT030 FEW040CB BKN050 22/20 Q1004

SAEZ 211035Z 25035KT 6000 TSRA FEW030 FEW040CB BKN050 26/22 Q1003

SAEZ 211000Z 34010KT 300V020 9999 TS FEW050CB BKN200 28/22 Q1000

SAEZ 210900Z 36010KT 300V050 9999 TS FEW050CB SCT100 28/22 Q0999

SAEZ 210836Z 01011G23KT 320V030 9999 TS FEW050CB SCT200 28/22 Q0999

SAEZ 210800Z 36010KT 310V040 9999 VCTS FEW050CB SCT200 28/22 Q1000

SAEZ 210700Z 34010KT 330V010 9999 VCTS FEW050CB 28/21 Q1000