BRUSSELS/PARIS - An overnight snowstorm in northwestern Europe forced the closure of Frankfurt Airport, caused record traffic jams in Belgium, and left British and French drivers sleeping in their cars.Take-offs and landings at Europe's third-busiest airport were halted at around noon on Tuesday to clear snow from the runways. It was set to reopen at around 1230 GMT.In France, a Tunisair plane slid off the runway on landing at Orly airport, forcing the closure of a runway at Paris's second hub while 140 passengers were evacuated.In Belgium, the breakdown assistance association Touring said the total length of tailbacks on highways and major roads at their rush-hour peak hit 1,670 km (1,038 miles), beating by far the previous record of 1,285 km set on February 3 last year.