Weather a major challenge for marathon runners

The LaSalle Bank Chicago Marathon runners face much more than a 26 mile challenge today. Starting this morning, strong winds will steer cold northern Canadian-source air into Chicago. As the morning progresses, diminishing rains will gradually change over to wet snow flurries.
Start time temperatures will be in the lower 40s and fall into the upper 30s by noon with associated wind chills dropping out of the 30s into the upper 20s. Winds may be the biggest aide and at the same time the largest obstacle. Flowing out of the northwest, 30 to 40 m.p.h. winds above the surface will slam into buildings along the route, sliding down the face of tall structures funneling even stronger flow down some streets. Stretches of other avenues may experience periods of almost eerie calm. Winds will be at the backs of runners on east and south legs and present a very intimidating headwind for those headed west and north.
-Paul Dailey WGN-TV Meteorologist