It is better to keep abreast of the current conditions and find shelter well in advance of a severe storm. These days it is not hard to do and its better then finding yourself out in a storm in the open and on a bike... There are a lot of dangerous things other then tornadoes that could ruin your day. Hail, wind, and lightning are far more likely to ruin your day! As for me if I'm riding toward an ominous looking cloud my preference is to turn around and go back to the nearest town if possible. Better to be in a restaurant enjoying a cup of coffee then enduring a cold wet storm!!!

One night about 7 years ago I was riding home from work in a very active electrical storm!!! That was very scary for me... I actually stopped at acquaintances home and asked to stay there until the storm was over.

As far as biking and tornadoes My personal decision would be to drive the bike into the ditch and lay it down... This is a far better idea then parking it along the road and allowing it to spill there or worse - Becoming storm debris! This would be only if the hit was inevitable...

I have been a storm chaser for NOAA for around 10 years and have only observed 5 tornadoes in my lifetime... The other 2 were not observed by me as they were at night and passed within 1/4 mile of me. Those were the worst! I know how to observe these storms relatively safely - usually LOL.

Yes, there can be a funnel effect under bridges that can and do amplify the winds strength!!!

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Most of All... Have Fun!

Bruce... kb0pgo