Depending on how fast you ride there is a very good chance you will in the middle of tornado season in Kansas and Missouri. While you stand a pretty good chance of missing a tornado, they are usually accompanied by severe storms with major hail (1-1.5" is common) and tremendous rain/lightening.
I am not saying don't do it, but be educated and prepared. Learn how to read the weather clouds, ask the locals, and bring a small AM radio. A weather radio is nice but it can be a pain by warning you of everything. With an AM radio, the broadcasts are much more specific, i.e "A tornado is down 16 miles SSE of Girard, KS and heading NE at 28mph. The storm will hit the following towns: McCune 4:24pm, Beulah 4:47pm,...." They are pretty accurate but they do gt excited at times.
One great weather sign is that if the birds are flying/singing it is OK even if it looks bad. If cows are flying, it is not good weather outside
. Serious about the birds though.
If a storm is on the way, take shelter. Do not be embarrassed to ask at a farm house. The people are very friendly in this part of the country, especially to the British and Australians (we love the accent!). While you can miss a tornado by as little as a 1/10 of a mile and be fine, hail is much harder to miss.
Wishing you an enjoyable trip and that the twins are not early!