Being from Oklahoma I can give you a bit of an insight of a pending Tornado on the ground.
Top 10 list of an inpending Tornado....
1. Horrific storm. Sideways rain. The house begins to move.
2. Sudden drop in temperature and hail.
3. Drop in pressure... if yer ears are popping, here's yer sign.
4. Bodies of severed Cows located high up in bent over trees.
5. Spinning chickens and other displaced farm animals.
6. Here comes the train... BTW notice no Railway tracks are within miles from you.
7. Some stupid girl calling out for Auntie Em.
8. Toto barks incessantly.
9. Flying Monkeys..... *shivers*
And last but not least on the Top Ten signs of an inpending Tornado...
10. Rosie O'Donnel first appears riding a bicycle and it turns into a broom.
Mac