Expert: Donald Rosenfeld - 12/23/2000

Question
Hi,
  I have a few questions. Last week I watched an f3 tornado devistate a neighborhood and it has peaked my curiosity. Is it true that tornadoes follow or seem to follow rivers and creeks.I have always heard this. This storm did seem to follow a creek or the river at all times.
  Is it possible though that when it crossed the river it intensified because of the river.
  It has always been said by the weather stations that tornadoes in alabama cant be seen as well as those in the midwest and I can buy that because of all the mountains and hills in my area. The weather forcasters say that it is impossible to see one unless you are behind the storm but even those that were hit saw it coming.(probably not good because it was exceptionaly fast moving for a tornado most did not have enough time to react) Any way as I was asking is there a reason that they are harder to spot here in alabama.
I know these are strange questions but I want to learn about these storms. I would appreciate any thing you can tell me about them.
thanks
Lori

Answer
Hi Lori:

It sounds, from your questions/observations, that you could answer your own questions!

"I have a few questions. Last week I watched an f3 tornado devistate a neighborhood and it has peaked my curiosity. Is it true that tornadoes follow or seem to follow rivers and creeks.I have always heard this.T his storm did seem to follow a creek or the river at all times.

Is it possible though that when it crossed the river it intensified because of the river."

Tornadoes, once created, seek the path of least resistance, thus a path along a river, being flat, would be the preferred track.

Hurricanes thrive on ocean moisture- tornadoes do not need additional moisture. Water sucked up from a river or lake actually slow down the wind speeds in tornadoes.
                
"It has always been said by the weather stations that tornadoes in alabama cant be seen as well as those in the midwest and I can buy that because of all the mountains and hills in my area."

It is true.

"The weather forcasters say that it is impossible to see one unless you are behind the storm but even those that were
hit saw it coming.(probably not good because it was exceptionaly fast moving for a tornado most did not
have enough time to react) Any way as I was asking is there a reason that they are harder to spot here in alabama."


It is true that it is easier to see a tornado leaving than one coming: reason is that the rainfall in the thunderstorm is very dense at the leading edge of a thunderstorm thus masking the tornado.

For more on tornadoes, see:

http://www.spc.noaa.gov/faq/tornado/

rosenfeld@mediaone.net