Weather Blog

April 1, 2008
     April is severe weather awareness month in the state of Oklahoma. There are three main types of severe weather that generally occur in the average Oklahoma spring. The first and most dramatic of these is a tornado. Tornadoes typically, though not always, form out of a supercell thunderstorm. They can happen at any time of day or night, but are most common in the late afternoon and evening hours. If a tornado watch is issued for your area, you should monitor NOAA Weather Radio or your favorite media source for possible warnings. If a tornado warning is issued for your area, you should proceed to your basement or storm cellar. If you don't have a basement or storm cellar, go to a small room in the center of the first floor of your house. Mobile homes should be abandoned for sturdier structures, as a strong tornado can lift them completely off the ground. The second type of severe weather is a severe thunderstorm. These must have either: winds greater than 58 miles per hour, hail greater than 3/4 inch in diameter (the size of a penny), or have produced a tornado. If a severe thunderstorm watch is issued for your area, it means that there is a chance of severe thunderstorms later. Keep an eye on the weather, but don't get too concerned. If a severe thunderstorm warning is issued, you should stay inside, well away from windows. A vehicle is an acceptable shelter from a thunderstorm; however, remember that most thunderstorms are capable of producing tornadoes, in which case a vehicle is a death trap. The third type of severe weather is flooding. There are two main types of floods: river floods and flash floods. A river flood (often just called a flood) happens when, over a period of time, the amount of water in a river becomes more than the river can hold, and it overflows its banks. This can happen because of repeated rainfall over the same area, or, in some places, because of quickly melting snow. These can take days, weeks, or even months to subside. The other type of flood is a flash flood. A flash flood is so named because it can occur in a flash -- when heavy rainfall passes over an area, it can fill small creeks and streams before they have a chance to drain. It can also cause ponding of water on roads. When water is covering a roadway, you can't tell how deep it is -- it's possible that the entire road has been washed away. It only takes 6 inches of swiftly moving water to knock a man down, and 2 feet to take a vehicle. Remember, "turn around, don't drown".
Sources: Travis Darling, NSSL (picture), NWS (info)
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