Monday, April 16, 2012

New Twist to Tornado Warnings

Tornadoes have been in the news a lot lately, both because this season has produced a good many of them, and because the National Weather Service is trying out a new type of tornado warning to people who are in immediate danger. When a tornado’s radar signature is detected, people in Kansas and Missouri will now read and hear warnings that include phrases like “catastrophic,” “extremely dangerous,” “mass devastation,” and “high-end, life-threatening event.” These warnings may have played a role in the fact that while a storm system spawned about 100 tornadoes in Kansas alone last Saturday, no one was reported killed. However, five people died in Oklahoma tornadoes on the same day.

There was a time when even mentioning the word “tornado” in a weather forecast could cost a weatherman his job. Until the late 1940s, tornadoes were regarded as more or less arbitrary acts of God that no one could predict, let alone give responsible warnings about. Consequently, the policy of the U. S. Weather Bureau (as it was known back then) was to not mention tornadoes at all, for fear of causing undue panic in the population.

However, during World War II the military developed its own staff of forecasters, and after the war kept many of them on duty for predicting weather for special purposes, such as predicting weather near military airbases such as Tinker Air Force Base in Oklahoma, where a tornado struck in March of 1948. Five days later, on Mar. 25, weather conditions were so similar to the ones that produced the earlier tornado that Maj. Ernest Fawbush and Capt. Robert Miller issued the nation’s first “official” tornado forecast, warning airbase personnel to make the planes secure and take other precautions. And sure enough, another tornado hit, but this time with minimal damage, owing to the precautions taken in response to the warning.

After that, military forecasters felt free to predict tornadoes if conditions warranted, but for some years afterward, the civilian Weather Bureau maintained its prohibition on tornado forecasts. This split gave rise to an informal “rumor mill” network around military bases when tornadoes were likely and military forecasters predicted them. When a tornado forecast came through military channels, military personnel would call their friends and relatives in the surrounding area and let them know to watch out. Eventually, because of the increasing availability of weather radars to track the storms and better understanding of the atmospheric conditions producing them, the Weather Bureau allowed mention of tornadoes in forecasts, in the form of watches and warnings. A tornado watch simply means conditions are favorable for their formation, while a warning means a tornado has been sighted and immediate precautions are required for people in its path.

We don’t often think of all the technology that is needed to provide up-to-the-minute warnings of tornadoes, but there’s a lot involved. Besides the conventional weather instrumentation on the ground, there are weather satellites that provide huge amounts of detailed data on large-scale movements of weather systems. Supplement that with both the National Weather Service’s radars and private radars operated by media outlets, most of which are modern Doppler units that can measure wind speed and direction within a storm. Couple those sources of information with the Internet, wireless phones, PDAs, iPhones, people watching live weather-radar feeds on their computers, and so on, and you have a lot of technology in the service of letting people know a tornado is coming.

As time has passed and the National Weather Service has gotten more confident in its predictions, people are getting perhaps a little complacent about tornado warnings, which may explain the experiment to hype the verbiage in the warnings. Of course, it’s not really possible to “hype” a tornado: death and destruction are death and destruction, after all. But tornado warnings are to be taken seriously, and the latest change seems to be paying off in the reduced number of fatalities. One death is still too many, and there are some people who are simply caught by a tornado in the wrong place at the wrong time. But for anyone in a fairly sturdy structure, heading for an interior closet or bathroom and covering up can mean the difference between life and death.

Growing up in Texas, I was familiar with the idea of tornadoes both from stories I heard from my relatives of twisters they’d seen or heard about in Dallas and Waco, and from radar images of tornadoes tracked by an early weather radar our local NBC outlet, WBAP-TV, maintained as long ago as the early 1960s. It was my privilege once to tour the studios around that time, and what I wanted to see most was the weather radar. I was disappointed to find that the actual screen was a little bitty thing only about four inches in diameter. It was an old World War II surplus set that the station had adapted for weather service. But it did its job until more sophisticated commercial units came along.

For anyone who watches the Weather Channel or bombs around on YouTube, tornadoes are no longer unfamiliar and almost mystically malevolent objects. We have seen dozens of videos made by storm-chasers with more curiosity than prudence, and can be as familiar as anybody can be of a phenomenon that you haven’t actually encountered in person. Still, a tornado on the ground is something you don’t want to mess with, and I for one am glad we have all the advanced machinery at our disposal to keep an eye on the sky for the next twister.

Sources: The online New York Times carried an article about the new verbiage in tornado warnings on Apr. 15, 2012 at The National Oceanic and Atmospheric Administration has a nice history of early tornado forecasting, including the Tinker Air Base story, at For a more in-depth look at tornado forecasting in the U. S., see historian Marlene Bradford’s book Scanning the Skies: A History of Tornado Forecasting (Norman, OK: Oklahoma Univ. Press, 2001).

No comments:

Post a Comment