Steel, Storms, and the St. Louis Arch
Cameron Barnes. Grade 12
Since 1963, local Mascoutahians have been noticing the same, curious thing when they turn on the weather channel: snow showers, storms, and other exciting meteorological phenomena appear to always split around the area of St. Louis. The “split” creates a pocket of seemingly better weather predictions for the surrounding communities, much to a winter school goers’ remorse. After years of this occurrence, the event has even been given a name: The Arch Effect.
Believers argue that the height of the St. Louis Arch creates a disturbance in weather patterns that protects the city and its suburbs with a blanket of milder weather. It seems evident to anyone who turns on the morning news and tracks the progression of a storm with the doppler radar. But, is it true? Have the architects of previous generations bestowed upon us an industrial, climatic gift, or is it all in our heads?
The truth is: kind of. Yes, it is true that on weather radars, storms seem to avoid St. Louis like the plague. However, there is no pocket of safety from a storm, and the phenomenon has more to do with the location of the radar than the height of the Arch. Dan Statterfield*, an air meteorologist from Florida, puts it this way: “Water covered ice is a very good reflector of radar energy, and this area of the storm will show up very bright on the radar. As the line of storms gets closer, the [radar] beam will be showing the lower regions of the storm, where there is usually just rain . . . The result, a line of intense storms 60 miles away will look intense as it approaches the radar.”
What Statterfield is getting at is that the beams of radars (used in doppler weather forecasting) have a broader field of effectiveness the farther away it goes from the origin. So, in rain and snow storms, the accumulation is reflected less the closer it is to where the radar came from. Since weather centers are usually in large cities, these cities are the origin for the radar. In effect, it appears on the doppler that storms are not as severe in these communities. St. Louis, it seems, is no exception.
Though the Arch Effect may not be completely real, the winter weather in Illinois certainly is. Remember to keep warm and dry this season, no matter what the doppler radar says.
* For more information, check out the rest of Statterfield’s article: https://blogs.agu.org/wildwildscience/2010/12/08/the-st-louis-arch-and-splitting-squall-lines/
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