Mother's Day of 2008 won't exactly be remembered for its picnic-prime weather in the St. Louis area. From severe thunderstorms Saturday evening to remarkable winds Sunday, the weekend weather was just plain ugly -- sorry Mom!
Saturday started with some promise. Sunshine was breaking through the clouds, and temperatures were fairly mild, but by mid-afternoon, rain and thunderstorms had moved into eastern Missouri and western Illinois. A handful of severe thunderstorm warnings, and even a couple of tornado warnings, were issued across our viewing area, mainly after dark Saturday evening. Thankfully, reports of damage were nearly nonexistent after these storms rumbled through the News4 viewing area.
The strong storms were only the beginning of a meteorologically interesting weekend. Behind the storms, winds shifted out of the west and northwest overnight Saturday night into Sunday morning. By the time most people were waking up Sunday morning, sustained winds were blowing between 35 and 45 miles per hour. It's not at all unusual for us to see wind gusts in that range, but to see a sustained wind blowing that hard is uncommon. By Noon Sunday, many locations in and around metropolitan St. Louis had recorded wind gusts in the mid-50 mile per hour range. I'll list a few of the more amazing gusts below.
The strong winds joined forces with very wet soil to topple numerous large trees in our area Sunday. From Hannibal to St. Louis, MO, from Belleville to Bethalto, IL, the reports of downed trees, limbs, and power lines covered nearly all of our viewing area. Some roads were even closed beacuse they were so littered with trees and limbs.
So, what causes winds to blow this strongly? When you stand outside and feel the wind, you're actually feeling air move from one place to another. Typically, the air you feel passing by is moving away from an area of higher pressure toward an area of lower pressure, just like air rushing out of a punctured tire. This pressure gradient, as we call it, is the basic answer to the age old question, "What makes the wind blow?" The tighter that pressure gradient (the greater the pressure change over a given area), the stronger the wind.
The wind speeds Sunday were remarkable. The sustained wind at Lambert Field at 7:00 AM was an amazing 40 miles per hour. That wouldn't be uncommon near a thunderstorm, but on an overcast day with a few passing showers, that is out of the ordinary. Here is a preliminary list of the strongest measured wind gusts from automated surface observation stations across our area...
Scott Air Force Base: 55 MPH
Lambert Field: 55 MPH
Litchfiled, IL: 54 MPH
St. Charles, MO: 54 MPH
Sparta, IL: 47 MPH
Salem, IL: 47 MPH
Spirit of St. Louis Airport (Chesterfield, MO): 47 MPH
Cahokia, IL: 45 MPH
As part of News4's Live WeatherBug Network, we have a set of weather observation equipment at Highland Middle School (in Highland, IL). Our wind sensors there recorded a gust to 56 miles per hour, the highest I've yet to see in our area from this weekend after sorting through all the data.