Severe snow thunderstorms in Illinois - February 12, 2003
 
 

While perusing the College of Dupage NWS text website, I was somewhat surprised to see this severe weather statement come out. It's not every day that you see snow thunderstorms accompanied by severe winds. I caught the radar loop a bit late for the region but it still shows the nature of these storms as appearing to be the tail end of an Alberta Clipper.

  The question I had was, how much of the severe winds came from synoptic flow? Looking at the 850mb map showed some pretty intense winds already. It wouldn't take much to bring those winds down.
  The Lincoln, IL sounding showed some pretty steep lapse rates just off the surface but nothing in the way of convective instability given what's seen here. Maybe the sounding was not exactly in the convergence zone of the frontal system.
  Unfortunately, I grabbed this image at 02 UTC. The cold front has passed Lincoln's area. But along the front there is a narrow dewpoint ridge with values approaching 30° F. It's still not enough to launch an updraft according to Lincoln's parcel. The frontal lifting probably modified the sounding enough in a really narrow wedge.
 

The storm reports are listed below

PRELIMINARY LOCAL STORM REPORT NATIONAL WEATHER SERVICE LINCOLN, IL 624 PM CST TUE FEB 11 2003 TIME(CST) .....CITY LOCATION.....STATE ...EVENT/REMARKS... ....COUNTY LOCATION.... 0545 PM GALESBURG IL 53 MPH TSTM WIND GUST 02/11/03 KNOX THUNDERSTORM WIND GUST WITH SNOW TO 61 MPH AT THE GALESBURG AIRPORT. IN ADDITION...LIGHT POLES AND POWER POLES BLEWN DOWN IN GALESBURG. FROM ILLINOIS STATE POLICE. GOETSCH

 
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