February 11, 2003

Does anyone in the midwest remember this strange day in weather? I'd like to see some kind of case study written up about the strange event that day.

A strong alberta clipper passed across Minnesota into Wisconsin during the day. Strong WAA was occurring to the south in IA and surrounding areas. A strong cold front drapped southwest into NE. In the early afternoon a 300 mile long line of convection formed along the front and raced southeastward with the front. It had properties similar to a low topped squall line, but it contained all snow!!! This line of convection raced southeast at over 40mph across IA with numerous lightning strikes showing up on the network. With the passing of the convection visibility was reduced to zero with wind gusts approaching 70mph being reported!


I happened to be off early this day and witnessed the whole event unfold. I waited in anticipation for the band of convection to arrive. I watched in awe as the reports from IA came in. Before the line arrived the sun was out in full force with strong southwest winds gusting to over 40mph. Temps had surged to just above freezing. As the line neared a bank of dark clouds roared in from the northwest. It seemed to have similar characteristics to a line of regular thunderstorms. As the updraft portion came overhead the winds dropped off to nearly calm. It became almost like night as the thick clouds came overhead, you could tell they had some height to them. It was only around 4pm. I could see the lighter looking snow shafts just behind the "snow free base" (lol). Over the horizon I could see the distant trees and buildings disappear into white. Soon an incredible blast of wind containing very large snow flakes hit. The winds gusts were probably over 40mph. Within a minute the winds got even stronger and the snow became VERY instense. The bare ground became dusted literally before my eyes! I have never witnessed snow this intense. Winds gusted between 50-60mph in my estimation. I had to run out in it to secure the garbage cans which went flying down the driveway. I became totally soaked in a matter of moments. I never did hear any thunder. Visibility was reduced to about 100 yards at most. The snow appeared to have a grainy texture, like soft grapal. In less than ten minutes the snow and wind rappidly decreased in intensity with blue skies all across the west again. We picked up nearly 1/2" of snow in less than ten minutes! Strong CAA commenced and by midnight the temps were down into the single digits. Till this day this is one of the strangest and most fascinating weather events I have ever seen.

I would love to see if there's anything written about this event, or similar events like it.
 
I remember the event though I didn't experience it directly nor do I know of any case studies. That line was most certainly convective and intense convection at that, though I'm not sure I'd call it deep moist convection. There was copious amounts of CG lightning detected on by NLDN. Some offices issued severe thunderstorm warnings for the event and took some flack for it. However, I supported it, it was severe and had lightning, period.

In addition to the rare severe convective snow event, there were also widespread snow rollers across Illinois and Indiana. It was quite a remarkable event.

http://www.crh.noaa.gov/ilx/events/roller.htm

Scott
 
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