Strong south winds ushered in unseasonably mild air northward into the region today. The first satellite image below was taken Saturday afternoon and shows extensive snow cover over northern Illinois extended south to Peoria, Bloomington and east into northwest Indiana.
As temperatures warmed into the 50s today the snow began to rapidly melt and the next satellite image shows what was left of the snow cover by around 1:30 PM CDT this afternoon! Notice all of the snow in the city of Chicago and south of I-88 and I-290 is completely gone! The only snow cover that was left was near the Wisconsin border!
The next several images are courtesy of the National Operational Hydrologic Remote Sensing Center (NOHRSC). The first image shows model calculated snow depth from Sunday afternoon based on recon flights and satellite imagery. The light gray area is estimated snow depth up to 2", while the first shade of light blue is between about 2" and 4" of snow depth.
The next image is an estimation of how much snow is left this evening based on the remote sensing and modeling techniques employed by NOHRSC. Notice that this next image confirms what we saw on the 2nd satellite image above, which is nearly all the snow over northern Illinois is gone, save for the Wisconsin border area.
Now the following image is an estimate of 24 hour snow depth change between Monday evening and Sunday evening. The orange areas are where snow depth decreased by approximately an inch and a half, while the darker orangish red area is where snow depth decreased by 2" or more!
Finally, this image is an approximation of the snow pack temperature. The areas in red are where the temperature of the snow is right around 32F, indicating it is melting or would melt very quickly as temperatures climb above freezing. As temperatures climb into the 50s and possibly even 60s Tuesday it is very likely most if not all of the snow in Illinois will be melted by Tuesday evening.
The information provided by NOHRSC is extremely valuable to hydrologists and is used in predicting how snow melt will impact river levels. This information is supplied to hydrologists who then input into their river models to help produce more accurate river forecasts.