Skilling: Analysis of where snow fell Thursday

Good Friday! Here’s a set of great Friday morning satellite view of the snow which fell with Thursday’s storm. The fresh cover of snow shows up clearly thanks to the clearer skies behind the departed storm. Images like these offer view of the area impacted by storm’s like Thursday’s.

From my National Weather Service-Chicago colleagues come this analysis of the snowfall and ice produced by Thursday’s winter storm

I’m posting analyses of where and how much snow fell.

My WGN meteorological colleagues Mark Carrol has broken out 24 hour snowfall reports from COCORAHS observers covering the period through 6am CST Friday morning. Note that lake-enhanced snows ended up totaling 1 to 3.6″ across northwest Indiana overnight:

Harvard 4.4 NNE 4.9
Marengo 0.7 NNW 3.8
Buffalo Grove 1.5 N 3.6
Geneva 3.9 WSW 3.5
Mundelein 1.6 WNW 3.5
Hoffman Estates 4.6 W 3.0
Hoffman Estates 1.6 SE 3.0
Lake Villa 1.1 SSW 3.0
Mundelein 0.5 NNE 3.0
Algonquin 0.7 N 3.0
Spring Grove 1.2 ESE 2.9
Cary 0.5 SSW 2.7
Bull Valley 2.5 WNW 2.6
Woodstock 3.8 SW 2.6
Palatine 1.2 NW 2.5
Riverwoods 0.4 ENE 2.5
McHenry 2.4 E 2.5
Algonquin 1.4 WSW 2.5
Lincolnwood 1.8 E 2.4
Schaumburg 2.0 E 2.4
Rogers Park 1.5 SW 2.4
Cary 0.3 NE 2.4
Crystal Lake 1.0 WSW 2.4
Palatine 1.3 E 2.1
Elgin 2.5 W 2.1
Sleepy Hollow 0.7 W 2.1
Bannockburn 0.5 ESE 2.1
Elk Grove Village 2.2 WSW 2.0
Harwood Heights 0.4 NNE 2.0
Mount Prospect 0.2 NNE 2.0
Naperville 2.4 SE 2.0
St. Charles 6.0 NW 2.0
Highwood 0.9 S 2.0
Elgin 1.0 S 1.8
Elk Grove Village 0.6 ESE 1.7
Palatine 1.4 NNE 1.5
Wheaton 2.0 NNE 1.5
Villa Park 0.8 ESE 1.5
Geneva 1.3 NW 1.5
Franklin Park 0.5 SSE 1.4
West Chicago 3.5 SE 1.3
Oak Lawn 0.5 SSW 1.2
Aurora 3.8 SE 1.2
North Aurora 1.5 NE 1.2
St. Charles 0.1 E 1.2
Lombard 1.2 E 1.1
Wheaton 0.8 WNW 1.1
Geneva 1.0 SSW 1.1
Batavia 1.5 WNW 1.1
Batavia 0.8 W 1.1
Aurora 3.6 SE 1.0
Burr Ridge 1.9 SW 1.0
Geneva 1.3 SSW 1.0
Aurora 3.5 ESE 1.0
Aurora 2.8 WSW 1.0
Plainfield 4.8 SW 1.0
Oswego 1.1 ESE 1.0

NW INDIANA

St. John 2.8 SE 3.6
Crown Point 1.1 N 3.3
Valparaiso 0.9 NNW 2.8
St. John 0.2 WSW 2.7
Porter 0.6 S 2.3
Dyer 1.0 WNW 2.2
Hebron 3.7 NE 2.0
Chesterton 3.9 ESE 2.0
Chesterton 1.4 ENE 1.8
La Porte 1.6 SW 1.7
De Motte 0.8 NNW 1.6
De Motte 4.1 SW 1.5
Gary 4.8 ENE 1.5
Valparaiso 4.3 SW 1.5
Valparaiso 5.5 SSW 1.2
De Motte 5.9 S 1.0
De Motte 1.2 SSW 1.0
Hobart 2.4 SE 1.0

NOTE: I’ve been asked how to read the numbers reported by COCORAHS observers as presented above. The distance in miles from the towns/cities listed above is the first number you see with each reported. The number of inches of snow which is being reported is the second number in each report above. Thus–the first line in the table above which reads:

“Harvard 4.4 NNE 4.9”

Means this snow measurement was taken 4.4 miles north/northeast of Harvard–and 4.9″ of snow fell there.

Full forecast details at the WGN Weather Center

The National Weather Service produces this analysis of the snow on the ground modeled from available observations.

Also interestingly, Mark Carroll has broken out some of the heavier two day snowfall tallies across northern Illinois from COCORAHS volunteer observers in the area. The storm produced as much as 11+” of snow as close-by as Iowa and you can see from from COCORAHS snowfall map the 7″+ totals which blanketed sections of southern Wisconsin with the storm.

IL-JD-8 Stockton 3.4 NNE 6.1
IL-JD-6 Hanover 0.2 NW 6.0
IL-JD-11 East Dubuque 1.7 SE 5.8
IL-SP-7 Davis 0.5 N 5.6
IL-WN-48 Rockford 3.8 NNW 5.6
IL-MCH-103 Harvard 4.4 NNE 4.9
IL-CR-22 Lanark 4.2 NNW 4.1
IL-BN-14 Capron 0.1 N 3.9
IL-BN-19 Belvidere 5.0 NNW 3.8

AN INTERESTING NOTE: Check out the water equivalent precipitation values from COCORAHS observers. It shows how the extended period with a wintry mix in a wide swath of the area cut into what might well have been much larger snowfall values has more of the precipitation fallen as snow rather than the mix of rain and freezing rain which coated portions of the area with ice.

Had all the precipitation been snow rather than the wintry mix which ended up occurring— and had that snow occurred with a 10 to 1 snow/water ratio, the region might well have have been blanketed under 4 to nearly 9″ of snow. It illustrates the challenge weather forecasters and our numerical models face when a storm delivers its precipitation in multiple forms rather than strictly snow.