UPDATE: Snow/Graupel Squalls, Strong Damaging Winds Pummeled Kane County

UPDATE: Snow/Graupel Squalls, Strong Damaging Winds Pummeled Kane County

Well, the National Weather Service Chicago warnings about the first snowfall of the year turned out to be prescient.

Kane County was hit by snow on Saturday (Oct. 20, 2018), and in a spectacular way.

Photo from St. Charles/Campton Hills. CREDIT: Geri Wilson via Bob Wazsak, NWS Chicago website.

Wind gusts of 45 mph to 65 mph were observed across northern Illinois and northwest Indiana — with Sugar Grove recording the highest in Kane at 54 mph. Geneva recorded 41 mph winds, according to the NWS.

Numerous snow showers, at times mixed with graupel and rain, moved over northern Illinois and northwest Indiana during the early to mid afternoon hours. These were convective showers, in that they were formed by similar processes to convection, or thunderstorms.

The squalls produced brief but heavy snowfall rates.

Combined with the winds, this brought brief near white-out conditions, including outside NWS Chicago in Romeoville just prior to 2 p.m. One-quarter-mile visibility was officially observed at the Lewis University Airport at 1:55 p.m. before power was knocked out by the strong winds gusting up to 60 mph.

The strongest winds were associated with fast-moving snow squalls. Multiple instances of wind damage occurred, including large trees and tree limbs and power lines downed, with isolated minor structural damage also reported.

The high winds caused fairly widespread power outages, with about 80,000 customers without power in northern Illinois at its peak according to ComEd.

The peak wind gusts at both Chicago O’Hare and Rockford were 61 mph, which were the strongest wind gusts observed at automated observation sites.

​The 61 mph wind gust observed at Chicago O’Hare was the highest wind gust there since 62 mph on Feb. 19, 2016.  The 61 mph wind gust observed at Rockford was the highest wind gust there since 65 mph on July 13, 2015.

Typical First Snow

According to the NWS Chicago website, the first snowfall typically occurs Oct. 30.

The earliest first snowfall was Sept. 25. That Sept. 25 snowfall happened twice, in 1942 and in 1948.

Looking at the data offers some interesting insights. For example, there are only four month of the year in which we don’t get snow — June, July, August and September. All the other months — including May and October — show snowfall numbers other than zero.

Of course, those “earliest” dates are for trace amounts of snow. We generally don’t get measurable amounts — of 0.1 inches or more — until Nov. 17, on average. Our “normal” date for a full inch of snow is Dec. 7.

One question on a lot of folks minds is how often we see snow on Halloween. Surprisingly, even though the statistics show Oct. 30 as the average first snowfall date, the NWS shows only three snowfalls on Oct. 31 since 1993. The most recent were 2013 and 2014.

Normals for Chicago O’Hare are from 1981-2010 unless otherwise noted. Records for multiple official Chicago sites are from 1886-present.

Here are some of the stats and links provided by the NWS for the Kane County area:

Normal and Record Snowfall

For seasonal and monthly normals and records, please visit the NWS Local Climate Page.

Trace or More of Snow

Normal First Date: October 30 Normal Last Date: April 14
Earliest First: September 25, 1942 Earliest Last: March 4, 2012
September 25, 1948
Latest First: December 5, 1999 Latest Last: May 22, 1917

Measurable (0.1 Inches or More)

Normal First Date: November 17 Normal Last Date: March 31
Earliest First: October 12, 2006 Earliest Last: February 28, 1994
Latest First: December 20, 2012 Latest Last: May 11, 1966

One Inch or More

Normal First Date: December 7 Normal Last Date: March 17
Earliest First: October 19, 1989 Earliest Last: January 18, 1927
Latest First: January 25, 2013 Latest Last: May 1, 1940

About The NWS Stats

The NWS website houses climatological snowfall data for the NWS Chicago County Warning Area, a 23 county area that includes a large portion of northern Illinois and northwest Indiana.

Much of the information is for two official climate sites, Chicago and Rockford, as these locations have longtime, quality-controlled climate data.

Besides climatology, the page can serve to help with snowfall risk assessment in terms of time of year, frequency, and magnitude.

For more on specific snow events of the past, please visit the NWS Past Events Page, WPC Storm Summaries and the NCEI Storm Events Database.