Peoria, Ill. (WMBD) — The National Weather Service has issued a Winter Weather Advisory over much of Central Illinois from Midnight tonight through Thursday evening. A storm system will bring widespread freezing rain, sleet and snow to Central Illinois Thursday resulting in slippery travel conditions.

Key Takeaways

  • Freezing rain and sleet develop after 1 am Thursday
  • Icy roads are likely throughout the day Thursday
  • Freezing rain and sleet transition to snow Thursday afternoon
  • Potential flash freeze Thursday night

A cold front is currently stalled across southern Illinois with colder temperatures gradually filtering into from the northwest. Temperatures are expected to drop near to below freezing across Central Illinois tonight, particularly west of I-39. Despite temperatures near the surface being near to below freezing, temperatures between 3,000 and 5,000 above the ground will be above freezing bringing a growing concern of widespread freezing rain and sleet.

Storm Timing

Rain is likely to start after midnight tonight but will quickly change to freezing rain and sleet as temperatures drop into the lower 30s. Off and on freezing rain and sleet showers are expected to impact areas west of I-39 through 7 am Thursday while a mixture of sleet and rain impact McLean and Livingston Counties. A dry slot could result in a loss of ice crystals along and east of the Illinois River Thursday morning resulting in freezing drizzle while a wintry mix changes to snow west of the Illinois River. Further east, the wintry mix of freezing drizzle, sleet and rain will change to snow Thursday afternoon.

12 am to 6 am Thursday

  • Galesburg – Sleet and Snow
  • Peoria – Freezing Rain and Sleet
  • Bloomington – Sleet and Rain

6 am to 12 pm Thursday

  • Galesburg – Sleet to Snow
  • Peoria – Freezing Drizzle to Snow
  • Bloomington – Sleet and Rain

12 pm to 6 pm Thursday

  • Galesburg – Snow
  • Peoria – Sleet to Snow
  • Bloomington – Wintry Mix to Snow

Ice and Snow Amounts

There’s been no significant changes to the snowfall forecast but ice accretions have been increased. Snowfall amounts will range from a trace to 3 inches with the heaviest totals across Knox, Henry, Stark, Bureau, Putnam and La Salle Counties. Should we end up with colder temperatures aloft, we could end up with more snow rather than sleet which would result in higher snow accumulations. As for ice accretion most areas west of I-55 are expected to see around a tenth of an inch of ice, but localized amounts up to 0.2 inches will be possible.

Road Conditions and Storm Impacts

Our exclusive road conditions forecast shows that much of Central Illinois will be dealing with icy roads for the Thursday morning commute and those impacts could linger into the afternoon. By the evening commute, any lingering precipitation should have changed, or will be in the process of changing, to snow but with temperatures dropping wet roads are likely to ice up again by mid evening.

While widespread power outages are not expected, the combination of ice, snow and the combination of 10-20 mph winds Thursday evening could result in localized power outages.

What Determines Precipitation Type?

Whether precipitation falls as rain, freezing rain or snow depends on the temperature profile of the atmosphere. Often, the difference between freezing rain and accumulating snow comes down to a degree or two difference in the air temperatures aloft.

Snow falls when the entire temperature profile of the atmosphere is below freezing.

Sleet, also known as ice pellets, form when temperatures aloft are warm enough to melt snow as it falls towards the ground. However, the rain falls through a deep layer of cold air before reaching the ground causing it to refreeze prior to contact with the ground.

Freezing Rain
Similar to sleet, freezing rain develops when temperatures aloft are warm enough to melt snow as it falls towards the ground. However, unlike sleet, the layer of subfreezing air is much shallower and rain does not have a chance to refreeze before reaching the ground. instead, rain freezes on contact resulting in surfaces becoming coated in ice.

Rain falls when a substantial part of the atmosphere is above freezing.