November-like temperatures expected later this week

Weather Blog

Peoria, Ill. (WMBD) – The week has started off with well above average temperatures and gusty winds, but Central Illinois is in for some big changes by the end of the week as a strong cold front moves through Central Illinois Wednesday night.

The Highlights

  • Mild temperatures and gusty winds through Wednesday
  • Well below average temperatures Thursday through Friday and again Sunday through the end of next week.
  • Increased chances for precipitation early next week

Temperatures will reach the upper 70s and lower 80s on Wednesday before a strong cold front brings much colder air to Central Illinois Wednesday night. The front could bring a few rain showers to the region Wednesday night and Thursday morning but rainfall amounts will remain light. Skies will clear Thursday afternoon and evening which will allow temperatures to drop into the lower to mid 30s Friday morning. This would bring widespread frost and a potential freeze to Central Illinois. Despite some periods of sun, temperatures will only manage to reach the mid 50s on Thursday and Friday making it feel more like the middle of November instead of the middle of October.

The weather is expected to remain cool through Friday before temperatures recover a bit on Saturday with highs reaching the mid 60s to start to the weekend. The warm-up comes ahead of yet another cold front that is expected to move through either Sunday or Monday of next week, at which point the forecast becomes very murky.

Could Illinois see snow early next week? The short answer…it’s possible but unlikely.

While models agree that the weather pattern will remain active into next week, they disagree with how fast next week’s blast of cold air will arrive. The American GFS model brings the front through on Sunday with temperatures dropping from the mid 40s into the 30s and changing rain to snow as the colder air moves into the region. Meanwhile, the European counterpart (ECMWF model) keeps the front north of the region until Monday evening with rain chances increasing Sunday night and continuing through Monday night. With the front further north, this solution suggest temperatures would be much warmer with highs in the 70s. The 30° to 40° temperature difference between the two models is not unusual six days out, especially this time of year.

Which one is correct?

As I’ve written about many times…neither! No model is ever 100% correct, though some handle various scenarios better than others. In order to increase confidence in one solution or another, we rely on model ensemble forecasts to hone in on a solution.

You can think of a model ensemble as a family with individual members. While the members of these families are similar to one another, there are small differences in their DNA (algorithm) that give us a slightly different look.

Here’s how many members are in each Ensemble…
GFS Ensemble (GEFS) – 31 Members
ECMWF Ensemble (EPS) – 51 Members

While there is value in understanding how each member of each family behaves, we are more interested in where they group together. While not perfect, if more members of a certain ensemble start to coalesce around a certain solution, and that solution is similar to other ensembles, then the confidence in a particular outcome increases

In this case nine of the 31 GEFS members show snow falling on Sunday or Monday, and out of those nine, only three show any type of accumulation. The snow potential is even lower when looking at the European model solution with only four of the 51 EPS members showing snow, neither of which show any real accumulation.

In the end, while there are a few scenarios where snow could fall early next week, those scenarios are unlikely. So beware of any social media posts that suggest Central Illinois will see snow next week.

Our current forecast leans towards the cooler model solutions, but not quite as cold as some of the more aggressive models would suggest. For now, the forecast calls for rain showers on Sunday and Monday with high temperatures in the 50s and low temperatures in the 30s with any snow staying north of the region.

It looks like this cool and active weather pattern will persist through next week. The Climate Prediction Center’s 6-10 Day Outlook (Oct. 19th through Oct. 23rd) calls for below average temperatures and above average precipitation.

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