Warmer Weekend Followed By February-Like Chill
Yesterday's gusty winds are gone so even though today might only be a degree or two warmer than Thursday it will feel much better. Wind chills yesterday were in the teens and 20s during the afternoon. This afternoon the wind chills will be in the lower to middle 30s.
We will recover after the coldest morning of the season so far at O'Hare today. The HRRR model has temperatures topping out this afternoon in the upper 30s to near 40°. Average highs for today's date are around 47°.
The worst wind chills this afternoon will be in the lower 30s. Winds will start off light out of the west early today then pick up out of the south this afternoon blowing around 10 to 15 miles per hour.
The GFS Model has us bouncing back above average this weekend. Highs on Saturday should be well into the 40s.
Sunday's highs will be close to 50°. Enjoy the warm up while you can. A strong cold front will arrive Sunday night and temperatures will drop dramatically. Wind chills will dip into the teens overnight Sunday and could get as cold as the single digits by early Monday.
The key difference between today and yesterday is the lighter winds. Yesterday's highest gusts got up to near 40 mph. Our highest gusts today won't occur until tonight and then they are only around 20 mph.
The hourly forecast shows a slight chance for snow early Saturday morning. I'm not buying it. I think the best chance for any precipitation will be late Saturday night into early Sunday morning. Just plain old rain expected then. Some patchy light rain possible Sunday but much of the day should be dry. A strong cold front Sunday night could bring rain initially that might briefly change to snow early Monday morning but no significant accumulation is expected.
The National Blend Of Models shows our warm up this weekend followed by a dramatic drop in temperatures by Monday. Monday's high should be around freezing for the coldest day in nearly nine months. We warm back up to near 50° by Wednesday and then drop a few degrees below average for Thanksgiving.
The GFS model temperature anomaly forecast contradicts the NBM forecast just a bit. It has Thanksgiving afternoon actually a few degrees above average. Average highs for next Thursday are around 44°. So far the holiday still looks to be dry.
Cold Pattern May Ease
We may be turning a corner on a colder pattern by the end of this month or the start of December for at least a few days. The long range temperature outlooks cover the period from next Wednesday through most of the week after Thanksgiving. The 6-10 day outlook has us favored for below average temperatures overall from November 24th through November 28th but at the lower end of the probability range. The longer range 8-14 day forecast then favors us for near normal temperatures overall from November 26th through December 2nd but the probabilities aren't as high. Average highs for this period are in the middle 40s to upper 40s with average lows in the lower 30s.
The even longer term 35 day temperature anomaly forecast hints at a colder pattern overall during the period between November 17th and right up to just before Christmas on December 22nd. Most of the area is outlooked to be about 2° to 4° below average during the period. The Global Ensemble Forecast System (GEFS) is a weather forecast model made up of 21 separate forecasts, or ensemble members The model tries to give an idea of the amount of uncertainty in a forecast by running an ensemble of multiple forecasts which are each tweaked a bit with their initial conditions. Average highs by the middle of December drop into the middle 30s.
Relatively "Warm" Winter Outlook
I want to share two seasonal temperature forecast for this winter. One is a product of the North American Multi-Model Ensemble. I'll refer to this as the "American Model". The other is from the Copernicus Climate Change Service. I'll refer to this as the "European Model".
First, let's look at the temperature anomaly forecast for December through January from the American Model.
It has our region outlooked for above average temperatures overall for this upcoming winter. It suggest we should be about a .5° to 1° above average. Most of the country is forecast to have a milder than average winter.
Now let's look at the European model forecast for this winter.
It looks amazingly similar to the American model's forecast. The Midwest and most of the country is outlooked to milder than average overall this winter.
They are both fairly consistent with the official National Weather Service temperature outlook for December through January.
This is potentially good news if you aren't a fan of frigid winters. It doesn't mean we won't have occasional bitter cold snaps. It does say that when all the numbers are in, we will end up above average overall for the period of December 2021 through February 2022.
Slim Prospects For Snow
The GFS model's meteogram for O'Hare hints at some light snow Saturday morning. The best chance for any precipitation comes next Wednesday and on Thanksgiving. That rain next Thursday could change to snow early Friday morning. Still now significant accumulation through the weekend after Thanksgiving.
Our snowfall deficit is growing despite five days so far this month with snow reported at O'Hare. Just a trace fell on all five of those days though so officially we have only seen a trace of snow so far this month. We are now down .8" below average so far this season.
The accumulated snowfall meteogram has output from several different weather models. A few are spitting out some light snow Sunday night into early Monday morning. Most models suggest just some snow showers with little to no accumulation.
The GFS model's total precipitation forecast through Monday spits out about light amounts of rain here in only a few spots. This would come mainly Sunday.
Now let's focus more on snowfall chances the next several days. The GFS model total snowfall forecast through a week from today only spits out a couple tenths of an inch of snow in a few spots. Most of that would come late Thanksgiving night into Friday.
The European model is just about as stingy with the snow. It has a few spots south and east of the city picking up around a third of an inch to nearly a half inch of snow. It has most of that falling early Saturday morning.
The longer range precipitation outlooks continue to suggest a less active pattern here. The latest 6-10 day forecast has us favored for below normal precipitation (which can take the form of rain or snow now) from November 24th through November 28th. The longer range 8-14 day forecast also has us outlooked for below average precipitation for the period from November 26th through December 2nd.
Here is my 7 day forecast:
Today: Sunny start then becoming mostly cloudy High: 40
Saturday: Mostly cloudy & milder Low: 33 High: 49
Sunday: Partly to mostly cloudy, spotty showers possible Low: 37 High: 48
Monday: Light snow possible early, partly to mostly cloudy Low: 21 High: 32
Tuesday: Partly to mostly sunny Low: 23 High: 39
Wednesday: Mostly cloudy, light rain possible Low: 33 High: 46
Thursday: Mostly cloudy, light rain possible Low: 36 High: 44