Focus Shifts To Frigid Air Arriving By Friday
All Caught Up On Snowfall
Snow lovers have to be jumping for joy, just like my daughter's dog chasing chunks of snow this weekend.
Hard to believe a week ago today we started off the day with a snowfall deficit of nearly 9" for our winter. We have since wiped away that deficit with the help of two significant snowstorms and now have a surplus of snow compared to average. The first storm actually began late in the day last Monday and continued into Tuesday. That storm laid down 6" of snow over two days at O'Hare. This weekend's storm brought us another 10.8" of new snow. We are now 5.7" above average to date for snowfall this winter. 24.7" of snow has fallen at O'Hare since December 1st.
The last time we had two snow events that produced 6" of snow or more within a week was way back in late 2013 and early 2014. 10.9" of snow fell on December 31, 2013 into January 1, 2014. A few days later another 11.7" fell over the period of January 4-5, 2014.
16.8" of snow fell between January 25th through the 31st making the week the snowiest week in over five years. It was the most in a week since 19.9" fell from February 1st through the 7th in 2015.
Here are some of the impressive storm totals from this weekend:
12.4" Downers Grove
12.1" Morton Grove
Here are the estimated totals for the two day event:
We get a break to dig out today through Wednesday. It will be dry & seasonably cold through the middle of the week. Highs today should reach into the lower 30s but a brisk breeze will make it feel like the teens and twenties.
Snow has been the big weather story this past week but now the focus shifts to the arrival of Artic air by the weekend. We will warm up through Thursday before a dramatic drop in temperatures just in time for the weekend. Highs Thursday will be near 40° but by Friday morning our wind chills will dip to near zero. Highs Friday and Saturday may not get out of the teens in some areas and single digit highs are possible Sunday. Lows by Sunday morning may dip below zero.
The GFS model model has lows plummeting to 15° to 25° below zero Sunday morning. Wind chills could be as cold as -40° to -50°. This is still several days away and these numbers may change but this model has now been consistently calling for a colder pattern to settle in fairly soon.
Average lows for this time of the year is in the middle teens. Sunday morning's forecast lows would be 35° to 40° below average for early February. The GFS temperature anomaly forecast shows this Arctic surge sliding as far south as Florida this weekend.
No Major Snow In Sight
The GFS model cloud cover and precipitation meteogram has some rain arriving by late Thursday that could mix with and change to rain by early Friday. Little accumulation is expected. There are two other chances for light snow beyond that. Light snow is possible Saturday and then late the following Monday into Tuesday.
The accumulated snowfall meteogram for O'Hare considers not just the GFS model but many different computer models. Thursday's snowfall range is anywhere between a bit more than a dusting to just over an inch of snow. Saturday's snowfall range from the models is as little as a half an inch to just under two inches.
Heavier Snow Stays North
The GFS model squeezes out a dusting of snow for most of us Thursday into Friday morning with heavier amounts staying north. Far northwester suburbs could see a couple of inches but several inches may fall in southern and central Wisconsin.
The European model lays down a bit more snow with Thursday's system. The total snowfall accumulation forecast through Friday morning calls for nearly two inches for most of the Chicago area.
Biggest Blob Of Blue Yet
I was noticing last week that the "blob of blue" on the temperature probability forecasts was getting bigger and expanding towards Chicago. The latest long range forecasts have the most blue on them I have seen so far this winter. This is signaling a long ago advertised shift towards a colder pattern. The latest 6-10 day temperature probability forecast has the Chicago area outlooked for below average temperatures overall from February 6th through February 10th. The particular shade of blue over us is dark which indicates a fairly high probability of this occurring. The longer range 8-14 day forecast continues to keep us outlooked for below average temperatures overall from February 8th through February 14th.
The even longer range Subseasonal Experiment (SubX) forecast seems to suggest February will stay frigid (overall) through nearly the end of the month. The forecasts for both the week ending February 19th and the week ending February 26th have us favored for below average temperatures overall.
Our recent active pattern may begin to ease up a bit as we move into the middle part of the month. The 6-10 day forecast favors us slightly for above average precipitation overall from February 6th through February 10th. The 8-14 day forecast has us outlooked for a return to about average precipitation overall from February 8th through February 14th.
Here is my 7 day forecast:
Today: Partly to mostly cloudy High: 33
Tuesday: Partly to mostly cloudy Low: 21 High: 32
Wednesday: Partly to mostly sunny Low: 15 High: 35
Thursday: Cloudy, light rain mixing/changing to light snow Low: 29 High: 39
Friday: Partly to mostly sunny Low: 14 High: 19
Saturday: Mostly cloudy, light snow possible Low: 6 High: 17
Sunday: Mostly cloudy, very cold Low: -2 High: 9