Quiet For Now But How Long Will It Last?
Couple Of Colder Days In Forecast
We have yet to see any brutal blasts of Arctic air this winter. December ended up more than 5° above average overall and January is now running nearly 8° above average. We have seen only 4 out of 48 days this winter with highs under 30°. There are at least 3 days in my 7 day forecast with highs in the 20s though. We won't set any records but with today probably being the 24th day in a row above average, you will definitely notice a change.
Today's highs should be near 30° which is right around average for the middle of January.
An up and down rollercoaster ride with temperatures this week. We warm up to near 40° by Thursday and then drop below average for Friday before rebounding back to near 40° again on Sunday.
The first encounter with colder air this week will especially be felt early Tuesday morning. The combination of temperatures and brisk winds will make it feel like the single digits. More single digit wind chills expected Wednesday morning too.
It gets even colder by the end of the week. Look for a frigid Friday morning as lows dip down into the single digits well northwest of the city. Wind chills by then could dip below zero for some of us. The GFS temperature anomaly forecast has northern Illinois about 10° to 20° below average.
No Big Snow In Sight
O'Hare has seen four straight days with snowfall but it has only added up to 1.4". We have seen plenty of days with snowfall being reported but the snow has been very light for most of them. There have been 18 days with snow this winter at O'Hare but on 11 of those days only a trace of snow has fallen. So far this winter there had been 6.1" of snow compared to an average to date of 13.9" for the season.
The GFS model cloud cover and precipitation meteogram shows more light snowfall or flurries possible Tuesday night into early Wednesday morning. The next chance of any precipitation after that isn't until late in the weekend. Late Sunday could see a mix of wintry precipitation that would linger into Monday.
The accumulated snowfall meteogram for O'Hare considers not just the GFS model but many different computer models. It suggests a dusting to a few tenths of an inch possible Tuesday night and then another round of snow on Sunday. That second system could bring anywhere between a dusting to nearly four inches. This is still a long way off and both the track and the strength of this second system could (and probably will) change between now and then so stay tuned.
Snow & Ice
The GFS model forecast spits out a dusting to a couple tenths of an inch of snowfall Tuesday night. Areas north of the city are spared entirely from the snow.
The European model has similar snowfall numbers for Tuesday night.
Looking longer term at the GFS shows very little additional snow expected for the next ten days. A few tenths of an inch of snow could come with Sunday's system.
The European model is a different story. It squeezes out over a half of foot in total over the next ten days. The bulk of that would come a week from this Tuesday. Confidence isn't very high though yet with this forecast since there isn't much model consensus at this point. Snow lovers do have at least some hope though. We'll have to see if the GFS model ends up falling in line with this.
This warmer than average winter so far has prevented a big build up of ice on the Great Lakes. Just 1.5% of the the Great Lakes were reporting ice cover on Sunday (lower left image). That is less than a third of the amount of ice cover compared to a year ago (lower right image). One of the big implications of this is the potential for some heavy lake effect snow if the conditions are right. The more open water over the lakes means the more moisture that potentially could feed future lake effect snowfall.
Long Range Temperature Forecast Not Clear Cut
The longer range temperature probability forecasts favor us for about average temperatures for the end of January. The 6-10 day temperature probability forecast has the Chicago area outlooked for about average temperatures overall from January 23rd through January 27th. The longer range 8-14 day forecast keeps the Chicago area outlooked for about average temperatures overall for the period from January 25th through January 31st. The dominant color on both maps is blue. This indicates the majority of the country is favored to finish this month below average overall.
The experimental multi-model ensemble temperature anomaly forecast for next month keeps the mild pattern we saw for the first two months of winter coming for February too. The only part of the country with below average temperatures on the map is a small portion of Washington and Idaho.
The precipitation probability forecast for February has the Midwest, including Chicago, and most of the northern half of the country outlooked for above average precipitation overall for next month. The southern tier of the US is outlooked for below average precipitation which is consistent with a La Nina pattern.
More Hints At Active Pattern
We are outlooked for above average precipitation overall for the end of January. The 6-10 day forecast from January 23rd through January 27th has us outlooked for above average precipitation overall. Most of the map is green which means most of the country is outlooked for more precipitation than average during that period. Less green on the 8-14 day forecast but it still keeps us outlooked for above average precipitation from January 25th through the 31st. The probabilities drop a bit northern Illinois.
Here is my 7 day forecast:
Today: A few flurries early, cloudy skies High: 31
Tuesday: Partly to mostly sunny (light snow overnight) Low: 20 High: 27
Wednesday: Partly to mostly sunny Low: 16 High: 35
Thursday: Mostly sunny Low: 28 High: 39
Friday: Partly to mostly sunny Low: 16 High: 26
Saturday: Partly to mostly sunny Low: 11 High: 28
Sunday: Mostly cloudy, wintry mix late Low: 19 High: 34