Let It Snow, Let It Snow, Let It Snow?
Wintery Weather Settles In
After six straight days with above average temperatures the coldest air of the season so far arrives today. This wintry weather with occasional snow will stick around through the weekend. We will experience some of the coldest temperatures we have seen in over seven months.
Snow showers today will be most widespread during the midday and afternoon hours then tapering off after sunset. There could be some brief heavier bursts of snow that reduce visibilities and could even stick on not just grassy surfaces but some pavement too. It is possible up to an inch could come down quickly in a few spots.
A more widespread sticking snow could come late Saturday night into Sunday. This forecast is very much in flux. It is the first real sticking snow of the season and that in itself creates challenges. The path this "clipper" system takes, warmth of the ground and duration of just snow versus a snow and rain mix will all factor into the amount of snow that actually sticks.
The meteogram above considers the forecast output from several different models. It spits out minor amounts of snow today into this evening but a more significant snow potentially overnight Saturday into early Sunday. At the low end the models suggest about an inch of snow but at the high end one model spits out over five inches. More snowfall discussion further down in today's post.
Let's talk temperatures.
We will fall shy of the average high of 50° for today's date. The morning will be the mildest part of the day with most of the area starting off in the lower 40s. The HRRR model has temperatures falling into the upper 30s this afternoon.
Gusty winds add insult to injury today. Most of the day our wind chills will be in the upper 20s to lower 30s.
The GFS Model keeps us unseasonably cold on Saturday too. It suggest highs struggling to get to 40°.
Sunday will be the coldest day of the weekend. Highs might not climb above the 30s.
Wintry weather will continue into early next week. The GFS model temperature anomaly forecast for Monday afternoon shows temperatures here between 10° to 15° below average. That would mean highs Monday in the middle to upper 30s.
So today and tomorrow we struggle to make it to 40°. Winds today gust to near 30 mph and tomorrow's gusts closer to 20 mph. Wind chills through Saturday will be in the 20s and 30s.
The best chance for snow showers today is midday through early this evening. Best chance for some widespread sticking snow comes after midnight Saturday into the morning hours of Sunday.
Today's snow showers could cause some trouble if you are traveling this afternoon. The National Weather Service has an excellent summary of what to expect:
Coldest Pattern Since Spring
50s are gone for now. The National Blend Of Models has our highs falling into the 40s today and staying near 40° Saturday. It then has even colder air crashing in here for Sunday and Monday with highs only in the 30s We bounce back by the middle of next week with highs in the 50s by Wednesday. It has highs soaring to near 60° a week from this Sunday.
The longer range temperature outlooks has us near normal overall from next Wednesday through Thanksgiving. The 6-10 day outlook still has us favored for about average temperatures overall from November 17th through November 21st. The longer range 8-14 day forecast also favors us for about average temperatures overall from November 19th through November 25th. Average highs for this period are in the middle 40s to upper 40s with average lows in the lower 30s.
The even longer term 30 day temperature anomaly forecast has not changed much from previous forecasts. Most of the area is outlooked to be near normal overall. This forecast covers the period from November 10th through December 10th. 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 early December drop into the upper 30s.
Looking More At Snowfall Amounts
Our snowfall deficit grew to about four tenths of an inch yesterday. That is the average amount of snow we should have by this point in fall. We may see that and more by the time the weekend is over. Our first flakes of snow usually fall around the end of October.
The most recent US Drought Monitor analysis was released last Thursday. Here is a recap:
After three reports in a row with good news for Illinois the latest report is a bit more ambivalent. There is no areal increase in any of the drought categories but there is no decrease either. Things have not changed at all compared to the previous report. 9.29% of the state is in a moderate drought (level 1 out of 4) and 1.22% is in a severe drought (level 2 out of 4). The drought continues to be focused in northern Illinois entirely.
The report was more of a mixed bag for the Midwest region. While the areas in a severe to extreme drought decreased slightly, the area in a moderate drought increased slightly.
The GFS model's total snowfall forecast through Monday morning lays down five to seven inches of snow. Most of this would fall overnight Saturday into Sunday. This still seems overdone. I am leaning more towards the European model below.
The European model is again suggesting far less snowfall. It spits out around a third of an inch to about an inch for most of us. Heavier amounts are shown in our far northwestern suburbs where two to three inches is suggested. I will have one more update tomorrow but for now, I am thinking about one to three inches is possible Saturday night into Sunday.
The GFS model's meteogram for O'Hare shows today's snow showers and the sticking snow Sunday. Next week we deal with just plain old rain on Wednesday.
The longer range precipitation forecasts trend us from near normal to below. The latest 6-10 day forecast has most of the Chicago area favored for about average precipitation (which can take the form of rain or snow now) from November 17th through November 21st The longer range 8-14 day forecast also has us outlooked for below average precipitation for the period from November 19th through November 25th.
Here is my 7 day forecast:
Today: Cloudy, cold, blustery, snow showers (minor accumulation) High: 42 (temps fall into the 30s)
Saturday: Few flurries early, mostly cloudy with partial clearing late Low: 32 High: 40
Sunday: Rain & snow now mainly early, mostly cloudy, pm snow showers Low: 30 High: 39
Monday: Partly to mostly sunny Low: 28 High: 38
Tuesday: Partly to mostly sunny Low: 30 High: 48
Wednesday: Mostly cloudy, chance of rain Low: 41 High: 54
Thursday: Partly to mostly cloudy Low: 35 High: 45