Cool Today But Some Snow In Forecast Next Week
Updated: Apr 16, 2021
More Like March At Lakefront
Yesterday's high of 51° at O'Hare was the coolest in nearly two weeks. Even though today's highs for most of us may be a few degrees warmer, along the lakefront it will feel more like March than April.
Average highs for this time of the year are near 60°. Most areas should top out in the lower 50s today but along and near the lakefront highs will fail to climb above the 40s. Expect some peeks of sun today and if skies clear enough tonight, there could be some spots west and northwest of the city that may fall to near freezing.
The key to the cooler temperatures along the lakefront is a wind shift expected this afternoon. Winds will turn off the lake and remain off the lake on Friday too. Highs Friday and through the weekend will remain in the 40s along the lakefront with this cool northeasterly breeze. The wind will be a bit blustery early today and diminish a bit on Friday and then lighten more for the weekend.
April Rain & Snow Showers
The GFS model continues to call for rain Tuesday changing to at least some light snow late in the day. It is still a long way off and very subject to change but as mentioned yesterday, there could be some minor accumulation. Looking even longer range, the model hints at some more light snow a week from this Friday.
We average 1.2" of snow for the month of April. The last significant April snow here was just two years ago when 2.5" of snow fell at O'Hare on the 27th of the month. It was the latest accumulating snow we had seen here in more than 25 years.
The GFS model is squeezing out between two inches to around three and a half inches in total late Tuesday into Tuesday night.
The GFS model spreads a swath of snow across northern and central Illinois and Indiana with the heaviest totals south of the city. Locally, there is a range from of around an inch in our northwest suburbs to nearly five inches south of Chicago along the Indiana and Illinois border.
The European model is more stingy with the snow. It squeezes out a few tenths of an inch to about a half inch for most of us with no accumulation south of the city and in northern Indiana.
Dramatic Drop For Tuesday
The hourly temperature meteogram compares many different forecast models. It keeps us cooler than average through the weekend before warming up to near 60° by Monday. Temperatures then tumble into Tuesday when highs will only be in the 40s.
The temperature anomaly forecast for Tuesday morning suggests northern Illinois and Indiana will be between 10° to nearly 20° below average.
Cooler Signal Strengthens
The signal in the longer range temperature probability forecasts has grown stronger for a cooler pattern to close out April. The latest 6-10 day forecast has us outlooked for below average temperatures overall from April 20h through April 24th with the bullseye of the highest probabilities over northern Illinois. The 8-14 day temperature probability forecast has us favored for below average temperatures overall from April 22nd through April 28th too. Average highs in Chicago for late April are in the lower to middle 60s.
The even longer range Subseasonal Experiment (SubX) temperature anomaly forecast is signaling a cooler than average end to April and a return to around average for the start of May. The temperature anomaly forecast for the week ending April 30th has us outlooked to be a bit below average overall. The forecast for the following week ending on May 7th has Chicago bouncing back to about average overall. Average highs by the start of May are in the lower 60s.
More Active Pattern Possible
The long range precipitation probability forecasts are transitioning from below average projections to above average by the end of the month. The latest 6-10 day forecast still has Chicago favored for below average precipitation from April 20th through April 24th. The longer range 8-14 day forecast has us outlooked for above average precipitation overall from April 22nd through April 28th.
Here is my 7 day forecast:
Today: Mostly cloudy, spotty sprinkles early, breezy High: 54 (46 lakeside)
Friday: Partly to mostly sunny Low: 38 High: 56 (47 lakeside)
Saturday: Partly to mostly cloudy Low: 54 High: 57 (48 lakeside)
Sunday: Partly to mostly cloudy Low: 39 High: 57 (49 lakeside)
Monday: Partly to mostly sunny, rain late Low: 41 High: 61 (cooler lakeside)
Tuesday: Rain & snow early (some accumulation possible), mostly cloudy Low: 38 High: 50
Wednesday: Partly to mostly sunny Low: 34 High: 51