This is the HRRR’s depiction of surface temps today. It has been spot on the last couple days.

Point Forecast:

O’Hare

Today: 55/35, Sunny.
Tomorrow: 64/43, Sunny.
Friday: 59/41, Sunny.
Saturday: 56/37, Sunny.
Sunday: 61/40, Sunny.

Rockford

Today: 62/34, Sunny.
Tomorrow: 66/39, Sunny.
Friday: 60/35, Sunny.
Saturday: 61/37, Sunny.
Sunday: 65/38, Sunny.

Quad Cities

Today: 64/36, Sunny.
Tomorrow: 66/39, Sunny.
Friday: 63/38, Sunny.
Saturday: 62/40, Sunny.
Sunday: 66/42, Sunny.

 

Forecast Discussion:

Ahhhh, such wonderful Spring-like weather has been gracing us in northern IL. And, it should continue to do so. For today, I am going to ride the HRRR (high resolution guidance) for temperatures. Despite strong northerly winds, areas outside of the immediate suburbs should moderate nicely from the mid-40’s of this morning, to the lower-60’s. Basically areas residing west of Dupage County should be able to reach that threshold of 60 degrees, and areas near and west of I-39, should see mid-60’s.

High pressure will move through our area overnight and trough the morning, and given the cloudless skies, and given the location of high pressure, temperatures in more rural areas should dip to the mid-30’s, with common cold spots like KARR possibly touching the lower-30’s. The 3km NAM is picking up on some possible cold spots in and around the Fox River valley. But, as high pressure moves out of the area, winds will turn more southwesterly ahead of a “cold front” approaching from our northwest. Despite the tendency of guidance to hold back temperatures, I am opting to keep temperatures in the mid-60’s for most of northern IL, aside from areas closer to the lake. Guidance continues to show a possible shower overnight on Thursday but forcing and moisture return look rather abysmal. Given that, I will opt for a dry frontal passage.

 

Despite a cold front, temperatures will not differ much from Thursday to Friday. Guidance continues to opt for an upper-level wave ejecting out of western Ontario which is a part of a more evolved 500mb shortwave whose axis is centered over eastern Ontario and northern Michigan. This should result in strong NW flow aloft, and the surface winds should also respond accordingly, with WSW winds in upwards of 20mph for sustained, and gusts probably nearing 30mph. Despite the surface low’s proximity, we will stay dry for Friday.
On Saturday guidance has trended cooler for northern IL, with the best warming coming west of I-39. Weak northerly flow at the surface, combined the prior day’s NW flow and high pressure to our north, temperatures forecasted by guidance are in the mid-50’s. Regardless of guidance, I will side with climatology on this one, and will keep areas (similar to today), west and south of the immediate suburbs, right around 60 degrees.

For Sunday guidance again tempers the highs for the day due to a delayed southerly return flow. Given time of the year, and changing sun angle and ample sunshine, I will opt for temperatures in the mid-upper 60’s on Sunday. As we get closer to Monday, a more favorable thermal axis will overtake our area, and upper-level ridging ahead of a strong shortwave will really help drive warmer temperatures for Monday and Tuesday.

 

The 3km NAM picking up on colder temps in the Chicagoland Area.

The GFS showing ridging heading into early next week.