AFTERNOON-OVERNIGHT: A line of rain and a few storms continues moving off to the southeast this morning ahead of a cold front. Through the morning the rain will continue to work to the southeast out of the area. By 12 PM both the front and associated area of rain will be out of zones 6 and 7 with only some isolated showers remaining.
Through the afternoon isolated to widely scattered rain showers will remain possible across zones 6 and 7, especially the eastern portions. This will be thanks to that pesky upper-level low that will remain in place over the region today. By 4-5 PM the HRRR does a good job of picking up on those showers.
With the upper-level low right over the top of us, temperatures aloft will be very cold. With that cold air in place it may help contribute to some small hail today as rain moves through, along with perhaps some cold air funnels.
Through the afternoon and into the evening we may get in on some sunshine. The latest HRRR model does depict the clouds breaking up and sunshine getting through. We are currently seeing this across western Illinois where scattered clouds to clear skies are being reported.
Through the overnight the upper-level low will start to move off to the southeast of the forecast area. The exiting low and the absence of daytime heating should allow for shower chances to gradually decrease overnight with only isolated showers remaining possible.
Lows overnight will be in the upper 30’s north to mid 40’s south.
THURSDAY: Thursday morning some places in eastern Illinois may start out with some patchy fog. However, with remnants of the upper-level low still meandering around the area some light showers or mist will still be possible.
Through the morning an area of high pressure will build into Illinois from the west. This will allow for drier air to move into the region with it. The dry air will allow the remaining showers to come to an end through the morning and clouds will be on the decrease throughout the day.
Through the day skies will continue to clear across Illinois. I do think most of the day will be dry. However, late in the day there is a remnant piece of energy aloft that moves through. While I doubt this causes much in the way of shower activity, perhaps a few stray showers could move through eastern Illinois around 6-7 PM.
Highs on Thursday will be in the low to upper 60’s. Winds will be breezy at times with gusts of 20-30 mph possible
Excluding the line that is currently moving through (as of 9 am Wed.). New rainfall totals through Thursday evening will be minimal with maybe .10-.20” in extreme eastern Illinois near the IL/IN state line.
Thursday night skies will be mostly to partly clear across the forecast area as high pressure will remain in place.
Lows overnight will be around 40 north to the upper 40’s south.
FRIDAY: An area of high pressure will be in control at the surface on Friday. This will allow for sunny to mostly sunny skies to persist across the forecast area.
At the upper-levels a ridge will be building in across the Great Plains and into the Midwest regions. This will allow for a surge of warmer air to move into the region setting up for a nice end to the workweek.
Highs on Friday will be in the low to upper 70’s.
SATURDAY: Saturday morning a cold front will be in place north of the forecast area. Throughout the day it will move southward into zones 6 and 7 by the evening hours.
While I do think most of the day will be dry with at least partly sunny skies, rain and storms will develop along the front. Right now it looks like rain and storm chances will increase across zone 6 and 7 after 4-5 PM. However, that time will likely need fine-tuned as we get closer to the forecast period.
While upper-level winds are not overly impressive with this system, the return of surface moisture and moderate instability may provide the potential for severe weather. The latest models do suggest 1500-2000 J/Kg of CAPE across Illinois by late afternoon and into the evening.
Highs on Saturday will rebound nicely with temperatures in the upper 70’s to low 80’s. Winds on Saturday will be strong with the front in place. Gusts of 30-35 mph will be possible.
SUNDAY: The front will slow Saturday night into Sunday across southern portions of the forecast area. I do think by Sunday morning the front will be mostly stationary across southern Illinois and southern Indiana.
As the environment warms on Sunday the front will once again become the focal point for rain and thunderstorm development. So while it doesn’t look like an all-day rain threat on Sunday, chances will increase through the afternoon and into the evening.
Highs on Sunday will be in the low to mid 70’s north of the front. To the south of the front temperatures will be in the upper 70’s to low 80’s. Highs across the region will depend greatly on the exact placement of the stationary front.
LONG-RANGE (NEXT WEEK): It does look like the pattern will remain active next week, especially through mid-week as we will be targeting another area of low pressure forecast to move through the area on the 10/11 timeframe.
Right now it is still too early to determine threats, timing, location, or impacts. However, we will fine-tune those as we get closer to next week.