AFTERNOON-OVERNIGHT: Clear to mostly clear skies remain in place across zones 6 and 7 this morning ahead of a cold front that will be moving in from the north/northwest today. As it does, the chance for some scattered areas of rain and some thunderstorms will increase from north to south across the forecast area.
Through the early afternoon the front will start to sweep into northern portions of zone 7. By 3-4 PM the front looks to be in place near Springfield, IL. Along the front some isolated to scattered areas of rain will be developing by this time as well.
Through the late afternoon and into the evening the front will work to the south into zone 6. By 7-8 PM scattered areas of rain and perhaps a couple t’storms along the front will be moving into southern zone 7 and zone 6.
While there may be a few hours where rain completely exits the state overnight, by midnight a piece of upper-level energy will move southward across Illinois. As it does, more scattered areas of rain and a few storms will once again develop.
Through the overnight isolated to scattered rain/storms chances will remain in place, especially across zone 6 and southern zone 7.
Lows overnight will be in the upper 50’s north to mid 60’s south.
TUESDAY: While the upper-level energy will be moving out of the region early in the day on Tuesday, it will remain with us at least through mid-morning. While models are not eager to fire any precipitation across the area with the disturbance, I still think some isolated areas of rain and a t’storm will be possible through early morning Tuesday.
By late morning into the early afternoon on Tuesday dry time is anticipated across the forecast area. This will be as the upper-level energy moves out of the region and an area of high pressure builds in from the west/northwest. This high will help move any morning clouds out of the state making way for more sunshine in the afternoon.
Highs on Tuesday will be cooler with temperatures in the low to upper 70’s. Winds will be out of the northwest at 10-20 mph.
While I do expect most places to continue with sunny dry conditions Tuesday afternoon, through the evening a very weak upper-level disturbance is forecast to move into zones 6-7. While it will be a very weak disturbance, perhaps a couple of very stray showers could get going across the forecast zones around 6-7 PM, but these will be extremely isolated in nature.
Tuesday night into Wednesday high pressure will remain in control at the surface. This will make for a clear and cool overnight.
Lows Tuesday night into early Wednesday will be in the upper 40’s north to mid 50’s south!
WEDNESDAY: The influence of the upper-level trough and surface high pressure will be felt as we go through the day on Wednesday. The upper-level trough will allow for cooler air to stick around at least through mid-week before we start our warm-up.
Highs on Wednesday will be in the mid to upper 70’s with winds from the northwest at 5-20 mph.
While we will be on that active northwest flow on Wednesday the area of high pressure at the surface will allow us to remain mostly sunny and dry through the entire day.
THURSDAY-FRIDAY: Through the day on Thursday the upper-level trough will start to break down across the forecast area. This will allow for an upper-level ridge of high pressure to build into the region. As it does temperatures will begin to moderate to Summer-like levels!
While most of the day on Thursday will be dry, a warm front will be moving into the area from the southwest. As lifting occurs along the front, afternoon showers and perhaps an isolated t’storm will be possible. However, with that being said, any precipitation Thursday afternoon looks very isolated.
Highs on Thursday will be in the upper 70’s north to mid 80’s south.
On Friday the upper-level ridge will continue to expand to the north and east. This will allow for very warm and very humid air to surge into Illinois by late in the week.
Highs on Friday will warm into the upper 80’s to low 90’s!
Rain and thunderstorm chances will be minimal to end the week. However, with a very hot and humid air mass in place over zones 6 and 7, afternoon pulse t’storms will be possible.
Through the end of the week models are pretty meager with rainfall numbers. Most show only .20” or less across the area with an average closer to .10-.15”, which as an average will not be a bad estimate. However, with the low-end chances of rain/storms this week localized areas of heavier rain will remain possible despite what models say. So don’t be surprised if you see a half-inch or more of new rainfall if you should get under a couple of areas of rain or a t’storm.
WEEKEND: Hot and Humid conditions will remain in place on Saturday as the upper-level ridge remains in place.
Highs on Saturday will be in the upper 80’s to mid 90’s across the forecast area!
Sunday will be another hot day with highs in the mid 80’s to mid 90’s. However, there will be a cold front moving in from the north. This looks to bring much cooler temperatures in behind it. Depending on the timing/location of the front on Sunday temperatures may need either increased or decreased, along with the overall chances for rain.
We will have to fine-tune the forecast for Sunday as we get closer to the forecast period.