AFTERNOON – OVERNIGHT: An area of low pressure will continue to develop and advance eastward closer to the region through the daytime hours today. This while a stationary front remains in place across the northern 1-3 of Illinois.
Initially across the area we may start out with some sunshine. However, through the late morning and afternoon, clouds will really start to thicken up across the forecast zones.
While there will be clouds in place throughout the day, the primary sources of lift will be to the north and west of the region. So overall very little to no rain is in the forecast. Any rain showers that do develop though the day will be very light and brief in nature.
Through the overnight the area of low pressure will move across northern Illinois. As it does the cold front will swing eastward across Illinois bringing increasing chances of rain and thunderstorms.
While most of the evening looks dry, rain showers will increase in coverage around 9-10 PM this evening.
By 1-2 AM a line of storms will be entering western portions of zone 6 and 7, with more isolated areas of rain and storms ahead of it. This as the main cold front remains out to the regions west.
Through the overnight the initial area of rain will continue off to the east across zones 6 and 7. By 5-6 Am that area of rain will be in eastern Illinois working into Indiana.
Lows overnight will be in the low 50’s north to upper 50’s south.
THURSDAY: Early Thursday morning the main cold front will enter western Illinois. While initially there may be little to no activity along the front, but storms are expected to develop around 7 – 8 AM along the front and move east through the day.
Through the morning the front and associated storms will quickly move off to the east and northeast across zones 6 and 7. By 11 AM – 12 PM this round of storms and the cold front will be in place across the IN/IL state line, exiting the forecast area.
Through the overnight into early Thursday morning winds aloft will increase from the southwest at 50-60 mph at 850 mb to 75-90 mph at 500 mb.
With a sudden increase in winds it should allow for the transport of southern moisture to become a bit more impressive by 4-7 AM. With this increase in moisture will come an increase in instability. The latest NAM models have 1000 J/kg of CAPE across western Illinois by 7 AM Thursday morning.
If instability is to verify some strong to even severe storms can’t be ruled out across western Illinois late tonight into the morning on Thursday. While I am not expecting a significant event, some reports of hail, damaging winds, and perhaps an isolated tornado can’t be ruled out.
Regarding new rainfall totals across the region, an average of .20-.40” of rain will be likely across zones 6 and 7. However, places that do get under some of the heavier thunderstorms could see 1-1.50” locally.
Highs on Thursday will come very early on in the day before the frontal passage. Morning highs will top out in the 50’s. Winds will be strong Thursday with 40-50 mph gusts possible!
Through the afternoon temperatures will quickly fall. The NAM 4 km does a great job of showing the drop in temperatures. At 9 AM it shows a temperature of 61 in Springfield, but by 5 PM Thursday evening it is only 44!
Through the evening some leftover moisture should allow for some light rain showers to remain possible, especially across zone 7 and northern zone 6.
However, as temperatures drop closer to the freezing mark, some of the rain will chance over to some light snow showers Thursday evening. However, no accumulations are expected. Lows Thursday night will be in the upper 20s north to mid 30’s south.
FRIDAY: Behind the cold front Thursday night into Friday an area of high pressure will build into the forecast area. This will allow for sunny to mostly sunny skies to end the week.
However, it will also keep temperatures cool with highs topping out in the mid 40’s to mid 50’s.
WEEKEND: Saturday we will be in between weather systems. This as the area of high pressure slips off to the east and another area of low pressure develops to our west across the Great Plains.
Regardless, Saturday does look to be a nice day with mostly sunny skies and temperatures warming into the upper 50’s north to upper 60s south.
Beyond Saturday models are in major disagreement how things will work out to end the weekend and for next week.
The Euro solution would favor rain chances Sunday, possibly turning into a heavy, wet snow for areas Sunday night. Then beyond that gives us a cooler start to the week as high pressure builds in for Monday.
The GFS would favor dry conditions on Sunday with rain chances not entering the forecast until late Sunday night into Monday. It would also support a warmer look to start the week.
The CMC would support rain through the day on Sunday like the EURO. However, there is no support for snow Sunday night into early Monday.
Overall, I would tend to favor the GFS more as it seems to match the pattern better. With that said, we will continue to watch the latest data and trends over the next few days.
7 DAY FORECAST
THURSDAY: MOSTLY CLOUDY WITH SOME SUNSHINE, A 50% CHANCE OF RAIN & T’STORMS, A FEW STRONG/SEVERE POSS. WEST. HIGHS IN THE MID 50’S WEST TO THE LOW 60’S EAST. WINDS FROM THE SOUTH TO WEST AT 10-20 MPH, GUSTING TO 40-50 MPH.
THURSDAY NIGHT: TEMPERATURES FALL, PARTLY TO MOSTLY CLOUDY WITH A 20% CHANCE OF RAIN TO SNOW SHOWERS. LOWS IN THE UPPER 20’S NORTH TO MID 30’S SOUTH.
FRIDAY: MOSTLY SUNNY, COOLER. HIGHS IN THE MID 40’S NORTH TO MID 50’S SOUTH. WINDS FROM THE NORTHWEST AT 6-12 MPH, GUSTS TO 20 MPH.
FRIDAY NIGHT: CLEAR TO MOSTLY CLEAR WITH LOWS IN THE MID 30’S EAST TO LOW 40’S WEST.
SATURDAY: SUNNY TO MOSTLY SUNNY. HIGHS IN THE UPPER 50’S NORTH TO UPPER 60’S SOUTH. WINDS FROM THE SOUTHEAST AT 5-15 MPH.
SATURDAY NIGHT: MOSTLY CLEAR TO PARTLY CLOUDY WITH A 10% CHANCE OF A SHOWER WEST. LOWS IN THE UPPER 30’S NORTHWEST TO UPPER 40’S SOUTH.
SUNDAY: PARTLY TO MOSTLY CLOUDY WITH A 30-40% CHANCE OF RAIN & T’STORMS. HIGHS IN THE MID 50’S TO MID 60’S. WINDS FROM THE SOUTHEAST TO SOUTHWEST AT 5-15 MPH, GUSTING TO 30 MPH.
SUNDAY NIGHT: MOSTLY CLOUDY WITH A 30% CHANCE OF RAIN, POSSIBLE SNOW NORTH? LOWS IN THE UPPER 30’S NORTH TO MID 40’S SOUTH.
MONDAY: PARTLY CLOUDY AND COOL, CLOUDS DECREASING WEST TO EAST. 30% CHANCE OF RAIN & STORMS. HIGHS IN THE UPPER 50’S TO UPPER 60’S.
MONDAY NIGHT: PARTLY TO MOSTLY CLOUDY WITH A 20-30% CHANCE OF STORMS. LOWS IN THE LOW 40’S NORTH TO MID 50’S SOUTH.
TUESDAY: PARTLY CLOUDY, RAIN ENDS. HIGHS IN THE UPPER 40’S TO UPPER 50’S.
TUESDAY NIGHT: PARTLY CLOUDY WITH LOWS IN THE UPPER 30’S TO MID 40’S.
WEDNESDAY: MOSTLY SUNNY WITH HIGHS IN THE UPPER 50’S TO MID 60’S.
WEDNESDAY NIGHT: INCREASING CLOUDS, CHANCE OF RAIN WEST. LOWS IN THE 50’S.