AFTERNOON – OVERNIGHT: A bit of a frontal boundary remains in place across western Illinois today as the main cold front still is in place to the regions west. There are currently a few showers across very western Illinois associated with this boundary, but overall the region is dry.
Through the day that boundary will lift off to the north and the cold front will move closer to the region. Partly to mostly cloudy conditions do look to persist through the day. However, the HRRR is showing afternoon sunshine as well.
While I don’t think there will be a tremendous amount of rain across zones 6 and 7 through the afternoon and evening a few isolated to widely scattered showers will remain possible. A better chance of rain may be in place across western zone 7 and northwest zone 6 around 4-5 PM, but overall a mostly dry afternoon is expected.
Highs today will be warm topping out in the upper 60’s north to mid 70’s south. If more sunshine can be realized then perhaps slightly warmer high aren’t out of the question.
This evening the cold front to the west will move eastward bringing rain and thunderstorm chances with it. It looks like the area of rain and thunderstorms will enter western Illinois after 8-9 PM this evening and spread eastward into the overnight.
By 1 am scattered areas of rain and thunderstorms will be ongoing across zones 6 and 7. Some of which will be capable of some heavy rain, gusty winds, and perhaps even some small hail.
Scattered rain and a few storms will remain possible overnight as they move off to the east and northeast. By 7-8 AM most of the precipitation will either be dying out or moving off to the east of the zones.
Lows overnight will be in the mid to upper 50’s.
Overnight rainfall looks to be to the tune of .30-.50” on average. However, places that do get under the heavier storms could see .90-1.2” of new rainfall locally.
WEDNESDAY: Once again Wednesday morning a frontal boundary will be in place across northern zone 6 into zone 7. With this in the forecast area isolated to widely scattered areas of rain and an isolated storm will be possible through mid-day on Wednesday.
Wednesday afternoon I expect a bit of a lull in precipitation as the stationary from lifts northward as a warm front, while the cold front remains to the regions west.
Highs on Wednesday will be in the mid 60’s north to mid/upper 70’s south. Winds will be relatively strong out of the southwest with gusts of 25-30 mph.
Wednesday evening rain chances will go up again from west to east across the forecast area. While models are a little different on the timing of this rain, I think better chances will be after 4-5 PM Wednesday evening.
By 7-8 PM a large “shield” of rain and perhaps a few t’storms will be moving across Illinois to the east and northeast. Again some heavy rain can be expected at times with this.
Wednesday evening into the overnight the atmosphere will be highly saturated as a steady stream of moisture continues into zones 6 and 7. Precipitable water values of 1.2-1.6” will be common across the area. So there will be plenty of moisture to work with.
With that being said, scattered rain and thunderstorms will continue across the region through the night Wednesday into Thursday.
Lows Wednesday night will be in the mid 50’s to low 60’s.
THURSDAY: Models are starting to take the heaviest rain on Thursday farther south. The primary reasoning for this is because the area of high pressure building in from the north is suppressing the system farther south, as we mentioned in yesterday’s discussion.
Thursday morning we will likely start out with only isolated to scattered rain chances.
However, as that front does sag south rain and thunderstorms chances will be on the increase by mid-day.
By the afternoon/evening rain and thunderstorms will become likely across the zones, with perhaps the heaviest rain across zone 6.
With PWATS of 1.2-1.6” still in place across the region the atmosphere will remain highly saturated, so heavy rain does look likely.
Highs on Thursday will be in the mid 60’s to low 70’s.
Thursday night the area of high pressure will build in from the northwest. This will start to suppress the system to the south and rain chances overnight will start to decrease.
FRIDAY: The area of high pressure will be in control of the weather on Friday. While I do think there will be some rain across very southern Illinois in zone southern zone 6, most of the area looks to remain dry.
With the dry air moving in with the high clearing will take place and some sunshine will likely get through.
Highs on Friday will be in the upper 50’s north to upper 60s south.
WEEKEND: The area of high pressure will move off to the east and northeast late Friday into Saturday.
As it does rain chances will be on the increase with rain possible both Saturday and Sunday. Timing of the rain will have to be fined-tuned this week.
Heavy rainfall is still anticipated over the next 7 days. By the time we get into next Tuesday night models continue to show rainfall totals of 2.5-3” being common across the forecast zones. However, where the heaviest rain occurs 4-5.5” can’t be ruled out locally. For this reason we remain concerned about the potential for flooding across zones 6 and 7.
7 DAY FORECAST
WEDNESDAY: MOSTLY CLOUDY TO OVERCAST. 50% CHANCE OF RAIN & SOME T’STORMS, SOME POSSIBLY HEAVY. HIGHS IN THE MID 60’S NORTH TO UPPER 70’S. WINDS FROM THE SOUTHWEST AT 6-12 MPH, GUSTING TO 25-30 MPH.
WEDNESDAY NIGHT: CLOUDY WITH A 60% CHANCE OF RAIN & AN ISOLATED T’STORM, SOME HEAVY. LOWS IN THE MID 50’S NORTH TO LOW 60 SOUTH.
THURSDAY: CLOUDY WITH A 60-70% CHANCE OF RAIN & T’STORMS, SOME HEAVY. HIGHS IN THE MID 60’S NORTH TO LOW 70’S SOUTH. SOUTHWEST TO NORTHWEST WINDS 6-12 MPH, GUSTING TO 20-25 MPH.
THURSDAY NIGHT: SKIES CLEARING FROM NORTH TO SOUTH, 30% CHANCE OF RAIN SOUTH. LOWS IN THE UPPER 30’S NORTH TO LOW 50’S SOUTH.
FRIDAY: PARTLY TO MOSTLY CLOUDY WITH 20% CHANCE OF RAIN & T’STORMS, MAINLY SOUTH. HIGHS IN THE UPPER 50’S TO UPPER 60’S. EASTERLY WINDS AT 5-15 MPH.
FRIDAY NIGHT: INCREASING CLOUDS WITH A 10-20% CHANCE OF RAIN. LOWS IN THE UPPER 40’S NORTH TO UPPER 60’S SOUTH.
SATURDAY: PARTLY TO MOSTLY CLOUDY WITH A 20-30% CHANCE OF RAIN & T’STORMS. HIGHS IN THE LOW 60’S TO MID 70’S. SOUTHEASTERLY WINDS AT 5-15 MPH.
SATURDAY NIGHT: CLOUDY WITH A 30-40% CHANCE OF RAIN. LOWS IN THE LOW 50’S NORTH TO UPPER 60’S.
SUNDAY: MOSTLY CLOUDY WITH RAIN AND T’STORMS POSSIBLE. HIGHS IN THE LOW 60’S NORTH TO LOW 70’S SOUTH.
SUNDAY NIGHT: MOSTLY CLOUDY WITH A SLIGHT CHANCE OF RAIN. LOWS IN THE LOW 50’S NORTH TO NEAR 60 SOUTH.
MONDAY: PARTLY CLOUDY WITH A SLIGHT CHANCE OF AM RAIN. HIGHS IN THE UPPER 60’S TO MID/UPPER 70’S.
MONDAY NIGHT: MOSTLY CLEAR TO PARTLY CLOUDY, ISOLATED RAIN SHOWERS POSSIBLE. LOWS IN THE MID 50 NORTH TO MID 60’S SOUTH.
TUESDAY: MOSTLY SUNNY TO PARTLY CLOUDY WITH HIGHS IN THE MID 70’S TO LOW 80’S.
TUESDAY NIGHT: PARTLY TO MOSTLY CLOUDY WITH LOWS IN THE UPPER 50’S TO UPPER 60’S.