AFTERNOON – OVERNIGHT: An area of low pressure is in place to the forecast zones northwest today and will continue moving to the areas north and northwest through the evening and overnight. As this area of low pressure moves to the north it will bring a cold front across the zones 6 and 7, along with the threat for some thunderstorms.
I expect the afternoon hours to remain dry across the forecast zones with mostly sunny to partly cloudy skies. The daytime hours will be very nice as we see temperatures warming into the mid 60’s to mid 70’s.
However, with that will come the tradeoff for rain and t’storms this evening into tonight. Some of which could be strong to severe.
With sunshine and warm, moist air in place the atmosphere will become increasingly unstable throughout the day. The latest models have 2000-2500 J/kg of CAPE, so the level of instability will be pretty impressive over much of the forecast area.
With that being said, model solutions have trended much different from what was forecast yesterday morning. The initial low that was forecast to be in southern Minnesota will instead move through eastern Iowa and northwestern Illinois. With the low pressure central and warm front/cold front triple point in play in northern Illinois, this will likely focus the attention for severe weather farther north as well.
So while we some storms could be strong to severe tonight, the main severe weather threat will be to the north and northwest of the zones.
Most of the daylight hours today will be dry across the forecast zones. By 8-9 PM this evening a cold front will enter western Illinois and move eastward. As it does a broken line of rain and t’storms will start to develop along the front.
This line will quickly race eastward across Illinois, by 10 PM the cold front and rain/storms will be moving across central portions of Illinois.
By 12-1 AM the cold front and storms will be exiting eastern Illinois into western Indiana.
I want to emphasize a couple of things. The first being this model may be underplaying the overall t’storm coverage, I think there could be isolated to scattered t’storms along the front from north to south.
Also, while the main risk is north and northwest of the forecast zones, I still think there will be some strong to severe storms tonight. The best chances for those will be across northern zone 6 and zone 7. So while the severe weather threat doesn’t look as impressive as previously anticipated, some damaging winds, hail, and perhaps an isolated tornado can’t be ruled out.
Once the front moves through I expect a pretty quiet overnight with only a few isolated rain showers. Lows will be in the 40’s.
With the better storm threat shifting northward forecast rain totals won’t be as impressive either. I think .20-.40” under some of the thunderstorms will be possible this evening into the overnight. If storms should become stronger, some locally heavier reports would be possible.
WEDNESDAY: The area of low pressure will start to stall out and occlude over the Great Lakes region on Wednesday. As it does the pressure gradient around the low will tighten and winds will pick up. Sustained winds of 10-20 mph with strong gusts up to 40 mph possible!
Some upper level impulses will move across the forecast zones through the afternoon and evening on Wednesday. As they do they will spark some isolated to widely scattered areas of rain and perhaps a couple t’storms in the evening hours around 7-10 PM.
However, these storms will likely be short-lived so I’m not anticipating anything significant with these.
Highs on Wednesday will be in the upper 50’s north to mid 60’s south.
Overnight Wednesday into Thursday the rain will fade out. Overall I think we will see clear to mostly clear skies with lows in the 40’s.
THURSDAY – FRIDAY: The surface area of low pressure will move to the forecast zones northeast Thursday. However, at 500 mb there will still be pieces of energy moving southward across the zones.
While this won’t produce anything significant some isolated showers will be possible once again Thursday evening.
Highs on Thursday will be in the low 50’s to mid 60’s. Winds will remain strong out of the west at 10-20 mph with gusts up to 40 mph possible.
Early in the night Thursday any rain showers will quickly fade out and a dry overnight is expected. Lows will be in the low 30’s north to around 40 south.
An area of high pressure will start to ridge in from the northwest through the daytime hours on Friday. This will allow cooler air to spread into the forecast zones. Highs on Friday will be in the mid 40’s north to mid 50’s south.
At the upper levels Friday there will be an upper level low moving across Iowa, Minnesota, and the Dakotas. While this low will not impact us Friday a piece of energy associated with it will move through giving us a slight chance of some afternoon/evening rain showers. These looks like they will be pretty isolated in nature.
WEEKEND: The upper level low/trough that will be to the northwest Friday will work into the region for the weekend. This will keep slight chances of precipitation in the forecast both Saturday in Sunday.
In fact, Friday night into Saturday and Saturday night into Sunday temperatures do look cold enough to support some snow showers in locations. This will be overnight as daytime temperatures will be warm enough to support rain.
Highs this weekend will be cool with temperatures topping out in the upper 30’s to low 50’s.
7 DAY FORECAST
WEDNESDAY: AM CLOUDS, THEN MOSTLY SUNNY. 20% CHANCE OF RAIN OR T’STORM LATE. HIGHS IN THE UPPER 50’S NORTH TO MID 60’S SOUTH. WESTERLY WINDS AT 10-20 MPH, GUSTING TO 35-45 MPH.
WEDNESDAY NIGHT: MOSTLY CLEAR WITH LOWS IN THE 40’S.
THURSDAY: MOSTLY SUNNY TO PARTLY CLOUDY WITH 20% CHANCE OF PM SHOWERS. HIGHS IN THE LOW 50’S NORTH TO MID 60’S SOUTH. WINDS FROM THE WEST AT 10-20 MPH, WITH GUSTS UP TO 40 MPH.
THURSDAY NIGHT: PARTLY CLOUDY WITH A 20% CHANCE OF RAIN AND/OR SNOW SHOWERS. LOWS IN THE LOW 30’S NORTH TO AROUND 40 SOUTH.
FRIDAY: PARTLY TO MOSTLY CLOUDY, WITH A 10% CHANCE OF SHOWERS. HIGHS IN THE MID 40’S NORTH TO MID 50’S SOUTH. WEST TO NORTHWEST WINDS AT 6-12 MPH, GUSTING TO 25 MPH.
FRIDAY NIGHT: INCREASING CLOUDS CHANCE OF RAIN AND/OR SNOW. LOWS IN THE LOW TO UPPER 30’S.
SATURDAY: MOSTLY CLOUDY, AM SNOW SHOWERS TO RAIN, 30% CHANCE OF PRECIPITATION. HIGHS IN THE LOW 40’S NORTH TO LOW 50’S SOUTH. VARIABLE WINDS AT 5-15 MPH.
SATURDAY NIGHT: PARTLY TO MOSTLY CLOUDY, 20% CHANCE OF SNOW SHOWERS. LOWS IN THE UPPER 20’S NORTH TO UPPER 30’S SOUTH.
SUNDAY: PARTLY CLOUDY, 20% CHANCE OF AM SNOW SHOWER TO RAIN SHOWERS. HIGHS IN THE UPPER 30’S NORTH TO UPPER 40’S SOUTH.
SUNDAY NIGHT: PARTLY CLOUDY WITH LOWS IN THE UPPER 20’S TO MID 30’S.
MONDAY: 30% CHANCE OF AM SNOW TO RAIN.HIGHS IN THE MID 40’S EAST TO MID 50’S WEST.
MONDAY NIGHT: PARTLY TO MOSTLY CLOUDY WITH 20% CHANCE OF SNOW/RAIN SHOWERS. LOWS IN THE UPPER 20’S NORTH TO LOW 40’S SOUTH.
TUESDAY: MIX OF SUN AND CLOUDS, 20% CHANCE OF RAIN. HIGHS IN THE MID 50’S TO MID 60’S.
TUESDAY NIGHT: PARTLY CLOUDY WITH LOWS IN THE MID 40’S TO MID 50’S.