Rock City, IL 61070 Weather

This Hazardous Weather Outlook is for portions of north central Illinois: northwest Illinois: west central Illinois: east central Iowa: northeast Iowa: southeast Iowa and northeast Missouri.

Day one: THIS AFTERNOON AND TONIGHT

No hazardous weather is expected at this time.

Days two through seven: FRIDAY THROUGH WEDNESDAY

Thunderstorms will be possible Friday through Friday night. Strong to severe storms are not expected.

Spotter information statement

Spotter activation will not be needed today or tonight.

Key messages

- A cool, dry night is expected tonight in the wake of a cold front that has largely exited our region this afternoon.

- Rain chances return Friday and Saturday (peaking at 60-90% chances Friday night) with isolated storms possible Friday and Friday night.

- A more active weather pattern looks to develop early next week, bringing rain and breezy conditions for Election Day.

Short term

Issued at 224 PM CDT Thu Oct 29 2026

Quiet conditions are expected through tonight as an area of high pressure builds across the area from the Dakotas. Outside of some high clouds blowing off of anticipated convection along a warm frontal zone over Kansas late tonight, we should see quite a bit of clear skies for most of the night. With the high pressure ridge axis in place, low temperatures should dip to the lower to middle 40s for most locations.

As we go into the day Friday, the aforementioned warm front and lingering moisture from the remnants of (currently) Tropical Storm Vance are progged to lift poleward over the region, bringing increasing chances of showers and isolated storms during the daylight hours Friday (30-70%). Instability appears to be pretty minimal, with both the HREF and REFS ensembles suggesting MUCAPE values less than a few hundred J/kg, but this could be enough to generate an isolated non-severe thunderstorm. Due to this potential for clouds and precipitation, we have lowered forecast high temperatures for Friday by a few degrees, with forecast highs ranging from the middle 50s northwest to the lower 60s south.

Showers and isolated storm chances will continue Friday night, with a bit more forcing from an approaching mid-level shortwave impulse and slight intensification in the 850 mb nocturnal low-level jet. This should result in widespread 60-90% chances of precipitation Friday night.

Long term

Issued at 224 PM CDT Thu Oct 29 2026

As we look toward the weekend, the active pattern will continue to remain active as the aforementioned warm front lifts northward. As it does, the overall synoptic forcing looks to weaken, leading to a drying trend in the afternoon. There may yet be an isolated thunderstorm in the area in the early morning, but with minimal instability, this potential appears quite low (10-20% per the REFS). As we go into Sunday, a bit more upper-level ridging will help largely stave off precipitation despite some lingering atmospheric moisture in place.

The main focus for the long-term continues to be on a large system that's slated to translate through the central CONUS for late Monday through Wednesday, including Election Day. The culprit for this active period is a high-amplitude upper-level trough and an associated surface low that's progged to translate through the Midwest. GEFS and EC ensemble guidance suggests a tropical moisture connection with this system, drawing some impressive environmental moisture into the area. In fact, the LREF ensemble mean for Pwats are hovering around 1.6" Monday night and Tuesday morning. If these values come to fruition during this time of year, these Pwat values would be well over the daily maximum for Pwats per the SPC sounding climatology. This is also backed up by the NAEFS ensemble climatological percentile values, suggesting these Pwats would be near the maximum of the climatology for early November. With this said, there remains uncertainty on the exact track of the surface low, given significant spread of the low tracks per the EC and GEFS ensembles. Where this surface low goes will dictate where the axis of the heaviest rainfall and strongest winds will be. Winds with this system generally look to be around 20-25 mph, so nothing too impactful. However, for areas that receive appreciable rainfall, this could make for some gloomy weather conditions on Election Day. In terms of rainfall amounts, there appears to be a consistent signal for amounts, but due to the uncertain low track, the location of the axis of rainfall remains uncertain. However, the latest NBM exceedance probabilities of 1" of total rain or more during this entire period is around 60-80% for most locations, with 2" probabilities around 30-50%.

Aviation

Issued at 1229 PM CDT Thu Oct 29 2026

Clear skies will continue to spread across the area behind a departing cold front early this afternoon, bringing a period of VFR. Northerly winds around 10 knots this afternoon will quickly weaken by this evening, becoming more light as an area of high pressure builds in. As winds turn more easterly tonight, high-clouds will move in ahead of a system that will bring increasing chances (30-60%) of showers for Friday. Confidence on the start time of this activity remains low, so used PROB30 groups for now. We will refine as confidence increases. The easterly flow will continue throughout the day Friday.

Watches, warnings and advisories

IA: None. IL: None. MO: None.