Lanark, IL 61046 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: TODAY AND TONIGHT

Isolated thunderstorms are possible through 10 AM mainly north of Highway 30. Lightning is the main threat.

Days two through seven: SUNDAY THROUGH FRIDAY

The probability for widespread hazardous weather is low.

Spotter information statement

Spotter activation will not be needed today or tonight.

Key messages

- Rain chances continue across the area this morning with 40 to 70 percent chances. However rainfall amounts will be light. Isolated thunderstorms are possible through sunrise.

- An active weather pattern early next week will bring rain and breezy conditions to the region, including on Election Day.

Short term

Issued at 152 AM CDT Sat Oct 31 2026

At 2 AM, showers and isolated thunderstorms sit along a line from KAMS to KGGI to KIOW to KGBG and then eastward to KVYS. This area of showers and thunderstorms is associated with lift and moisture on the 310K surface. This is forecast to linger along this axis and slowly dissipate through 6 AM.

Models show another round of increasing lift and moisture on the 310K isentropic surface at 12 UTC and lifting northward through 18 UTC. This will bring another round of rain showers to the area this morning. Rainfall amounts will generally be light with amounts of a tenth of an inch or less. It will remain cloudy through the remainder with isolated rain shower possible otherwise as the parent mid level trough lifts across the area. Otherwise it is expected to be dry through the reminder of the day and into this evening for any trick-or-treating activities. High temperatures will be warmer with temperatures in the 60s.

Another shortwave is forecast to move across the area Saturday night but dry conditions are expected to prevail with a lack of moisture with this shortwave. Dry conditions are expected to continue through the day on Sunday as ridging builds across the area ahead of the next storm system. This will also lead to periodic breaks in the cloud cover through the day on Sunday. High temperatures on Sunday will be warmer and be in the mid to upper 60s.

Long term

Issued at 152 AM CDT Sat Oct 31 2026

Forecast focus remains on the evolution of a longwave trough early next week into Wednesday. A synoptically driven mid-latitude system is progged with a Colorado low deepening as it tracks into the Great Plains on Monday. As the previous shift mentioned, impressive moisture transport ahead of this system is expected with the 12z LREF still showing PW values around 1.5" or near the 99th percentile and a daily max for Nov 2nd. The question becomes when do we see rain and gusty winds arrive from this system. Unfortunately and expected at this time range, there is considerable variability in the track, strength, and location of the main surface low. For now, will continue with the NBM chance to likely PoPs Monday through Wednesday. The GFS deterministic solution is the fastest and strongest with the surface low, followed by the NAM, and then the ECMWF. Taking a look at their respective ensembles, it appears the GFS may be the most bullish likely resulting in a mostly dry Monday and better chances for wet conditions on Election Day. The GFS and to some extent the NAM also show a strong northern stream system over south central Canada, whereas the ECMWF keeps this system further north over the Hudson Bay. How this wave interacts and possibly phases with the southern wave will be key to its impacts over the Midwest.

Regarding temperatures, it does appear our area will remain in the warm sector Monday and Tuesday (Election Day). Well above normal highs in the upper 60s/low 70s are forecast, which is still 5-8 degrees below records for the day. If the system slows more, as often is the case with Fall systems, then we could see even warmer temps and breezy conditions. In terms of rainfall amounts, new NBM 72-hr exceedance probabilities of 1" ending 12z Thu has come down slightly than 24hrs ago but is still around 60-80% for most locations, with 2" probabilities now around 20-40%.

Wednesday onward, behind the main synoptic system there will be periodic slight chances for rain, but amounts should be under a quarter inch. Temperatures will be cooler with highs in the 60s and lows in the 40s, albeit still above normal for early November.

Aviation

Issued at 540 AM CDT Sat Oct 31 2026

Scattered showers are possible at eastern Iowa TAF sites through 18 UTC. There is lower confidence that showers will occur at KBRL and KMLI where a prob30 group was used. Showers are expected toVFR ceilings are expected with periods of MVFR ceilings and visibiltieis possible in the strongest showers. Ceilings are forecast to lift to 10kft. Mainly easterly winds are expected throguh the TAF period with a brief period of southeast winds this morning of 5 to 10 knots.

Watches, warnings and advisories

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