Clintonia Township, IL Hourly Weather Updates

Key Messages

• There is a significant threat of flash flooding across portions of central Illinois overnight into early Saturday morning, where thunderstorms track over areas that have already seen 4-6 inches of rain since Thursday. Areas north of a Havana to Bloomington line are most at risk.
• Some of these storms also have the potential to produce damaging winds, mainly after midnight.
• The heat and humidity remain a concern for the weekend, with the highest chances of seeing more than a 105 degree heat index (40-60%) in areas from Beardstown southeast to Marshall.

Discussion

... Issued at 231 PM CDT Fri Aug 14 2026

The busy weather trend continues, and focus efforts has primarily been with the first 24-36 hours of the forecast.

Flooding Concerns:

The earlier rainfall has finally moved out, and the Flood Watch for east central Illinois was cancelled.

Rainfall amounts of 4 to 6 inches were fairly widespread from the I-74 corridor and then southward in east central Illinois to I-70. While the earlier watch from Havana-Bloomington northward was allowed to expire at 10 am, a new watch has been issued for this area beginning at 10 pm tonight. The next MCS is expected to develop across Iowa this evening, as an upper wave moves across that area, and then move into Illinois shortly after midnight. HREF precipitable water values over 2.2 inches remain in place overnight across the northern third of Illinois, and probabilities of over 2 inches of rain tonight are highest from Galesburg to Lacon (40-60%). However, its LPMM guidance suggests 3-5 inches are a valid concern, depending on where exactly the MCS tracks. While the flooding is the main focus with this MCS, there remains a level 2 severe weather threat with it, primarily for scattered damaging winds.

Heat Concerns:

Extensive rain today has significantly kept temperatures lower than earlier projections. While skies are now becoming partly sunny south of I-72, it is unclear whether enough sunshine will get heat index readings up to 100 degrees in any of the advisory area today. The current advisory area is expected to have less impact from the overnight MCS, and guidance continues to point toward heat index values 105-110 degrees on Saturday and Sunday. No changes in the Heat Advisory were made in that area for this reason. Further north, NBM guidance is also showing similar heat index for Saturday for all of central Illinois. However, the lingering effects of the next MCS suggest the guidance is overdoing projections. HREF probabilities of greater than 105 degree heat index on Saturday are highest from Beardstown southeast through Taylorville to Marshall (40-60%), and tail off pretty quickly north of there. Will leave any headline changes for the overnight forecast cycle, once the MCS shows its hand.

Aviation

/00Z TAFS THROUGH 00Z SUNDAY/... Issued at 640 PM CDT Fri Aug 14 2026

Forecast cycle will repeat itself across central Illinois this evening and overnight as storms once again increase in coverage in response to a strengthening low level jet. Storms will move across the central IL terminals late tonight into Saturday morning. Meanwhile, MVFR ceilings persist just north of PIA/BMI and are expected to spread south overnight, lowering to IFR along portions of the I-74 corridor. This next round of precip will end by around mid morning Saturday with conditions improving back to VFR as southerly winds overspread the terminals during the afternoon.

Watches / Warnings / Advisories

/WARNINGS/ADVISORIES... Flood Watch from 10 PM CDT this evening through Saturday morning for ILZ027>031-036>038. Heat Advisory until 8 PM CDT Sunday for ILZ049>052-061>063- 066>068-071>073.