Severe Storm Threat Increasing for Friday

Weather Blog

Peoria, Ill. (WMBD) – The weather pattern is trending more active and a slow moving cold front will bring the risk of strong to severe thunderstorms to Central Illinois. The Storm Prediction Center has placed parts of Central Illinois within and Enhanced (Level 3 out of 5) Risk.

Key Takeaways

  • Severe Weather Window: 5 pm Friday through 3 am Saturday
  • Storm Threats
    • 75 MPH wind gusts
    • 2.5″ in diameter hail
    • Localized flash flooding
    • Isolated tornadoes

What is an Enhanced Risk?

An Enhanced Risk is a level three threat level on a scale of 1-5 and means that numerous severe storms are possible. The storms will likely be persistent, widespread and potentially intense.

SPC Severe Storm Outlook for Friday and Friday night

What to Expect

While a few thunderstorms will be possible Thursday night north of I-74, the risk of severe weather will mainly be across Wisconsin and northern Illinois. These storms will develop along the Iowa/Minnesota border and track east/southeast into northern Indiana by Friday morning. The remnant outflow boundary from these storms will then become the focal point for storm development late Friday afternoon and evening across Central Illinois, which at this point looks to be near I-74.

Hot and humid conditions will contribute to a moderate to highly unstable atmosphere across Central Illinois Friday afternoon. Despite the high instability, a layer of warm air loft known as a cap will likely prevent thunderstorms from developing throughout much of the afternoon. An upper-level wave will help break the cap by early evening as temperatures aloft begin to cool. This type of environment leads to explosive storm development once the cap breaks allowing thunderstorms to quickly become severe.

The window for severe storms opens at 5 pm Friday but most storms may not develop until after 8 pm when the upper-level wave begins to move into the region. Multiple rounds of severe storms will be possible with swaths of destructive winds over 75 mph possible. Currently this risk is highest east of the Illinois River but could expand westward in future updates.

Model simulation of storm development Friday and Friday night.

While damaging winds are greatest risk the high instability and shear could also lead to the potential for hail up to 1.5″ in diameter and training thunderstorms could lead to localized instances of flash flooding, especially late in the evening. The risk of tornadoes is low but isolated tornadoes cannot be ruled out with any supercell thunderstorms that develop along the remnant outflow boundary early in the evening. Brief spin up tornadoes would also be possible within the small bowing segments that move through overnight.

Rainfall amounts will vary greatly from one location to another. Wherever the strongest storms develop rainfall amounts of 1-3 inches should be expected with locally higher amounts possible. Where severe storms don’t develop rainfall amounts will generally be less than a half inch.

Remember to have multiple ways of receiving life saving weather information including a NOAA Weather Radio and the CiProud 2 Go Weather App. Make sure you know the difference between a watch and a warning and that you have a plan in place for when warnings are issued.

Dangerous Heat

In addition to the severe weather potential it will be a very hot day with temperatures in the mid 90s and heat index values in the triple digits. Pavement temperatures will likely climb to 140° in parts of Central Illinois which could cause pets to injure their paws during afternoon walks and lead to more instances of buckling pavement on area roads. Remember not to leave children or pets locked in unattended vehicles as the interior temperature of the car can climb to 129° in just 30 minutes.

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