Peoria, Ill. (WMBD) — A strong cold front is expected to sweep across Illinois Friday evening bringing multiple rounds of showers and thunderstorms to Central Illinois. Some storms may be strong to severe and could produce heavy rain that could lead to localized flooding. The Storm Prediction Center has placed Central Illinois within a Slight Risk (Level 2 Threat) for severe weather Friday evening.
- Most of Friday will be dry, storms develop Friday evening
- Primary Severe Threats
- Damaging winds
- Large hail
- Flash flooding
- Rain & thunderstorms continue through Saturday
Breezy southerly winds will once again bring a warmer and muggier airmass to Central Illinois on Thursday and Friday. A strong cold front will move in from the northwest on Friday setting up a clash of airmasses over Illinois which will result in multiple rounds of storms across the region from Friday evening through Saturday.
Storms that develop will likely do so after 7 pm and behind the cold front. This should limit the potential for tornadoes but there enough elevated instability for storms to pose a risk of large hail and damaging winds along with heavy rain. If storms are able to develop ahead of the cold front the risk of tornadoes could increase.
While the warm and muggy air will bring a relatively unstable airmass to Central Illinois ahead of the cold front, there are a couple of limiting factors that will likely keep this from becoming a bigger severe weather event.
- The upper-level support for this system is expected to remain well to the northwest. This means that storms will have to rely on the cold front and other forms of lift to develop.
- Elevated Mixed Layer (EML) over Central Illinois
- The EML is a layer of warm and dry air aloft (also known as capping inversion) that originates over eastern Colorado and moves east over the plains and Midwest. This will act to keep air near the surface from rising and therefore preventing any storms from developing, at least during the day. You can see the animation of the EML in the loop below
Given the strength of this cap storms will likely struggle to develop on their own and will likely hold off until the cold front moves in Friday evening and the low-level jet ramps up forcing air to rise through the well defined cap. Once this happens, the amount of instability and shear over the area will be sufficient for strong to severe thunderstorms capable of large hail and locally strong wind gusts. Training thunderstorms will create a localized risk of flash flooding as the storms move parallel to the slowing cold front.
Model guidance has trended slower with the cold front over the past few days and it now appears that this front will remain over the region through Saturday afternoon. Showers and storms are expected to continue to impact the area throughout the day with periods of moderate to heavy rain. Depending on where the cold front stalls strong to severe storms could once again be possible, particularly east of the Illinois River. In fact, the severe weather potential for Saturday could end up being higher than Friday if the front stalls far enough to the west.
It’s still to early to establish rainfall amounts for the area but the general consensus is for most of Central Illinois to pick up 1-2 inches of rain with locally higher amounts possible. Be sure to monitor the forecast for adjustments that are bound to come our way.