


Area Forecast Discussion
Issued by NWS Central Illinois
Issued by NWS Central Illinois
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420 FXUS63 KILX 151050 AFDILX Area Forecast Discussion...Updated Aviation National Weather Service Lincoln IL 550 AM CDT Tue Jul 15 2025 .KEY MESSAGES... - Increasing warmth and humidity will bring heat indices into the triple digits Wednesday afternoon. This will increase the risk of heat illness for vulnerable populations. - Daily chances (30-60%) for thunderstorms exists today through the weekend. There is a slight risk for severe weather and excessive rainfall Wednesday. && .DISCUSSION... Issued at 219 AM CDT Tue Jul 15 2025 Today, the stationary front starts to shift northward, bringing in more showers and thunderstorms. The storms will be of the typical summertime airmass variety. They have already been popping up down south of I-70 this morning. They will pop here and there for much of the day. Any storms that do occur could produce decent rainfall locally. A quick inch in rainfall would not be surprising. However, location of where that rainfall will occur is uncertain due to the scattered nature of the activity. Forecast soundings in southeastern IL show a long, skinny CAPE profile, slow storm motions (~20 knots), and PWATs around 2-2.3 inches, which would support very heavy rainfall and localized flooding risk. SBCAPE values are around 2000- 3000 J/kg, with no CIN and low shear. Severe threat is not expected, but strong wind gusts (up to 30-40 mph) would be possible within any stronger downbursts. Tomorrow (Wednesday), there is a slight risk for severe weather that encompasses the northwestern corner of our forecast area and a marginal risk that extends down to I-70. A shortwave is expected to pulse across northern/central IL. Currently, this is looking to be a late afternoon into evening event. The models are showing PWATs around 2 inches, astronomical SBCAPE values (40-60% chance of >3500 J/kg), MLCAPE around 2000-3000 J/kg, and DCAPE around 1000-1400 J/kg. Concerns will be with a 2% tornado risk, and 15% wind risk. There is some indication of bowing segments along a linear system. Slow storm motions are shown on forecast soundings and potential for training, so another flooding threat is being closely monitored. WPC has added a slight risk ERO for the IL River and north. Beyond Wednesday, periodic chances for showers and thunderstorms exist into the weekend. WPC is already showing a slight risk of excessive rainfall on day 5 (Saturday) for the I-74 corridor and north. Temperature wise this week. The hottest day of the week is Wednesday, with the WAA in place pulling much more humid and hot air. We can see heat indices of 100-105 degrees ahead of the shortwave`s arrival. It will cool off ever so slightly on Thursday and Friday. Then heat indices get back near or just above 100 again for the weekend. Copple && .AVIATION... (For the 12z TAFs through 12z Wednesday Morning) Issued at 550 AM CDT Tue Jul 15 2025 VFR conditions are expected for the 12z TAF period. There is a 30-50% chance for showers and thunderstorms today, but coverage will be widely scattered. PROB30 groups for thunder for all sites but PIA was added for this afternoon to cover the uncertainty of location of any of the storms today. Ceilings and/or visibility may drop in the event a shower or storm moves over a TAF site. Copple && .ILX WATCHES/WARNINGS/ADVISORIES... None. && $$