Area Forecast Discussion

KEY MESSAGES

- There is a marginal, level 1 out of 5, risk of isolated severe storms along and south of I-80 this afternoon and evening.

- Rounds of nocturnal and diurnal convection through Monday night will bring a risk of locally heavy rainfall due to weak winds aloft. If storms stall, excessive rainfall is possible.

- Heat and humidity will return the second half of next week with temperatures in the 90s and heat indices pushing 100 or higher. The probability of heat headlines for part of next week is currently 30 to 40 percent.

SHORT TERM /THROUGH MONDAY NIGHT/

Issued at 218 AM CDT Sat Jun 6 2026

Weak inhibition aloft has so far prevented more widespread storms from developing and based on atmospheric profiles, this weak inhibition will continue through sunrise. The net result is that only isolated to low end scattered storms will be seen as the weak support aloft moves through the area.

Much of the daylight hours Saturday will be dry. Diurnal convection is expected to develop again this afternoon and continue through the evening hours. Steep mid-level lapse rates developing this afternoon and the proximity of a weak boundary over the area does raise the potential for isolated severe storms developing south of I-80 this afternoon/evening. If severe storms develop, damaging winds from and hail would be the main risks.

The same scenario will repeat on Sunday and Monday. The upper level disturbances Sunday and Monday are much weaker than the Saturday disturbance. Thus the probability of an isolated severe storm Sunday and Monday is less than 10 percent.

A bigger concern for today through Monday is the slow movement of storms due to weak winds aloft. With PWATS over 1.5 inches, slow moving storms would be capable of producing locally heavy to excessive rainfall. Urban areas would be most at risk for localized flash flooding if a storm would stall.

Some models are showing a weak signal south of I-80 for storms potentially stalling this evening with opposing Corfidi vectors of 5 knots. This signal will need to be watched for trends and whether or not a flood watch would be needed.

LONG TERM /TUESDAY THROUGH FRIDAY/

Issued at 218 AM CDT Sat Jun 6 2026

Tuesday through Saturday Assessment...high (>80%) confidence of temperatures well above normal. Low (20-25%) confidence for rain.

A heat dome will build into the Midwest and send temperatures well above normal next week.

Temperatures will climb above 90 on Tuesday and remain in the 90s through Friday. Some relief from the heat is possible on Saturday.

Heat indices on Tuesday generally look to be 95 to 100. Heat indices exceeding 100 have a 50 percent probability of occurring Wednesday and Thursday. Currently there is a 30-40 percent probability of heat headlines being needed in the Wednesday/Thursday time frame.

Slightly lower humidity levels will be seen on Friday but heat indices of 95 to 100 have a 50-60 percent probability of occurring.

The main question Tuesday through Saturday are rain chances, especially when the main heat dome builds into the area.

The models vary considerably on their respective solutions for rain chances. The net result is general 20-30 percent chances each day through Saturday but not everyone will see rain. There is a diurnal trend with the rain chances with the afternoon/evening being the highest. The slightly better chance for rain may be late Thursday afternoon/night when a cool front pushes into the area.

The edge of the heat dome will be where the organized storm complexes are found. Right now the signal for the organized storm complexes is in the northern Plains. However, the models have a weak signal for organized storm development across western Iowa Wednesday afternoon that could move into eastern Iowa Wednesday night. This signal will need to be watched to see if it remains consistent into early next week. Right now given the weakness of the signal, the probability of organized storms Wednesday night is 10-20 percent.

AVIATION /18Z TAFS THROUGH 18Z SUNDAY/

Issued at 1216 PM CDT Sat Jun 6 2026

Quiet VFR hours will begin the forecast period today, as light winds and partly cloudy skies with bases over 3kft will continue through the afternoon hours. A few isolated thunderstorms may fire in the heat of the afternoon, and if they form they will move slowly, and produce a period of torrential rainfall, gusty winds and small hail. This coverage is limited and unfocused, so I have not placed into any TAF except for a prob30 at Burlington. Otherwise late this evening and overnight, a band of showers ands storms could form over the entire area, and lift northeast by sunrise Sunday. This is not certain, and handled with Pro30 groups at all sites except for DBQ. Some MVFR cigs are expected overnight at times with storms and possibly more consistently at DBQ where a temporary conditions of BRK025 is included for stratocumulus formation late tonight.

Sunday morning through afternoon, additional showers and storms may be forming in the area, but these are not yet included in the TAF.

DVN WATCHES / WARNINGS / ADVISORIES

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