textproduct: Paducah

KEY MESSAGES

- Daily chances of showers and thunderstorms continue into Tuesday. A few isolated strong to severe storms are possible between 12-7PM when rain chances peak at 40-60%. Localized flash flooding issues are also possible with heavy rainfall rates.

- A Heat Advisory and Extreme Heat Warning are both now in effect through Tuesday evening. Heat index values of 100 to 106 are expected today and 110 to 116 on Tuesday.

- Unhealthy air quality conditions from the Ontario wildfire smoke will continue through Tuesday mainly across portions of southern Illinois and southwest Indiana.

DISCUSSION

Issued at 1244 PM CDT Mon Jul 20 2026

Weak northwest flow aloft and a sfc boundary will allow for isolated rain chances this afternoon, especially across southeast Missouri. The boundary lifts north overnight with some improvement to the unhealthy air quality conditions across portions of southern Illinois and southwest Indiana on Tuesday. However, a strong cold front will begin to approach the FA from the northwest with increasing shear from a 40-50 kt jet at 700-500 mb. While most of the CAMs show the bulk of scattered convection occurring during the afternoon hours, the FV3/ARW have a decaying complex of storms moving across southwest Indiana after 12z. Meanwhile, the HRRR/NSSL show scattered development mainly south of the Ohio confined to the afternoon hours. Despite the uncertainty, the risk for isolated strong to severe storms will be the greatest between 12-7PM when 4000 to 5000 J/kg of MLCAPE is progged by the RAP13 along with 7.0 C/km sfc-3km lapse rate. Although the best shear will be lagging behind the front, a robust theta-e difference of 30-40K will favor 60-70 mph damaging wind gusts as the main hazard of concern. Torrential downpours will also be capable of causing localized flash flooding issues with runoff on roadways.

A Heat Advisory and Extreme Heat Warning are now in effect through Tuesday as heat index values between 110 to 116 are progged for tomorrow. However, locations along I-64 are only under a Heat Advisory as the earlier timing of storms will help to keep heat indices a bit cooler in the 105 to 109 range. High temperatures in the low to mid 90s are expected over most of the FA setting the stage for the hottest day of the week. The air quality will also still be unhealthy across portions of southern Illinois and southwest Indiana due to the wildfires in Canada. Temperatures will then be 10 degrees cooler behind the front on Wednesday with highs only in the low to mid 80s. Humidity levels will also be significantly lower with dewpoints dipping down into the 60s and 50s. Rain chances return on Friday as a shortwave moves through, followed by a significant warming trend with an increase in humidity over the weekend as the eastern extent of a 597 dm ridge over the southern Plains builds in. Temperatures by early next week will once again reach the 90s.

AVIATION /00Z TAFS THROUGH 00Z TUESDAY/

Issued at 610 PM CDT Mon Jul 20 2026

Timing of tomorrow's convective chances is the key in this issuance. Confidence is not the highest and so PROB30s were used for EVV, OWB, and PAH. Convection should stay clear of MVN and CGI but this is not a guarantee. Light winds tonight turn west- southwest between 6-11 kts Tuesday morning with isolated gusts around 20 kts.

PAH WATCHES/WARNINGS/ADVISORIES

IL...Heat Advisory until 11 AM CDT Tuesday for ILZ075-080>082- 084>094. Extreme Heat Warning from 11 AM to 7 PM CDT Tuesday for ILZ075- 080>094. Heat Advisory from 11 AM to 7 PM CDT Tuesday for ILZ076>078. MO...Heat Advisory until 11 AM CDT Tuesday for MOZ076-086-087-100- 107>112-114. Extreme Heat Warning from 11 AM to 7 PM CDT Tuesday for MOZ076- 086-087-100-107>112-114. IN...Extreme Heat Warning from 11 AM to 7 PM CDT Tuesday for INZ085>088. Heat Advisory from 11 AM CDT /noon EDT/ to 7 PM CDT /8 PM EDT/ Tuesday for INZ081-082. Air Quality Alert until 11 PM CDT /midnight EDT/ this evening for INZ081-082-085>088. KY...Heat Advisory until 11 AM CDT Tuesday for KYZ001>017-021-022. Extreme Heat Warning from 11 AM to 7 PM CDT Tuesday for KYZ001>022.