Area Forecast Discussion

KEY MESSAGES

- A Heat Advisory remains in effect this weekend, with high temperatures 15 to 20 degrees above normal in the middle 90s to near 100 degrees.

- The passage of a cold front will begin a cooling trend by Monday. Temperatures by Tuesday finally cool closer to or even a little below seasonal normals, where they hold through the end of the week.

- The cold front brings 40-70% chances of showers and storms late Sunday night through Tuesday, with the highest chances Monday into Monday night.

DISCUSSION

Issued at 1200 PM CDT Sat Sep 19 2026

There is little change to the forecast. The H5 ridge will finally begin to breakdown, but not before continued sweltering and record or near record breaking temperatures are forecast both today and tomorrow. Forecast highs in the mid-upper 90s will run 15-20 degrees above climo norms, and combine with dews in the 60s to output peak daily HI's right around the century mark; the Advisory was maintained due to the prolonged duration heat of the week, thru the weekend, for a heightened risk of health related impacts with virtually no relief from the dangerous heat realized all week.

The metamorphosis from our recent heat blast to more climatologically normal readings will occur thanks to a cold front that approaches tomorrow and makes passage tomorrow night- Monday. A transition day Monday occurs as the airmass is replaced, with mid 80s (north) to mid 90s (south), while temps settling around norms for the remainder of the week may well see much of us with highs in the upper 70s/around 80F daily over its back half. The price to pay to get there will be some mid chance to likely category pops that accompany the air mass replacement, including a marginal risk of severe. Dew points make an analagous fall as well, thru the 60s to potentially some upper 50s/around 60F appearance over th latter half of the week.

AVIATION /18Z TAFS THROUGH 18Z SUNDAY/

Issued at 1200 PM CDT Sat Sep 19 2026

It remains a high pressure and subsequently a prolonged duration heat dominated forecast until a cold front can enter the forecast picture, but that's just beyond the purview of this package. Other than patchy daybreak fog potential, there is no other impediment to Visual Flight Rules forecast conditions the next 24 hours.

PAH WATCHES / WARNINGS / ADVISORIES

IL...Heat Advisory until 7 PM CDT Sunday for ILZ075>078-080>094. MO...Heat Advisory until 7 PM CDT Sunday for MOZ076-086-087-100- 107>112-114. IN...Heat Advisory until 7 PM CDT /8 PM EDT/ Sunday for INZ081-082- 085>088. KY...Heat Advisory until 7 PM CDT Sunday for KYZ001>022.