Area Forecast Discussion

KEY MESSAGES

- Warmer and mostly dry weather is expected for the first half of this week.

- The potential for widespread showers and thunderstorms returns to the forecast late this week.

SHORT TERM

(Through Late Monday Night) Issued at 138 PM CDT Sun Apr 19 2026

A weak cold front is pushing through the northern forecast area this afternoon, allowing a cool airmass to graze northeast Missouri through south-central Illinois tonight and resulting in similar temperatures to last night. Seeing as little to no frost developed this morning, confidence is low in widespread frost building tonight. However, radiational cooling will be at play, so the potential for patchy frost to develop on elevated surfaces is higher than yesterday. The cool airmass will push east on Monday, opening the region back up to low-level southwesterly flow by the afternoon. Weak WAA will work in tandem with a second day of clear skies to lift afternoon highs into the low 60s to low 70s - just a touch warmer than today.

Jaja

LONG TERM

(Tuesday through Next Sunday) Issued at 138 PM CDT Sun Apr 19 2026

The pressure gradient in the low-levels will tighten over the Mid- Mississippi Valley on Tuesday as low pressure to our north pushes into high pressure to our southeast. The stronger flow will advect much warmer air into the region with widespread mid to upper 70s forecast for highs Tuesday afternoon. After a similarly warm Wednesday, temperatures will rocket into the low-80s Thursday afternoon ahead of our next notable system. Deterministic models match each other well, all placing a southwest-northeast oriented cold front in northwestern Missouri at 06z Friday. The set-up looks similar to what we've been seeing these past couple of weeks: A cold front in the eastern Plains initiates convection that's weakening by the time it reaches the eastern half Missouri after sunset. How quickly it does or doesn't weaken will determine our potential for stronger thunderstorms. The cold front is forecast to clear the CWA to the south late Friday before buckling back northward as a warm front and ushering another chance of rain this weekend.

Jaja

AVIATION

(For the 18z TAFs through 18z Monday Afternoon) Issued at 1149 AM CDT Sun Apr 19 2026

Dry and VFR conditions will prevail through the TAF period. A weak front is shifting winds to northerly as it passes through the area. Between this afternoon and tomorrow afternoon, winds will veer to southeasterly. Gusty winds will become light this evening before increasing to near 10 kts tomorrow morning.

Jaja

LSX WATCHES / WARNINGS / ADVISORIES

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