Area Forecast Discussion

KEY MESSAGES

- Very cold this morning but trending warmer starting Tuesday.

- There is a 30% to 40% chance of showers, and perhaps a thunderstorms, Tuesday night. Thereafter, showers and thunderstorms Friday.

DISCUSSION

Issued at 209 AM EDT Mon Apr 20 2026

Very cold this morning with a freeze warning in place. Expansive 1028mb high pressure spans from Minnesota through the northern reaches of the Ohio Valley. Light wind today, mostly sunny and high temperatures creeping toward 50 degrees. High pressure continues its influence tonight has low temperatures tumble into the 30s once more. However, a developing southerly wind near 5 to 10 mph may be enough to limit frost formation.

Sharply warmer Tuesday through at least Friday with high pressure and upper-level troughing transitioning to somewhat zonal flow aloft. An orphaned frontal zone drags through the Midwest Tuesday night. This front encounters warm, moist flow from the Gulf amid continued Southeast US high pressure (significant need for rain in the Carolinas) and sparks scattered showers and perhaps a thunderstorm for the overnight hours.

An upper-level ridge is maximized overhead Thursday when temperatures near 80 are forecast, before a cold front arrives from west to east late Friday afternoon. Upper-level energy with this system is focused over the upper-Great Lakes as the parent low occludes, but a developing secondary 500-mb jet may provide enough upper-level support for thunderstorms. Drier for the weekend with temperatures closer to more seasonable levels; 60s/40s high/low.

AVIATION /12Z TAFS THROUGH 12Z TUESDAY/

Issued at 605 AM EDT Mon Apr 20 2026

High confidence in VFR conditions through the TAF period beneath high pressure. Light and variable wind to begin the TAF becomes westerly this afternoon, followed by increasing southerly flow late.

IWX WATCHES / WARNINGS / ADVISORIES

IN...Freeze Warning until 11 AM EDT /10 AM CDT/ this morning for INZ005>009-012>015-017-018-020-022>027-032>034-103-104- 116-203-204-216. OH...Freeze Warning until 11 AM EDT this morning for OHZ001-002-004- 005-015-016-024-025. MI...Freeze Warning until 11 AM EDT this morning for MIZ078>081-177- 277. MARINE...None.