Area Forecast Discussion

KEY MESSAGES

- Freeze Warning Tonight

- Some Storminess by Friday

DISCUSSION

Issued at 245 PM EDT Sun Apr 19 2026

- Freeze Warning Tonight

Sharp upper trough moving through today combined with sufficient low to mid level moisture has resulted in convective updrafts with scattered showers this afternoon. Lake shadow and high clouds has prevented widespread deeper updrafts, lowering the potential for ice pellet/graupel. Showers will diminish end this evening as the trough axis moves east and with the loss of insolation.

Cold surface high builds in overnight with drying and subsidence with winds decoupling after midnight. Radiational cooling conditions become optimal by 12Z with the surface high progged to be centered over southwest Lower Michigan. A hard freeze is expected as temperatures will be below freezing for several hours.

- Some Storminess by Friday

The surface high moves east by Tuesday with southerly flow developing but the moisture return does not immediately result in precipitation as shortwave ridging is expected during the middle part of the week ahead of an upper low over the NW CONUS that eventually moves into Upper Plains and Canada by the end of the week. A cold front trailing a surface low moving into northern Minnesota before it occludes and moves into Canada will concentrate showers on Friday with the chance for thunderstorms during the afternoon.

AVIATION /18Z TAFS THROUGH 18Z MONDAY/

Issued at 200 PM EDT Sun Apr 19 2026

VFR weather is expected through the 24 hour TAF period of 18Z Sunday to 18Z Monday. Diurnal heating has resulted in fairly widespread cumulus and altocumulus clouds this afternoon with bases in the 4,000 to 8,000 foot range. These clouds will continue to work through the area this afternoon and dissipate this evening with the setting sun. We are expecting mainly clear skies tonight and Monday morning. Scattered showers will work through the TAF sites this afternoon, but these should not affect ceilings or visibilities much at all as they will move through any one location fairly quickly. Cannot rule out some small hail in the deeper convective towers. At this point given the nature of the showers, we have covered them with VCSH wording. Winds are gusty at 18Z from the west sustained at 10-20 knots with gusts of 20-30 knots. Winds will decrease substantially as we approach and move through sunset. Light winds are expected tonight.

MARINE

Issued at 245 PM EDT Sun Apr 19 2026

High pressure brings tranquil conditions on Lake Michigan tonight and Monday. The high will move east and southerly winds increase and waves will build Monday night. A SCA will be needed from late Monday through Tuesday.

GRR WATCHES / WARNINGS / ADVISORIES

MI...Freeze Warning from 11 PM this evening to 11 AM EDT Monday for MIZ050>052-056>059-064>067-071>074. MARINE...None.