Area Forecast Discussion

KEY MESSAGES

- Scattered rain and/or snow showers this afternoon and evening with gusts above 30 mph at times; a rumble of thunder cannot be ruled out.

- A Freeze Warning is in effect tonight for most of Southeast Michigan with lows in the 20s.

- Temperatures warm back toward normal Tuesday, climbing well above normal through the rest of the week.

AVIATION

High based, widely scattered showers have developed across all of southeast Michigan this afternoon. Beneath these high based showers and ceilings, steep low-level lapse rates have allowed for robust mixing to develop and continue to favor west to northwest winds with gusts of 25-30 knots. Throughout the afternoon and evening hours, west winds will gradually become northwesterly as a weak cold front drops south across the area.

Wind gusts in excess of 30 knots are possible, especially with more robust shower activity. Given the thermal profiles, more robust showers may end up a mix of graupel/rain and/or wet snowflakes. While we still cannot rule out a rumble of thunder, the best chance for a thunderstorm this afternoon appears to be in the vicinity of KDET and areas to the northeast where surface convergence along the surface front will be maximized.

Tonight, clearing skies are expected with light northwest winds as high pressure moves into the region. Northwest flow continues into Monday, then winds gradually back westerly and southerly as high pressure continues to move east of the region late Monday.

DTW THRESHOLD PROBABILITIES

* Low to medium for ceilings at or below 5000 feet through the evening.

* Very low for a rumble of thunder this afternoon until 23z.

PREV DISCUSSION

Issued at 305 AM EDT Sun Apr 19 2026

DISCUSSION...

Satellite trends this morning show a definitive back edge to the clouds with clearing working into the forecast area. Morning sunshine will give way to afternoon clouds. Not making any changes to the temperature forecast but temperatures today may be a touch mild, conditional to the radiational cooling that occurs ahead of sunrise.

Composite H3-H5 trough axis and associated absolute vorticity maximum will track directly over Southeast Michigan this afternoon. Plan views of 300mb winds depict an additional northern stream jetlet merger into the broader left entrance region over the eastern contiguous US resulting in ageostrophy and increased 850mb frontogenesis over Southeast Michigan between 17-23z. Cooling aloft provided by the shortwave in combination with minor low level thetae advection is expected to result in steep lapse rates from the LCL at 6.0 kft agl upwards to 17.0 kft agl. Given the dynamics and the relatively high convective depths, feeling is that coverage of shower activity will be fairly high. Therefore, intermittent cellular showers are anticipated this afternoon and increased PoPs to greater than 60 percent for most of the area. Saturation through the DGZ does bring the potential for some melting snowflakes particularly north of Metro Detroit, but the more likely scenario for mixed phase precipitation is brief graupel/snow pellets. Cloud ice supports a potential for lightning see SPC SWODY1. Inverted V supports gusty wind potential with the showers, perhaps 30 to 40 mph possible.

Stout cold air advection with polar air mass brings high confidence and high certainty that surface temperatures will drop into the middle to upper 20s after midnight tonight. NBM provides an interquartile range on temperatures late tonight of between 23 to 30 degrees. With collaboration considerations, upgraded to a Freeze Warning from 11 pm this evening until 11 am Monday morning.

Strong 1000-500mb geopotential height rises and confluence aloft will support high pressure on Monday with ridging persisting into the daytime on Tuesday. Cool, below normal temperatures (40s) are expected Monday before moderating significantly Tuesday afternoon (60s). Warm advection in combination with exit region dynamics may provide enough ascent for some scattered shower activity particularly over the southern forecast area Tuesday evening/night. The current forecast has slight chance PoPs south of Detroit.

High amplitude ridge is forecasted to build into much of eastern North America for the end of the week. A notable warming trend with upper 70s temperatures and dewpoints in the 50s possible.

Not the highest of confidence in the deterministic solution space for next weekend as recent model runs are suggesting more progressive weather across the Great Lakes. Huge sensible weather variance exists across the region as timing and southward extent to occlusion of central United States low pressure system will matter. For now, the cold front is forecasted to push into Southeast Michigan Friday night and Saturday morning per ECMWF and GFS.

MARINE...

A persistent pressure gradient maintains breezy westerly wind through the morning. A cold front tracks across the area this afternoon, bringing a chance for rain/snow showers and potential for a rumble of thunder. Small Craft Advisories remain in effect during the day for Lake St. Clair and western Lake Erie where the westerly flow ahead of the front will become gusty to around 25 kt. Behind the front, wind shifts northwest and gradually increases to the 20 to 30 kt range across Lake Huron tonight. Additional Small Craft Advisories go into effect this evening for the Lake Huron nearshore waters as wave heights build over 4 feet. High pressure builds directly into the Great Lakes on Monday allowing winds and waves to subside. Gusty south wind then develops Monday night into Tuesday ahead of the next cold front tracking across the upper Midwest.

DTX WATCHES / WARNINGS / ADVISORIES

MI...Freeze Warning from 11 PM this evening to 11 AM EDT Monday for MIZ053-060>063-068>070-075-076-082-083.

Lake Huron...Small Craft Advisory until 10 AM EDT Monday for LHZ421-441>443.

Small Craft Advisory until midnight EDT tonight for LHZ422.

Lake St Clair...Small Craft Advisory until 10 PM EDT this evening for LCZ460.

Michigan waters of Lake Erie...Small Craft Advisory until 10 PM EDT this evening for LEZ444.