textproduct: Detroit/Pontiac

KEY MESSAGES

- Stretch of colder conditions will exist tonight through Tuesday with temperatures remaining below normal during this time.

- Potential for a mix of light rain and snow exists late tonight and again Monday afternoon into Monday night. A dusting of accumulation on grassy surfaces will be possible.

- The next good chance for rain will be Thursday into Friday.

DTW THRESHOLD PROBABILITIES

* Moderate for ceiling at or below 5000 ft initially but high again after 08Z through Monday. * Moderate for ptype to be rain/snow mix Monday morning and Monday afternoon.

PREV DISCUSSION

Issued at 321 PM EDT Sun Apr 5 2026

DISCUSSION...

A brief interval of below to well below normal temperatures can be expected the next couple days as the Great Lakes region resides along the southern edge of the broad upper level trough under deep layer northwest flow. Brief mid level subsidence/negative differential vorticity advection will sustain dry conditions through the first half of the night and will allow some partial clearing this evening. A mid level short wave impulse now over nrn MN will quickly move across Se Mi overnight. The resulting large scale scale ascent and deep layer moisture will support a chance of showers. Steep mid level lapses rates will result in a convective component to the showers. A subtle low level warm layer will advect into the southern portions of the area overnight, supporting a rain or rain/snow mix in the south. The thermal profile will be cold enough to support wet/melting snow in the north.

The passage of this wave will usher in a reinforcing shot of cold air Monday into Tuesday. Steepening low level lapse rates as a result of cold air advection and daytime heating Monday will result in expanding diurnal cu and showers Mon afternoon. While temps are expected to rebound into the 40s across most of the area, low wet bulb zero heights will support some snow in the heavier convective showers, especially across the northern half of the forecast area. Given forecast weak surface based instability, some of these showers may produce brief intense snowfall rates. There is some indication in a few hi res solutions of an expanding region of low level convergence developing along a surface cold front/trough axis sliding south Monday evening/night, warranting a lingering chance of snow showers. The push of cold air behind this is quite impressive for early April as 850mb temps drop into the negative teens. This will drive Mon night lows into the 20s and will warrant Tuesday highs only in the 30s to near 40. Strong high pressure expanding across the region will at least support dry conditions on TUesday.

A warming trend will then ensue Wednesday into Thursday within the return flow of the departing sfc high and in advance of a closed mid level wave forecast to move along the cntl US/Canadian border region. As this wave lifts north of the region, it is forecast to drag an associated cold front into Lower Mi, paralleling the mid level flow. The broad array of ensemble guidance generally suggests high chances for rain late in the week due to the projected slow movement of this front.

MARINE...

The pressure gradient and cold advection weaken tonight, allowing WNW wind to subside and current headlines to expire. A clipper system passes through on Monday bringing snow showers and an uptick in north to northwest winds Monday night in its wake. Gusts Monday night are forecast to peak between 25 and 30 kt before weakening Tuesday morning. High pressure builds in briefly on Tuesday, then flow strengthens out of the south on Wednesday as the next low pressure system tracks into the upper Midwest. This system will send a slow-moving cold front across the Great Lakes Thursday and Friday.

DTX WATCHES/WARNINGS/ADVISORIES

MI...None. Lake Huron...Small Craft Advisory from 4 PM Monday to 10 AM EDT Tuesday for LHZ421.

Small Craft Advisory from 4 PM Monday to 4 AM EDT Tuesday for LHZ422.

Small Craft Advisory from 8 PM Monday to 4 PM EDT Tuesday for LHZ441>443.

Lake St Clair...None. Michigan waters of Lake Erie...None.