textproduct: Detroit/Pontiac

KEY MESSAGES

- Windy and warmer today.

- Mild and breezy Monday. A chance of thunderstorms late Monday and Monday night.

- Showers expected Tuesday. Much colder temperatures Tuesday through the end of the week.

DISCUSSION

A broad warm air advection pattern will expand across Lower Mi later this morning into tonight, enhanced by strengthening low to mid level southwest flow. The result will be increasing mid and high level clouds. A more notable mid level theta e ridge will expand into Se Mi late this afternoon and persist into tonight. This moisture will be accompanied by fairly steep 700-500mb lapse rates of 7.5 to 8 C/km. Despite this, model soundings suggest the warm 700mb temps contributing to these lapse rates will form a weak cap on potential elevated convection. This and dry air below 800mb will limit shower chances to less than 30 percent late this afternoon through tonight. A 925mb wind max of 35 to 40 knots will move across srn Mi early this morning. Daytime boundary layer growth into this wind field will result in gusty winds today, with 30 to 35 knots in the mixed layer supportive of 30 to 40 MPH wind gusts during peak daytime heating. Wind gusts may get close to advisory criteria (gusts to 45 MPH) across the Saginaw Valley and thumb were model soundings indicate 40-45knots across the top of the mixed layer. The southwest winds will drive 925mb temps up toward +11C this afternoon, which combined with the mixing will push afternoon highs well into the 60s.

A slow moving cold front will be driven across the Upper Midwest/western Great Monday in advance of a broad long wave trough expanding into the northern plains/nrn Minnesota. Sustained southwest flow ahead of this front will support persistent warm air advection into Se Mi Monday, pushing daytime highs into the 70s. While still breezy, low level wind fields and mixing depths are forecast to be a little lower in comparison to today, likely capping peak wind gusts around 30 MPH.

Modest boundary layer destabilization across the Ohio Valley Monday is forecast to advect into the southern portions of the forecast area toward evening, mainly along/south of the I-94 corridor. Mid level capping and limited forcing suggests low convective chances. While boundary layer moisture may be limited, any deep convection that is able to initiate will be capable of localized strong wind gusts and hail in light of the steep mid level lapse rates and dry air in the mid levels. Mid level height falls will expand across the northern Great Lakes Mon night as the long wave trough builds eastward. This will force the sfc cold front into Se Mi. Weak elevated instability and deep layer moisture is forecast to advect into Se Mi Monday night along/ahead of the cold front. This will provide a better chance for showers and thunderstorms. While the better convective potential looks to precede the stronger shear profiles, steep mid level lapse rates may still support isolated strong storms into the night.

A more organized deep layer frontogenetical forcing along the cold front is forecast by Tuesday across Se Mi resulting from amplification of the long wave trough, increased baroclinicity and corresponding upper jet dyanmics. Latest probabilistic guidance places the highest rain chances generally east of a Bad Axe to Howell line Tuesday. Given the quasi stationary nature of the front, there is at least a low chance for some persistent rain to push total rainfall amounts up to or over an inch. Shallow post frontal cold air will bring temps back down below seasonal averages by midweek, with daytime highs likely in the 50s and nighttime lows in the 30s through the end of the work week.

MARINE

A warm front will pass through today which will sustain southwest with with increasing wind speeds through the morning and afternoon hours. Locally stronger winds will be found within the Saginaw Bay through central Lake Huron given the favorable fetch. Localized gusts around 30 knots will be possible through the Bay, with other nearshore locations seeing gust potential on the order of 20 to 25 knots. Small Craft Advisories remain in effect.

Wind speeds diminish late tonight into tomorrow morning, but return with similar intensity during daylight hours which will likely result in another round of Small Craft Advisories. Isolated to scattered showers will be possible today and tomorrow along with a very low chance for a rumble of thunder.

HYDROLOGY

Showers and a few thunderstorms are forecast to develop across the region Monday night and persist into the day Tuesday along a slow moving cold front. Latest model guidance and probabilistic guidance suggests high probabilities for total rainfall between a quarter inch and three quarters inch. There is low to moderate confidence that rainfall totals will reach an inch generally across metro Detroit/Ann Arbor and points south, with low confidence totals will exceed an inch and a half. While initially convective, the rain is forecast to transition toward a more steady light to moderate rain on Tuesday. This will keep hourly rainfall rates generally light.

PREV DISCUSSION

Issued at 1153 PM EDT Sat May 2 2026

AVIATION...

SE Mi is between Ohio valley surface high pressure and the next low pressure system in northern Ontario late tonight. Light SW wind between the systems will solidify during the morning under a gradual increase in VFR mid and high clouds. A late morning to early afternoon chance of light rain showers shows a northward shift in the MBS area by late morning. There is a substantial virga footprint toward DTW until a stray light shower materializes late in the day. SW wind becomes the weather highlight as gusts approach 30 knots during the afternoon still under VFR mid level clouds Sunday evening.

D21/DTW Convection...No thunderstorms expected through this TAF period.

DTW THRESHOLD PROBABILITIES...

* None.

DTX WATCHES/WARNINGS/ADVISORIES

MI...Frost Advisory until 8 AM EDT this morning for MIZ047>049-053>055- 060>063-068>070-075-076-082-083.

Lake Huron...Small Craft Advisory from noon today to 10 PM EDT this evening for LHZ441>443.

Small Craft Advisory from 10 AM this morning to 10 PM EDT this evening for LHZ421-422.

Lake St Clair...Small Craft Advisory from noon today to 10 PM EDT this evening for LCZ460.

Michigan waters of Lake Erie...Small Craft Advisory from noon today to 10 PM EDT this evening for LEZ444.