textproduct: Detroit/Pontiac

KEY MESSAGES

- Numerous showers and scattered thunderstorms today, mainly this morning and early this afternoon.

- Seasonally cool this week.

- Dry Monday, but showers and possible storms return Tuesday afternoon and late Wednesday/Wednesday night.

-Heaviest rainfall looks to be Wednesday night, with the potential to exceed 1 inch.

DTW THRESHOLD PROBABILITIES

* Moderate for ceilings at or below 5000 ft this morning. Low this afternoon.

* Low for thunderstorms before 19z.

PREV DISCUSSION

Issued at 253 AM EDT Sun Jun 14 2026

DISCUSSION...

The advection of an instability axis in advance of a slow moving prefrontal trough will sustain showers and thunderstorms across Se Mi early this morning. A weak instability axis is forecast to slowly exit southeast of the metro Detroit area between 15Z and 17Z. Can not rule out isolated strong convection early this AM given the strength of the deep layer shear overhead (0-6km bulk shear values ranging from 35 to 60 knots, with the higher values north of the I- 69 corridor). Ascent along/in advance of an associated trough axis will invoke an increase in the frontogenetical response in the mid levels, resulting in the emergence of a more widespread pattern of showers late this morning into early this afternoon. As the main region of showers exits east, diurnal heating is shown to support weak late day instability which combined with convergence along the main cold front will support a chance of lingering showers during the afternoon. The inland push of the Lake Huron marine layer has dropped temps into the 50s across the northern thumb early this morning. Some additional morning cooling will occur with the showers, although model soundings suggest diurnal mixing boosting afternoon temps into the 70s.

Seasonally strong cold air advection within northwest flow will force 850mb temps into the single digits during the course of the afternoon and evening. Clearing skies with sfc dewpoints dropping into the 40s will result in a relatively chilly night as forecast min temps will range from the mid to upper 40s (low 50s in the Detroit urban area).

A strong upper low will remain positioned over or just south of Hudson Bay through the week, maintaining slightly cooler than normal temps through the forecast period. Forecast concerns will revolve mainly around timing of mid level waves pivoting around the base of upper low. There is reasonable agreement in timing of the next short wave into the Great Lakes late Mon night into Tuesday. Backed flow in advance of this wave will advect instability back into Se Mi within increasing SW flow. Current indications among probabilistic guidance suggests instability advection may only support weak daytime instability across Se Mi, with the better instability remaining just southwest of the forecast area. Nonetheless, high chances of showers/thunderstorms will remain warranted during peak daytime heating Tues aftn/evng. The next wave is set to arrive in the Wed night/Thursday time frame. Longer range deterministic solutions all indicate the instability remaining south of the state line, with srn Mi most likely within a region of cool rain/showers.

MARINE...

Winds veer toward the northwest this morning as a cold front crosses through the central Great Lakes. This boundary leads to some showers and thunderstorms, some of which may be strong to marginally severe. Gradient winds increase during the day, approaching 20 knots. Small Craft Advisory criteria be reached for parts of Saginaw Bay during late afternoon and early evening hours, although duration should be brief. Breezy conditions return each afternoon early next week, and dry weather prevails through at least Tuesday morning.

DTX WATCHES/WARNINGS/ADVISORIES

MI...None. Lake Huron...Small Craft Advisory until noon EDT Monday for LHZ421-422-441.

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