textproduct: Detroit/Pontiac

KEY MESSAGES

- Isolated thunderstorm development possible this afternoon, mainly along and south of I-94. There is a marginal risk for damaging winds and large hail.

- Dry Sunday and Monday followed by building heat with reoccurring periods of thunderstorms Tuesday onward.

DISCUSSION

Subsidence in the wake of overnight convection brought partly to mostly sunny skies for much of the area today, with drier air filtering southward behind a weak frontal boundary. This boundary is currently stalled from north of Jackson to Downriver, marking the northern extent of dew points in the mid to upper 60s. Convergence has capitalized on instability south of the front and caused several thundershowers to develop so far this afternoon. Mean flow will steer this activity south and east over the next several hours before it exits the area. Lightning and gusty winds are possible south of I-94 through about 6pm, but confidence is low for severe weather at this time. Satellite imagery north of the boundary suggests very low probability for additional convection that far north.

Weak height rises and confluent flow aloft promote broad subsidence overnight into Sunday morning, offering mostly clear skies and light winds. Could see some lake cloud move into the Thumb early Sunday morning, otherwise surface high pressure building in favors mostly sunny conditions tomorrow. Upper ridging amplifies overhead with stable and dry conditions holding into early Monday. The upper ridge axis then quickly passes east on Monday as a southern Plains cutoff low lifts into the Midwest. Gulf moisture will accompany this system and gradually advect into the area Monday into Monday night. The bulk of LREF grand ensemble membership maintains dry conditions into early Tuesday, but the GEFS (and 06.12z operational GFS) are quicker with the inbound wave and bring a chance for showers as soon as late Monday evening.

Deep southerly flow directs the moisture plume across the area on Tuesday with high confidence in showers and storms as the wave passes overhead. Available soundings show several factors that could point toward localized heavy rain potential: deep saturation and weak flow through the column, deep warm cloud layer >10kft, and PWAT rising over 1.75" or near the daily record. Bulk of latest ensemble output produces QPF between 0.25" and 1.00" but a few members indicate the potential for over 1.50". The lack of instability and absence of LLJ forcing/moisture advection should keep these heavier amounts isolated. Severe weather is also not likely given moist adiabatic lapse rates and weak wind shear, but could see precip- loaded downdrafts that produce gusty winds at times.

Southwest return flow emerges in the wake of Tuesday's wave, with 850mb temps forecast to increase to around 20C Wednesday into Thursday. Absent of cloud and convection, these values support highs in the lower 90s. Available guidance shows high surface moisture and weak capping, so daily chances for convection are noteworthy and may interfere with reaching the higher end of temperature guidance currently reflected in the forecast. If stronger capping emerges and dry conditions look more favorable, heat headlines would be a consideration for the mid to late week period.

MARINE

A high pressure system to expand from Ontario into the eastern Great Lakes today into tomorrow which will diminish the elevated wind speeds (gusts 20 to 25 knots) across Lake Huron overnight. Light north to northeasterly flow holds tomorrow with winds veering east to southeast by Monday. Low pressure to then enter Tuesday into Wednesday which will bring some unsettled weather including periodic rain showers with some embedded thunderstorms. Winds still generally remain light through time time frame with gusts holding aoa 20 knots outside of any thunderstorm activity.

PREV DISCUSSION

Issued at 117 PM EDT Sat Jun 6 2026

AVIATION...

Low level VFR CU field in place across the southern tafs sites (DTW- YIP-DET) with modest low level convergence and sufficient instability around to potentially allow for isolated to scattered showers/thunderstorms to develop this afternoon, but confidence remains low in storms directly impacting terminals. Surface pressure gradient has weakened compared to this morning, which will make for lower westerly winds speeds, mostly under 10 knots.

Drier air this evening allows for clear skies with light northerly winds trending northeast Sunday morning. Thus, there is some concern the prolonged flow off lake Huron could be sufficient to generate low stratus by sunrise, with MBS standing the best chance of being impacted. Introduced few-sct015 group in the northern tafs for now to advertise this possibilty, as confidence is low. Otherwise, mostly clear skies expected tomorrow, with just a touch (few-sct) of diurnal VFR CU development. D21/DTW Convection...Low probability for an isolated thunderstorm through 21Z.

DTW THRESHOLD PROBABILITIES...

* Low in thunderstorms this afternoon.

* Moderate for ceiling at or below 5000 ft this afternoon.

DTX WATCHES/WARNINGS/ADVISORIES

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