textproduct: Detroit/Pontiac

KEY MESSAGES

- Hot and humid conditions arrive Monday with highs in the low-mid 90s and heat indices nearing 100 degrees.

- Hottest conditions expected Tuesday through Friday with potential for highs to reach 100 degrees and heat indices in excess of 105 degrees. There will be little nighttime relief with lows in the mid 70s.

- Low thunderstorm chances for most of the work week, then increasing Friday into the holiday weekend.

DISCUSSION

Quiet / quaint conditions are courtesy of high pressure, centered east of Lake Superior. Only notable feature is a field of shallow diurnal cumulus perking across the Thumb, which will mix out as the afternoon progresses. The high will be slow to migrate through the region, so another seasonable weather day is queued up for Sunday. As we exit into the workweek, there is an outside shot at some decaying shower activity to tumble in from the northwest early Monday.

The well advertised longwave pattern transformation will commence Sunday and reach its zenith mid-late week. The aggressive ridge amplification and subsequent deep subsidence response will warm the entire column dramatically early next week. The centroid of greatest response will be across the Great Lakes, Ohio Valley, and Upper Mississippi Valley regions. Monday will be become appreciably hotter with highs crawling above 90-F with increasing dewpoints (climbing into the lower 70s-F). The next level of hot arrives Tuesday and will certainly maintain voracity through Thursday. Highs will make a run at 100-F each day - with heat index values approaching 110-F at peak heating each afternoon. Lows will only settle back into the low-mid 70s-F - maybe upper 70s-F in the urban areas.

The post-amplification phase of the episode has a few exit paths. Ensemble envelope has broadened some in the end of the week time window - with a tendency for greater spread. Ensemble sensitivity analysis strongly suggests the variance is a culmination of the differences in decay rates associated with the wave train PV induction. The net result is a broadening and flattening of the ridge axis - opening the opportunity for shortwave preservation and deep convective response along the periphery of the heat dome. The best first opportunity for the central Lakes region to get into thunderstorm action is in the Friday timeframe. If storms delay, Friday will be another very hot day. The overall pattern configuration will remain supportive of above average conditions through the upcoming holiday weekend.

MARINE

High pressure will hold over the region through the weekend resulting in light northeasterly winds under 10 knots through Sunday. A warm front will lift north through the region on Monday opening the door for very warm air to move into the region for next week. There will also be a chance of showers and thunderstorms for northern Lake Huron Monday as the front lifts north. Winds will turn southeasterly on Monday with gusts increasing to around 20 knots.

PREV DISCUSSION

Issued at 229 PM EDT Sat Jun 27 2026

AVIATION...

Diurnal cumulus has developed this afternoon supported by lake moisture under the E-NE flow. Highest coverage is across the Thumb with a SCT/BKN coverage at borderline line MVFR creeping across MBS/FNT. Mostly clear skies towards the south at press time towards metro terminals, but could still see a FEW/SCT VFR cu through remainder of the afternoon. Expect scattered high clouds tonight with light winds holding out of the NE-E. Lingering low moisture offers some potential for patchy fog to develop in spots late tonight, but confidence is low at this time in development over any terminal given some presence of high clouds. Largely VFR for tomorrow with a more easterly wind direction by the afternoon.

D21/DTW Convection... No thunderstorms forecast through Sunday.

DTW THRESHOLD PROBABILITIES...

* Low for ceiling at or below 5000 ft through this afternoon and again tomorrow.

DTX WATCHES/WARNINGS/ADVISORIES

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