textproduct: Detroit/Pontiac

KEY MESSAGES

- Dry conditions this evening.

- Scattered to numerous showers with some embedded thunderstorms will be possible overnight.

- Increasing temperature trends this weekend into early next week. High confidence for temperatures in the 80s Monday and Tuesday.

- Multiple opportunities for thunderstorms over the weekend and early next week with low confidence on timing and coverage.

DISCUSSION

Quiet weather this afternoon and evening as mid-level clouds stream out of the region early this evening, leading to a brief period of clear skies a brief period of clear skies. Lows drop into the low 50s.

Attention for tonight will turn to convective initiation across the Plains, specifically monitoring upscale growth that is expected to occur across Iowa. A pseudo-stationary turning to slow moving front will serve as the focus for initial storm development, with activity expected to grow upscale and congeal into an MCS/MCV as it tracks downstream. A strengthening nocturnal low-level jet will support this evolution by increasing moisture transport and maintaining elevated instability into the system. A convectively enhanced shortwave associated with the storm complex is projected to move just south of the state line but latest hi-res output still retains high PoP coverage overnight across SE MI given some degree of elevated frontal convergence and associated ascent, noting a tightening theta- e gradient over SE MI 10-15Z, coincident with strengthening backed flow through the mid and upper-levels. Strong mid-level lapse rates and MUCAPE ranging between 500-1000 J/kg will help support convective updrafts and will sustain thunderstorm potential overnight. However any convection will be far removed from surface based instability and will remain elevated, and noting the strengthening inversion around 5kft, any severe weather potential will be very low.

Low-end lingering shower potential will exist through the late morning to early afternoon hours. most favorable near or south of I-94, but a weakly capped environment looks to limit convective potential through the day despite the uptick in instability. Zonal flow through the low to mid levels will usher in the warmer temperatures across the Plains into the Great Lakes, pushing daytime highs in the mid 70s across the cwa, upper 70s into the urban Metro region and up through the Tri- Cities.

A northwest Pacific wave will carve across the western US and through the Rockies Sunday into Monday which will amplify ridging across the the Great Lakes and eastern US through the early week period. This will push 850mb temperatures towards 17C and will open up Gulf moisture through the Plains and Great Lakes both Monday and Tuesday. Some showers and storms will be possible Sunday along the leading edge of the warm front with the isentropic ascent, with additional chances for showers and thunderstorms late Monday into Tuesday. The uptick in warm air advection will help push temperatures into the mid to upper 80s on Monday with another round of above normal temperatures on Tuesday. Latest NBM output shows potential for temperatures to reach near 90 or 90 into the urban Metro area Tuesday, but confidence in this is low as it will be predicated in early day shower potential and coverage. A cold front sweeps through on Wednesday, returning temperatures to more normal values while high pressure behind the front brings a period of dry weather through the midweek.

MARINE

Low pressure tracks across Ontario tonight, with a surface trough extending well into the southern Plains at issuance. This leads to downstream strengthening of the pressure gradient and increasing southwest flow locally through the evening. Gusts peak around 20 to 25 knots. This system initially sends an elevated warm front across the Great Lakes overnight, creating stable conditions over the cool waters and allowing gusts to subside. Meanwhile, showers and thunderstorms develop west of the Great Lakes this evening, reaching the local waters around daybreak Saturday. Variable winds expected as convection comes through, with localized gusts over 30 knots possible. A weaker signal exists for a second round of thunderstorms early Saturday afternoon south of Lake Huron. Drier conditions emerge by Saturday night with a brief period of split flow across the lakes as a cold front drops in from the north and the southern stream ridge strengthens. Ultimately the southern stream wins out and brings seasonably warm/unstable conditions to the Great Lakes early next week. Breezy southerly flow is expected Monday-Tuesday along with shower and thunderstorm chances before a cold front mid-week.

PREV DISCUSSION

Issued at 204 PM EDT Fri May 15 2026

AVIATION...

Combination of lead midlevel warm air advection and absolute vorticity advection has led to an extensive altostratus deck over Southeast Michigan today. Subsidence and dry air trailing the shortwave energy will result in scattering of the deck early this evening. More focused low to midlevel warm air advection at the nose of low level jet forcing is expected to shuttle convective vorticity maximum through portions of Southeast Michigan between 10 to 13z Saturday. Have maintained a prevailing shower group with a TEMPO for thunderstorms 10-13z. Confidence is low on the coverage of both rain shower and thunderstorm activity. A Prob30 for thunderstorms has also been introduced at DTW between 18-20z. Low confidence exists on occurrence for the 2nd round, however, a surface warm front is in vicinity and expected to rapidly sharpen Saturday afternoon.

D21/DTW Convection... No thunderstorms expected through early tonight. An embedded thunderstorm will be possible with shower activity 10-13z. Thunderstorm redevelopment is possible between 16- 18z Saturday afternoon, but confidence is very low in the wake of the morning activity.

DTW THRESHOLD PROBABILITIES...

* Low for thunderstorms Saturday morning.

DTX WATCHES/WARNINGS/ADVISORIES

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