textproduct: Detroit/Pontiac

KEY MESSAGES

- A warming trend is on schedule for highs in the 60s today and in the 70s Tuesday.

- The warmer air fuels an active period of showers and thunderstorms beginning tonight. A Marginal Risk of isolated severe thunderstorms remains in place for hail as the primary hazard.

- There is a Slight Risk for greater coverage of severe thunderstorms and for all hazards Tuesday. Damaging wind is the primary but also including potential for large hail and tornadoes.

- A strong cold front fuels storms but also a chance for excessive rainfall. There is a Marginal Risk of excessive rainfall mainly along and south of M-46 Tuesday afternoon and evening.

- After the front Tuesday night, temperatures drop back to normal or slightly below normal for Wednesday through late week.

- The weather pattern the remains active late week into the weekend.

AVIATION

VFR conditions hold across the area into this afternoon with a mix of mid cloud and lower 5-6kft cloud. Surge of moisture arrives over region this evening supporting ceilings falling toward low VFR as well as spurring scattered shower development. Initially, these showers are favored towards the southern terminals before expanding northward as a low level jet noses into southern lower MI- did add wind shear mention from PTK south overnight due to this jet. Persistent moisture transport overnight offers enough elevated instability to support scattered thunderstorm development. For both showers and thunderstorms, lack of a strong forcing feature leads to a more nebulous forecast with low confidence in exact timing and placement of activity. As such, continued to lean into Prob30 groups for 'higher' probability windows at each site. The one exception late tonight is MBS who resides near the slow moving cold front sagging into northern lower MI. Proximity to this boundary lends more confidence in thunderstorm potential around/over the airport so opted for a Tempo group.

DTW THRESHOLD PROBABILITIES...

* Medium for cigs aob 5000 ft this afternoon and evening.

* Low for thunderstorms this evening/night.

PREV DISCUSSION

Issued at 357 AM EDT Mon Mar 30 2026

DISCUSSION...

The next stage of the warming trend is on schedule for today as most of SE Mi remains in the building warm sector east of the large central Plains low pressure system. The Tri Cities and northern Thumb are the exceptions where the northern Great Lakes cold front leaks into the area late in the day. HREF mean shows this occurring late in the day and likely after MBS reaches mid 60s for afternoon highs. Onshore wind develops a few hours earlier along the northern Thumb shoreline which holds readings there in the lower 50s. Mid and upper 60s are reachable across the rest of SE Mi even as clouds thicken during the afternoon, and even with a stray shower toward metro Detroit.

The late day to early evening showers in the south are the first sign of accelerating moisture transport from the Ohio valley into Lower Mi tonight. Surface pressure falls within the Plains to Midwest low pressure system support considerable strengthening of the low level jet shown in model theta-e and wind in the 850-700 mb layer after sunset. The moisture transport occurs within an increasingly unstable mid level thermal profile drawn in from a pool of 700-500 mb lapse rate averaging 8 C/km in current early morning hourly mesoanalysis across a wide area of the central and southern Plains. HREF mean projections indicate this moisture/lapse rate combination lifts MUCAPE into the 1000-1500 J/kg range over SE Mi after midnight extending westward to where MUCAPE exceeds 2000 J/kg over WI/IL. The chance for elevated supercells then arises when added to the strong westerly wind profile offering effective bulk shear in the 40 kt range. The small Slight Risk area upstream into a larger Marginal Risk area across southern Lower Mi appears very reasonable given the potential for 1+ inch hail in this setup. There is also a chance for a stray damaging surface wind gust as model soundings show stable surface based temperature profiles during the evening becoming more neutral after midnight. A sneaky high surface wind gust could occur from the base of the low level jet even outside of convection late tonight and Tuesday morning.

A short break in activity is expected Tuesday morning as nocturnal showers/storms move into the northern Great Lakes, along and north of the central Lower Mi warm front. This opens up the warm sector to better daytime heating as low level RH projections also show less cloud cover to contend with early in the day. Preference is then to lean toward higher end HREF mean MUCAPE estimates likely exceeding 1500 J/kg to go along with a still outstanding wind profile still offering 60 kts at 500 mb. The tornado risk is tied to better low level directional shear near the central Lower Mi warm front and with any discrete warm sector cells tracking in the direction of their FFD. Storms then grow upscale into linear modes to ramp up the damaging wind threat along and ahead of the cold front mid afternoon into Tuesday evening. A Marginal Risk for excessive rainfall also continues for this phase of the event along and east of the cold front until it exits south/east Tuesday evening.

Post frontal showers linger toward the Ohio border late Tuesday night and Wednesday morning while the surface front settles into the Ohio valley. This frontal zone remains the focus of an active weather pattern for the area from Wednesday night through late week. The next central Plains low pressure system reactivates moisture transport back into Lower Mi Wednesday night with a chance for a short period of rain/snow mix or wintry mix until the low pressure center tracks west and pulls warmer air back northward during Thursday.

MARINE...

Broad southwest flow will veer to the east for most of Lake Huron by this evening as the next low pressure system and its warm front gain influence locally. The shift in flow will also be accompanied by an expansion of showers and elevated thunderstorms overnight into Tuesday morning, where hail will be the primary threats. The surface low tracks across northern Michigan Tuesday afternoon, drawing a cold front across lower Michigan and adjacent marine waters in its wake. A line of strong to severe thunderstorms will be possible along the frontal passage Tuesday evening, in which localized gusts in excess of 35 knots will be possible. Elevated winds and/or waves will be driven mainly by thunderstorm activity, as otherwise stable conditions prevent gusts from mixing to the surface. A cooler post- frontal airmass then moves in mid-week as flow shifts to the northwest Tuesday night with the fropa. High pressure then drifts across Ontario Wednesday, causing winds to veer around the southern edge of the high before the next system lifts into the area Thursday.

HYDROLOGY...

Showers and scattered thunderstorms expand across SE Michigan tonight then continue Tuesday after a relative break in the morning. Rainfall amounts average around 0.25 inch tonight with an additional 0.25-0.5 during Tuesday. There is a chance for localized totals near 1 inch south of I-69 and across metro Detroit where a Marginal Risk of excessive rainfall remains in place late Tuesday and Tuesday evening. This is when showers and strong to severe thunderstorms have greater potential to line up along a strong cold front crossing the area. The rainfall occurs during a short enough time span to raise the chance for ponding of water on roads and minor flooding in urban areas.

DTX WATCHES/WARNINGS/ADVISORIES

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