textproduct: Detroit/Pontiac

KEY MESSAGES

- Showers and thunderstorms will increase in coverage tonight. The potential exists for storms to become severe capable of producing wind gusts to 60 mph and large hail for all location. An isolated tornado possible along and south of the I-94 corridor.

- Winter Weather Advisory is in effect for the Tri Cities region and northern Thumb from this evening until late Wednesday morning. Ice accumulations of up to 0.10 inch is expected to result in travel impacts Wednesday morning.

- Rain showers continue Wednesday with brief change over to melting snow showers by Wednesday night possible.

- Accumulating snow is likely Friday with a dynamic clipper system tracking through the Great Lakes. Strong west winds in excess of 40 mph may be possible during the daytime Friday.

- Another strong low pressure system may impact the Great Lakes to start next week.

AVIATION

A cold front will inch its way across metro Detroit early this evening. A cold moist marine modified airmass on the cool side of the boundary will support stratus. As low level moisture increases during the night, IFR and low end MVFR based stratus will increase in likelihood. Upscale convective growth to the west-southwest of the area will result in clusters of showers and thunderstorms tracking across the terminals late this evening into the overnight, most likely during the 03Z to 07Z time frame. Additional upper level short wave impulses within an approaching sfc low will support occasional showers, with additional chances for thunderstorms late tonight into Wed morning. Sfc temperatures will be around the freezing mark at MBS. A mention of freezing rain will be maintained at this airport late this evening into the overnight. Strengthening low level wind fields overnight atop the stable boundary layer will warrant a mention of low level wind shear.

For DTW...Current observational trends and latest model guidance suggest scattered to numerous thunderstorms advancing across the airspace in the 03Z to 09Z time frame. Additional rounds of convection are possible after 09Z through Wed morning, the probabilities are lower, leading to reduced forecast confidence.

DTW THRESHOLD PROBABILITIES...

* High for ceilings at or below 5000 feet through the forecast.

* High for thunderstorms after 03Z into early Wed morning. Low on Wednesday.

PREV DISCUSSION

Issued at 342 PM EDT Tue Mar 10 2026

DISCUSSION...

20z surface analysis shows a sharpening low level baroclinic zone slowly migrating southward toward the I-94 corridor. While firm cold air advection continues north of the boundary, initial attention focused along and immediately south of the boundary as the frontal slope engages a gradually destabilizing profile with temperatures now in the mid 70s in Ann Arbor/DTW. Collective consensus across the hires solution space indicate roughly 1000-1500 j/kg will exist across this corridor with a peak in the 21z-00z window. Mixed signal yet on the convective response, acknowledging some lingering stability concerns atop the boundary layer which may prove limiting for updraft growth/depth. Background deep layer wind field certainly supportive of greater convective organization should a better updraft root at the surface, while the frontal zone offers an inherent focused region of low level shear/SRH. Window to monitor, but certainly plausible little to nothing manifests before the boundary eases further south and pinches off the better low level instability to the south.

Main window for widespread convective activity remains centered within the 02z to 08z period. Convective expansion occurs upstream this evening as the surface low and subtle height falls work across the boundary and moisture transport strengthens atop the elevated frontal zone. Inbound activity to remain elevated for nearly all areas given the depth and strength of low level stability held in low level east/northeast flow. The I-94 to Ohio border corridor will continue to carry more tenuous positioning with some vulnerability yet for brief near surface destabilization to remain/materialize if the surface front wobbles north. There remains a small subset of solutions that leave that door open. Forecast will continue to highlight associated tornado potential in line with the SPC outlook for this small footprint of southeast Michigan tonight. Elsewhere, brief heavy rain and hail potential will exist as deeper theta-e transport engages sufficient elevated instability residing along the frontal slope. Higher magnitude of cold air advection, with some influence from onshore flow off the marine waters, will bring temperatures down into the low to mid 30s across the Saginaw valley and northern thumb regions tonight. This increases the probability for some areas of freezing rain to materialize where surface temps flirt with freezing. Efficiency of ice accretion may prove limited given the marginal/warm conditions just off the surface, but probabilistic data maintains a high probability for a glaze of ice with around a 25% chance of exceeding .05" in Midland/Bay City and Bad Axe.

Surface low migrates through Wednesday morning. A weakly unstable low level environment briefly materializes 12z-18z /mainly southeast/ as pre-frontal southwest flow provides very modest warm/moist air advection. Boundary layer destabilization appears capped at less than 500 j/kg at this stage, but sufficient to maintain a higher probability for scattered shallow convection. Better mid level dynamics appear to shear northeast within the immediate post-frontal environment, affording a trend toward drier and more stable conditions overall by mid-late afternoon. Narrow opportunity for some wet snowflakes mainly north late afternoon and evening within the south end of the deformation axis. Overnight cold air advection will bring temperatures below freezing all areas by Thursday morning.

No significant wx Thursday with deep layer stability held under confluent mid level northwest flow and surface ridging. Seasonable resident thermal profile now entrenched. A highly dynamic mid level wave projected to eject across the northern great lakes Thursday night and Friday. Lead wing of isentropic ascent tied to strengthening elevated warm air advection lifts across the local area Thur night. Some variation yet in both moisture quality and available ascent with southward extent. Greatest precip potential focused Friday morning as pronounced height falls collocate with favorable upper jet support. Burst of wet, accumulating snow plausible mainly across the north assuming a supportively cold environment. Stronger wind potential to accompany the post-frontal cold air advection Friday afternoon/evening, with a notable increase in wind magnitude captured by improving mixing depth. Yet another mid level wave of north Pacific origin forecast to deepen upon arrival for the weekend period. This system will present another opportunity for some accumulating snow for portions of southeast Michigan sometime Saturday night into Sunday. Further forecast revision likely as detail in system trajectory, timing and strength become more apparent.

MARINE...

Deepening low pressure tracks along a cold front that is south of Lake Huron at issuance and will lift back north as a warm front during the day Wednesday. The front will act as a trigger for shower and thunderstorm development this evening, with potential for strong to severe storms over Lake St. Clair and Lake Erie. All severe hazards remain possible. Strong low level jet winds pair with this system to generate sporadic gale potential overnight, but stability limits headline issuance at this time. Widespread rain and embedded thunderstorms persist Wednesday as the front lifts back north toward southern Lake Huron. Cyclonic flow around the low transitions to broader northwest flow Wednesday night that introduces 30+ knot gust potential as cold advection ramps up, albeit brief duration. Active stretch of weather continues for the latter half of the week, with a return to wintry conditions. Increasing confidence in gale potential for Friday as strong low pressure tracks across the Great Lakes, alongside wintry precipitation.

HYDROLOGY...

Widespread showers and thunderstorms will develop tonight and Wednesday as a low pressure system tracks northeastward across Lower Michigan. Expected rainfall totals range from 0.75-2.00 inches by Wednesday afternoon. This may lead to some minor flooding of prone urban and low lying areas, as well as rises on area rivers.

DTX WATCHES/WARNINGS/ADVISORIES

MI...Winter Weather Advisory until 10 AM EDT Wednesday for MIZ047>049- 053-054.

Lake Huron...Small Craft Advisory until 4 PM EDT Wednesday for LHZ421-441.

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