textproduct: Detroit/Pontiac

KEY MESSAGES

- Hail and heavy rainfall will remain possible with thunderstorms overnight and early Wednesday morning.

- Winter Weather Advisory is in effect for the Tri Cities region and northern Thumb through 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

The upstream cluster of showers and thunderstorms will track across Se Mi during the pre dawn hours. Additional showers with some embedded thunderstorms will persist through Wed morning and into the early afternoon along/in advance of a surface low lifting northward along a cold front. Ceilings will undergo wide variability during the morning hours as low level moisture continues to advect into a residual cool lake modified boundary layer across Se Mi. The passage of the sfc low and cold front between 15Z and 18Z will result in a veering of the winds to the west-northwest. Post frontal cold air advection will allow wind speeds/gusts to increase steadily during the afternoon and evening, possibly peaking over 25 knots at times.

For DTW...Upstream radar suggests numerous thunderstorms tracking across the metro airspace between 07Z and 11Z. Isolated to scattered thunderstorm may then occur in advance of the cold front during the mid to late morning hours. Confidence on the later morning convection is low at this time.

DTW THRESHOLD PROBABILITIES...

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

* High for thunderstorms early this morning. Low after 12Z.

PREV DISCUSSION

Issued at 810 PM EDT Tue Mar 10 2026

UPDATE...

Ongoing upscale convective growth will evolve into a region of showers and scattered thunderstorms as it tracks across Se Mi during the overnight. The cold front has pushed into far northern Lenawee and central Monroe Counties. While this front may stall or lift a bit northward overnight with the approaching sfc low, the marine influence has contributed to a very strong density gradient along the front which will make it more difficult to be advected too far northward into Se Mi. This will keep the risk of surface based convection (damaging winds and isolated tornadoes) primarily confined to the far south tonight (likely along or south of line from Ann Arbor to Monroe). An influx of elevated instability (0-3km MU cape upwards of 1500 to 2000 J/kg) will pose the risk of large hail with any thunderstorm tonight across most of the forecast area. Overall, the going forecast looks in good shape. No major forecast updates are warranted.

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 this morning for MIZ047>049- 053-054.

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

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