textproduct: Detroit/Pontiac

KEY MESSAGES

Rapid warming trend continues today and Thursday.

Showers and thunderstorms develop Thursday afternoon and evening. A few severe storms are possible, primarily south of the M-59 corridor, with all hazards (wind, hail, and tornadoes) in play.

Sharply colder air arrives Thursday night and Friday, followed by a steady warming trend through the weekend and into early next week.

AVIATION

Light southeast winds this morning will turn toward the southeast around 16Z as daytime heating supports boundary layer growth. Speeds will generally range from 8 to 12 knots, with slightly higher speeds at MBS where the gradient flow is stronger. The low level airmass will remain very dry today, limiting the clouds to bases above 6000 feet.

DTW THRESHOLD PROBABILITIES...

* None.

PREV DISCUSSION

Issued at 308 AM EDT Wed Mar 25 2026

DISCUSSION...

Strong upper level wave and jet energy (175 knots at 250 MB per 00z KUIL raob) moving into the Pacific Northwest/British Columbia. Multiple 500 MB height fall centers to track through the northern Plains into northern Ontario today and Thursday. Strong wind fields setting up over the Great Lakes region on Thursday with tightening baroclinic zone draws concern for severe thunderstorms toward the southern Michigan border and a dramatic temperature swing.

A progressive, low-amplitude ridge currently centered over the Upper Mississippi Valley will shift across the Great Lakes today. This transition will initiate a robust confluent warm advection regime. Model soundings for Wednesday show a significant surge in 925mb temperatures, progged to reach +8C to +10C by late afternoon. Despite a persistent canopy of mid-level clouds (700-500mb layer), strong southerly return flow will drive afternoon highs into the mid to upper 50s, well above late March normals.

Wednesday Night and Thursday: The primary forecast challenge remains the evolution of a surface wave tracking along a cold front on Thursday. The 00z NAM continues to push an aggressive surface-based instability axis (SBCAPE 500-1000 J/kg) across the southern Michigan border into the I-94 corridor as surface dew points surge into the lower 60s. The 03z RAP is even more robust, indicating a deeper surface low and a farther north track, which yields MLCAPE values upwards of 1500 J/kg. Accordingly, the SPC Day 2 Outlook has expanded the Slight Risk northward to include Washtenaw, Wayne, Lenawee, and Monroe counties. Given 0-1 km bulk shear of 30-35 knots and sufficient low-level helicity, all severe hazards (wind, hail, and tornadoes) are in play, as rotation within any discrete supercells is a distinct possibility. The 00z HRRR composite reflectivity lends some credence to this, though it suggests the most intense development may initiate just north of the boundary.

Conversely, the 18z ECMWF and its ensemble mean (EPS) remain adamant that the surface low track will stay farther south. This solution maintains a more stable boundary layer with limited surface moisture, keeping the most robust convection elevated. However, even in this more stable scenario, a strong kinematic field (0-6km shear of 55+ knots) could support a broken line of storms capable of producing damaging wind gusts and hail near the MI/OH border. Highs Thursday will be highly dependent on the front's position; currently forecasting upper 60s to near 70 degrees for Detroit, while locations north of M-46 struggle in the 50s. A caveat remains: if pre-frontal showers develop Thursday morning and low-level cloud cover persists, insolation will be limited, effectively curbing the surface-based instability.

Thursday Night and Friday: A powerful cold front will sweep across the region between 00z and 06z Friday. Strong cold advection kicks in with 850 MB temps diving into the negative mid to upper single numbers by 12z Friday, per Euro. Pronounced mid level dry slot looks to end precipitation before sufficient cold air sweeps in to allow for a changeover to snow, but will allow for a chance of melting snow at the tail end. Better chance for flurries or light snow showers over the Thumb region Friday morning with the prolong northerly flow off Lake Huron, but low inversion heights suggest it will be a struggle.

Weekend Outlook: The post-frontal chill will be transient. GEFS and EPS members show high confidence in a weekend rebound as the upper- level flow becomes more zonal. Highs will return to the 50s by Sunday with a mix of sun and clouds.

MARINE...

Midweek period is characterized by low pressure passing just to our north over Lake Superior/northern Ontario. Aside for a chance at rain-snow showers over northern Lake Huron, southerly winds remain modest around or below 20kts. This system eventually drags a cold front through the Great Lakes latter half of the day Thursday bringing scattered to numerous rain showers as well as thunderstorm chances Thursday evening over the southern Great Lakes. A few of these storms could be strong to severe with wind and hail being the main hazards. Northerly winds quickly strengthen behind the front late Thursday evening/night with a few hour period where gusts could approach gales, though probabilities have been decreasing- under 25% now.

HYDROLOGY...

Showers and scattered thunderstorms are expected to develop Thursday afternoon ahead of a cold front sweeping through Lower Michigan. Consensus model guidance maintains QPF totals between 0.25 and 0.50 inches for most locations through Thursday evening. While the broader flood potential is low due to high infiltration capacity from recent dry weather, localized ponding in low-lying or poor- drainage areas is possible. This is especially true across the southern tier of counties near the MI/OH border, where embedded thunderstorms may lead to localized exceedance of 0.50 inches. Dry conditions will return for the weekend.

DTX WATCHES/WARNINGS/ADVISORIES

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