textproduct: Detroit/Pontiac

KEY MESSAGES

- Areas of light rain today, with a chance for a thunderstorm.

- Colder and dry tonight and Monday.

AVIATION

A potent cold front is currently draped across southern Lower Michigan and will continue its steady southward progression throughout the morning. VFR conditions persist for the morning hours at the southern terminals (DTW/DET/YIP/PTK), while MVFR ceilings should begin infiltrate the MBS/FNT corridor shortly after 12z as showers moisten the low levels.

LAMP guidance remains aggressive with the timing of the moisture surge, suggesting a drop to MVFR at DTW by late morning or early afternoon (16z-18z) as low-level convergence intensifies along the boundary. Numerous rain showers will develop along and behind the front. While the bulk of the activity will be light, a narrow corridor of elevated instability near the Ohio border may support a few isolated thunderstorms today; however, confidence in terminal impact remains too low to include a VCTS at this time.

Post-frontal winds will veer sharply from the southwest to the north- northeast, with gusts increasing to 20 to 25 knots late in the day. As cold air advection (CAA) strengthens tonight, expecting MVFR clouds to persist downwind of Lake Huron. Surface winds do trend north-northwest after midnight, thus confidence in cigs then begins to decrease overnight as some drier air attempts to move in.

DTW THRESHOLD PROBABILITIES...

* Low for ceiling 5000 feet or less this morning, then high this afternoon and evening, followed by moderate confidence overnight. * High for all rain as precipitation type today.

PREV DISCUSSION

Issued at 300 AM EDT Sun Mar 22 2026

DISCUSSION...

The highly dense cold stable layer over Se Mi held the warm front just west of the forecast area yesterday. Weak surface low pressure now moving into nrn Lake Huron and veering and strengthening of the inbound boundary layer winds is now attempting to drive the warm front into Se Mi. This trend will continue during the pre dawn hours. There is reasonable agreement among the hi res suite in suggesting the upstream cold front getting forced south of the state line by 12Z. Some degree of diurnal recovery is shown from Ann Arbor to Detroit and points south into early afternoon, allowing temps to hold/rise into the 50s and possibly 60s. Increasing north flow during the day will however drive a secondary cold front across the forecast area during the course of the day, marking the lead edge of a more notable cold air push. Given the earlier arrival of this cold air across the northern portions of the forecast area, there will be a respectable temperature gradient across Se Mi during the first half of the day.

An axis of mid level frontogenetical forcing is driving the region of precip ongoing across western Upper Mi. The hi res model suite bring this region of ascent across Se Mi this morning. A reintensification of the mid level frontal forcing is then forecast this afternoon, primarily across the southern half of the forecast area, as entrance region upper jet support strengthens. The end result will be occasional areas of rain oriented in a banded fashion across the forecast area. There is strong agreement among the hi res suite that surface based instability will develop well south of the state line this afternoon. There is however a plume of inbound steep lapse rates (700-500mb lapse rates of 8 to 8.5 C/km) set to overspread much of the forecast area this morning. This will result in elevated convective instability and will at least warrant a chance for thunderstorms. Convective chances look highest during the first half of the day as the elevated instability axis is forecast to shift south during the afternoon. While machine learning tools indicate very low potential for hail, the steep lapse rates at least argue for a mention of hail in the hazardous weather outlook.

Low and mid level anticyclonic flow will expand across the Great Lakes region from the northwest tonight into Monday. Cold air advection will persistent into tonight, dropping overnight temps into the upper 20s/low 30s. The gradient flow and some lingering stratus will likely suppress the degree of nocturnal cooling to some degree. The high will maintain dry and seasonally cool conditions Monday. A low amplitude mid level wave is forecast to track across the northern lakes Tuesday, sending a weakening cold front into srn Mi. Limited forcing will keep precip chances minimal with this wave an associated front. Zonal flow is forecast to prevail across the conus next week, with the the Great Lakes likely falling into the baroclinic zone. This may result in highly varying temperatures across the region, not too unusual for March in the Great Lakes.

MARINE...

Low pressure, now centered over the eastern Great Lakes, drags a cold front across the local region over the course of today supporting additional scattered rain showers and potentially a thunderstorm or two over the southern Great Lakes this evening. Moderate north to north-northeast flow develops behind the front with peak gusts occuring latter half of the day into the first half of tonight. Given the fetch, the southern half of Lake Huron will see the strongest wind gusts (20-25kts) with the rest of the region holding closer to the 15-20kt range. Onshore flow brings higher wave action into the Thumb nearshore waters warranting a Small Craft Advisory into Monday. Strong high pressure builds in behind the front on Monday, then the next cold front is expected to glance the central Great Lakes by late Tuesday.

DTX WATCHES/WARNINGS/ADVISORIES

MI...None. Lake Huron...Small Craft Advisory from 10 AM this morning to 4 PM EDT Monday for LHZ421-441>443.

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