textproduct: Detroit/Pontiac

KEY MESSAGES

- Mild and breezy this evening with southwesterly gusts to around 30 mph, then weakening after dark.

- Accumulating snowfall expected late Saturday with totals of a half inch to two inches by Sunday morning.

- Colder and drier on Sunday, followed by an extended warming trend during the upcoming workweek.

- The next opportunity for widespread precipitation occurs Tuesday.

AVIATION

Low amplitude shortwave ridging will build across Southeast Michigan this evening. Low-midlevel warm advection to the south of the dynamic shortwave invof Lake Superior will result in some higher static stability in the 2.0-6.0 kft agl layer early tonight. A cold front will then push across the area after 06z which may steepen lapse rates for some isolated shower activity east of the terminals. Cold advection will then become increasingly shallow resulting in strengthening midlevel static stability my 12z Saturday morning. Low confidence exists in saturation and cloud below the inversion at 2.5 kft agl around daybreak. Will look at guidance this evening. No real model signal for gusty winds Saturday with top down saturation occurring in the afternoon. Frontogenetic light snow band is expected to push into the area after 22z Saturday. Some uncertainty on the preferred track of the snow.

DTW THRESHOLD PROBABILITIES...

* Low in ceilings aob 5000 feet this evening, moderate Saturday daybreak.

* High in precipitation type of snow Saturday evening.

PREV DISCUSSION

Issued at 312 PM EST Fri Feb 27 2026

DISCUSSION...

Southwest flow and warm advection help capitalize on a low afternoon cloud fraction to boost high temperatures into the low to mid 50s. Meanwhile, a closed low through 400 mb tracks across central Ontario this evening and overnight which pulls an enhanced low-level wind field across Lower Michigan. Timing of this feature lags the diurnal cycle, limiting the efficiency of mixing down 40+ knot flow from 1- 1.5 kft AGL. Forecast soundings still offer at least some potential for an uptick in gusts late tonight or early Saturday, after the passage of a (mainly) dry cold front. The frontal passage also causes gradient flow to veer WNW, initiating cold advection and weak lower column instability for gusts to exceed 20 mph through the early morning hours. Can't completely rule out a few nocturnal sprinkles along the frontal slope (01-05Z). Anticyclonically curved downglide reinforces subsidence in the wake of the frontal passage, which could lead to a brief period of clear skies prior to sunrise.

Seasonably cooler conditions return Saturday while clouds start to fill in ahead of the next system. Weak area of surface high pressure slides from the eastern Plains into the Ohio Valley as the next phase of mid-level height falls arrives. Axis of low-level ThetaE convergence will be slow to move in from the west, closer to 21Z Saturday as dewpoint depressions at 5 kft may still be in excess of 30C. However, the mid-levels should become saturated (with respect to ice) earlier, and given an omega signal indicative of ascent, ice nucleation quickly activates within the DGZ. Still, this process appears to unfold later than previous forecasts, pushing back the onset timing by an hour or two. Confidence continues to increase in dry conditions until later Saturday afternoon. Initial snowfall should be rather light in intensity until column saturation depths improve after 00Z.

Higher than usual spatial and temporal variability exists within the solution space as onset timing now falls within 24 hours. As a result, the outgoing snowfall totals carry low confidence of a half inch along/south of I-94 to over 2 inches for the Tri-Cities. Overall, the preferred window for peak snowfall rates is now expected between 00Z and 04Z Saturday evening. Areas north of M-46 currently exhibit the better potential for hourly rates to briefly exceed 0.5 in/hr, and possibly approach 0.75 in/hr. Still, this scenario will be highly dependent on the placement of the maximum zonally-oriented FGEN enhancement. Another complicating factor will be 2m temperature trends. A distinct thermal gradient bisects the CWA Saturday with highs barely in the 30s for the northern half, and possibly into low 40s for the south. Should the primary snowfall axis settle further south, a melting component will affect the front end of the event, cutting down on accumulations. This problem will be less prevalent with northward extent, thus favoring higher totals, assuming the band materializes in the vicinity. From a QPF perspective, the NBM (13Z population) has shifted the highest liquid totals (up to around a tenth of an inch) further north, mirroring solutions such as the HRRR, RAP, ICON, and RRFS, but the 18Z run has reintroduced QPF in excess of a tenth for areas south given more 12Z Hi-Res support. Regardless, with expected totals holding below 3 inches, no winter headlines are needed.

Snow should conclude before sunrise Sunday morning, followed by lower tropospheric anticyclone influence sliding into the Upper Midwest. The thermal gradient/secondary front then clears south across southern Lower Sunday morning leading to greater homogeneity in 850 mb temperatures in the negative teens Celsius. Sunday should be the chilliest day of the 7-day forecast period as highs struggle to surpass the freezing mark. The drier weather continues into Monday but winds flip from northerly to southeasterly as surface high pressure translates over the lower peninsula, into the Mid- Atlantic. The next opportunity for widespread precipitation occurs Tuesday, followed by an extended warming trend during the upcoming workweek.

MARINE...

Moderate southwesterly winds this evening veer to the northwest after midnight as an arctic cold front is driven across the central Great Lakes by strong northern Ontario low pressure. Strong cold advection behind the front supports a 5-8hr period of gales over the northern third of Lake Huron with peak gusts ranging between 35- 40kts. While there is a subset of models that suggest a few hour period immediately post-front of gusts in excess 40kts, these probabilities have trended lower (~30%) in most recent runs. Could see a brief period of gusts to gales in the central waters of Lake Huron along the front itself however duration doesn't appear to be long enough to warrant an expansion of the current warnings. Freezing spray develops overnight over most of the open waters of Lake Huron in response to increasing waves with areas of heaving freezing looking likely over the northern waters- a Heavy Freezing Spray warning has been issued tonight into Saturday morning for the same zones as the Gale warning. Gradient weakens fairly rapidly through the day Saturday dropping winds sub 30kts with sub 20kt flow developing Sunday as strong high pressure builds across the central Great Lakes.

DTX WATCHES/WARNINGS/ADVISORIES

MI...None. Lake Huron...Gale Warning from 10 PM this evening to 9 AM EST Saturday for LHZ361-362.

Heavy Freezing Spray Warning from 10 PM this evening to 9 AM EST Saturday for LHZ361-362.

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