textproduct: Detroit/Pontiac

KEY MESSAGES

- Accumulating snowfall begins late this evening with totals of a half inch to two inches by Sunday morning. Locally higher amounts expected across the Thumb due to lake enhancement.

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

- The next opportunity for widespread precipitation occurs Tuesday with a wintry mix possible.

AVIATION

An area of light snow now moving toward srn Lake Mi is located along an elevated frontal boundary. This region of ascent will move across the Se Mi terminals late this afternoon and evening. The position of radar returns upstream is supportive of those model solutions which bring the axis of strongest ascent across the KPTK and possibly KFNT terminals, with the metro Detroit terminals along the southern edge of the stronger forcing. The onset of light snow is forecast to arrive between 21Z and 00Z. Given the very dry low level airmass, the initial intensity is likely to remain light under VFR conditions. As the column moistens, snowfall intensity will increase toward 00Z, with the strongest ascent then persisting through 04 to 05Z. Low level moistening with the snow and low level cold air advection will support MVFR and some IFR conditions in the light snow. An inch or two accumulation is forecast during the evening. As the forcing wanes during the overnight, lingering low level moisture will maintain some lingering light snow showers/flurries and low clouds until a more notable push of dry air infiltrates the region from the north late tonight into Sunday morning.

For DTW...There is still some uncertainty as to whether the stronger forcing and thus the region of better accumulation potential will extend into metro or remain just north. The latter would put around an inch of accums into play across metro.

DTW THRESHOLD PROBABILITIES...

* High in ceilings aob 5000 feet this evening and overnight.

* High in precipitation type as snow this evening and overnight.

PREV DISCUSSION

Issued at 326 AM EST Sat Feb 28 2026

DISCUSSION...

Strong cold front departs this morning with cold advection rushing into lower Michigan in its wake. Expecting the 12z.KDTX raob to sample near 0 C h8 temperatures as a sharp thermal gradient sets up north-south. This leads to a roughly 10-15 degree spread in forecast highs for today, low 40s near the Ohio border to upper 20s-low 30s in the Thumb-Saginaw Valley regions. Limited cloud cover expected through the morning hours as high based cirrus works across the area. Nighttime Microphysics RGB however is already showing good moisture flux off of Lake Superior in the cold advective regime, which will combine with eastward flux of synoptic moisture to bring increasingly cloudy skies to SE Michigan this afternoon.

Aggressive shift in the solution space over the past 24 hours regarding tonight's system, with a downward trend in forecast snowfall amounts noted. The overall driver of this trend comes from the separation of the local deformation axis and the developing Ohio Valley surface low. Earlier model runs were phasing these features and producing a tightly packed thermal gradient and strong FGEN circulation, with more recent model runs backing off significantly. The surface low circulation is now forecast to be further south and broader, keeping moisture transport to our south. A prominent 850- 700mb dry layer has been noted consistently in model runs which holds off snow onset until after 00z (7pm), and with the latest moisture trends reduces QPF especially south of I-96. Snowfall totals have trended below an inch toward the Ohio border. Northern areas still have a shot to see 1 to 2 inches of accumulation as the snowband advects into the area along the developing deformation axis. Weaker FGEN signature favors more stability aloft, which takes away much of the mesoscale forcing needed to overachieve in the band. QPF is broadly 0.10-0.15", but with increasingly favorable microphysics through the event as profiles cool and the dendritic growth zone deepens. General trend will thus be toward large and fluffy flakes leading to a couple inches of potential accumulation before the band dissipates early Sunday morning.

High pressure begins to settle into the northern Plains Sunday morning, leading to a veering trend in wind profiles toward northeast flow. The cold airmass and northeast flow activate moisture flux off of Lake Huron, although with a muted response given the current extent of ice cover. Nonetheless, steep low level lapse rates of 7 C/km intersect with deeply saturated RH (wrt ice) profiles up to 12.0 kft agl. Thus expecting some degree of lake enhancement to generate additional accumulations for the Thumb and may push totals above 3 inches. Inbound subsidence then lowers inversion heights and strips away column moisture to decrease snow shower coverage by Sunday afternoon.

Broader forecast for SE Michigan focuses on well below average temperatures Sunday and Monday as the core of the thermal trough settles overhead. Lows drop into the teens Sunday morning and single digits Monday morning, with potential for wind chills in the single digits each day. The colder airmass is short-lived, however, as the high pressure center drifts overhead and southwest flow initiates a strong warm advective response. High pressure anchors off the Atlantic Coast, establishing a Gulf moisture feed as well. This leads to the next low which ripples into SE Michigan Tuesday. Initial indications are for wintry mix potential with this system as warm air surges atop the existing cold/shallow airmass.

MARINE...

Northwesterly winds begin to decrease by mid morning ending further gale potential as northern Ontario low pressure lifts into northern Quebec. Gradient quickly weakens once this occurs with 20kt or less flow looking likely by this afternoon. A weak mid-level wave swings across the southern half of the region late today/tonight supporting light snow showers but no increases to wind speeds. Strong Canadian high pressure quickly follows maintaining lighter (sub-20kt wind) to close out the weekend. Active but milder pattern favored to develop next work week limiting any stronger wind chances.

DTX WATCHES/WARNINGS/ADVISORIES

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