textproduct: Detroit/Pontiac

KEY MESSAGES

- Accumulating snow is likely overnight into Friday morning, with brief intervals of heavy snow and reduced visibilities possible.

- A High Wind Warning is in effect from 5 am to 10 pm Friday for southwest wind gusts of 50 to 60 mph.

- Another round of accumulating snow is likely Saturday night into early Sunday. Thunderstorms are then possible Sunday night with strong winds late Sunday into Monday.

- Much colder Monday through Wednesday with highs in the 20s and 30s and lows in the teens to potentially single digits.

UPDATE

Upstream radar/satellite composit, recent trends within the probobolistic guidance and recent runs of the HRRR are suggesting some upward trends for potential snow accumulation overnight into Friday morning. Of note is the RAP indicating strongly unbalanced flow in the mid levels, courtesy of strong advective processes along the nose of a 76 knot 850mb speed max. The strongest ascent looks to be focussed across the Saginaw Valley and thumb region. A plume of steep mid level lapse rates is also forecast to rotate into the region along the back edge of the strongest ascent, arriving roughly around 12Z. This will result in a brief window of enhanced elevated convective instability, again better across the northern half of the forecast area. This will increase the chances for a brief period of higher snowfall rates. Of note is the increase in chances for one inch per hour rates generally along/north of the M 46 corridor (Saginaw to Sandusky). A winter weather advisory has therefore been issued in this area from 3 AM to 11 AM.

No changes will be made to the high wind warning with this evening update. While the more persistent high winds are likely to occur during the afternoon and evening, there are some solutions within the model prob space which have a secondary peak in wind gusts in the 6AM to 10AM time frame, concurrent with the interval of higher intensity snow. This may result in a brief period of near blizzard conditions, possibly limited to a degree by the high liquid content of the snow.

PREV DISCUSSION

Issued at 648 PM EDT Thu Mar 12 2026

AVIATION...

A ridge of high pressure will translate from srn Lower Mi into the eastern Great Lakes this evening. A period of clear skies and a weakening gradient will result in rapidly decreasing wind speeds with the onset of nocturnal cooling. A strong compact low pressure system will move across northern Michigan on Friday. A period of good ascent will track across Se Mi overnight into early/mid Friday morning in advance of this wave, resulting in a period of snow. Snowfall duration and intensity will likely vary across the area, with periods of moderate to possibly heavy snow possible from PTK up through MBS. This will result in some accumulations. Brief drying will be followed by occasional rain/snow showers into the afternoon. A deepening mixed layer combined with very strong low level wind fields will lead WSW wind gusts over 40 knots at times Friday.

For DTW...The most probable window for light snow will be between 08Z and 14Z. The ascent will be a little more brief at metro in comparison to locals farther north. This should keep accumulations under an inch. West-southwest winds will strengthen rapidly after 15Z, with frequent gusts in the 40 to 50 knot range expected through the afternoon. There will be a slight wind direction shift to the west into the evening hours Friday.

DTW THRESHOLD PROBABILITIES...

* High for ceilings at or below 5000 feet late tonight through Friday.

* Moderate in precip type as all snow Friday morning.

* Moderate in crosswind thresholds being exceeded Friday afternoon and evening.

PREV DISCUSSION... Issued at 302 PM EDT Thu Mar 12 2026

DISCUSSION...

Active pattern in store through the upcoming weekend, as conditions remain governed by an oscillating 140 knot upper jet core of north pacific origin. This environment responsible for directing two distinct, dynamic pv features toward the region. Lead wave ejecting across the northern plains early this afternoon on pace to arrive locally late tonight into Friday. No meaningful wx prior to midnight as dry and stable conditions hold within existing surface ridging. Period of deep forced ascent tied to a combination of moist isentropic ascent and pronounced dcva along the inbound height fall gradient will then sweep across the lower peninsula during early-mid morning hours. Most meaningful response noted across central and northern lower Mi, but sufficient for all areas to witness a 4-6 hour burst of snow between roughly 1 and 8 am. Potential for brief hourly snowfall rate to exceed half inch per hour north of M-59. This affords a quick accumulation of an inch or two across this corridor, with moderate probability for a narrow axis north of M-46 to potentially exceed to 2 inches. Healthy proportion of accumulation confined to grassy/elevated surfaces given the warmer pavement condition and air temp of 31-32 degrees and trending higher with time, but expectation for a slushy accumulation to exist for some during the morning commute. High magnitude, impactful wind event at the forefront for the Friday period. Cold front accelerates through midday. High likelihood for additional convective shower development as lapse rates briefly steepen along the frontal convergence and within the immediate cold air advection during the afternoon. Sounding data supportive of a mix of rain, melting snow and graupel within a chaotic coverage of healthier convective cores as daylight temperatures recover into the upper 30s to mid 40s. Notable strengthening of the deep layer wind field at the same time will establish a conducive environment for strong southwesterly gusts, with peak gust magnitude potentially enhanced by the shower production. Absent of a more meaningful convective response, a peak in gust magnitude will commence as 925 mb speed reaches near 60 knots around daybreak and again as mixing depth peaks mid afternoon into the evening under ongoing cold air advection/isentropic descent. In collaboration with surrounding offices, belief that the probability is high enough to reach into the 55 to 60 mph range to highlight the impact with a high wind warning headline.

Main baroclinic zone sags to the south Friday night and Saturday, leaving a brief stretch of dry conditions with seasonable temperatures this period. Attention then turns to the potential impacts of the dynamic mid level system forecast to deepen while ejecting from the southern plains into the great lakes during the latter half of the weekend. Increasing depth to southwest flow immediately downstream will draw the elevated warm front back into the area Saturday night and early Sunday. Sustained moist isentropic ascent along the active portion of the frontal slope will establish a band of accumulating snow across lower Michigan during this time. Some model variability yet at this stage in both the placement and duration window. Probabilistic data currently indicates roughly a 50% chance for 2" in metro Detroit, 3" along the I-69 corridor and 4+ inches across the Saginaw valley and thumb.

Higher impact winter storm conditions expected northwest/west of the area given projection of low track across the heart of lower Michigan. Assuming a progressive northward propagation of the warm front Sunday as the warm sector makes aggressive inroads along the eastern flank, forecast favors a brief drying and notable warming trend for the latter half of Sunday. Potential for temps to reach mid 50s to mid 60s depending on pace of the warming relative to lingering stability. Convective potential along the trailing cold front and along the interface of the inbound low sometime Sunday night. Inherently strong kinematic field, but likely lacking on instability given unfavorable early season nocturnal timing. Turning windy with increasing snow shower potential late Monday and Monday night as colder air floods in behind this system. A much colder airmass then entrenched Tuesday, with temperatures a solid 10+ degrees below average. Single digits lows possible some locations Wednesday morning.

MARINE...

A ridge of high pressure will briefly move across the Great Lakes through the evening which will bring a short period of lighter winds through tonight. Attention quickly turns to a seasonably strong low pressure system which will move across northern lower Michigan and central Lake Huron through tomorrow morning. A strong pressure gradient will accompany this system and will result in a rapid uptick in wind speeds and gusts through Friday morning. Periods of sustained winds to gales and gusts to high-end gales will be likely with this system, along with sustained periods of snow, heavy at times, especially across central and northern Lake Huron. A very strong low level jet fills in south of the low across Lake Erie and possibly into Lake St. Clair. If mixing depths overachieve, sporadic gusts to storm force will be possible and a short fused upgrade to a storm warning may be needed.

A brief lull in gales will be possible directly under the low pressure system as it passes central Lake Huron, however, cold air fills in in the wake of the departing low which will sustain favorable mixing depths and quickly bring renewed gales leading into Saturday morning. High pressure fills in for the later part of the day Saturday and will quickly diminish wind speeds.

A second very strong low pressure system is looking likely to impact the southern Great Lakes Sunday into Monday. This will bring increasing chances to see another round of gales along with winter weather, including the chance for sustained heavy snow across northern or central Lake Huron.

DTX WATCHES/WARNINGS/ADVISORIES

MI...Winter Weather Advisory from 3 AM to 11 AM EDT Friday for MIZ047>049-053>055.

High Wind Warning from 5 AM to 10 PM EDT Friday for MIZ047>049- 053>055-060>063-068>070-075-076-082-083.

Lake Huron...Gale Warning from 4 AM Friday to 4 AM EDT Saturday for LHZ361>363- 421-422-441>443-462>464.

Lake St Clair...Gale Warning from 4 AM Friday to 4 AM EDT Saturday for LCZ460.

Michigan waters of Lake Erie...Gale Warning from 4 AM Friday to 4 AM EDT Saturday for LEZ444.

Low Water Advisory from 4 AM Friday to 4 AM EDT Saturday for LEZ444.