textproduct: Detroit/Pontiac

KEY MESSAGES

- Bitter cold temperatures for the weekend into Monday. The coldest period will be tonight and Sunday morning when actual air temperatures bottom out at zero to 5F above. Expect wind chills to range between -15F to -10F by Sunday morning.

-Light snow activity along the southern Michigan border this afternoon, and snow showers along the eastern Thumb shoreline Sunday.

- A dramatic warmup is then forecasted Tuesday-Thursday next week, as temps likely push aoa 40 degrees, setting the stage for rain Thursday.

DISCUSSION

Light snow showers moving through early this morning with an arctic front passing through, clearing southeast Michigan around 12z Saturday. Jet streak/wave tracking through the Ohio Valley this afternoon, and model consensus is for the snow shield to mostly pass to our south. However, locations south of I-94 to the southern Michigan border will likely get glanced by some higher based forcing/fgen/modest moisture advection or a low level streamer coming off Lake Michigan, and would expected a dusting to an inch of accumulation right along the border. Otherwise, arctic air streaming into the Great Lakes region through tonight will be the big weather story. 00z International Falls raob indicated an 850 MB temp of -25 C, while Pickle Lake Ontario came in with -26 C. Some modification expected as the airmass crosses Lake Superior/Lake Michigan, but 850 MB temps of -20 to -22 C (per 00z NAM/regional GEM) over southern Lower Michigan seems reasonable tonight. With unfavorable northwest flow for Lake Effect, should see at least partial clearing, but passing flurries are possible from time to time. Still counting on surface winds to not fully decouple to keep mins in the zero to 5 degree range for most locations. However, with winds around 10 mph, that will allow wind chills to reach 10 to 15 degrees below zero. Still marginal for cold weather advisory. Did take a look at the record lows for December 14th, and Flint's daily record low of zero (1944) seems to be in jeopardy, as the Euro ensembles are clustered around that mark.

Still have concerns for lake effect snow showers to impact eastern Thumb shoreline on Sunday as winds veer around to the north- northwest with pronounced surface trough dropping south through Lake Huron. Bulk of the hi-res solutions still keep the multi-bands mostly offshore, but it will bear watching. A quick inch or two along the shoreline is possible at the very least.

Shortwave coming over the top of the upper level ridge over the Rockies swings through Lake Huron on Monday. Model trends suggest best forcing tracking through northern Lower Michigan/Lake Huron, and will continue with just low chance pops back across southeast Michigan.

Big warm advection pattern develops early next week with 500 MB heights rising to at least 558 DAM with increasing low level southwest flow, sending temps well above freezing and likely in the 40s on Thursday. Rain appears likely on Thursday as well ahead of a strong cold front, with post frontal wind gusts likely reaching at least 30-40 mph.

MARINE

The arctic front will finish pushing through the region during the early morning hours with winds turning westerly in its wake. There will also be an increase to wind speed due to a tighter gradient and cold air advection into the region with gusts of 25 to 30 knots possible across parts of central and southern Lake Huron. Winds will remain elevated in the upper 20 knot range through the day with the coldest of the arctic air arriving late this evening and overnight which will cause a boost to the winds to around 30 knots across the southern basin. At this time, guidance suggests we'll stay below 35 knot gales but that will be something to watch in the upstream observations. A long duration Small Craft Advisory is in effect through Monday morning to account for this cold unstable airmass and period of wind and waves. The cold airmass and elevated winds will also lead to potential snow squalls and freezing spray as well.

CLIMATE

The record low min temps for Sunday, December 14th.

Detroit: -1 Degrees (Set in 1914) Flint: 0 Degrees (Set in 1944) Saginaw: -7 Degrees (Set in 1917)

PREV DISCUSSION

Issued at 1203 AM EST Sat Dec 13 2025

AVIATION...

A cold front will progress across the terminals early this morning bringing widespread MVFR ceilings with pockets of IFR ceilings and scattered light snowfall that may reduce visibility to MVFR and IFR conditions. Total snow accumulations are expected to be well less than an inch. Greater snow potential and greater VSBY/CIG reductions are expected across FNT and MBS with lesser VSBY/CIG reductions across the southern metro terminals. Snow showers come to an end before 12Z as post frontal winds out of the west pick up around 11-12Z with gusts to around 20 knots. Cold airmass will result in a return to lake effect regime off Lake Michigan this afternoon with low clouds persisting through the afternoon. Aside of any scattered lake effect flurry activity, a passing system to the south brings low chance for VFR light snowfall during the afternoon for the metro terminals. Will highlight with a PROB30 group. Dry air will try to scatter out some clouds after 00Z this evening.

For DTW...Best chance for snow showers will be between 07Z and 11Z. Weak forcing should result in mainly a dusting of accumulation overnight.

DTW THRESHOLD PROBABILITIES...

* High in ceilings below 5000 feet through this morning and afternoon.

DTX WATCHES/WARNINGS/ADVISORIES

MI...None. Lake Huron...Small Craft Advisory until 4 AM EST Monday for LHZ421-441.

Small Craft Advisory until 4 PM EST this afternoon for LHZ422.

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