textproduct: Detroit/Pontiac

KEY MESSAGES

- A Wind Advisory is in effect today with gusts of 45 to 50 mph possible.

- Mild and rainy this morning with temperatures dropping this afternoon and evening.

- Rain and wet snow Saturday transitions to snow showers Saturday night and Sunday. Snow squalls are possible Sunday.

AVIATION

Low pressure system lifting into the northern great lakes will draw a cold front across southeast Michigan during the late morning hours. Existing gusty pre-frontal south/southwest wind will see an increase in magnitude through late morning as mixing depth, with a shift to westerly with the frontal passage. Gusts in excess of 30 knots will be common, with occasional gusts peaking in excess of 35 knots. Low cloud will briefly vacate the region this morning as slight drying commences ahead of the front. Renewed expansion of MVFR stratus expected after 14z, with some pockets of convective showers possible into midday. Lower stratus persists within the immediate post-frontal environment this afternoon. Steady decline in gust magnitude and frequency with time late in the day. Cloud trends carry much lower confidence tonight, as a strengthening inversion works to erode the lingering low level moisture layer. This will lead to a gradual decline in cloud base, with potential for some degree of clearing to emerge. Very low confidence overall on overnight cloud trends given a mixed signal of the clearing potential. Forecast will maintain an optomistic outlook at this stage.

For DTW... Gusty south/southwest winds early today, becoming westerly this afternoon. Projected gust magnitude brings potential for crosswind concerns.

DTW THRESHOLD PROBABILITIES...

* Medium for ceiling at or below 5000 this morning. High this afternoon and evening. Low tonight.

* Moderate for exceeding crosswind threshold between 15Z and 20Z Friday.

PREV DISCUSSION

Issued at 422 AM EST Fri Jan 9 2026

DISCUSSION...

Very mild start to the day for January standards as temperatures are in the 50s and climbing toward 60 degrees as noted over northern OH/IN. Temperatures are well within reach of daily records (see Climate section). The thermal ridge responsible for this warm spell blankets the eastern half of CONUS, while thermal troughing deepens across the west. This has led to strengthening baroclinicity overnight that stretches from the southern Plains into the Great Lakes, and becomes the favored storm track for several Pacific waves today into the weekend. The first of these waves tracks from southern Wisconsin to the Mackinac Straits through the course of the day, along with its strong surface reflection (central pressure of 990mb). The northeast track of the low keeps SE Michigan well within the warm sector, even affording a brief window for shallow surface- based instability this morning (50-100 J/kg of MLCAPE). Pronounced mid level dry slotting keeps any convection shallow, but the well- mixed profiles will see be impactful as they tap into a strong 50-55 knot low level jet. Mechanical mixing of these winds to the surface brings gusts to Wind Advisory thresholds as gusts approach 45 mph.

Strongest gusts occur with the passage of a strong cold front early this afternoon, but will subside quickly thereafter as the low level jet exits with the front. H8 temperatures quickly drop from close to 10 C this morning to below 0 C by this evening, with much of this cold pool resulting from diabatic cooling in the TROWAL region of the low. At the surface, this equates to a ~30 degree drop in temperatures between 12z today and 12z Saturday.

The thermal gradient remains well-established over central CONUS into Saturday, serving as the storm track for another Pacific wave. The difference in this setup is the phasing of this wave with a northern stream perturbation, causing geopotential heights and surface pressure to fall quickly over SE Michigan Saturday afternoon. There is impressive vertical depth to the omega field, with additional synoptic support coming from coupled jet streak dynamics, warm advection, and deformation along the low's trajectory. Moisture quality is not as impressive as the main swath of low level moisture transport slides east of the forecast area. That said, some models (e.g. 09.00z ECWMF) generate a cyclonic branch of the warm conveyor that brings a surge of low level moisture into SE Michigan to complement the upper level moisture associated with the upper low. Overall, this looks to bring another period of widespread precipitation to the region Saturday afternoon- evening.

Main source of uncertainty attm is precipitation type. This stems primarily from the depth of the warm layer rather than ice nucleation concerns or melting-refreezing potential. So generally expecting precip to fall as snow, rain, or a rain-snow mix. The uncertainty comes from where the rain-snow line sets up. Hi-res models have been on the colder side, keeping temperatures near freezing across the Saginaw Valley/Thumb and into the Irish Hills region. On the other hand, the global models keep temperatures in the mid 30s which would prevent accumulations even across the north. Given the deep vertical motion expected with this system, favored outcomes are the colder solutions which bring accumulating snowfall to most of SE Michigan by Saturday night ranging from a few inches north of I-69 to a light dusting in the metro area. If the colder solutions do verify, the higher terrain of the Irish Hills could also see over an inch of new snowfall.

As the low shifts into Lake Huron/Ontario, a strong surge of arctic air fills in which drops temperatures into the mid 20s Saturday night. A second wave of accumulating snow is possible late Saturday night into Sunday morning as the low sends a post-frontal trough axis south across the forecast area. The arctic airmass provides a more favorable environment for snowflake growth than Saturday evening, so expecting snowfall rates to be more efficient even with less QPF. The narrow forcing axis and potential for a quick heavy burst of snow raises concern for snow squalls Sunday, although snowfall amounts will be limited by the progressive nature of the trough axis.

High pressure then provides a brief reprieve from the active weather stretch late Sunday into early next week, with temperatures expected to moderate back above freezing.

MARINE...

The arrival of a low pressure system, now across the northern Great Lakes, will maintain a strong pressure gradient, producing sustained winds on the order of 20 to 30 knots. Despite the very stable low level profiles, the strength of the pressure gradient will continue to afford a window for some low-end gales this morning, favored across southern and central Lake Huron, where Gale Warnings remain in place.

A strong cold front will then move across the Great Lakes as the low pressure system departs, which will veer wind direction from south to northwest this afternoon. Cold air behind the front will rapidly decrease over lake stability and will boost mixing depths, bringing higher confidence for gust to gales leading into the evening hours. Immediately along and behind the front, a quick pop of an isolated gust to high-end gales around 45 knots will be possible in the afternoon across Lake Huron.

Small Craft Advisories remain in place for the outer Saginaw Bay and Lake Huron shoreline, down to western Lake Erie, where gusts around 30 knots are expected. There remains a window on the afternoon with the passage of the cold front that can bring some brief gust to gales. Given the brevity of this gale potential, likely holding to just around or under the three hour mark, will preclude the issuance of any Gale Warnings at this time. Last, widespread rain will accompany the low pressure system through the morning. High pressure rapidly builds in behind the cold front, diminishing stronger winds leading into Saturday.

CLIMATE...

The record high temps for Friday, January 9th.

Detroit: 55 Degrees (Set in 1949) Flint: 54 Degrees (Set in 1939) Saginaw: 54 Degrees (Set in 1939)

DTX WATCHES/WARNINGS/ADVISORIES

MI...Wind Advisory until 4 PM EST this afternoon for MIZ047>049-053>055- 060>063-068>070-075-076-082-083.

Lake Huron...Small Craft Advisory until 7 PM EST this evening for LHZ421-441>443.

Gale Warning from noon today to 7 PM EST this evening for LHZ361.

Gale Warning until 7 PM EST this evening for LHZ362-363-462-463.

Lake St Clair...Small Craft Advisory until 7 PM EST this evening for LCZ460.

Michigan waters of Lake Erie...Small Craft Advisory until 7 PM EST this evening for LEZ444.