textproduct: Detroit/Pontiac

KEY MESSAGES

- Rain chances increase late Saturday night and early Sunday. Brief chance for light freezing rain Sunday morning mainly across the Thumb and northern Saginaw valley, before temperatures climb above freezing.

- Milder conditions Sunday with intervals of rain lasting into Sunday night. Potential exists for heavy rainfall to develop.

- Turning much colder and windy Monday. Potential exists for wind gusts in excess of 35 to 40 mph. In addition, snow showers will increase in coverage Monday and Monday night, with some accumulation possible.

- Colder conditions exist Tuesday and Wednesday. Minimum wind chill in the single digits.

AVIATION

Low pressure exiting into the eastern Great Lakes has left behind widespread low ceiling on the IFR/LIFR threshold with areas of MVFR fog that remain locked in for much of tonight. The cloud conditions extend broadly into northern Ontario and across the upper Midwest within a diffuse surface pressure pattern that is slow to evolve tonight and early Saturday. There is a chance for incremental ceiling improvement as boundary layer wind organizes with a stronger northerly component, which is a downslope flow from northern Lower Mi into the MBS area, but it is a brief time window on the way to continued veering wind toward the NE-E east by morning. A stronger SE wind develops Saturday afternoon which holds greater promise for clouds building higher into MVFR between larger scale pressure systems into Saturday night.

For DTW... Precipitation has ended leaving just fog and low clouds over the terminal area for the rest of tonight.

DTW THRESHOLD PROBABILITIES...

* High for ceiling below 5000 feet tonight through Saturday.

PREV DISCUSSION

Issued at 337 PM EST Fri Dec 26 2025

DISCUSSION...

A few patches of light freezing rain or drizzle will come to an end shortly, as supportive forcing offered by a mid level trough passage declines and improving depth to northwest flow establishes a drying profile. Unusual event overall from the stand point of qpf (almost an inch in spots) relative to ice accretion, with two observations now (including here at DTX) where the accretion was only around a tenth of the overall rainfall total. A tremendous amount of runoff given the high rainfall rates, with a fairly generous area of thunderstorms ultimately contributing to a solid back end response. Most locations arriving with flat ice accumulation in the .1-.2" range, but notably less from DTW southward as temperatures lingered much closer to freezing and rates/duration where lacking. For tonight, deeper layer stability takes hold as high pressure builds in beneath weakly anticyclonic mid level flow. This maintains more tranquil conditions. Modest cold air advection within this pattern as low level flow veers with time. This will edge temperatures back into the upper 20s.

Deep layer stability held within existing low-mid level ridging offers benign weather conditions Saturday. High magnitude warm air advection commences this period above 925 mb, but effectively muted below as low level flow maintains an east/southeast component. Modest diurnal thermal recovery lead by an increasing mean thickness field will yield an afternoon high temp invof normal for late December. Increasing depth and magnitude of the advective process with time Saturday night and Sunday will anchor a more sizable corridor of moist isentropic ascent. Initial moisture surge arrives late Saturday night into Sunday morning accompanying an inbound warm front. Onset timing relative to pace of warming at the surface will dictate the probability for another brief window of freezing rain /mainly north/ during this time.

High quality theta-e ridge takes residence Sunday and Sunday night, as southwest flow attains greater depth immediately downstream of a consolidating region of height falls. Intervals of showers likely throughout this period, with a particular focus where forcing peaks near the stalled frontal zone and along the north/east flank of the surface low tracking northeast across the region. Potential for enhancement of rainfall rate, and possible thunder, as column stability diminishes. This brings the potential for some areas of heavier rainfall. Outgoing forecast now highlights a broad qpf swath of generally three quarters to inch and a quarter over a 24 hour period, with these values closer to the 75th percentile across the grand ensemble solution space. Warmer conditions Sunday, but with a notable gradient from south to north with some uncertainty yet on where the warm front stalls.

Strong arctic front arrives sometime late Sunday night. A rapid decline in temperature thereafter, while wind magnitude strengthens Monday as the governing system deepens with time while exiting to the north. EPS offers a high likelihood of exceeding 35 mph Monday, while exceeding 40 mph resides near the 25th percentile. Frontal timing means a high temperature Monday morning, with temperatures falling through the day. Snow shower/brief squall potential increases Monday as synoptic level moisture pivoting through the cyclonic flow augments increasing lake Michigan moisture flux. An inch or two of accumulation in play for some locations. Arctic air entrenched provides the coldest conditions Tue-Wed with wind chill in the single digits to lower teens.

MARINE...

Low pressure tracks just south of Lake Erie through this evening, quickly giving way to high pressure. This offers weaker wind tonight into Saturday, and Small Craft Advisories will be allowed to expire this evening. Wind organizes out of the southeast on Saturday, gradually increasing to the 15 to 20 kt range by the evening as the next low begins to develop over the Plains. This system will deepen considerably and track across northern Lake Huron Sunday night into Monday. Widespread rain and southeast to east wind holding generally below 25 kt will precede this system on Sunday. Strong arctic cold advection follows on Monday, causing rain to change over to snow and bringing strong northwest wind. Gales are likely and there is potential for a brief period of gusts to storm force depending on the strength/track of the low. Gale Watches will be issued with a subsequent forecast package. Freezing spray and snow showers will continue through at least early next week as the cold northwest flow persists.

HYDROLOGY...

Periods of rain will develop Sunday and Sunday night. Potential exists for heavier rainfall to develop at times. Basin average rainfall totals in excess of one inch will be possible. This could lead to some minor flooding of prone low lying and urban areas.

DTX WATCHES/WARNINGS/ADVISORIES

MI...None.

Lake Huron...Small Craft Advisory until 10 PM EST this evening for LHZ421- 441>443.

Lake St Clair...None.

Michigan waters of Lake Erie...None.