textproduct: Detroit/Pontiac

KEY MESSAGES

- Isolated showers possible Tuesday, becoming wetter with rising thunderstorm potential Tuesday night into Wednesday. The potential exists for severe storms early Wednesday morning.

- Rain showers continue Wednesday with brief change over to melting snow showers by Wednesday night possible.

- A clipper system may produce wintry precipitation Friday.

DISCUSSION

Active stretch of weather this week as we continue to reside near the main baroclinic zone that has been wavering over the Great Lakes of late. Strong northern stream of the jet will start off the week nearly zonal but will start becoming more amplified mid week as the next trough starts working across the country. This trough will combined with a cutoff low over Texas that will be ejecting several weak waves up into the region during the weak leading to multiple opportunities for showers and thunderstorms. Cooler air in the long term keeps the door open for mixed precip or periods of snow this weekend.

Starting off this afternoon and tonight we'll have a backdoor cold front dropping through the area off Lake Huron which will force the once stalled front southward tonight. Meanwhile, an initial weak wave embedded in the southwesterly warm air advection will interact with the front over southern MI to produce a low end POP late tonight, mainly after 09Z. There is a few hundred J/kg of elevated CAPE so a thunderstorm cannot be ruled out.

Warm front stalls once again across southern portions of the state Tuesday with continued warm air advection bringing waves of moisture into the area which could activate showers on elevated portions of the front through the day. At a minimum it looks like most of the CWA will reside north of the front which currently looks to set up around I94. This will lead to a large thermal gradient across southern MI with highs in the 40s over the northern Thumb and Lake Huron shoreline and possible into the low 70s near the Ohio border.

A stronger wave will lift northeast overnight Tuesday bringing the next chance of severe weather to southern MI. A 40-50 knot low level jet will bring a surge of theta e up through the region between 00- 06Z bringing widespread showers and thunderstorms. Additional ribbons of theta e and vorticity will then follow through the night before a surface low riding up the stalled front starts tracking through SE lower MI 12Z Wed. As the low approaches it will attempt to bulge the warm front northward up through M59 by morning. Always a question this time of year as to how far north the warm front will make it before stalling due to the stable and cool air in place with the northeasterly flow off the lakes. For those locations along and south of the warm front severe weather will be possible. Low level jet will be strong leading to good shear and favorable hodographs. CAPE will advect into the region with 500-1000 J/kg of surface based CAPE and possibly a bit higher in the vicinity of the low itself early Wednesday morning. Risks overnight into Wed morning include damaging winds and large hail along with a tornado threat especially near and along the warm front. SPC continues to have most of SE MI in a Marginal Risk area with a Slight Risk nosing across SW MI into the area. Upper level northern stream trough will then sweep through Wednesday afternoon pushing the cold front through MI and providing another opportunity for showers. There is also a Marginal Risk of Excessive Rainfall as QPF Tuesday night through Wednesday range from 0.75-2 inches.

Should be noted that several models and local probabilistic guidance advertise a chance for freezing rain Tuesday evening into the overnight across Mid MI and the Thumb as the precip begins with temps just below freezing. Latest NBM solution keeps any mention farther north out of our CWA. Thinking has been, and continues to be, that the dewpoints won't be cold enough at the surface to offer enough cooling to offset the warmth of the rain due degree of warm air just above the inversion.

Models are faster as the trough/cold front clearing out the moisture with lower probabilities of a deformation band bringing a rain/snow mix or all snow to the region late Wednesday on the backside of the low. The next compact northern stream shortwave will then target the area on Friday. We'll be on the colder side of the main baroclinic zone during this system so expecting mixed phase precip.

MARINE

A surface low over south-central Ontario has crossed into Quebec this afternoon, preceding the expansion of an elongated trough axis into the southern Great Lakes late overnight. Gusts drop-off quickly after sunset with split-flow developing over the central waterways into Tuesday. Winds over Lake Huron veer northeasterly with time tonight while southerly flow persists to the south. The pressure gradient sharpens again on Tuesday across the Huron basin, ahead of a more active stretch of weather Tuesday night into Wednesday. Non- thunderstorm wind gusts may approach 30 knots for Huron late Tuesday night into Wednesday as low pressure, 29.50 inches, lifts across Lower Michigan. Expect several rounds of showers and thunderstorms, including some strong to severe storms. All severe hazards will be possible. The system's frontal passage eventually leads to cold advection, a transition to melting snowfall, and steep low-level lapse rates leading to more efficient mixing. Low-end gale potential exists Wednesday night.

HYDROLOGY

Widespread showers and thunderstorms will develop Tuesday night into Wednesday as a low pressure system tracks northeastward across Lower Michigan. Expected rainfall totals range from 0.75-1.75 inches by Wednesday evening, followed by a changeover to melting snow from north to south. Ensemble data suggests rises on area rivers will be expected with a chance for minor flood stage for river systems.

PREV DISCUSSION

Issued at 1250 PM EDT Mon Mar 9 2026

AVIATION...

SE Michigan resides in the transition zone between low pressure to the north and high pressure anchored over the Atlantic. This leads to a tight southwest gradient with sustained wind speeds of 15-20 knots and gusts up to 30 knots that subside by this evening. Generally clear skies persist through the rest of the daylight hours ahead of a surge of low level moisture that drops ceilings toward low MVFR/IFR early Tuesday morning. This moisture surge intersects with a backdoor cold front Tuesday morning, triggering scattered shower coverage invof the front. The frontal passage causes winds to quickly shift to the northeast, and will trap/lower the stratus deck for the rest of the TAF period as the inversion strengthens. A low chance for showers/drizzle persists after 14z, but with lower confidence as the front moves south of the airspace and cuts off instability.

For DTW...Ceilings quickly drop from VFR tonight to low MVFR/IFR early Tuesday morning. A cold front moving south reaches DTW around 15z Tuesday, shifting winds to the northeast. Increasing shower chances exist ahead of the frontal passage (10-14z Tuesday), and cannot rule out a rumble of thunder with this activity.

DTW THRESHOLD PROBABILITIES...

* High for ceilings at or below 5000 feet Tuesday morning and afternoon.

* Low for thunderstorms Tuesday morning.

DTX WATCHES/WARNINGS/ADVISORIES

MI...None. Lake Huron...Small Craft Advisory until 4 PM EDT this afternoon for LHZ421.

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