textproduct: Detroit/Pontiac

KEY MESSAGES

- Stretch of warm conditions throughout the work week with daytime temperatures in the 70s each day for most locations.

- An active pattern continues brining periodic chances for showers and thunderstorms tonight through Thursday.

- There is a Marginal Risk of severe thunderstorms tonight into Tuesday morning.

- There is a Slight Risk of severe thunderstorms Tuesday night.

- Locally heavy rainfall potential also increases during the mid week period.

DTW THRESHOLD PROBABILITIES

* High for ceilings aob 5000 feet today and tonight.

* Low for thunderstorms tonight into early Monday morning.

PREV DISCUSSION

Issued at 311 AM EDT Mon Apr 13 2026

DISCUSSION...

Longwave trough over the west coast and ridging over the SE conus continue to remain firmly in place to start the week keeping the central conus up into the Midwest/Great Lakes in a pattern of deep layer southwesterly flow. This will result in warmer than normal temperatures with highs mainly in the 70s (outside of locations along Lake Huron shoreline), gusty daytime winds, daily rain chances, strong to severe storms at times, and a risk of flooding. While consistency in the longwave pattern adds some confidence to the forecast this week, inconsistencies in the short range models resolving mesoscale features (like potential upstream MCS development) still leaves questions about precip timing and QPF placement. Convective nature to most of the precip also brings into question model QPF output which likely will fall on the low side where the storms line up.

Helping to dictate placement of showers and storms will be a warm front extending eastward from a surface low setting up over the central/northern Plains. The front will largely be positioned over northern MI with typical fluctuations due to convective complexes. This paints central and northern MI with the highest QPF and highest confidence of these periods of rain/storms as the mid level waves pass over that region as well. Farther south over most of SE MI, we'll have waves of storms pass over with periods of dry in between. I'll highlight higher confidence time windows tied to mid level features, but there will be likely be convective complexes that will be handled with shorter fused forecast updates.

For today, SPC has all of lower MI in a Marginal Risk for severe storms. Early morning rain should be ending soon after sunrise this morning with warm and dry conditions most of the day. There are 2 windows for potential showers/storms mainly later this evening and tonight. First from 23-03Z as the potential convection firing over eastern Iowa rides the elevated instability gradient into southern MI. The Canadian hires models are most bullish with bringing widespread stronger convection across the area. Most of the rest of the model suite advertises more scattered activity but something to watch none-the-less. SPC outlook likely more for the later round of storms as a surface low riding the warm front with the nose of the next stronger llj after 05Z. Strong mid level lapse rates and MUCAPE up around 1000 J/kg for both events with strong capping from WAA so elevated storms would be most likely with a hail threat, but there is a wind threat as well.

By Tuesday the longwave trough will have crossed the Rockies which will continue eastward passing through the Great Lakes late Thursday. Several more shortwaves will pass through the region during this time. Things are continuing to look like Tuesday evening could get quiet active locally though as the overnight low crossing northern MI strengthens the front stalled across Mid MI while the next strong llj around 50 knots surges into the region. CAPE will rise greater than 2000 J/kg with models soundings showing the instability become surface based. Very strong lapse rates will be present with strong shear. Timing looks most likely after 00Z but carrying through much of the night with an west-east orientation allowing for training storms. Some models are targeting Mid MI for the highest QPF while others suggest earlier convection will push an outflow boundary down to near M59 which will have additional storms focusing down there. SPC Day2 outlook has most of lower MI in a Slight Risk designation with all hazards possible. In addition to the severe chances, we are in a ERO Marginal Risk so rainfall amounts will need to be monitored.

Storm chances continue Wed and Thurs as the main upper level trough passes over the region. Friday into Saturday looks dry as shortwave ridging builds overhead but the next longwave trough is already working across the conus and will bring storm chances back to the forecast Saturday and Sunday. Strong cold front looks to pass through the region Sunday dropping highs back into the 50s with lows in the 30s.

MARINE...

Small Craft Advisories remain in effect this morning for the southern Lake Huron nearshores, in addition to Lake St. Clair and western Lake Erie. Waves are responding to stronger gradient winds, in excess of 20 knots. A few gusts to gales remain possible early this morning until a 65+ knot low-level jet axis exits the central Great Lakes. The main area of concern amidst the constricted southwest flow remains Saginaw Bay, funneling/converging off-shore, but also near The Straits. Conditions quickly improve this evening after shortwave ridging moves in. Several additional rounds of showers and thunderstorms are likely throughout the week due to a series of troughs, low pressure systems, and fronts.

DTX WATCHES/WARNINGS/ADVISORIES

MI...None. Lake Huron...Small Craft Advisory until 10 AM EDT this morning for LHZ421-422- 441>443.

Lake St Clair...Small Craft Advisory until noon EDT today for LCZ460.

Michigan waters of Lake Erie...Small Craft Advisory until noon EDT today for LEZ444.