textproduct: Detroit/Pontiac

KEY MESSAGES

- There will be a chance of showers and thunderstorms Friday, through the weekend and into Monday.

- Temperatures remain seasonable through the weekend, with highs mainly in the 80s.

DISCUSSION

A region of showers and scattered thunderstorms across nrn Indiana is occuring within the lead ribbon of ascent tied to a remnant short wave. This wave is forecast to lift across the Toledo/western Lake Erie region this evening into the overnight. This combined with subtle upper divergence within the entrance region of an upper jet streak will result in at least some degree of larger scale ascent brushing across the eastern portions of the forecast area tonight. A chance of showers/thunderstorms therefore remains warranted over much of the area tonight. While cloud cover has held some limitation on diurnal instability this afternoon, 0-1km ML CAPE around 1000 J/kg is shown by latest meso analysis. Lake enchanted convergence across the thumb and eastern sections of the forecast area remains supportive of convective initiation late this afternoon and evening, with a continued subtle mid level warm layer offering some limitation on coverage.

While large scale ascent will be lacking on Friday, model soundings continue to indicate an uncapped environment. Residual boundary layer moisture will support sfc dewpoints near 70 with afternoon temps forecast into the 80s. This will contribute increased daytime buoyancy with various hi res models indicating SB CAPE ranging from 1200 to 2k J/kg. Forcing via boundary layer convergence along sfc troughs across Se Mi will support a chance for convection given the lack of capping. Although wet microbursts may contribute to some strong storms, bulk shear values generally under 25 knots will limit the severe risk.

While there remains some timing differences, there is general model support in a progressive trough axis moving across srn Mi Fri night/Saturday. Convective potential/coverage will have some reliance on timing as a later timing would offer the potential for the associated ascent to coincde with increasing diurnal instability Saturday. Probabilistic guidance suggests enough timing uncertainty to maintain blanket chance pops through the Fri night/Saturday periods. The trough and associated sfc front will support a push of drier air into Se Mi in its wake.

The pattern is forecast to become more favorable for repeated MCS's across the Great Lakes and/or Ohio Valley Sunday through Tuesday. This will occur as the baroclinic zone and instability gradient sets up across the region. Fast mid level flow will favor forward propagating MCSs. However, there are indications for possible regenerative MCSs capable of producing locally heavy rainfall. At this stage in the forecast, there is ample spread within the probabilistic guidance with respect to QPF, timing and location. Trends will be monitored over the next couple days for both severe weather and heavy rainfall potential.

MARINE

A stalled frontal boundary located across southern Michigan will bring the continuation of showers and some thunderstorms through the afternoon and into the evening. Most of the activity will be confined south of the northern Lake Huron zone, aligned where the front resides. Winds generally remain light and variable outside of any thunderstorm activity. High pressure then builds in the wake of the front late tonight through tomorrow, before another cold front moves through Friday into Saturday. Winds on Friday will remain lighter as the flow becomes more southerly. This will bring additional chances for showers and thunderstorms going into the weekend.

PREV DISCUSSION

Issued at 104 PM EDT Thu Aug 6 2026

AVIATION...

Low clouds have finally dissipated/lifted into VFR across all taf sites early this afternoon. However, a slowly increasing chance of showers will exist the rest of the afternoon and this evening. The greater the coverage, the better chance for MVFR cigs to redevelop tonight. Enough instability will build up this afternoon to support isolated-scattered thunderstorms, but confidence remains low regarding direct impacts to the terminals. Southern TAFS appear to be the favored area area. With elevated low level moisture (surface dew pts in upper 60s) and winds dropping off tonight, a similar scenario with low clouds (IFR/MVFR) is expected late tonight, though confidence is not high. Another round or two of scattered-numerous showers and embedded thunderstorms is likely tomorrow, but timing is uncertain, as some shower activity could develop in the morning with a surge of moisture.

D21/DTW Convection... A mid afternoon to mid evening time window remains open for the possibility of isolated-scattered thunderstorms in and around the DTW airspace.

DTW THRESHOLD PROBABILITIES...

* Medium for ceiling aob 5000 ft.

* Low for thunderstorms this afternoon and evening.

DTX WATCHES/WARNINGS/ADVISORIES

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