textproduct: Detroit/Pontiac

KEY MESSAGES

- Frost Advisory is in effect tonight from Midnight to 7am.

- Frost is likely again Monday night.

- The next chance of rain arrives late Tuesday into Tuesday night.

- Above normal temperatures possible next weekend.

DISCUSSION

Strong surface anticyclone and deep midlevel subsidence will build out of Manitoba southeastward into the Great Lakes region through early Tuesday. A very dry low level airmass, PWATS at less than a 1/3rd of an inch, combined with deep midlevel subsidence will ensure relatively quiet weather the remainder of today and Monday. Southeast Michigan will still reside within the main composite axis of broad upper level troughing. This supports intervals and periods of high cloudiness as individual shortwave maxima pivot and work through the trough.

One such very low amplitude feature will work out of Northeast Wisconsin through the Saginaw Bay region early this evening. Midlevel cooling between 6.0 and 12.0 kft agl may good enough for a rouge high based shower but the potential impact or coverage is too low to include. Moisture progs in/around Great Lakes is always a difficult endeavor, but model solutions (hires NAM and GEM) suggest a variable coverage of thin high cloud for tonight. With subzero 850mb temperatures, the forecast will call for lows in the 30s for most areas outside of the urban heat island. Despite a gradient wind that may remain light and sustained out of the north tonight, cannot discount microclimate cooling potential and will issue a Frost Advisory tonight for areas north of I 94 including Washtenaw county. Another cold, below normal night is anticipated Monday night with the center of high pressure building overhead. More Frost or Freeze headlines may be needed.

Model data continues to support categorical precipitation chances, greater than 75%, late Tuesday afternoon and Tuesday night. A notable aspect of the Tuesday system are the low dewpoints (40s) holding and likely wetbulbing at least through the 00-06z timeframe Wednesday. Latest forecast soundings support higher static stability holding in the lowest 3.0 kft agl with largely moist adiabatic lapse rates between 900-500mb. The potential will exist for thunder, but no strong or severe weather is anticipated. A more compact jet streak structure and tight curvature of the upper level jet streaks overhead Tuesday suggests some moving parts yet on the timing and duration of the best forcing. There is at least good support for a period of stronger low level frontogenesis with the warm advection surge. Confidence is low on the expected QPF amounts.

Pattern change then looks to happen Friday and into the beginning of next weekend as high amplitude ridge structure advances through central North America. Still some uncertainty with how progressive the ridge becomes which may cause flow to become more zonal locally. The current forecast suggests daytime highs climbing into the 70s.

MARINE

High pressure continues to drift over the region through Monday maintaining lighter winds. Next low is set to sweep across the Great Lakes late Tuesday bringing widespread showers and a few chances for thunderstorms mainly over the southern Great Lakes. In advance of the system, southerly winds strengthen though with ongoing warm advection, thermal stability over the waters is expected to cap peak gusts around 30kts. Moderate NNW winds follow Wednesday as cooler air filters back in behind the low however a diminishing gradient should keep winds under 30kts. High pressure briefly follows to close out the work week.

PREV DISCUSSION

Issued at 125 PM EDT Sun May 10 2026

AVIATION...

Diffuse high pressure to support dry weather while steep lapse rates under cold air advection increases coverage of strato-cu this afternoon. Ceiling heights range between 7-9kft, with waning coverage after sunset. There is some weaker model signal for periodic mid-layer clouds through the overnight hours. Otherwise, light winds overnight as high pressure becomes better established.

D21/DTW Convection...No thunderstorms through TAF period.

DTW THRESHOLD PROBABILITIES...

* None

DTX WATCHES/WARNINGS/ADVISORIES

MI...Frost Advisory from midnight tonight to 7 AM EDT Monday for MIZ047>049-053>055-060>063-068>070-075.

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