textproduct: Detroit/Pontiac

KEY MESSAGES

- Dry and pleasant weekend.

- Next rain opportunity midweek.

DISCUSSION

An extremely dry airmass is in place over southeast Michigan today, as the 12z DTX sounding indicated a dew pt depression of 49 C at 850 MB, 47 C at 700 MB, and a PW value of 0.21 inches. The PW value appears to set a new daily record low based on the SPC climatology page. With this dry air and an upper level ridge expected to hold over the northern Great Lakes this weekend, it comes as no surprise that dry weather remains in store. Expect mild days and cool nights this weekend into early next week. Shallow ground fog is not out of the question with the longer nights, but uncertain if the surface/near surface moisture is sufficient. Nam surface condensation pressure deficits stay mainly above 5 MB.

A slow evolving upper level pattern will feature deep, stacked lows near the Mid-Atlantic coastline into early week. So although heights lower modestly Monday/Tuesday over the central Great Lakes, the ridge axis remains mostly entrenched.

The next chance of rain arrives on Wednesday as a shortwave trough tracks through. Medium range models then significantly diverge, as the strength and interaction between the upper level low/trough over central Canada and the closed low coming out of the Four Corners region needs to be sorted out.

MARINE

The expansion of a strong Canadian high pressure system from Quebec and Ontario into the Great Lakes will provide an extended period of light winds and dry weather through early next week. Some periodic wind gust potential around 20 knots will be possible across southern Lake Huron this weekend, but otherwise, wind gust potential at or below 15 knots is expected. Wind direction will mainly hold from the north to northeast as high pressure fills in across Michigan.

PREV DISCUSSION

Issued at 219 PM EDT Fri Sep 25 2026

AVIATION...

Quiet aviation conditions into tomorrow. This afternoon carries only BKN high clouds streaming across Michigan with clear skies developing this evening. The only aviation item to mention is the potential for shallow ground fog or shallow low cloud that may develop with the help of light northeast flow off the lake and affect the PTK to MBS corridor. There will be a dry airmass to compete with though, so confidence is low for any reduction to MVFR or lower in the VSBY or CIG. Otherwise, VFR conditions prevail tomorrow with light winds holding out of the northeast.

D21/DTW Convection...Thunderstorms are not forecast through the forecast period.

DTW THRESHOLD PROBABILITIES...

* Low in ceilings aob 5000 feet through the TAF period.

DTX WATCHES/WARNINGS/ADVISORIES

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