textproduct: Detroit/Pontiac

KEY MESSAGES

- Dry weather with mild afternoon highs and cool morning lows will persist into the weekend.

DTW THRESHOLD PROBABILITIES

* None.

PREV DISCUSSION

Issued at 300 AM EDT Tue Oct 20 2026

DISCUSSION...

An elongated sfc to mid level ridge axis extending across the Great Lakes region today through Wednesday will maintain the persistent dry pattern across the forecast area. A northern stream short wave forecast to track across northern Ontario Wednesday will drive a weakening sfc cold front into the Great Lakes region Wed night. This frontal boundary will essentially wash out as long wave ridge amplification takes hold across the central US Thurs into Friday, resulting in rebounding mid level heights across Lower Mi. This will strengthen the large low-mid level anticyclone across much of the eastern US, the influence of which will affect Se Mi through Saturday sustaining dry conditions with relatively little cloud cover.

The dry ambient airmass will continue to support relatively cool nights with ample afternoon sunshine today through Saturday. Forecast mixing depths and thermal profiles remain supportive of afternoon highs from the mid 60s to lower 70s today through Thursday. Sfc high pressure is forecast to strengthen to 1035mb across Quebec by Friday. This may drive a slightly cooler airmass across the eastern Great Lakes, warranting a little lower forecast highs on Friday. With the center of the sfc high pressure already centered across NE Ontario and Quebec, light easterly winds off the lakes will contribute to some enhanced fog potential. There are some indications in the hi res suite for some degree of fog expansion across the thumb this morning. A more notable moisture push tonight into Wed morning may allow a more expansive advective fog event off Lake Erie, with the stronger easterly flow possibly supporting the better fog chances farther west toward Adrian and Ann Arbor.

There is indication in Ecwmf and GFS ensemble members that a forecast deeper upper wave tracking across central Canada Sunday into early next week will break down the ridging across the Great Lakes, suggesting a possible pattern change for next week.

MARINE...

The influence of high pressure sustains benign marine conditions today and through the week. An uptick in easterly wind occurs across northern Lake Huron this morning as the center of the high pressure strengthens just north of Georgian Bay, with gusts up to 20 kt. Wind weakens by this afternoon then gradually veers to southwest by Wednesday afternoon. A dry cold front washes out overhead Wednesday night with another broad area of high pressure then taking residence through the end of the week.

DTX WATCHES/WARNINGS/ADVISORIES

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