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 Mon Oct 19 2026

DISCUSSION...

The persistent subsidence the last couple of days has resulted in an extremely dry airmass across Se Mi. The 00Z KDTX sounding had an impressively dry Precipitable Water Value of 0.22 inches. The resident moisture starved airmass will hold in place over Se Mi for several more days within persistent low to mid level anticyclonic flow across much of the eastern US, ensuring a dry forecast with mainly clear skies through the end of the week into if not through the weekend.

Rising 500mb geopotential heights across the Upper Midwest and Great Lakes region today into Tuesday will strengthen the low-mid level anticyclonic flow across the Great Lakes, with gradually strengthening sfc high pressure becoming centered north of Lake Huron tonight, then expanding toward southern Quebec by Tuesday afternoon. An elongated ridge axis will extend through Lower Mi, ensuring weaker winds in comparison to yesterday. Similar thermal profiles and afternoon mixing depths will support daytime highs generally in the mid 60s to around 70 today through Thursday. The dry airmass and light winds will support ideal radiation cooling potential, dropping nighttime lows in the upper 30s to mid 40s for the next several nights. With the repositioning of sfc high pressure to the northeast of the region, light east-northeast winds off the lakes may drive a little higher moisture into the boundary layer, the result of which being a chance for some shallow fog the next couple nights.

A progressive northern stream trough forecast to track across northern Ontario and Hudson Bay Wednesday will drive a weakening front into the northern Great Lakes Thursday. Rapid long wave ridge amplification forecast across the central US will effectively allow sfc high pressure redevelopment across the Great Lakes, eroding any remnant sfc frontal feature and sustaining dry conditions. Further strengthening of the surface high into eastern Canada and New England on Friday will attempt to advect slightly cooler air into Se Mi, justifying slightly cooler forecast highs Friday before southerly return flow trajectories drive a little warmer back into Se Mi for the weekend.

MARINE...

The pressure gradient relaxes through this morning as high pressure coalesces over the Great Lakes. This causes gusty southwest wind to quickly diminish with wave heights subsiding through late morning. The high pressure stalls over the region through Tuesday while shifting toward southern Quebec - favoring emergence of a modest east to northeast wind. High pressure then looks to strengthen overhead again midweek, maintaining tranquil marine weather through the end of week.

DTX WATCHES/WARNINGS/ADVISORIES

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