textproduct: Detroit/Pontiac

KEY MESSAGES

- Notably colder conditions today as most areas hold in the 30s with 20s in the Thumb.

- Passing low brings flurries and widely scattered snow showers tonight. Some minor accumulations of a dusting to a few tenths possible mainly in the Saginaw Valley/Thumb.

- Warming trend into the weekend with dry conditions.

DISCUSSION

Zonal polar jet axis over the northern tier of states with the shallow cold air mass in place down through the Tennessee River Valley will result in below normal temperatures through the first half of the upcoming weekend. Low amplitude composite trough and associated absolute vorticity will dig through northern Lower Michigan this evening and the Thumb tonight. Low-midlevel cold advection from the trough will steepen lapse rates modestly in the surface to 8.0 kft agl layer contributing to supersaturation with respect to ice through the dendritic growth zone. Best mesoscale convergence forcing is progged for northern Lower Michigan this evening with a weakening in the convergence field as it crosses the area 3-9z. The going forecast has a slight chance for snow showers. Perhaps a couple of tenths or up to a half inch will be possible on grassy surfaces.

Large scale subsidence will support surface high pressure over the region on Saturday. Chilly but sunny conditions are expected with morning windchills in the upper teens/lower 20s only making it into the middle to upper 30s.

Anticyclonically curved jet exit region pushing across the northern Great Lakes brings rising geopotential heights and air mass recovery for Sunday and the beginning of next week. 850mb temperatures are forecasted to warm from around 0C Sunday morning to +12C Tuesday. Consensus of global deterministic solutions suggests a mid-latitude cyclone tracking in vicinity of Lake Superior and Lake Huron with the warm sector in place over all of the forecast area. This supports a warm rain precipitation type for the area with a lower confidence on the timing of the cold front. Current NBM data suggests some uncertainty with the northward progressive of the cold front, however 25th and 75th percentiles suggest 70s will be likely Tuesday for those locations south of any low level baroclinic zone or warm front.

MARINE

Small Craft Advisory waves across the southern Lake Huron nearshores fall below criteria this evening as high pressure influence weakens existing onshore flow. The advisory will be allowed to expire on- schedule. A weak cold front brings widely scattered snow showers to the central Great Lakes overnight, followed by a shift to increasing northwest flow into Saturday, behind the front. The northwesterly direction keeps higher waves more so over the open waters of the Huron basin, until winds lessen and back southwesterly Saturday night. An additional brief Small Craft Advisory may be needed between Port Austin and Harbor Beach for occasional waves to 5 feet early Saturday. Winds and waves then remain in-check with dry weather Sunday and Monday. An extended window for showers and thunderstorms exists late Monday through Tuesday. Stronger prevailing winds are expected Tuesday with the arrival of a low pressure system, although gale-froce gusts are unlikely at this time horizon.

PREV DISCUSSION

Issued at 208 PM EDT Fri Mar 27 2026

AVIATION...

Mostly VFR this afternoon with a brief window of MVFR possible as low level moisture tries to redevelop a cu field after the dry air overnight helped scour clouds out. High pressure is starting to build into the area from the NW but there is a mid level shortwave that will pass over the region tonight. There continues to be support for a brief 1-2 hour window of light snow as the system passes SE over the area around 04-08Z. Will keep a prob30 going to account for this low impact snow potential. Skies should clear out again early in the morning before another round of clouds returns tomorrow afternoon.

DTW THRESHOLD PROBABILITIES...

* Low for ceiling 5000 ft or less this afternoon, moderate tonight.

DTX WATCHES/WARNINGS/ADVISORIES

MI...None. Lake Huron...Small Craft Advisory until 4 PM EDT this afternoon for LHZ421- 441>443.

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