textproduct: Detroit/Pontiac

KEY MESSAGES

- Scattered light rain showers this morning.

- Temperatures roughly 10 degrees below average the rest of the week, bringing potential for frost/freeze conditions each morning thru Sunday.

DTW THRESHOLD PROBABILITIES

* Moderate for ceilings at or below 5,000 feet this morning. High this afternoon and evening.

PREV DISCUSSION

Issued at 405 AM EDT Wed Apr 29 2026

DISCUSSION...

A mid-level trough passing through the Midwest merges with a convectively enhanced shortwave over the Ohio Valley this morning. The result will be a deepening sfc low that develops along the stalled baroclinic zone to our south and tracks into the Mid- Atlantic region. The deeper moisture transport with this system will be shunted to the south and east, but will see pockets of light showers track through this morning as transient fgen excites the 600- 700mb front overhead. Highest confidence in measuring around 0.10" will be south of Metro Detroit where the most organized forcing and deepest moisture is progged to set up.

Low-level dry air is shown to spread back in from the north as the elevated forcing peels away midday, favoring mainly dry conditions east of US-23 the rest of the afternoon. As PVA associated with the Midwest trough tracks in late afternoon and this evening, additional spotty showers expand in coverage over interior Lower MI and persist into parts of tonight. This wave passing through also produces a healthy coverage of lower cloud overnight, which with a weak gradient wind is forecast to prevent wider development of frost. Some patchy frost still possible as 2m temps settle into the mid 30s outside of urban areas.

The trough stalls over the northern Great Lakes tonight, evolving into a closed low that meanders over the region the rest of the week. Cool northwest flow dominates local conditions with temps falling roughly 10 degrees below average for late April and early May. Mostly benign conditions during this period, but expect a daily flare-up of showers as the cold pool aloft induces steep lapse rates within the broad moist cyclonic flow. Daily highs within a few degrees of 50 favor rain showers but wet snowflakes possible at times as wet bulb zero heights fall below 2kft.

The upcoming cool period is uncommon but not completely unheard of for early May, with historical data showing temps falling below freezing during the first week of May roughly once every 3 to 7 years on average. However, with the warm spring so far - ranked in the top-10 warmest up to this point for most sites in SE MI - this cold comes with potential impacts to sensitive vegetation. Friday, Saturday, and Sunday morning remain targets for potential frost/freeze headlines, particularly Saturday morning. If the current forecast for lows in the upper 20s Saturday morning verifies, some low min records will be within reach.

The thermal trough is nudged out early next week which favors a slight warm-up, but longwave troughing remains the dominant pattern over the eastern CONUS well into next week. This offers several opportunities for widespread precip events, and temps generally near or below normal. CPC 6-10 day, 8-14 day, and week 3-4 outlooks maintain a lean toward chilly conditions well into the month of May.

MARINE...

A more diffuse surface pressure field emerges today as the central Great Lakes becomes positioned between several weak surface high pressure areas to the west. Mid-level troughing persists overhead, lifting a weak surface low through the Ohio Valley. This lends potential for periods of light showers, but a lack of instability precludes thunderstorm concerns. Local winds generally hold from the northwest through the rest of the workweek with some additional chances for weakly forced light precipitation. Stronger high pressure then attempts to build in from central Canada/CONUS over the weekend. Low predictability exists in the large-scale pattern evolution this weekend as stalled low pressure over The Northeast retrogrades toward the Great Lakes. No marine headlines are expected through Saturday given current wind and wave trends.

DTX WATCHES/WARNINGS/ADVISORIES

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