4Warn Weather – A prolonged stretch of dangerous heat will continue across Southeast Michigan through Friday before multiple rounds of thunderstorms bring the potential for severe weather and heavy rainfall heading into the Fourth of July weekend.
A 4Warn Weather Alert remains in effect as the region faces a combination of dangerous heat, severe weather potential and localized flooding.
Dangerous Heat Continues
The National Weather Service has extended the Extreme Heat Warning through 8 p.m. Friday for most of Southeast Michigan, including Metro Detroit and communities generally along and south of I-69.
Thursday afternoon’s heat indices rose to around 105 degrees in the hottest locations in Metro Detroit.
Friday will remain dangerously hot as temperatures climb into the mid-90s with heat index values once again reaching up to 105 degrees before thunderstorms become more widespread later in the day.
Continue to take precautions during this heat wave:
- Stay hydrated.
- Spend time in air conditioning.
- Wear lightweight, loose-fitting clothing.
- Limit strenuous outdoor activities during the hottest part of the day.
- Check on elderly neighbors and those without air conditioning.
- Never leave children or pets inside parked vehicles.
Storm chances increase Thursday night
Only an isolated thunderstorm is likely to develop Thursday evening, with the best chances near the Lake Huron shoreline, the Thumb and possibly south of I-94.
Any storm that develops could produce:
- Wind gusts up to 60 mph
- Hail
- Frequent lightning
Storms will generally move from west to east around 30 to 40 mph.
Another round of thunderstorms may arrive late Thursday night as storms developing over Wisconsin and the Upper Midwest move toward Lower Michigan.
Friday brings higher severe weather risk
Friday is expected to be the most active day of the weekend forecast.
As the atmosphere becomes increasingly unstable, scattered to numerous thunderstorms are expected to develop during the afternoon and continue into Friday night.
The Storm Prediction Center places:
- Areas around M-59 and north under a Marginal Risk (Level 1 of 5).
- Areas south of M-59, including much of Metro Detroit, under a Slight Risk (Level 2 of 5) for severe weather.
The strongest storms could produce:
- Damaging wind gusts exceeding 60 mph
- Large hail
- Frequent lightning
- Torrential rainfall
- Localized flooding
Heavy Rain Could Lead to Flooding
The 4Warn Weather team is watching the potential for thunderstorms to repeatedly move over the same locations Friday afternoon and Friday night.
Some storms may produce rainfall rates of 1 to 2 inches per hour, creating localized flooding in urban and poor-drainage areas.
The greatest concern currently appears to be south of the I-69 corridor.
Holiday weekend forecast
Temperatures will lower slightly over the holiday weekend, but rain and thunderstorm chances continue.
Saturday highs should reach the upper 80s, but scattered thunderstorms remain possible, especially during the afternoon and evening.
A Marginal Risk (Level 1 of 5) for severe weather currently extends across much of Southeast Michigan along and south of I-69.
Storms that develop Saturday could again produce damaging wind gusts, heavy rainfall, and dangerous lightning.
Additional showers and thunderstorms remain possible Sunday before drier weather returns early next week.
Recap
The weather story is evolving from one dominated by dangerous heat into a multi-day stretch of changing hazards. Be prepared for oppressive heat through Friday, then remain weather-aware for the potential of strong to severe thunderstorms and localized flooding through the start of the holiday weekend.
Share your weather photos with Local 4 at MIPics.