By now you know the drill: increase the heat and humidity, and we increase our storm chances, too. All it takes is a trigger to initiate the convection (violent upward motion of surface air parcels), and away they go.

These triggers can take many forms: sometimes it’s a front, sometimes a trough of low pressure, sometimes a lake breeze (basically, a mini-cold front moving inland from the colder Great Lakes), and sometimes it’s just a line of higher moisture or a little upper level disturbance.

In the case of this evening, a tongue of higher moisture across western Michigan has ignited a line of thunderstorms that will give us the threat for some storms this evening. The better chances are farther north, with more of a scattered pattern farther south.

Although I’m not expecting any widespread severe weather, do remain alert if you have outdoor plans – check the radar often on our free Local4Casters app (just search under WDIV in the app store if you’re one of the few people who don’t have it yet). It’s going to be a warm, muggy night, with lows only dropping into the low to mid 70s (that’s 22-23° Celsius for those of you using the Metric System). Southwest wind at 5 to 10 mph. Oh, and by the way, one of my models is suggesting the potential for some patchy, dense late-night fog. I’m not sure that this will materialize but, if it does, it should burn off between 9:00 and 10:00 AM.

Forecast

Wednesday will be another hot and humid day, with scattered thunderstorms developing by late-afternoon into the evening hours. Based upon today’s computer model upper air forecast data, I do believe there’s the potential for some severe storms. Again, keep a close eye on our app’s radar tomorrow, and remember to follow me on Twitter (@PGLocal4 and @Local4Casters) for personal updates. Highs once again should reach the low 90s (33° Celsius), with a southwest wind at 10 to 15 mph. At this point, it appears that the storms will hold off until after the 34th annual Metro Detroit Youth Day on Belle Isle, which runs from 8:30 A.M. to 2:30 P.M. This is a big deal – over 35,000 kids and 1600 volunteers will pack the island! It’s obviously going to be a very hot day, and I’m told that they’ll have plenty of cold water for the kids.

Wednesday’s sunrise is at 6:09 AM, and Wednesday’s sunset is at 9:09 PM.

Wednesday evening storms will move out, we’ll be quite for a while, and then showers and thunderstorms are possible again later at night. Lows in the low 70s (22° Celsius).

Showers and thunderstorms are possible Thursday morning in advance of the cold front that will finally give us some relief from the heat and humidity (but not until Friday). Skies should become partly cloudy Thursday afternoon, with highs jumping into the upper 80s (31° Celsius).

Mostly clear Thursday night, with much more tolerable lows in the mid 60s (18° Celsius).

Partly cloudy on Friday, cooler, and less humid, with highs near 80° (27° Celsius).

Mostly clear Friday night, with lows near 60° (16° Celsius)…that’s going to feel REAL nice.

Mostly sunny on Saturday…a perfect summer weekend day…with highs in the low 80s (28° Celsius).

Sunday looks good, too, with mostly sunny to partly cloudy skies, and highs in the mid 80s (30° Celsius). Note: some models try to bring in a chance of thunderstorms Sunday night. Obviously, I’ll need to keep an eye on the timing of the weak trigger that would kick off these storms and, if there’s any acceleration of the timetable, I’ll let you know ASAP. After all, this is our weekend and, when it comes to weekends, I’m a professional…I know how important they are to you.

