Humidity builds this weekend, a few storms possible

Another Clean Air Action Day Friday
Posted at 5:58 PM, Jun 18, 2020
and last updated 2020-06-18 19:14:09-04

WEST MICHIGAN — The very warm, but dry, weather we are enjoying right now will turn more humid Friday and Saturday as a south flow develops ahead of an approaching cold front. This increase in humidity will be gradual -- but noticeable -- and enough to create at least a slight chance of storms by late Saturday afternoon.

Here's a look at where that cold front is as of this writing:


Temperatures will also be on the rise this weekend. Here is a look at forecast highs for Friday:


And for Saturday:


These forecast highs are likely 2 to 4 degrees cooler than reality (and more like 10 degrees cooler than reality by the lakeshore), but one can see the warming trend when looking at these graphics back to back.

The very warm to hot, humid conditions along with plenty of sunshine will result in high levels of ozone this weekend... Especially for counties along Lake Michigan. Plus, a southwesterly flow developing will carry some of that pollution from larger cities on the other side of the lake (such as Chicago and Milwaukee) into our area. For that reason, Friday is a Clean Air Action Day for the counties highlighted in gray below:


According to the Michigan Department of Environment, Great Lakes, and Energy, pollutant levels will become unhealthy for sensitive groups on Friday in the above counties. People who fall into this category should limit the length of outdoor exertion. To reduce the level of pollution in the air, it's also recommended that people carpool if possible, and avoid activities that use gasoline powered equipment.

The chance of storms ahead of that approaching cold front on Saturday are limited to the late afternoon and evening hours, and any storms that do develop will be widely scattered. According to Future Track HD, many or most of us will stay dry:


The European model also suggests very little (if any) rainfall will occur on Saturday:


Although there is a Marginal Risk of severe thunderstorms off to our southwest on Saturday, no severe weather is expected here. Any storms that do develop here should be of the "garden variety."


Although shower and thunderstorm chances will increase somewhat on Sunday as that cold front presses even closer, it will still be far from an all day wash-out. Here is a look at how Sunday morning may look according to Future Track HD:


The image above does not include how Sunday afternoon might appear, but this is as far as this particular model (the RPM) goes out. The European model does go out though Sunday night and beyond, and it does suggest some decent rainfall totals for parts of the area... Especially by the lakeshore:


Showers and possibly a few thunderstorms will be with us in scattered fashion for much of next week. Temperatures will also be on an overall downward trend as the cold front we've been talking about moves through on Monday, and a cooler trough of low pressure sits over central Ontario and the Great Lakes region. Be sure to tune in to FOX 17 for updates!