Much needed weekend rainfall with a cooler start to August on the way

A low-pressure system will lift out of southern Illinois to Indiana late Saturday, Aug. 1, 2020 through Sunday. The chance for heavy rainfall is most likely farther east, but some spots in West Michigan will still see some much needed rain. (WWMT)

The recent above-average temperatures and lack of rainfall has left many locations a bit parched, however a system on the way could provide some much needed rainfall, but not everyone will see impressive totals.

A system was expected to live out southern Illinois and southern Indiana beginning Saturday afternoon, heading for the eastern Great Lakes by late Sunday, Aug. 2, 2020.

The system could bring some soaking rain for the east side of Michigan, but rainfall totals over 1 inch were looking less likely in West Michigan, at least throughout the day on Sunday.

System track is key

There appears to be some disagreement among the two primary forecast models, commonly referred to as the European and American models. The American model, or Global Forecast System (GFS), delivers a better chance for a period of rain starting late Saturday and lasting throughout the day on Sunday.

The European model also features rain Sunday, but the timing is pushed back a bit later and the track of heavier rainfall is shifted a bit farther east. This scenario would cause a majority of our area to miss out on the potential for any more impressive rainfall totals.

Analyzing the two in conjunction, we could say the most likely area in West Michigan to see rainfall over 1/2 inch will be east of U.S. Route 131, especially in locations east to southeast of Kalamazoo throughout the day Aug. 2. Locations along and east of Interstate 69 could see even more impressive rainfall totals over 1 inch.

A shift in the system track farther east would mean more of West Michigan would get almost entirely missed by rain on Sunday. A shift west would translate to more locations seeing more impressive rain. Models have been trending farther east in the system track over the last 24 hours.

We could use it

With all of West Michigan officially labeled "abnormally dry" on the latest US drought monitor, released July 30, any rain in the forecast has the potential to offset a deficit most of the area is starting to feel.

With only 1.46 inches of rain measured in total, 2020 would go down as the 22nd driest July of about 120 years on record in Kalamazoo. That's a little over 2 inches less than what we see in an average July.

Farther north, Grand Rapids actually measured over 4 inches throughout the month, and ends the month wetter than average. A majority of that rain, however, fell in the first 10 days of July.

According to forecasters with the National Weather Service in Grand Rapids, soil conditions are also telling of just how dry the region is. The top 15 inches of soil currently has less than 30% of the water it can hold over a majority of our area.

Monday brings another rain chance

A stronger dip in the jet stream enters West Michigan throughout the day Monday, Aug. 3, which should provide enough forcing to trigger another batch of showers and non-severe thunderstorm during the afternoon and evening.

For those that miss out on rain Sunday, it's looking like Monday's rainfall could be a bit more widespread. A cold front will also be diving through the area, which could also enhance our chance for rain during this time frame.

A few showers and storms may linger on Tuesday, but that would be much more isolated.

What about Hurricane Isaias?

Our weather shouldn't be directly affected by Hurricane Isaias at all. All direct impacts should remain concentrated along the east coast this weekend and into early next week, mostly in the form of rough surf and heavy rainfall.

By Tuesday, the same trough over West Michigan could help Isaias accelerate north-northeast up the East Coast.

That being said, sometimes tropical systems with this sort of track could block or slow down systems moving through our region, but that doesn't appear to be one of those scenarios.

Cooler pattern follows

If you're a fan of summer, but not significant heat and humidity, early August is probably one of your favorite times of the year. Typically, West Michigan see highs in the lower 80s and lows around 60 degrees, and it's the time of year the humidity starts backing off as well.

The first full week of August 2020 could bring at least a few days cooler than these already comfortable thresholds.

The coolest air we've seen since mid to late June arrives behind the front during the first week in August. How cool you ask? Highs look to stay in the mid to upper 70s, while lows dip into the middle 50s during the overnights.

It seems the more pleasant air could stick around through the end of next week, and into next weekend as well.

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