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Temps soar today and Saturday, but tank next week

Pattern Change to Drive Colder Temps
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Posted at 6:21 AM, Sep 25, 2020
and last updated 2020-09-25 09:31:22-04

WEST MICHIGAN — Our FOX 17 Meteorologists have been mentioning all week to get out and enjoy the weather now! High temperatures today and again on Saturday should be pushing 80 degrees or so, but a sharp transition to colder temperatures will arrive next week with a shift in our upper level jet stream forcing a pattern change.

This week in West Michigan weather has been dry, quiet, and frankly, unprecedented with the warmth we've experienced. Normal highs for this time of year have us around 70, and our temperatures have been running mid/upper 70s all week. With a stiff south to southwesterly flow the next two days, we expect to reach 80 or better both Friday and Saturday, and still hold on to about mid 70s on Sunday.

By the beginning of next week Monday and Tuesday, we'll increase the clouds and our rain chances. Eventually as the jet stream begins to shift further to our south, we'll see temperatures drop and colder air spill in from Canada and highs only in the 50s. In fact, it may be cold enough for lake effect or lake enhanced rain showers as the air coming across the warmer waters of Lake Michigan may generate clouds and showers. This is similar to lake effect snow, but of course its not cold enough to snow...so its just plain rain showers. Take a look at the image below at about 18,000 feet or 500 millibars above the surface. You can see the manner in which the core of our jet stream has opened up a huge trough or dip over the Great Lakes. Note also the huge ridge or bubble in the western United States. Temperatures will be warmest there. It may also be cold enough to see waterspouts over Lake Michigan next week. Colder air coming over the top of the warmer waters of the lake can induce a spinning motion in the atmosphere. These circulations (tornadoes that occur over water) tend to be much weaker than a typical severe thunderstorm produced tornado on land and are usually short-lived.

If we look at upper level temperatures...which is a good proxy for what's occurring here at the surface, the image below shows the air mass or temperatures at about 5,000 feet above the ground on Saturday. Note the warmer tones. It's easy to see with the yellows and reds over our area, we will indeed be above normal.

Now look at the same image below...valid for next week Tuesday evening. Again, sharply colder air masses and tones have replaced what was mild air. The colors over Michigan have changed to light blue.

We should also note that while it may be a great weekend to take the boat out for the last time or perhaps winterize it, beachgoers on Saturday will need to exercise some caution in the water. SMALL CRAFT ADVISORIES and a HIGH BEACH HAZARD RISK will be in effect with waves running about 3 to 5 feet. Our Meteorologist Ty Shesky wrote an article on this. Click here to see it.

Enjoy the weather this weekend. It will be far above normal, mainly dry, and downright gorgeous for Fall. Get the complete West Michigan forecast at www.fox17online.com/weather.