Doug Simonian

Widely scattered t-storms this afternoon, heat returns this weekend

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Good afternoon! It has for the most part been quite the pleasant day, as a cold front came through last night and made conditions much less humid and more pleasant today than yesterday. For the most part, this nice weather looks to continue for the next several days.

However, since yesterday’s inclement weather was caused by a large trough, there is still leftover energy rotating on the back side of the trough, which is where we are located. There are pieces of vorticity, or counterclockwise spin in the atmosphere, which can often trigger localized areas of lifting. Usually, when the airmass is as dry as it is currently, it is hard for thunderstorms to form. But when you are sitting under a large upper-level trough, cold temperatures aloft combined with a heating surface can still yield instability, and the vorticity causes the lift that taps into the instability. This is why some isolated thunderstorms have formed in our northwest suburbs.

Elsewhere, there has been a general increase in cumulus clouds, which is generally for the same reasons; though it is still quite pleasant. As the afternoon progresses, a few of these storms could hit the region, but they are looking very isolated, so most areas will not see a storm at all, and any storm that does arrive will be quick-hitting. Temperatures will generally remain in the low 80s. The most likely spot for a storm is in our NW suburbs.

The dry airmass will prevent the storms from getting too strong and from having too heavy of downpours, but the cold and dry air aloft from the trough may help the storms generate some downward momentum in the form of wind gusts up to 40mph.

Fortunately, even in areas that do get a storm, skies should easily clear out quickly enough to get a good view of the Perseid meteor shower tonight.

Other weather highlights include:

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John Homenuk

Perseid meteor shower peaks tonight, here’s how to see it

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The annual Perseid meteor shower peaks tonight into the early morning hours of Thursday, and astronomers are suggesting the potential for up to 100 meteors per hour.

There’s something humbling about laying in the grass and watching meteors streak throughout the night sky. The Perseid meteor shower provides arguably the best show of meteors in the night sky each year. Its annual occurrence during warm summer nights makes it easily the most comfortable meteor shower to watch of the bunch of “major” showers, many of which fall during the colder winter months. This year, a very dim moon will make viewing even more ideal during the peak of the meteor shower.

Why is the moonlight so important? To put it simply, it upstages the light of the meteors streaking throughout the sky. When the moon is full, you may still see meteors — but the smaller, dimmer activity (which is typically more frequent than the bright ones) is blocked out by the bright light of the moon in the sky. This year, the thin crescent moon is not expected to interfere at all.

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