Tuesday, June 18, 2019

Details on potential severe weather Wednesday night

After a couple of days of scattered showers and storms but no major impacts, the primary weather system for the week is heading our way and will move through Wednesday night. This system brings our best chance of widespread rainfall, lightning and thunder, and the potential for scattered severe storms.

First, overnight tonight (Tuesday) and much of Wednesday appears to be dry for most, as there are no real "triggers" for showers and storms despite the humid airmass in place. In fact, tomorrow will likely be pretty hot (actually, right at normal) with highs near 90 and heat indices well into the 90s. Southwest breezes will also pick up in the afternoon with gusts in the 20s. A stray shower or thunderstorm is possible in the heat of the afternoon, but your guess is as good as mine as to where. We'll go with a 30% chance of rain.

The mid levels of the atmosphere (18,000 feet or so) are shown by the GFS model, which loops out to Friday morning. Of primary importance is the "trough" or disturbance that moves through about two-thirds of the way through the loop, indicated by the shades of orange to red. That upper level support will provide some fuel for potential severe storms on Wednesday night.

Wednesday night is when a frontal system approaches, but more importantly, some upper level support that will serve to fire off thunderstorms in our humid and unstable air. The timing on these is still hard to pin down, but most of us will likely hear thunder overnight, and perhaps multiple rounds. By dawn, most of the rain and convective weather will be to our east, leaving diminishing clouds in their wake Thursday.

The morning run of the high-res NAM model, looping through Tuesday night, Wednesday and Wednesday night, shows minimal activity expected until Wednesday night when multiple rounds of storms are possible. (Take exact placement with a grain of salt at this point.) (WeatherModels.com)

As for the severe weather chances, the Storm Prediction Center currently has our area in the middle of a Slight Risk (level 2 of 5) for the overnight hours. Damaging wind will be the main concern, while some hail can't be ruled out. Of course, heavy downpours and lightning are a given. Tornadoes are not a concern.

Many areas could pick up over an inch of rain (and for many of us, that would be kind of welcome!). Chances of this risk increasing seem pretty low, especially given the overnight timing of the storms. Keep an eye on our social media feeds for any changes on Wednesday.

Heading into the weekend, rain chances appear pretty low (0-20%) from Thursday afternoon through Sunday morning. It will be very toasty with highs creeping back up above normal (lower 90s) and lows in the muggy mid 70s. The next frontal system that should have an impact arrives Monday.

Erik Proseus
MWN Meteorologist

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