Weekend Weather Blog: Looking at Sunday’s thunderstorm threat

Lightning bolt striking Blatnuk Bridge in Duluth.
Lightning bolt striking Blatnuk Bridge in Duluth.((KBJR/CBS 3))
Published: May. 14, 2022 at 3:56 PM MDT
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TWIN FALLS, Idaho (KMVT/KSVT) — Tis the season for spring thunderstorms - even though they don’t happen quite as often here in southern Idaho as they do in the Midwest, they still do happen here in southern Idaho.

In fact, about 2 weeks ago, we saw our first severe weather of the season in Idaho, after numerous severe thunderstorm warnings were issued due to a line of thunderstorms that trekked through the forecast area. Just look at the tweet below from May 2.

Sunday’s event won’t be quite as potent. In short, the upper level support with this system is much weaker than what we saw 2 weeks ago. However, we will see enough support for organized thunderstorms.

While, as of 3 PM Saturday, the Storm Prediction Center hasn’t put the region under a severe thunderstorm risk, there is a chance they might later on. What’s the SPC seeing that’s keeping them from placing the region under a severe weather risk, though? It all has to do with the available moisture we’ll have to work with.

Thunderstorm energy, or the technical term, CAPE, relies on a few ingredients to be present - specifically moisture near the earth’s surface, and temperatures cooling rapidly as you go up in height.

Where’s the uncertainty? As always with Idaho, it’s the available moisture. The models we use to forecast are not very certain on how much low level moisture will be present throughout the day tomorrow. One model says we won’t have much moisture, which will limit the amount of thunderstorm energy available, while another model says we’ll have more moisture - allowing thunderstorm energy to be much more plentiful.

The larger your thunderstorm energy is, the better chances you have at seeing severe weather, particularly hail. While the models are definitely showing sufficient thunderstorm energy for the development of thunderstorms the uncertainty lies in whether or not we’ll see enough for the development of hail.

Another uncertainty? The coverage of thunderstorms. As I said earlier, it’s looking likely that there won’t be very strong forcing with this system, meaning air won’t be forced to rise all that much. It’s looking likely that these thunderstorms will be mainly confined to the mountains.

In my opinion, it does look like we do have a chance of 1 or 2 thunderstorms becoming severe if they do form. These thunderstorms will be very isolated in coverage, and some (almost all) of us may see partly cloudy skies throughout the day. With that said, I would not be surprised if the Storm Prediction Center upgraded us to a marginal risk (level 1/5) of severe storms tomorrow.

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