Why a slight storm chance?

If you caught my weathercasts this morning, you may recall that I mentioned very slight storm chances over the next few days - to the tune of about a 10% chance. Too small to mention under normal circumstances, but since our computer model we show on-air keeps putting in some storms, I thought I should explain why it's doing that and why I believe the chance is pretty slim.

Our atmosphere is pretty stable - we have some warm air aloft. However, when we get into a warming trend in the summertime, something called "elevated" showers or thunderstorms can develop. They're especially common at night when the low-level jet stream kicks in and supplies a reinforcing shot of moisture.

I'll describe it with my amazing image I made in Paint (I'm very high-tech, as you can see). During these warm-ups, we (of course) get more warm air to move in. That warm air can be thought of as individual blobs. Those blobs will tend to rise in situations like what we have now. However, there's warmer air aloft - a "cap" to keep the blobs from going up higher. However, what complicates things a whole lot is that this cap may be a little weaker in a localized area, or one of the blobs may have more of an upward push. In those cases, blobs may start to get above that cap. Then they're able to keep rising... then they condense and form clouds... and if all goes correctly, a thunderstorm will form.

(By the way, they're considered "elevated" because they can only form up above the warm layer. In essence, they're elevated up above where a more typical thunderstorm would form.)

Predicting even IF these storms will develop is exceedingly difficult, let alone figuring out the timing and location of them. Here's the general rule of thumb: if we're experiencing a significant warming trend during the summertime, then we probably have at least a very slight risk of getting some rain.