6:33 p.m. ET, August 7, 2023
How a sunny morning helped fuel today's dangerous storms
From CNN meteorologist Mary Gilbert
Monday’s severe weather threat across the eastern United States is formidable – but the day began for many with mostly clear or sunny skies. If it’s bright and sunny in the morning, how can there be severe thunderstorms later?
Thunderstorms need three things to bubble to life — moisture, lift and instability. Heating from sunlight fuels two of these factors.
On days without a cloud in the sky, the sun quickly and efficiently heats the ground, giving the air at the surface plenty of instability and then forcing it to rise. Rising air of this nature will quickly climb until it reaches its saturation point — the point where the air is cooled enough for rain to form — and then a storm is born.
This is lift, anything that forces air upward, and instability, a measure of how much air is able to move upward when forced via lift, in action.
Abundant instability was in place for locations like Washington, DC, after early morning clouds largely dissipated and allowed plenty of sunshine to reach the surface, leaving the atmosphere primed for dangerous storms.
Once a storm forms, it can strengthen further under the right conditions and become severe. Severe thunderstorms are then able to unleash damaging wind gusts, hail and even tornadoes.
Given enough instability, lift and moisture, thunderstorms can quickly turn a seemingly great morning to be outside into a dangerous endeavor during the day.