Weather Blog

Views from the edge of the Convergence Zone

Views from the edge of the Convergence Zone

The wind on Friday was fairly fierce, but what most people in the Seattle area will remember was the big rain and hail (and a little lightning) event after, courtesy of a raging Puget Sound Convergence Zone.

The zone is caused by colliding winds when we have northwest flow aloft, and the conditions after the cold front passed on Friday were spot-on perfect.

The zone was just in its infant stages when I drove home from KOMO Friday evening but by the time I got home to Mukilteo, the zone was going strong, and boy was it a good one!

But Mukilteo was just on the northern edge of the zone, and there was a dramatic edge to the cloud bank, with a peculiar cloud bank that stretched out like a finger:



You can see how tall the cloud stretches and imagine how the hail that fell across King and southern Snohomish County. Those strong updrafts that make the cloud so tall also keep the hail stones aloft until the stones gets heavy enough to where the updrafts can't keep it aloft, and the stone falls to the ground.

Here is another time lapse videos from Friday. Watch how the zone radically shifts the wind in the afternoon: