Monsoon Weather Today

It is summertime. The days reach around 99'F. They are usually completely dry. We've got fires burning. There's a big one near Middletown on the slopes of Mount St. Helena, or thereabouts. There's another big fire burning around Lake Berryessa, near Monticello Dam. Started by fireworks, both of them. This is not to say the only sort of fires we get, the human caused ones. We also get lightning fires despite being a state with few thunderstorms. There is a certain time of year where hot humid weather surges up from Baja, spinning off disintegrating eastern Pacific Hurricanes. They surge up the Sea of Cortez and flow into Arizona, the Mojave desert, and up into the Great Basin north of Las Vegas. These storms ALSO come into California from the South, bringing exactly the sort of wet air that turns into thunderstorms.

Right now we're getting those clouds. Yesterday the humidity was 1%. Today it is 37% and slowly falling. It's going to be just as hot as yesterday, but today we might get rain. Big heavy drops. Easterners find nothing wondrous about this, being common on the great plains and along the gulf stream, but here it is nearly miraculous. Our seas are icy cold, even in summer. Summer rain is rare. It is also contrary. It brings fire. The water that falls often evaporates before it hits the ground. You can see this in the skies. It is called Virga. However, its is the motion of hail in the clouds circulating and adding layers to the hail which actually generates the charge differential for lightning. It never has to hit the ground. And the mountains here are excellent for forcing the thunderheads higher, and providing places for lightning to arc to. For the strikes to cause fires. Which they do.

Summer and Fall are fire season in California thanks to these thunderstorms. They mostly hit the highest parts of the Sierra, but sometimes they strike the Coast Ranges and the lower foothills. We might see some here today.

The clouds this morning, billowing with stored heat just after dawn, uncharacteristically energetic despite the early hour. These look like the pictures I've seen of hurricane clouds skidding over Florida. With the smoke clouds dark beneath them down in the Valley, to my West, it looks layered, beautiful, and surreal. I should have brought my camera on the walk today. Missed some great pictures.