The monsoon moisture has arrived in full force and we have already seen some thunderstorm activity in the mountains. As the thunderstorms develop one of the concerns is not only lighting but flooding. The storms are not expected to have much movement which would mean a lot of rain in one area over a fairly long period of time leading to flash flooding. This is why the National Weather Service has issued a Flash Flood Watch for Lassen, extreme Eastern Modoc (does not include Alturas) and eastern Plumas County. Click here for more details.
Even though the bulk of the monsoon moisture will move out by Friday we will still have some left over. This means there will be a continued slight chance for isolated showers and thunderstorms at least through Saturday. Most of the activity is expected to be in the mountains, in particular Siskiyou, Modoc and Lassen Counties but it's not out of the question for parts of the valley to see a stray sprinkle or light shower.
We are also expected to see a drop in our temperatures by the end of the weekend and into early next week as a weak storm rides to our north. This will give us a few clouds but more importantly cooler air dropping our highs to the upper 80s to low 90s in the valley. It should warm back up closer to normal (100 degrees)by the middle of next week