We could see our first significant storm of the year early next week

Here is the First Alert FOX 12 weather forecast for the morning of Friday, Sept. 22, 2023.
Published: Sep. 22, 2023 at 3:23 AM PDT
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Good morning! Today will be our last warm and sunny day for quite a while. The weather pattern is about to take a sharp turn toward the rainy season, so take advantage of this beautiful day ahead. Temperatures aren’t quite as cold as they were yesterday morning, but most cities are in the 40s and 50s. A few outlying spots may briefly drop into the upper 30s around sunrise. Expect to see sunshine all day long with valley highs in the upper 70s.

Clouds will begin to stream in tonight ahead of a developing weather system over the Pacific. This deep trough of low pressure will basically park itself over the northeast Pacific Ocean this weekend. Initially, a shortwave will pass overhead Saturday, bringing scattered morning showers to the coast, and afternoon showers inland. Most of these showers should be on the lighter side of things. Consider this the appetizer to the main course. Sunday looks like it will be a classic gray/drippy day with light rain throughout most of the day. Temperatures will only reach the mid to upper 60s this weekend.

Sunday night into Monday is when things will get more interesting. The strong upper level low over the Pacific Ocean will inch toward the West Coast, bringing in a slow-moving cold front. This frontal boundary will interact with a moderate to strong atmospheric river, enhancing rainfall rates along & west of the Cascades. An inch or more of a rain is almost a certainty along the coast & Coast Range. We should see a pretty good soaker inland as well. Atmospheric rivers enhance rainfall rates, so there will probably be at least a few hours of heavy rain (as the front slides through). Considering how dry our weather has been, river flooding isn’t much of a concern. However, heavy rain over burn scars may lead to some debris flows. That’s something we’ll be keeping an eye on.

Sometime between Monday afternoon & Tuesday is when our weather will turn more showery. Our atmosphere will become more unstable after the cold front slides through, so downpours and isolated thunderstorms will be possible. There’s a bit more uncertainty beyond Tuesday, as some models are bringing another organized weather system onshore. Gusty winds will be possible if this type of scenario materializes. Otherwise, just expect another wave of rain around Wednesday, with a transition back to showers Wednesday P.M. – Thursday. The entire workweek should feature highs in the 60s.

Enjoy this final gasp of summer weather, and have a great Friday!