Residents of California's Central Coast got a significant drop in temperatures as an unseasonably cold upper low continues to influence the region. This cooling trend, already noticeable with temperatures up to 25 degrees cooler this morning compared to yesterday, will persist through Saturday. Highs are expected to fall to 5 to 10 degrees below normal, with low clouds and fog becoming more widespread along the coast and into some valley areas.
Short-Term Forecast:
The cooling trend is driven by an upper low off the Washington and Oregon coasts, which, although not bringing rain this far south, is pushing much cooler maritime air inland due to increasing onshore flow.
This has led to a significant drop in temperatures. Additional cooling of around 5 degrees is expected by Friday, particularly in inland areas, where highs could reach 10 to 15 degrees below normal. Forecast soundings indicate a deepening marine layer tonight into Friday, likely resulting in cloudy skies across most coastal valleys on Friday morning.
The upper low will finally move inland this weekend, but little change is expected on Saturday. Low clouds and fog will continue to push inland, keeping highs similar to Friday.
Sundowner Winds and Wind Advisory:
The north-to-south pressure gradient will trigger Sundowner winds along the Santa Barbara Southwestern Coast tonight and tomorrow night. A Wind Advisory may be issued for this evening for the Western Santa Ynez Range and adjacent coastal areas.
Increasing onshore flow will also bring west-to-southwesterly wind gusts of 25 to 35 mph across much of the interior this afternoon through the evening.
Weekend Outlook and Early Next Week:
As the upper low moves inland, high pressure will begin to rebuild over the region starting Sunday, leading to a significant warmup into mid-next week. The onshore flow will weaken, and gradients may even turn slightly offshore, particularly to the north. While this won't be a true "Santa Ana" event, it will bring some light north to northeast winds across the deserts and mountains, leading to a rapid rise in temperatures, especially for coastal and valley areas. By Sunday, most valleys will climb well into the 90s, with inland coastal areas reaching the mid to high 80s. Marine layer coverage will also be significantly reduced.
Long-Term Forecast (Monday - Thursday):
Building high pressure will continue into Monday, leading to additional warming and minimal marine layer coverage. However, ensemble models suggest a slight weakening of the ridge after Monday, which, combined with increasing onshore flow, will lead to a slight drop in high temperatures by 2-5 degrees from Wednesday through Friday.
Looking ahead, there is still a chance that monsoonal moisture could reach the region mid to late next week. Although the signal is not strong enough to include thunderstorms in the forecast, there is a 5-10% chance of activity across the eastern Los Angeles Mountains and Antelope Valley. This is something to monitor as the weather pattern evolves.
