Warm and dry conditions through Friday. Cooler temperatures this weekend with chance of showers late Saturday night and Sunday. Highest chances of showers over the mountains and higher elevations. Next week, a varying range of forecast possibilities with dry/windy or showery/breezy; stay tuned for more details.
Discussion
Clear skies are evident in the latest GOES West satellite imagery. High pressure continues to strengthen over NorCal, leading to well above normal temperatures today. High temperatures are expected to peak today, where many locations in the Valley, Delta, and Foothills will reach and exceed 90 degrees.
The National Blend of Models (NBM) is currently projecting a 60-100% chance of reaching and exceeding 90 degrees for much of the aforementioned areas. Areas of Moderate HeatRisk develop today from the unseasonably warm temperatures. The Extreme Index Forecast (EFI) highlights most of the area as trending above normal, which supports the anomalously warm daytime and nighttime temperatures for this time of year.
Warm temperatures will continue on Friday, although they will not be as warm as Thursday as the ridge begins to move out of the area and into the Four Corners region and a troughing pattern develops offshore.
Onshore flow and lowering of heights will help temperatures lower slightly into the upper 80s for the Valley and mid 70s for higher elevations.
Saturday, we will see a significant drop in high temperatures, with highs forecasted to be in the middle 70s for the Valley and mid 60s for higher elevations. As the trough begins to move onshore, precipitation chances (20-45%) arrive late Saturday night for the Coastal Range and the northern Sacramento Valley.
Sunday brings the best chances of showers and thunderstorms for the entire forecast area. Generally, a 30-60% chance of showers will be with us throughout the day, with the highest chances remaining in higher elevations and northern Sacramento Valley. The NBM is projecting a 20-40% probability of meeting or exceeding 0.25″ of rainfall for our area, with the highest probabilities in higher elevations. Rain chances last through early Monday morning.
Extended Discussion (Monday through Thursday)
Lingering showers possible early Monday, mainly over the Sierra Nevada, otherwise drier weather as upper ridging moves over the CWA.
Locally gusty north to east possible Monday into early Tuesday. Forecast confidence through midweek as deterministic models continue dry weather under ridging, while NBM brings another threat of precip Tuesday into Thursday.
Higher confidence in cooling trend next week with below normal high temperatures.