WATER YEAR PRECIPITATION (October – April 10th)
An active storm pattern during the winter and mid-spring months continued with above-normal precipitation across interior NorCal. Water Year precipitation totals ranged from 125 to 190% of normal precipitation through mid-April.
STRONG ATMOSPHERIC RIVER STORMS
Several atmospheric river storms impacted NorCal from December 26, 2022 – January 17, 2023, resulting in substantial ﬂooding, wind, and heavy snow impacts. The storms brought impressive precipitation totals ranging from 1-2” in the Valley to over 3-5” in the mountains. The southern Cascades and the northern Sierra received multiple feet of snow. Peak wind gusts in the Valley ranged from 50 to 60 mph, locally up to 75 mph. These winds resulted in numerous reports of downed trees, power lines, and power outages. Looking at storm reports throughout winter, we logged over 200 snow reports, over 100 ﬂooding reports, 83 wind reports, 5 hail reports, and 2 conﬁrmed tornadoes.
The weather was relatively quiet from January 17th to February 20th with only minor precipitation and snowfall events. February would then conclude with several atmospheric river storms impacting NorCal. Additional atmospheric river storms impacted NorCal throughout much of March, adding more precipitation to an already wet water year.
Record rainfall was observed on New Year’s Eve across several locations as a strong weather system impacted interior NorCal. Below are the 24-hour precipitation totals for the heavy rain on NYE (see image below).
Precipitation totals throughout the entire winter were very impressive, with the heaviest rain falling in the month of January. Below are the winter 22-23 precipitation totals for some regional climate locations, with record-breaking winter precipitation totals at Stockton and Modesto.
A strong and cold storm brought signiﬁcant low-elevation snow in late February, with snow levels down to around 500 feet. Several inches of snow were reported in the northern Sacramento Valley on February 24th, including the city of Redding.
Impressive snowfall amounts were observed across the Sierra Nevada, southern Cascades and Coastal Range, with seasonal totals exceeding 30 feet of snow.
As shown above, in the U.S. Drought Monitor, October started off with abnormal dryness depicting moderate to exceptional drought across much of California. The signiﬁcantly above-normal precipitation and snowpack throughout January, February, and March improved drought conditions, including reservoir levels. Even so, after several very dry years, long-term drought conditions continue across portions of California, ranging from D0-Abnormally Dry to D1-Moderate Drought (Image above).
3-Month Outlook [April-May-June]
The latest 3-Month Seasonal Temperature Outlook from the Climate Prediction Center (Image left), and the Seasonal Precipitation Outlook (image below), indicates ‘equal chances’ for above, below, or near normal temperatures and precipitation for April-June.
So what does that mean, then? There is no clear signal for temperature or precipitation, and the range of possibilities doesn’t clearly fall in any category.
Seasonal outlooks do NOT capture speciﬁc periods of hot weather (i.e. heat waves); those are in the 7-10 day forecast. Individual weather systems cannot be captured in seasonal outlooks.