English: Image Credit: National Weather Service

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I treat my photo-stream like a blog, but hey, this is the only one I have! If you're interested, then read my local reporting and "fun facts", below. ___________

The latest rainstorm to hit California was billed as one the biggest in the past 10 years. Yes, it did rain here, and it was a long, soaking type of rain. Yesterday, just before dawn, it started raining, and it literally came down for more than 24 hours without a break. Where I live, the 24-hour rain total was 3.6 inches, or 0.15 inches per hour. That rainfall rate is fairly miniscule compared to thunderstorms, hurricanes and tropical downpours, but if you give it a 24-hour run, it adds up quickly.

This storm helps drought-stricken California, but we have a long way to go until we’re clear of water restrictions. As an example, here are some facts about Shasta Lake, one of the major points of infrastructure in the Central Valley water system. [UPDATE: all facts reflect conditions at 4pm on December 13, 2014, which includes 72-hours of runoff in the Shasta Lake area].

•Total capacity of Shasta Lake when it's full is 4,522,000 acre feet (about 1.47 TRILLION gallons). •Actual lake volume as a percent of lake capacity before the storm began at 4pm, 12/10/2014 was 25.16%. •Actual lake volume as a percent of lake capacity 72 hours after the storm began was 30.77%, up 5.61% in three days. •Run-off to Shasta Lake during the 72 hour period after the storm began was 230,947 acre feet (and continuing). •Shasta Lake still needs another 3,130,488 acre feet to fill to capacity. •Shasta Lake level has risen about 18.2 feet in the 72-hours since the storm began. •Shasta Lake is still 149-ft below the crest of the dam. •The storm produced a peak inflow rate of 97,962 cubic feet per second; that’s equivalent to 2.25 acre-feet per second, or 732,755 gallons per second.

Another 41 days of runoff at an average rate similar to that experienced with this storm (an average rate of about 77,000 acre feet per day for the first three days) would be required to fill the reservoir. That's not likely to happen this year alone since this is one of the biggest storms to hit the state in a decade. In other words, this storm helps the drought situation, but it will not end the drought by itself.

Assuming that an average of 3-inches of rain fell on the northern half of California during this storm (which is probably on the low side by as much as a factor of 1.5), that would equate to more than 12,750,000 acre feet of water, or enough to completely fill the major lakes in Northern California; but we all know that much of the rain falls below our reservoirs, and, except for the amount that seeps into our groundwater, makes its way to the ocean with minimal long-term benefit.

The forecast for next week calls for more rain. Let’s bring it in gently and consistently because we need every drop, but we don’t need the localized flooding, mudslides and other disasters that monsoonal systems tend to produce.