BadMomGoodMom sent me this nice URL to the National Weather Service who have a nice graphical tool for looking at precipitation, both current and historical. She's got a current post about local rainfall, and I thought I'd sing along.
I've graphed here the precipitation for calendar year 2007 across the entire U.S. I've been unable to find a way to graph the water year, which runs from Aug 1 to July 31, but these pictures will suffice. The scale of the images is in percentage of normal, as shown below. What's normal? I'd assume that the NWS uses median rainfall as "normal", but regardless of what they use if they indicate 0-50% of normal, then that means little rain.
Remember all the drought news from Georgia last year? You can see it here as the yellow-red zones at the right of the country. We're looking similar to Georgia in terms of percentage of normal rainfall over on the west coast. The differences in impact last year (it seemed a larger news story that Georgia was dry) seem mostly due to the fact that Georgia has a fast growing population and no history of prior water shortages that would have forced it into planning for drought.
Now let's look at January of 2008 in a region a little closer to home, below.
That's Catalina Island off the coast of California. The city names are readable if you click on the images.
Wasn't January 2008 a nice change from 2007? It shows a comfortable margin above normal almost across the board. If the trend had continued, we wouldn't be talking about drought quite so much. Now take a look at February below. February is traditionally a heavy rainfall month for us, but as you can see we were pretty parched.
And March, below. I expressed the opinion around early March right here in this blog that we'd still recover a normal rainfall based on a purely statistical look at typical rainfall. I was wrong.
And April. More of the same:
Lather, rinse, repeat until we get to today and start talking about drought.
You could argue that local rainfall doesn't matter too much since we get lots of water from the State Water Project. That's true, but the Sierra snowpack, which started out normal to high, didn't last due to warmer than normal temperatures and didn't get replenished due to lack of late winter storms.
Local rainfall also matters to local streams which host wildlife, whether intended as wildlife sanctuaries or not.