Rain gauge calisthenics

This time of the year we have about nine hours of potential alleged “daylight” [as if] and typically enter the wet “season” [more like 6 months].  Not exactly mood enhancers for sane folk. Unless you are into winter sports, or sweating in a gym, tis the season to be a couch potato [btw, is that an insult in Idaho?].

While much has been made of surface temperature records [albeit with similar results no matter how you make the sausage], precipitation measurements are arguably more important on daily-to-interannual time-scales and far more spatially variable. Take for instance a product that NOAA creates daily by incorporating radar and gauged based precipitation for a 24-hour precipitation total on Nov 23rd.

A strong midlatitude fetch of moisture and intense westerly winds created some pretty sizable precipitation totals in western Washington and Oregon [though also eradicating lower elevation snowpack], with a strong rain shadow in its wake across the deserts. In northern Idaho much of the Lewiston-Clarkston valley was dry due to the strongly southern winds driving a rain shadow in the lee of the Blue Mnts, and nearly three times as much precipitation was reported on Moscow Mountain (4500ft) than in Moscow-Pullman (2500ft).

While it is cliché to use the phrase every drop counts, it is probably true in this case.  Mountain snowpack and streamgauges can provide proxies for water quantity at regional scales; however, more high quality observations are clearly needed to supplement our observational precipitation network.  Cocorahs (Community Collaborative Rain, Hail and Snow Network) is your chance to be a citizen scientist and contribute to the observational network by filling holes in the precipitation record. All that is required is the purchase of a 4″ raingauge ($20) and ability to use the internet. I have been an active participant in Cocorahs for a few years now and in the wet season, it is a great way to get some morning exercise. The exercise is pretty short (i.e., 2 minute “abs”) and includes a 10-m sprint to the rain gauge (or snowboard) and a really light bicep curl (to empty the gauge). Note: you can practice your 10-m sprint to the gauge on dry-days just to be sure the gauge is bone dry.  Often times, the National Weather Service will use Cocorahs data in their daily precipitation reports, especially in areas of relatively low station density.

Observations suggest that the number of times one performs Cocorahs calisthenics increases substantially in the northwest when La Nina makes her appearance. Using the historical climate network (HCN-v2) dataset I made a map here illustrating the number of additional days (versus climatological “normal”) of measurable precipitation during La Nina winters (here defined as November-April).  During years like what this winter is shaping up to be, one can expect on the order of an additional 5-15 days of measurable precipitation thanks to a persistent storm track oriented into the northwest, while the southwest counts the number of days with measurable precipitation on its hands and feet.

That being said, after this weekend we’ll see a rather quiescent weather pattern for much of the inland northwest with relatively mild and dry conditions.  I’m not worried as I’ll get plenty of sessions of Cocorahs calisthenics in this winter.