Wednesday, February 27, 2013

Eastern Washington Drought?

The last two months have been extraordinarily dry east of the Cascades crest, even for the sage brush laden, semi-arid zone extending into the Columbia Basin.  To explore this, lets start with the precipitation during the past 60 days (see image below).  Some locations on the eastern slopes have gotten less than .1 inches during the period.
The percentage of normal precipitation shows a similar story: many folks on the east side had less than 25% of normal.  You can see that much of the rest of the state was fairly dry...but not that dry.
 Let's plot the precipitation at Yakima for the past twelve weeks.  Essentially nothing since early January.
 Pasco was a bit wetter, but not by much.
So, how serious is this "drought?"  The answer has a lot of economic implications for eastern Washington crops, particularly the dry land farmers of the Palouse.  Last year they made out like bandits, as drought in the Midwest and Plains caused crop prices to skyrocket, while eastern Washington farmers had excellent crops.

The National Weather Service has a "drought monitor" website that summarizes the sub-surface water situation (see graphic).  No drought in eastern Washington (white color), while much of the southwest  and Plains States were dry.  It turns out that although the past two months have been dry in eastern Washington, the last year has been near normal.


To illustrate this fact, here is the observed and normal precipitation at Pasco. 
Basically, a wet fall balanced out a dry winter.
Pretty much the same story at Yakima:
Snow over the Great Plains has put a small dent in the severe drought in the nation's midsection, but at this point I suspect that eastern Washington farmers will again have a highly profitable year as their fellows over the Great Plains and Midwest suffer from the effects of drought.  At least that is what the National Weather Service is predicting:

Reminder;  the NW Weather Workshop, which is open to all, starts on Friday.  To see the agenda and to register go to http://www.atmos.washington.edu/pnww


5 comments:

RB said...

Thanks for this Cliff. IMHO you have the best blog on the net. I live on Vancouver Island and though I know we in the Pacific Northwest are blessed as far as climate change goes I am concerned about the steady creep of drought I expect (Hadley Cells and all that).

I like to keep track of the drought progress over time via this page. http://www.ncdc.noaa.gov/temp-and-precip/drought/nadm/indices.php?mdf=map&divstn=div&indicator=pctpcp

The above page is also what I use for Mexico as few other sources pay it any attention. Kind of important to us North Americans.

More similar links for your readers here http://rickbateman.com/weather%20links.htm

John D said...

Where do you get those cumulative precipitation plots?

Hindu said...

Thanks for the great post. I farm winegrapes near Mattawa and on Red Mountain. Unlike most wheat farmers we have irrigation so I have no room to complain. Still I do because it's so dry here now. But when you live and farm (at least for us) in an area that gets around 7 inches of precip a year, it's a fine line between drought and wet.

lemonlye said...

Cliff, slightly off-topic though certainly related to cloud cover: since Comet PANSTARRS is on its way here soon, could you please keep an eye on the best places for us to get a clear sky when the comet becomes visible? I'm hoping for a miraculous sunset clearing every night, but here in Seattle in March, that cannot be counted upon. :) Thanks!

Dan McShane said...

Good pick up on the smoothing of drought conditions caused by soil moisture from earlier fall rains. In addition, a significant portion of the eastern dry land wheat farming is an every other year crop to allow moisture levels in the soil to accumulate. Otherwise the yearly precip is not high enough. The easternmost sections of the Palouse are moist enough for every year planting. Hopefully for those farmers the soil moisture retention is still high enough. One advantage of those fine silt soils.