Drought conditions develop in Columbia Basin despite healthy snowfall in the mountains

Recent snowfall in Washington’s mountains has brought the amount of snow up there to near-normal values for this time of year. Some of this snow even caused the record-setting flood event seen Walla Walla and Pendleton earlier this month, but this winter’s storms have not been quite as generous in the Columbia Basin and Yakima Valley.

As the featured image above shows, moderate drought conditions are in place around the Tri-Cities, Yakima, and Wenatchee. Walla Walla and the Blue Mountains were under the same category before the flood event, but that has improved somewhat. That area is still listed as being abnormally dry, which may seem weird given the flood. Keep in mind, though, that droughts can be a very long-term thing. Furthermore, the water that caused the flood came from the Blue Mountains, which are no longer listed as being in any of the drought categories.

In fact, many parts of Washington have had drought conditions removed by recent precipitation. At the beginning of January, most of the Cascades, half of the Olympic Peninsula, and the I-5 corridor south of Tacoma were all listed as being in moderate drought. This week, these locations aren’t even considered to be abnormally dry. This is a big win for our region.

Because our hydrology in the Northwest is dominated by winter snowfall, scientists often look at things in terms of a “water year” rather than using the standard calendar year. Each new water year begins October 1 rather than January 1 so that climate statistics can take into account the entire snowy season rather than splitting it in two. We also do this for lowland locations like the Tri-Cities so everything is kept to the same standard, because while our precipitation isn’t nearly as significant as mountain snow, it does contribute to the system.

In the Tri-Cities, we have only received about half the precipitation we usually do for this time of year. This is almost exactly the same for other cities listed as being under moderate drought conditions. For comparison, Spokane is pretty much at their average for this time of year and Pullman is over 25% above theirs.

This certainly isn’t a worst case scenario, though. The dry conditions are likely to elevate the fire risk in the desert as we ease into our warm season, but the lack of rain through the winter means that there has been less native grass growth. In many respects, an unusually wet winter followed by an unusually warm and dry spring would be worse because there would be more dry fuel. As always, it is important to be cautious and aware of your surroundings so you don’t accidentally start a fire. If your home is adjacent to an undeveloped area, now is a good time to make sure you have a defensible space around your home in case a fire heads your way.

Some farmers in the area may experience negative impacts from this, especially those who aren’t able to rely on irrigation from rivers to water their crops like in the higher portions of the Horse Heaven Hills. Fortunately, favorable snow pack in the mountains should help to dampen the impact felt from this drought for those who are able to rely on area rivers.

Drought conditions are expected to continue in the Columbia Basin for a while. There aren’t any major precipitation events on the horizon for the Tri-Cities and conditions in the Arctic make it seem that winter is more or less over for the Pacific Northwest lowlands. Strong atmospheric river events and other potential rainmakers become less likely as we move into spring. The Climate Prediction Center is forecasting drought conditions to expand in Eastern Washington through May.

That said, if we don’t have a strong early heatwave to decimate our mountain snow, it doesn’t look like that expansion will include the Cascades. Weak systems that don’t bring any precipitation to the Columbia Basin are still capable of bringing modest snow accumulations up in the mountains, so hopefully we will continue to see these over the next few months.

Thank you for reading! As a reminder, voting is open for the Tri-City Herald’s People’s Choice Awards. I would greatly appreciate it if you were to vote for me, Mark Ingalls, in the Best Weathercaster category! You can vote every day through March 20 at this link, so please head there often!

The featured image for this post is the drought map for Washington State from February 20. It comes from the National Drought Mitigation Center in Lincoln, Nebraska.