The Unusual; Yakima Flooding in Mid-February

The Yakima River has experienced very high flows and brought some flooding the past few days, which is somewhat unusual for mid-February.  Yakima flooding is normally a spring-time phenomenon, caused by melting as temperatures surge.

In this event, the Yakima first flooded closer the the Cascade foothills and then the water surge moved downstream.   Right now, the Yakima gauges near Parker and Kona are near flood stage, breaking all time record flows for this period (see the area map, with red dots at these points, as well as the hydrographs (plots of flow with time)).

As you can imagine, the flux of water into the Yakima system was accompanied by a rapid rise of the Yakima reservoirs.   Here is the proof.

So why the unusual event?   Two big things.  First, we had a temperature surge this week associated with warm, moist southwesterly flow.  Yakima hit 67F on Monday, a record for the date, and 60F on Tuesday.  With a healthy snowpack in the mountains, that resulted in a surge of melt.

In addition, there was substantial rain in the mountains, with the Cascades being hit by 200-400% of normal precipitation during the last week (see below).

For the Yakima and this event....the worst is nearly over.  Temperatures will cool modestly the next few days and heaviest precipitation will be over northern CA, where it is acutely needed.  We have enough.

Northwest Weather WorkshopThe big local weather workshop is less than a month away (March 4-5, Seattle).  If you are interested in attending, the agenda and registration information can be found here.  This gathering is the place to be if you want to learn more about local weather research and operations.