March 2017 recap
March was wet in the inland NW. Make that record wet (since 1895) for a good portion of eastern Washington through NW Montana. Rain in March might be a blessing to some, but it adds to the climate misery in the NW after enduring a long winter. March has so much potential. Consider that March has nearly the same daylength and potential solar radiation as September. Yet, this potential is rarely met in the month of March due to incessant cloud cover. And March of 2017 was certainly no slouch when it came to cloud cover and rain. March has 31 days, the official COOP station in Moscow reported measurable precipitation on 27 of those days, Spokane reported measurable precipitation for 21 days last month – both records. Alas, March mudness.
The jet stream and storm track in March had it out for the NW and brought a relentless sequence of weather systems through the region without much of a break. The mean jet bisected the NW which will be apparent in the temperature anomalies seen below.
The west-southwest flow that advected a lot of moisture in also brought seasonal to above normal temperatures across most of the interior NW south of the main jet stream. By contrast, much of Washington state was normal to below normal being on the northward side of the mean jet stream.
Water, water, and more water
For the water year to-date it’s getting a bit silly. Nearly the entire NW is in the top tercile, with the most amount of cumulative precipitation since Oct 1 since 1895 for about 16% of the domain. There might be a leaky rain gauge in Morrow County Oregon.
River levels were so high along the Boise river late last month that it brought flood concerns for sockeye salmon. Read that last part again.
For a bit of context on just how much water flowed through regional rivers in March, take a look at the map below which shows the runoff rankings. A majority of the reporting sites in Idaho are coded black for highest on record for the month as a whole.
Another way to look at runoff for the state of Idaho is shown below where the cumulative runoff for the water year to date is shown. The black line shows 2017, way above normal. Plus, we know there is a good amount of snow left in the mountains that will melt and runoff in the coming months.
Speaking of that snowpack, nearly all of the western US is at or well above normal.
Flood to Fire?
Beyond mud and misery, all of this precipitation is a good thing, right? Of course, this depends on who you ask. Talking about the fire season in the northwest while rivers are rivaling records seems silly. The above average snowpack currently likely portends a delay in the commencement of the fire season in regional mountains. A different story may unfold for rangeland/grassland systems across the region however. Large fire seasons in rangeland such as those across the northern Great Basin across southeastern Oregon and southern Idaho tend to be limited by how much grass accumulates and dries out. What determines how much grass accumulates? In these semi-arid systems, moisture is the limiting factor and hence wet conditions like we are having this year are likely to yield a bounty crop of fine fuels that will make for a fun fire season — although that will likely be for the summer of 2018. However, do recall that last year was quite wet across the region and that should prime the lower-elevations for an active fire season this year.