Weather Musings for 2022

By Chris Smallcomb, NWS Reno Meteorologist and DPMR Member

Winter 2021-22 Has Been One of Big Peaks and Valleys…

…much like many of our favorite races. Ha ha. Hey everyone! So, as I write this, watching Peavine melt off snow steadily on the southern aspects already, our winter seems to have gone into hibernation. Is this our fate for the rest of winter? What does this mean for our running season?

Well, after one of the hottest and smokiest summers on record, winter showed up bigtime in late October with one of the most intense atmospheric rivers I have seen in nearly 15 years at NWS Reno. It actually set records for the amount of moisture and wind energy, how AR’s are measured, for so early in the winter storm season. The Reno airport received nearly 3 inches of rain as the rain shadow was non-existent, which amounts to 40% of the average annual precipitation total in just one storm! There was enough rain that some of it found a way through my chimney and into the house. Our long-standing station at Boca Reservoir near Truckee received 5.4” of rainfall, the 8th highest two-day total dating back to 1906, and the highest two-day amount in any October, November, or December. Lake Tahoe rose nearly half a foot, only the 8th time in 121 years that’s happened in October. Again, a massive storm any time of year, but especially so early in the storm season!

So we were off to a grand start. The soils moistened up, the smoke was truly gone, and everything seemed to have more life about it. Regardless of how the rest of winter pans out, this one wet storm set the stage for much more efficient snowmelt runoff this coming spring and summer – more water into our streams, lakes, and running flasks, and less into a parched ground. I remember running the TRT in early June last year, and running out of water as everything was so dry – that shouldn’t be the case this year.

After a dry and mild November, which isn’t terribly unusual even in big winters like 2016-17, December roared back to life with multiple large winter storms. These storms were colder than the October ones so our snowpack and friends in the ski community benefited tremendously. Probably the most striking statistic, of many, is that the Central Sierra Snow Lab near Donner Pass saw it’s 3rd snowiest month of any month dating back to 1980. That’s only behind monster months of January 2017 and February 2019! Snowpack in the Truckee and Tahoe areas went from 50% of normal ahead of the December storms to 200-300% of normal in just a few weeks. This of course resulted in avalanche concerns and prolonged closures on our roadways. So at that point around New Years I think many of us were looking for a break, but perhaps not this long of a break.

While it’s not unusual to see multi-week breaks in storms mid-winter, January 2022 has been rather prolonged with not even low-end storms to mix things up a bit. As of this writing, our dry streak at Reno is 30 days. While that sounds like a lot, the record mid-winter dry spell is 56 days during the 2011-12 winter. At this rate, Reno could feasibly not see a single raindrop or snow flake all month, something never seen for January dating back to 1893. Tahoe City will likely be in the top-5 driest Januaries at this rate. To contrast the measly 0.17” of precipitation at Tahoe City this January, the same month during our massive 2017 winter saw 21.33”, or 125 times more.

So, what’s the outlook? As of this writing, the fight for storms does not go well. Most of our models are projecting a ridge of high pressure off the west coast for the first two weeks of February that will essentially block large, moisture-laden storms from the Sierra. This pattern does tend to favor cooler, drier inland “slider” storms but those do not produce big snows. Looking further out into the 3-4 week time horizon into the 2nd half of February, called the sub-seasonal forecast, honestly I’m not optimistic about big storm potential there either as models favor the current pattern remaining. But atmospheric predictability in this timeframe does go down quite a bit, so that allows for perhaps some hope. Generally we can start to see major storm patterns take shape in our models about 2 weeks out, maybe 3 if we’re lucky, but even then it’s a big picture hand-waving type of outlook.

Into March and April, there is no clear signal and honestly our models tend to struggle at these lead times especially for the Sierra. So really any scenario is on the table at this point as we head spring. We’ve had some March produce significant precipitation in recent years, most recently 2020 just as the pandemic was taking off. The latest sub-seasonal models are indeed hinting at a trend towards wet in early March, so we’ll see how that pans out.

One interesting experiment we can do is use past data to project possible scenarios going forward. The plot below shows the average snow water content (SWE) for the Truckee River basin, from NRCS.

The black line shows the observed SWE for this winter so far. The shading shows percentiles based on past years back to the early and mid 1980’s, and the lime green line is the median SWE trace. What I also did here is plotted three future traces showing what would happen if the remainder of winter behaved like a couple possible extreme scenarios:

• 2019 (purple) – a massive 2nd half of winter – remember that February and the cold prolonged spring snowpack!? I guess at this rate this scenario seems a lot less likely…
• 2020 (yellow) – a big March into early April – which would lead us to near or just above normal median peak snowpack
• 2013 (dark green) – the winter leading into that severe drought where the atmosphere basically shut off after the New Year.

Even in the latter scenario our SWE this year would end up roughly 80% of normal, but you’ll also notice the much earlier than normal melt-off which would have ramifications for fire season onset time and backcountry water availability during the summer.

Overall, based on past years, we have about a 70% chance of hitting at least the normal median peak SWE in the Truckee and Tahoe region – and honestly all it takes is one or two large storms to do the trick. In summary…

Regardless of the long-range weather outlook, a few things we can glean based on the weather we’ve seen so far:

• Flood Risk: At this point our risk of flooding remains elevated. We have an appreciable snowpack and the soils remain quite moist relative to normal. So if we were to have a major atmospheric river that’s on the warmer and rainier end of the spectrum, flooding would be a big concern for us. Typically we look for rain-snow line elevations above 8,000 feet for those flood scenarios along the Truckee River basin. Thankfully right now we’re not seeing that scenario for at least 2+ weeks.

• Fire Season: Assuming we have a “normal” end to winter and into spring, right now the odds favor a lower (though not zero) risk of massive fires in the Sierra, compared to 2020 and 2021, but a busier fire season in the Great Basin including around Reno and Carson City. Typically fires in Nevada are driven by grasses and shrubs which tend to grow well in wet years such as this. The good snowpack and wet ground should help increase vegetation moistures in the Sierra this year, but big wildcards that could counter that include 1) large areas of drought-stressed or dead trees, 2) a warm/dry spring with a very early melt out of snow.

• Running Season: So again, assuming a “normal” balance of winter and into spring, I think we can expect snow along our trails later into the spring and early summer compared to the last couple years, so be prepared for that. That will most definitely depend on spring temperatures and precipitation! I also think we’ll see more readily available water from streams and ponds for adventures in the backcountry, at least into early to mid summer – due to more efficient runoff from snowpack. April through July streamflow forecasts on the Truckee & Carson Rivers are running 90-120% of median right now, which can be a good surrogate for water flows on streams and into ponds. To compare, last year’s anemic values were 20-35% of median flows.
  
  Regarding upcoming races – my gut feeling is that we’ll see higher elevation snow fields for races like Broken Arrow, Western States, and Tahoe 200. Had you asked me this at the end of December – I’d have said “slam dunk yes” to snow on those courses in June – but our super dry January and latest February models has upset that confidence a little. TRTER – not sure on that one depends on how big the rest of winter is. In the super snowy and cold 2019, we saw appreciable snow fields on that course even in mid-July, but I’d say at this rate barring a “Miracle March” odds favor most of the course being dry. 

• Wildflowers: This one is a bit outside my professional lane but I have some speculations here. In the past I’ve seen that wet autumns translate into really good desert wildflower seasons. The famous Death Valley superbloom in early 2016 was the result of a very wet series of fall rain events. Something about the long dormant seeds getting “activated” by the heavy rainfall. So perhaps there’s hope of some great purples and pinks and more for Silver State 50/50.

That’s what I’ve got. Hope you got a few nuggets out of that stream of consciousness. By all means feel free to ping me for weather info ahead of a race or adventure – @nvsunriserunner on Instagram, Chris Smallcomb on Strava, or chris.smallcomb@noaa.gov via email.