As readers should know from previous posts on the subject, winter and early spring snowfall and how this snow melts from April into June are the most important drivers of summer water conditions in our area. I make reports on the progress of the snowpack through the end of the spring runoff in late June or early July, with the reports getting more detailed as the season progresses and we start to get a firm handle on what to expect.
In general, we like to see snowpack between 100% and 120% of normal, with 105-110% absolutely ideal. With snowpack at this level, waters drop out of the spring runoff at about their normal time (between early June and July 10 depending on the water in question), but flows remain high enough and therefore cool enough through late July and early August for the fish to remain aggressive and happy. With higher snowpack, the fishing once the water clears is great, but we start late and miss much of the prime summer tourist season. In 2011, we weren’t able to begin floating the Yellowstone until July 28, for example. If snowpack is dramatically low, we get an early start and have good fishing until about mid-July, but mid-July through late August can be tough fishing and we may need to start and end early.
As of right now, here’s where we’re at. Our approximate operations area is circled in red. I have also added in the drainage basins for the Upper Yellowstone system in Wyoming and Yellowstone Park (including the Lamar and Gardner Rivers) and the Madison/Gallatin basin in Yellowstone Park, including the Firehole and Gibbon Rivers.
As you can see, things are looking good right now, with drainage basins in our operations area ranging from 98% to 111% of normal. By far the most important basins for our operations are the Upper Yellowstone basins in Montana and Wyoming/YNP. These are edging right into the “sweet spot.” The only basins that we would like to come up are the Jefferson and Madison basins outside YNP. Considering we run less than five guided trips in these basins each year, this isn’t a huge issue for us so far.
The upcoming weather forecast for the remainder of this week looks like we’ll see the heaviest snowstorm of the winter so far from Wednesday (tomorrow) evening through Friday morning. The longer-range outlooks through February look cold and wet, as well. I wouldn’t be surprised if everything is up in the 115% of normal range by the middle of next week. Considering the long range late spring and summer outlooks are calling for warmer-than-normal temperatures, we’ll take it.
I should note that assuming the “average to somewhat high” snowpack numbers we’re seeing so far continue, we should have good to excellent water conditions for this summer, the fourth year in a row things have run average to a bit above. This will be the first time in my career (20 seasons counting 2020) that we’ve had this many years of solid water conditions in a row. We had great fishing and healthy fish last year, with the Yellowstone seeing probably its strongest average size range in at least ten years. Will this trend continue in 2020? I wouldn’t bet against it…