Early January Snowpack Update and Summer Streamflow Predictions

Early January Snowpack Update and Summer Streamflow Predictions

It’s not too early to start preparing for likely summer streamflow and fishing conditions. Things can still change quite a lot, but we’re far enough into the winter to start seeing some patterns emerge. When the current conditions are coupled with the official NOAA weather outlooks for the next few months, we start getting a reasonable idea of what kind of water levels we’ll be looking it.

Likely Snowpack and Effects on Summer Water Conditions and Fishing

In short, anglers visiting Yellowstone Park and southwest Montana should begin planning for:

  1. A mild and probably early spring melt, which ends early (mid-late June rather than early July).
  2. Excellent water conditions from sometime in the last few days of June into early August, with low water and tough conditions for a month thereafter.
  3. Clearer and warmer water than normal, making for spooky fish and a need to fish earlier in the day and be done by midafternoon, especially in hot spells.
  4. Restrictions or at least bad fishing on some low-elevation and geothermal rivers due to low flows and high water temps.
  5. Everything in the first three and a half months of the June-October high season happening “early.”

We will go into more details on likely water conditions and what they mean for specific fisheries in later updates. For now, here are some graphics to illustrate things.

Current Snowpack

Early January Snowpack
Early January snowpack, with our operations area circled in red.

Current snowpack in our operations area ranges from 63% of normal in the Madison and Gallatin River headwaters in Yellowstone Park (including the Gibbon and Firehole) to 104% of normal in the Gallatin basin north of the park. Our primary operations areas are the Yellowstone basins inside and north of the park, the areas labeled at 88% and 93% of normal.

Except for the Madison-Gallatin Basin, these numbers aren’t bad. They don’t tell the whole story, though. The snowpack numbers have been trending downward since the beginning of December in all basins, with pretty consistent warmer than normal temperatures and high pressure. The warm temperatures really tell the story. We have had zero days of below zero temperatures in Livingston this winter, and very few in the single digits. Most days have seen highs in the 30s-40s. Gardiner has been a little cooler, but not much. This is WAY above normal, and makes for a wet snowpack that will be eager to melt when the time comes in April-June.

Future Outlooks

The general NOAA outlooks for January-March don’t show much or any improvement. Here’s the precip and temperature outlook for the next three months, indicating a high likelihood of above-normal temps and an equal chance of above normal, below normal, and normal precip through the core of the winter, though we’re closer to the area forecast to be below normal:

January through March NOAA temperatue outlooks
January through March NOAA temperatue outlooks.

 

Comparison to Previous Years

Based on current conditions and the outlooks above, I expect low to very low water levels this summer and early fall. Late fall, meaning after September 15, conditions will as always depend more on day-to-day weather, particularly fall rain and snow.

For visitors who come year-in and year-out, comparable years will be 2001-2007, 2012-2013, and 2015-2016. We hope more for 2002-2005, 2012, or 2016 results, as these were less onerous in the end than the other years (except for the Yellowstone whitefish mortality in 2016).

For visitors coming to the region for the first time, low water basically means the following:

  1. The Good: Earlier start to the summer fishing season (mid-late June rather than early July), better float fishing during the Salmonfly hatch, easier wading, more-visible trout during the summer, probably better or at least easier fishing on the Yellowstone in July than most years, better multispecies fishing on the upper Missouri
  2. The Neutral: Greater need for small flies and lighter tippets from late July onward, spookier fish offering a better challenge to experienced anglers
  3. The Bad: Low and warm water conditions in late July and most of August, meaning early start and end times might be necessary, possible stream closures especially on low-elevation rivers (Jefferson, Lower Gallatin, Lower Madison, Yellowstone east of Big Timber especially) and on geothermal rivers (Firehole, Gibbon, Madison in YNP), tougher fishing in Yellowstone Park for beginners after early August, worse private and other lake fishing, worse fishing on the flatter and shallower sections of the Yellowstone during August and early September, shorter fishing seasons on the Boulder, Stillwater, Jefferson, and Lower Madison.
  4. The Ugly: Greater likelihood of late summer forest fires, possible fish mortality due to increased disease (Yellowstone River) and thermal shock (Firehole and Madison Rivers in YNP).

Conclusion

It’s still early yet, and ALL of the above can change radically with just a few good storm cycles. The week 3-4 outlook for western Montana and NW Wyoming released Jan 4 is actually calling for good moisture just north and east of our area in late January, and a few big storms could bump us right back to normal except in the Madison-Gallatin drainage in the western part of the park. That said, the weather-guessers have been calling for a warm-dry winter (related to El Nino) since the summer, and except for a cold and wet autumn they’ve basically been right on the money so far. As such, if you are planning your trips now, I would take the above into consideration.

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