Big Hole River Conditions & Drought Management Plan

From Jacqueline Knutson, Montana Fish, Wildlife and Parks Hydrologist. As of 5/15/2019:

Streamflows: Seasonal gages are near average throughout the basin. Some gages are a little above, some are a little below. Forecasted precipitation should bump streamflows up this weekend and through early next week. The uppermost gage at Saginaw Bridge is not reporting due to some maintenance issues that I’m working on with DNRC. Streamflow forecasts for the April 1^st – July 31^st period are below average for the Big Hole River so please keep an eye on forecasts and be ready for potential shortages if summer precipitation is sparse once again.

Snowpack: At this time the Big Hole Basin is at 72% of average. The Jefferson Basin in its entirety is at 82% of average (that’s down another 6% from this weekend). The warm weather of April was not kind to our snowpack. A month ago, we were sitting at 97% and now we’re down to 72% of snowpack. Snowpack has likely peaked, and we will no longer be adding to those totals; this is what we’re down to. We may get some reprieve over the next 10 days, but I do not see this wet pattern adding to our snowpack. The water supply forecast doesn’t look great for the Big Hole this summer and we will certainly be hoping for favorable (wet) weather patterns this year.

Precipitation: Precipitation was above average throughout the state in April. It seems our pattern this winter and spring was to have one incredibly dry month followed by one incredible productive month. April was decently wet, however, warm temperatures pushed precipitation into rain rather than snow accumulation or snow that fell melted quickly. Precip was above average but the state average snowfall was well below average.  

Temperatures: April temperatures were above average, particularly in our corner of southwest Montana. This contributed to the rapid loss of midlevel snowpack over the month and initiated melt in the upper elevations the first week of May.

Forecast: There has not been a change to the El Nino advisory still in effect for this spring and the most recent forecast has the chance for El Nino continuing through the summer at 70% and even now through the fall at 65% which is increased odds since last month. Temperatures are likely to be above average but the weather patterns we’ve been seeing over the past few months have been wet and look to remain that way. With luck and a decent flow of moisture we may be able to get through a hot summer with a continuation of the precipitation we’ve been seeing from time to time this spring.

The three-month outlook currently favors above average precipitation depending on the flow of incoming weather systems through the rest of the spring and above average temperatures we’ve seen over the last month. These outlooks will be updated at the end of the week and I urge folks to take a look at these as we head into summer.