Posted: Aug 30, 2013 8:56 AM by Meteorologist Matt Elwell
Updated: Aug 30, 2013 9:07 AM
Once again we are looking at a dry year so far in southwest Montana. Looking at the numbers so far this year, most of the area is over 2 inches below average. Bozeman's numbers would typically be at 10.43" with the official reading at 8.30". That puts Bozeman 2.13" below average year to date. Butte is a little drier. With the average rainfall, Butte averages 9.79" with the actual number coming in at 7.20" for the year. That puts Butte 2.59" below average for the year.
The extended forecast for the next three months is interesting to say the least. The trend is for temperatures to be warmer than average for much of Montana through December. With the trend continuing to be warm, that does bring some concerns for snowpack for the beginning of the winter season.
The silver lining is the precipitation forecast during that same timeframe. The trend is for southwest Montana to pick up more rain than average precipitation. This is a good trend for Montana as a whole, and as we head toward the winter months, the only question will be how the snowpack will be affected.
The logical conclusion is that the snowpack will be less than average because of the warmer temperatures, but the devil is in the details on this. From a meteorological standpoint, it really depends on the timing of the rain/snow. The shorter-term prospect is for the temperature to be near average until December. If that holds true, then we should pick up normal or even above average snowpack for the early season with most of the moisture coming in October and November.
When temperatures begin to slide above average in December is the concern. Will temperatures in the high country be cold enough to hold the snowpack in place? I think the answer is yes... mostly. It is hard to draw a concise conclusion on a long-term forecast. It certainly doesn't help for December to be above average for temperatures, but our average highs are generally cold enough in this part of Montana to hold higher elevations at a good temperature to hold most of the snow in place.
So, what does all of this mean? The short answer is that the models are showing that we should pick up plenty of moisture early in the season with near-average temperatures. December temperatures will be warmer than average which could, and probably will, affect snowfall and snowpack at least to some degree.