Spring rain subpar in May


MISSOULA, Mont. - It's one of the wettest months of the year, but May of 2014 ended up drier across the region than March. May is the second wettest month in our state on average, only trailing June. Both months average over 2 inches in cities NOAA maintains daily climate data for.

Below are rainfall statistics for those 5 cities for the month of May: Kalispell: 1.20", 0.78" below normal Missoula: 1.00", 1.01" below normal Butte: 0.82", 1.26" below normal Bozeman: 1.54", 0.91" below normal Dillon: 1.51", 0.44" below normal

Included in these totals are snowfall events during the beginning of the month. Each of these cities had measurable snow during the month of May.

Looking at meteorological spring -- March through May -- a broad area stretching from Butte to Helena to Missoula to the Big Hole and back to Butte again has less than 70 percent of its average spring rain. Many areas are close to having only half.

Temperatures are up too; 1 to 2 degrees above average for many of our valleys during May.

Despite the warmth, the snowpack is so formidable this year that runoff isn't close to being over. Even with half of this year's water stored in the mountains gone, the Bitterroot Basin has twice as much water trapped in snow than average. Other basins around the state have less water remaining, but are still far over 100 percent of normal.

As we go through the month of June, any deep areas of snow remaining in the mountains will be 3 to 4 times more than average.

The lack of rain this month certainly helped keep rivers from going to far past their banks in May, but where rivers and irrigation don't reach a slow withering is already beginning.

Precipitation in May and June is a key factor in keeping vegetation moist for the upcoming wildfire season, when monthly rainfall drops to tenths of an inch.

Forecasts from the NOAA Climate Prediction Center give areas west of the Continental Divide a better than equal chance for seeing above average temperatures during June. Much of Montana also has a better chance for above-average rainfall this month as well.

June precipitation, and where the most rain falls, will be the thing to watch in the Montana weather world. To examine maps of climate data, visit the website for the Western Regional Climate Center. To see how much water is trapped in our snowpack, click here.