Mountain rain will take a piece of the snowpack this weekend

SPOKANE, Wash. — A washout weekend of weather won’t just impact the valleys with melting snow and potential flooding. It will get warm enough that the mountains will experience issues of their own.

When atmospheric river systems like this one move in, they bring tropical levels of moisture — and tropical warmth. As temperatures warm this weekend, the snow level will rise, pushing most elevations in the Inland Northwest into the rain zone. The rain-snow line this weekend is expected to be between 6,000 and 8,000 feet. That means rain will fall at all but the highest mountain peaks, including local ski areas. All of the local ski hills will experience rain on Sunday. It’s likely to be a slushy, disgusting washout of a day on the slopes.

With the rain comes another threat: avalanches. Rain weakens snowpack layers from previous storms, creating heavy, water-laden snow sitting atop drier snow lower down. This creates a lot of stress in the snowpack and a higher potential for avalanche. This not only increases the danger for backcountry skiers and riders but could also lead to travel delays on mountain passes early next week if avalanche control is required.

All of this high-elevation snow melting quickly is a key reason for the rising flood threat this weekend. Many smaller rivers and creeks will be completely full by the end of the weekend. Use extra care around the rushing water. KXLY.com will keep you updated on flooding over the next few days.

There are longer-term implications for this abrupt weather change too. Inland Northwest snowpack is only just recovering after a dry January. With warm temperatures following the rain, much of the recently gained snowpack may melt quickly, especially in the middle and lower mountainsides. The start of the spring melt is only weeks away and this warmer pattern will last at least 7 to 10 days. That doesn’t leave much time for snowpack to leap up to normal before April.