Mountain Weather Forecast

Time and Day: 0720 Friday

The Snapshot: Get ready for a busy weekend! Continued cold temperatures with snow beginning this afternoon. A break in the action Saturday mid-day with more snow Saturday night.

The Science

Current Observations:  No measureable snow overnight, temperatures remain cold with the base area at 7 degrees and the upper mountain at 10. Winds are light from the W/SW. The barometer is basically steady.

The Forecast: A low pressure system in NW flow will drop into our area this afternoon and bring light to moderate snow with increasing winds. Winds will be westerly and moderate to strong which is favorable for a convergence zone to setup. The general pattern remains the same with high pressure in the Pacific, allowing cold north/northwest upper level flow to impact the PNW. There is a break between systems during the day Saturday with another, stronger, system moving into our region overnight Saturday. This second system has a more pronounced front and more moisture behind it, along with westerly winds and possible convergence. This will bring a snowy and stormy day on Sunday.

Snow nerd stuff: Actual snowfall totals are difficult to predict at cold temperatures. This is because of the properties of water vapor and how temperature affects it. A parcel of warm air can hold more water vapor than the same parcel of relatively colder air. At warmer temperatures, the snow is made up of a greater percentage of water (“denser”), and at lower temperatures there will be a higher quantity of snow produced from the same amount of water. It is because of this that from an avalanche forecasting perspective, we are often more concerned with the amount of water that fell from the sky than the amount of snow.

The Long Range: When it’s on, it’s on. There’s a reason we have glaciers. After a relative break on Monday, another system affects the region Monday night and Tuesday. Storms continue at winter temperatures during next week. Details will emerge as time allows.

24hr values daily 4am to 4am.

Precipitation: Friday’s   24hr water:  .75   snow: 8-12” Saturday’s   24hr water:  .75   snow: 8-12” Trend and Timing: Snow starting after 12pm Friday, becoming moderate overnight ending Saturday morning. Beginning again Saturday night.

Temperature: Low: 7    High: 22 Snow level: 0-500’ Trend and Timing:     Daytime warming, with a warmer airmass between 4pm and 7pm, then cooling down.

Winds Base: W10-15 Ridge Top: WSW 25-30 with gusts Trend and Timing: Winds will be calm Friday morning, becoming moderate to strong and gusty Friday night.