A storm slated to arrive from the Pacific later this weekend will strengthen as it moves inland and southward in the West spanning Sunday to Tuesday.
Aside from the risk of travel problems and adverse weather, beneficial moisture will reach some needy areas of the West from the storm and a couple of other systems preceding it.
The track and how quickly the storm Sunday to Tuesday strengthens will determine the extent of wind, thunderstorms, rain and snow over the region.
The storm will pull much cooler air over the West from north to south and will lower snow levels spanning later in the weekend into the first part of next week.
A track farther south would translate to a greater amount of shower and thunderstorm activity from Southern California to the deserts of Arizona and New Mexico.
At this point, the most likely scenario is for limited rainfall in these areas with a storm track north of Southern California and the deserts. However, a potential for strong wind gusts still exists as well as areas of blowing dust in the I-10 corridor.
Farther north over part of the I-40 corridor, the chance of a burst or two of snow increases, along with the potential for a thunderstorm with hail and strong wind gusts.
Farther north still, the potential for showers, thunderstorms and higher elevation snow increases over the I-15, I-70 and I-80 corridors. Heavy snow could fall on the Cascades of Oregon to northern California as well as the northern Sierra Nevada. The storm could bring accumulating snow to the Denver area next week.
The details of all of these points will unfold over the next couple of days as the parent storm nears the Washington coast.
In the meantime, a couple of storm systems will impact part of the West ahead of the main storm for Sunday through Tuesday.
These systems will take the edge off the warmth that has built over the region in recent weeks.
Clouds and rain were already cooling areas from central California to Washington, Oregon and Idaho during Thursday from the first of the two preliminary storm systems.
The second system will bring another dose of rain and cool conditions, albeit a bit farther north later Friday into Saturday.
Snow during both of the systems prior to Sunday will be restricted to very high elevations, generally above pass levels in the Northwest. However, rain along the coast of Washington and Oregon during both systems can be heavy enough to cause urban and flash flooding, as well as mudslides.