Rain at the base of Mt Shasta Ski Park | Cover: NOAA

Snow is coming to the upper reaches of Mt Shasta and the 14’er volcano in Northern California should have a fresh coat near its peak by this time next week.

NOAA forecast models indicate that the higher elevations above 12,000′ could see more than 18″ of fresh snow by Friday alone. And with two low pressure systems setting up in the Pacific, more moisture is on the way!


Forecast Discussion:

DISCUSSION… Current observations are showing a line of clouds over northern California and it is lifting to the north. Overall, this is consistent with what is expected over the area. Our near term forecast is a bit tricky since northern California and southern Oregon are located between two low pressure systems. The first is low pressure system which is developing near San Francisco and will move into central California later in the week. This low, however, will bring moisture up from Pacific Ocean from the southwest.

Meanwhile, the second developing system is a trough located off the coast of British Columbia which will move into the Pacific Northwest later today. These two systems will work in tandem to bring some rain to the forecast beginning later this morning.

Overall rainfall amounts are expected to be less than what we saw with the system we saw this past weekend, but any rainfall will be helpful in suppressing fires.

As these systems move inland on Tuesday, their positioning will lead to increased stretching deformation over our area. This will allow for increased lift, and thus another chance for precipitation. Our forecast depicts more widespread precipitation than what the models are showing, but this is reasonable due to the increased lift with the moisture fields expected from the moisture transport today.

Still, any rain that falls will be extremely light in nature. The main focus on the precipitation will shift from our entire area on Tuesday to northern California with an emphasis on Modoc County on Wednesday and Thursday as the low pressure system in California slowly meanders eastward. Precipitation amounts have increased in this forecast package for Modoc County on Wednesday, and could be similar to what fell with the showers this past weekend. The general troughiness of this pattern will keep temperatures at or below normal for the week.

Models are beginning to come into great agreement regarding the timing and strength of the next frontal system poised to reach the area on Friday. This front will provide a better chance for the stratiform rain systems that we are used to in the fall (as opposed to the heavy showers we saw last weekend). This looks like it could bring some moderate rainfall to the area. Preliminary amounts look to be less than what we saw this weekend for many areas of southern Oregon and northern California, but it is still in the extended forecast, so more changes are expected.

Sunday is expected to be a quick transition day where a short period of dry weather is possible before another frontal system approaches. The models depict this system as an inside slider, which may bring some more light rain, but will continue to keep temperatures from warming up. The extended forecast continues the unsettled pattern with another low digging into southern Oregon and northern California beyond next weekend. Although no particular rain event will be large enough to definitively put out our fires, the combined long-period nature of the unsettled weather will likely aid in firefighting efforts.

The one other tricky part of the forecast worth noting is the forecast low temperatures and snow levels. For now, snow will only be expected at the highest peaks; so impacts to travel are not expected. That being said, there may be times where we see periods of clear skies, particularly at night. This could be enough to bring colder temperatures to the area, particularly on the east side. Have lowered temperatures in our traditionally colder spots (Sprague River, Chemult, Crescent etc.). So the forecast may look a little strange with a low of 30 degrees with rain in the forecast. This is because when the clouds are afoot, temperatures will be above freezing. Still, very minimal travel impacts are expected since road temperatures are still pretty warm. Regardless, this part of the forecast is tricky, and changes are expected as the solutions evolve. Therefore, I recommend staying tuned to the forecast. -Schaaf