As we head into the weekend, we can still expect to see some shower activity here and there, but in the large scheme of things, it’s going to be relatively benign through Sunday afternoon. Temperatures will reach near 50 degrees through the weekend, after which another moderate to strong atmospheric river hits the coast late Sunday into Monday. Very heavy rain up to about 7,-8,000’ will once again cause some flooding concerns, especially in the small creeks and drainages, but could also strongly impact the rivers north of Reno (Feather and Susan Rivers, for instance), as well as the lowland areas in the Carson River region. An Areal Flood Watch has been posted for the Reno-Tahoe areas from Monday morning through Tuesday morning.
More on contrails: If you have high humidity aloft, the contrails that form behind commercial air traffic won’t evaporate very quickly, and with all the jets crisscrossing our skies, a spider-web of contrails can pretty quickly cover the skies. High-altitude moisture is also a possible sign that a storm is incoming. So in this respect, contrails can be a sign of future showers.
But it is tough to rely too heavily on those kinds of signs in this neck of the woods. Forecasting by cloud patterns works better in other parts of the country than it does here in the Silver State. Part of the reason for that is our location on the lee side of the mountains. Being located in a rain shadow tends to mess with a lot of “weather rules” that apply elsewhere. But that’s not the only reason.
We have another aspect of our weather that you have to take into account. We are located in the transition zone between two dominant airmasses. The marine airmass which dominates the weather over the Pacific Ocean transitions to a continental airmass once it gets to the Rocky Mountains. We’re in that zone where the change occurs, which changes a lot of “rules” about what works forecast-wise. Sometimes our weather plays by ocean rules, and other times by continental rules, which can get very confusing.
Most of the cloud-forecasting charts you see were developed in the central and eastern part of the country, and tend not to work as well in our neighborhood.