The “atmospheric river’ terminology is one that has really captured the imagination of the media, and we are hearing it quite a bit right now as rainfall is inundating southern California. The atmospheric river is simply a strong active jet stream, and when it comes from the sea, there is more moisture available, and “more moisture” isn’t something we think of when talking about southern California. In fact, last month when we were forecasting for San Luis Obispo, I thought the few showers showing up in the area were remarkable enough to call them out ostentatiously. The rain seen now in the LA Basin is several orders of magnitude larger than that, so if this is the atmospheric river, then what we saw in late January was a mere stream. A trickle. For the day, WeatherNation had the forecast victory, being the best temperature forecaster among outlets that left rain in the forecast on the 25th.
Actuals: January 25th, .01 inches of rain, High 66, Low 51
January 26th, High 75, Low 48

Grade: B-C