KMSP - It’s the weather phenomenon that brings California the majority of its precipitation every year, called the atmospheric river. It’s the jet stream, that steering current at the top of the atmosphere that’s the storm track across the globe. Storm systems are moved by this river of air. These “streams” typically separate colder air to the north from warmer air to the south and will meander northward and southward depending on the overall pattern. Well, there are times during the winter where these jet streams can interact with the oceans and pick up a LOT of moisture. These streams then basically become rivers of moisture, a firehose if you will, and anyone in the path of these can expect to get wet… like REALLY wet.
Well, California is in a fairly arid climate with a dry season (summer & fall) and a wet season (winter & spring). The only true difference is that in the wet season, this atmospheric river is nearby and will meander about the state over the course of the season. But by the summertime, this “river” lifts northward putting an end to the wet weather that the state enjoyed until the following winter when the river returns.
This week though, there are TWO rivers returning at the same time. The polar jet stream and the pineapple express (the jet stream originating from the tropics near Hawaii which is how it gets its name) will combine forces and pump in a tremendous amount of moisture over the next few days. Several storms systems are expected with upwards of 6 inches of rain likely in the valley, a foot of rain in the foothills, and anywhere from 15 to 25 FEET of snow in the highest Sierra Nevada Mountains. Basically, the state could get more moisture this week than in the last year combined! Clearly, this will cause some short term issues with mudslides and flooding, but this could be the beginning of the end for the long term 5 year drought in that part of the country.