Lots of Rain on the Way

The pattern thus far this month has been fairly quiet, dry and mild. In fact, we are nearly a half-inch below normal in terms of precipitation totals since the calendar flipped to December. The reasoning behind the quiet pattern has been a less-active jet stream, which El Niño has influenced. This pattern is going to switch to more of a wetter pattern beginning this weekend. The temperature pattern is going to continue to be above average, however, despite the increase in precipitation expected over the next two weeks or so.

Why is the pattern changing from dry and calm to wet and active? It starts with the jet stream, which is the main dictator in determining the activeness of the weather pattern. The jet stream, as mentioned above, has recently been less-active as the eastern two-thirds of the country has been located within a ridge pattern (which typically results in quiet patterns). That is going to be changing around starting late this week and throughout the weekend. The jet stream will dip as a large disturbance moves in from the Pacific Northwest, creating a significant trough (usually meaning a more active pattern).

This is what the trough looks like on the GFS, a forecasting model we use. Note the yellows and reds. Those colors signify very strong winds--which we call the jet stream--well up into the atmosphere. Also important in this image--which is valid this weekend--is the evident "dip" in that jet stream that makes a "V" shape across the country. That dip is what will give the eastern half of the United States an active weekend and first half of next week. Everything from severe thunderstorms to very heavy rainfall and flooding to heavy snow is expected to accompany this storm system.

Locally, the system is going to deluge us in rainfall beginning Saturday afternoon and lasting through Monday evening. The rain will fall heavily at times during that duration. Also, the rain won't fall constantly. There will be times of drier weather thrown in there as well. How much rain could we see? Well, the latest models are suggesting 2"+ for much of the Stateline by the time all is said and done.