Meteorologists know that "teleconnections" -- what is occurring in one part of the atmosphere that can affect other parts of the atmosphere -- are an important element of long-range forecasting. One of the most important teleconnections for significant moisture in the central U.S. is the development of a high pressure system in the upper atmosphere in the Pacific around 130°W. Today's European model shows just that (arrow) in ten days. Once the high forms, storms are guided into the West then Central parts of the U.S.
The United States' NWS Global Forecast System (GFS) which forecasts farther into the future than the European, shows exactly that occurring.
Storm 1's forecast location on December 10.
Storm 2's forecast location on December 12.
Storm 3's forecast location on December 16.
So, how much rain (and snow) might result? Here are the forecast totals for storms 1 and 2 in the central U.S. (the quantitative precipitation forecast doesn't go far enough to capture the moisture from storm 3)
|click to enlarge, from NWS GFS model|
Keep your fingers crossed.
Update, at 5:30pm Saturday. My commenters below express skepticism and the same is true on Facebook. Let me give you a little secret from an experienced central U.S. forecaster. As I said on Facebook yesterday, the long range models, until we get about 72-84 hours from the actual start of the event, start the precipitation too far east. Over time, the models start moving the precipitation west. That happened on the latest version (18Z Saturday) of the U.S. GFS model.
Look how the heavier precipitation starts farther west (arrow) than on the identical graphic above which is from the 12Z Thursday run. This is exactly the behavior of the models I would expect based on years of central U.S. forecasting. I'm still feeling good about moisture in the central U.S. the middle third of December.