For most of November, the jet stream has been staying up along the Canadian border and a dome of high pressure has brought sunny, warm weather to much of the lower forty-eight. At the same time, this high-riding jet has directed a series of Pacific storms into the northwest, drenching coastal areas and bringing heavy snows to the Cascades. Now these steering winds have buckled, producing a deep trough over the mountain west and allowing cold, Arctic air to spill southward.
While snow is flying out west, Missouri remains east of the trough and warm, moist air is moving up from the Gulf of Mexico. As the leading edge of the cold air nears our State, these gentle showers will likely change to late autumn thunderstorms and, within another day or so, the rain will change to snow. By then, high temperatures are forecast to be in the twenties.
