The upcoming holiday weekend will be stocking-stuffed with unsettledweather from the Southwest and the Rockies to the Heartland and GreatLakes. The culprits responsible are two upper level disturbances; one inthe Pacific Northwest and a closed upper low tracking into southernArizona this evening. The disturbance over the Northwest will bring aboutperiods of mountain snow and valley rain from the Washington/Oregon coastto the northern Rockies and northern Great Basin tonight. The more potentof the two features is the closed low approaching southern Arizona as itfunnels rich subtropical moisture into the Desert Southwest. The WeatherPrediction Center has a Slight Risk for Excessive Rainfall in place fromfar Southern California and the Lower Colorado River Valley to southeastArizona. A little farther north, heavy snow is expected in the higherterrain of the Southern Rockies where over a foot of snow is possibletonight and into Saturday. In the Great Lakes, a weak wave of low pressuretracking along a stalled frontal boundary will generate showers from theMiddle Mississippi Valley to the Lower Great Lakes this evening andovernight.