Temperatures will tumble over much of the western United States from the middle to late part of the week with the lowest temperatures since last spring. The chiller air will also be accompanied by some snow over the higher elevations of the region, AccuWeather meteorologists say. The extended period of heat, which has featured temperatures of 4-8 degrees above the historical average in some areas of the interior West, including double-digit anomalies in recent weeks, is coming to an end. Since A