Short Range Forecast Discussion NWS Weather Prediction Center College Park MD 236 AM EST Tue Dec 04 2018 Valid 12Z Tue Dec 04 2018 - 12Z Thu Dec 06 2018 ...Below normal temperatures expected for much of the nation... ...Rain and mountain snows return to California Tuesday and Wednesday... The short range period begins in a relatively quiet weather pattern across much of the lower 48 as sprawling surface high pressure dominates resulting in below average temperatures from nearly coast to coast. The greatest departures from normal on Tuesday will be from the Great Basin to the Midwest/Appalachians where afternoon highs of 10 to 20 degrees below early December normals are expected. This shifts into the Eastern states by Wednesday, with the Southwest and Central U.S. seeing a warm-up to near or slightly above average temperatures. The best signal for active weather during the short range will be across parts of California ahead of an approaching upper level system. Rain and mountain snow chances steadily increase Tuesday afternoon and evening in northern California, dropping southward by Wednesday with precipitation expected to pick up in coverage and intensity across southern California. Moderate to locally heavy rainfall is possible, with flash flooding and debris flows a marginal threat particularly over recent burn scar areas. Light accumulating snows are also expected across the higher terrain of the Sierra Nevada mountain range. Elsewhere across the country, showers along a cold front sinking slowly through Florida will end by Tuesday, and light snow showers will be possible Wednesday from the northern Plains to the Upper Great Lakes associated with a weak cold front. Santorelli Graphics available at www.wpc.ncep.noaa.gov/basicwx/basicwx_ndfd.php