Short Range Forecast Discussion NWS Weather Prediction Center College Park MD 211 AM EST Tue Nov 21 2017 Valid 12Z Tue Nov 21 2017 - 12Z Thu Nov 23 2017 ...More heavy rain expected for the Northwest and another cold front will sweep through the central and eastern states... The West Coast north of San Francisco will be quite active weatherwise through the middle of the week with persistent onshore flow and deep moisture moving inland. The result of this atmospheric river will be a heavy rainfall event along and west of the Cascades, with the potential for amounts in excess of four inches possible, particularly for western Washington. Moderate to heavy rain can also be expected for parts of the northern Rockies. Given the warm nature of this weather pattern and the resulting high snow levels, very little in the way of snow is expected, except for the highest peaks. Some instances of flooding will also be possible. East of the Rockies, an arctic front will quickly sink southward across the Plains and then reach the East Coast by Wednesday. A brief moderating trend in temperatures is expected across the eastern U.S. ahead of this boundary, making for a pleasant day for many locations on Tuesday. By the time this front reaches the coast, the airmass will have modified and not be as cold as what the Plains and Midwest will experience. Showers and a few thunderstorms will be possible across Florida owing to easterly flow from the Atlantic. Warm and dry conditions will continue for the Desert Southwest with highs near 90 degrees for the lower elevations. D. Hamrick Graphics available at www.wpc.ncep.noaa.gov/basicwx/basicwx_ndfd.php