Short Range Forecast Discussion NWS Weather Prediction Center College Park MD 234 PM EST Wed Jan 20 2021 Valid 00Z Thu Jan 21 2021 - 00Z Sat Jan 23 2021 ...Heavy rain and possible flash flooding across portions of the Desert Southwest... ...Heavy rain developing across the Lower Mississippi Valley/Southeast on Thursday... ...Lake effect snow returns on Thursday... A low pressure system off the Baja coast will continue to produce heavy rain over the Desert Southwest tonight. A Slight Risk of Excessive Rainfall leading to Flash Flooding is in effect over this region as a result. This system, and the associated heavy rain threat, is likely to weaken and dissipate tomorrow. Meanwhile a cold front will track across the Plains and Mississippi Valley before arriving in the Southeast tomorrow. This boundary along with another boundary draped across the Gulf states will produce rain over the Deep South on Thursday and Friday. Between 1-3 inches of rain are expected from eastern Texas to Southern Alabama through Friday. A stationary front draped across the Northwest will help generate measurable snow across the mountains of the Northern Rockies, Cascades and Sierra through Friday. Some freezing rain may fall over parts of north-central Oregon and south-central Washington. The associated area of low pressure will strengthen and descend over the Great Basin late on Friday as it continues to spread snow over the Central/Southern Rockies. Elsewhere, heavy lake effect snow is expected downwind of the Great Lakes, on the backside of a deep area of low pressure. Between 8-12 inches of snow are likely to fall downwind of Lake Ontario while 4-6 inches are possible downwind of the other lakes. A tight pressure gradient, due to the deep area of low pressure currently tracking across central Canada, will elevate the risk of fire weather over a portion of the Central Plains tonight. High Wind Advisories and Warnings are in effect for parts of the Dakotas and the Front Range as a result of this tightened gradient. Kebede Graphics available at www.wpc.ncep.noaa.gov/basicwx/basicwx_ndfd.php