Short Range Forecast Discussion NWS Weather Prediction Center College Park MD 355 AM EDT Sat May 16 2020 Valid 12Z Sat May 16 2020 - 12Z Mon May 18 2020 ...There is a slight risk of excessive rainfall over The Lower Mississippi Valley and parts of the Southern Plains... ...Heavy rain and possible Flash Flooding will move into the Great Lakes on Sunday and into the Lower Great Lakes/Central Appalachians by Monday... ...Surface low near Southern Florida is being monitored for tropical development as it moves away from the coast... A quasi-stationary front over the Southern Plains is connected to a front over the Central Plains eastward to the Mid-Atlantic that will slowly move northward across the Ohio Valley to the Mid-Atlantic as a warm front on Sunday into Monday. Moisture from the Western Gulf of Mexico will stream northward east of the quasi-stationary front over the Southern Plains and overrunning the returning warm front over the Ohio Valley into the Great Lakes. The WPC has issued a slight risk of excessive rainfall over The Lower Mississippi Valley and parts of the Southern Plains. The resulting showers and thunderstorms will produce heavy rain over the region producing mainly localized scattered flash flooding. As the warm front moves northward the area of heavy rain will move northward into the Great Lakes on Sunday and into the Lower Great Lakes/Central Appalachians by Monday. As the associated slow moving cold front moves eastward a general area of rain and showers/thunderstorms will continue from the Gulf Coast to the Great Lakes that will, likewise, move slowly eastward to parts of the Central/Eastern Gulf Coast to the Lower Great Lakes/Northeast by Monday. In the West, an approaching upper-level low and associated front will increase precipitation chances for the Pacific Northwest and Northern California on Saturday and spreading eastward on Sunday. Rain totals could be up to 2 inches in portions of Northern California and far Southwestern Oregon. Mostly rain is expected, with some snow possible in the highest elevations. Elsewhere, a surface low near Southern Florida is being monitored for tropical development as it moves away from the coast. Ziegenfelder Graphics available at www.wpc.ncep.noaa.gov/basicwx/basicwx_ndfd.php