Short Range Forecast Discussion NWS Weather Prediction Center College Park MD 404 AM EDT Wed Oct 21 2015 Valid 12Z Wed Oct 21 2015 - 12Z Fri Oct 23 2015 ...Flash flooding possible through Thursday for portions of the southern plains... ...Severe thunderstorms possible today across portions of the Southwest and southern plains... An upper-level low will drift eastward across the southwestern U.S. today before becoming absorbed in stronger upper-level flow and lifting northeastward toward the central plains on Thursday. East of the upper-level low, abundant moisture is flowing into the Southwest, the central Rockies, and the southern plains from the eastern Pacific and the Gulf of Mexico. A cold front moving southward across the central Rockies and the central/southern plains, along with a surface trough of low pressure, will provide the necessary lift to support widespread showers and thunderstorms today from portions of the Southwest into portions of the southern and central plains. Heavy rainfall amounts are forecast, with 2 to 5 inches of rain possible through Thursday across portions of the southern plains -- and flash flooding is possible both today and Thursday. Additionally, the Storm Prediction Center is forecasting a risk of severe thunderstorms today across portions of the Southwest and southern plains. At the higher elevations of the Colorado Rockies, sufficient cold air will be in place for precipitation to fall in the form of snow, where 1 to 4 inches of snowfall are expected through Thursday. On Thursday into early Friday, showers and thunderstorms will also expand northward across the northern plains in response to the upper-level low moving northeastward. Meanwhile, a relatively fast-moving low pressure system will move eastward across the Upper Great Lakes and into southeastern Ontario today, reaching Quebec by Thursday morning. Showers and a few thunderstorms are possible in association with this system across the Great Lakes and Northeast today into Thursday. The rain may mix with snow, sleet, or freezing rain tonight into early Thursday morning across portions of northern Maine. Ryan Graphics available at www.wpc.ncep.noaa.gov/basicwx/basicwx_wbg.php