Short Range Forecast Discussion NWS Weather Prediction Center College Park MD 352 PM EDT Tue Mar 16 2021 Valid 00Z Wed Mar 17 2021 - 00Z Fri Mar 19 2021 ...Widespread thunderstorms causing dangerous severe weather and flash flooding are forecast for central/southern portions of the Plains into the Tennessee/Ohio Valleys and Deep South through Thursday... ...Another round of snow expected for the central/southern parts of the Rockies and High Plains through tomorrow morning... ...Critical fire weather threat continues through tomorrow in the Southern Plains... As the low pressure system that has caused the wintry weather across the Rockies and central U.S. over the past few days continues to weaken, another energetic upper-level trough is forecast to cause another surface low to strengthen and spread additional active weather to the central and eastern U.S. over the next couple of days. Through tonight, this low pressure system is forecast to track over the Southern Plains with convection spreading ahead of it. Thunderstorms across the south-central U.S. could be severe, and the Storm Prediction Center has a widespread Slight Risk in place with a localized Enhanced Risk for portions of northern Oklahoma and south-central Kansas. Meanwhile, a Moderate Risk of flash flooding is located over the Deep South today, where ongoing heavy rain is likely to continue over a narrow corridor of southern Mississippi and Alabama along and south of a stationary front serving to focus the storms. Additionally, on the backside of the surface low, snow is once again possible for the Rockies and spreading into portions of the Plains, though amounts are forecast to be lower and focus south compared to this past storm. However, 6-12 inches of snow can be expected across the higher elevations of southern Colorado to northern New Mexico through tonight, and accumulating snow of a few inches is also possible for the Oklahoma and Texas Panhandles. A Blizzard Warning is in place for far southeastern Colorado as winds increase as well. As the low pressure system tracks eastward Wednesday, thunderstorms will again be widespread ahead of it across the southeastern quadrant of the country. A Moderate Risk of severe weather is forecast for parts of the Lower Mississippi and Tennessee Valleys and into the Southeast through Wednesday night, with tornadoes, high winds, and large hail all dangerous threats that can be expected. Also, with rainfall totals of 2-4 inches across parts of the Central Plains and Middle Mississippi Valley and into the Tennessee Valley and Southeast, flash flooding is another concern. A large Slight Risk of excessive rainfall is in place for these areas for Wednesday and Wednesday night. Light mixed precipitation or snow is possible along the northern edge of the precipitation shield, and light accumulations are possible for parts of the Middle Mississippi Valley. The low system will continue shifting eastward Thursday, and could cause severe weather across eastern portions of the Ohio Valley toward the Southeast and Carolinas--currently an Enhanced Risk of severe weather is in place. Locally heavy rain is also possible Thursday. In the Southern Plains, low humidities and gusty winds as well as dry ground could lead to fire danger today in the Southern High Plains and over southern Texas/the Rio Grande Valley tomorrow, so Critical Risks are outlooked by the Storm Prediction Center and Red Flag Warnings are in place. Elsewhere, the Pacific Northwest and the northern half of California can expect precipitation chances to increase by Thursday morning as an upper-level low and frontal system move slowly toward the region. Tate Graphics available at www.wpc.ncep.noaa.gov/basicwx/basicwx_ndfd.php