Short Range Forecast Discussion NWS Weather Prediction Center College Park MD 400 AM EDT Mon Mar 20 2023 Valid 12Z Mon Mar 20 2023 - 12Z Wed Mar 22 2023 ...Widespread below freezing and near record low temperatures this morning across the South will begin to moderate on Tuesday... ...Widespread rain/snow moving across the western U.S. today will be followed by a stronger storm to be moving onshore across California on Tuesday with high winds, heavy rain, and heavy mountain snow... ...Snow is expected to spread east across the northern Plains Tuesday to Wednesday morning while more widespread rain/heavy mountain snow overspreads the Great basin to the Four Corners... Increasingly active weather is forecast to impact the western and northern U.S. over the next couple of days as the eastern and southern U.S. recover from chilly to near record cold temperatures. An expansive cold high pressure system spanning from the south-central U.S. to the East Coast will deliver the coldest temperatures early this morning with freezing temperatures expected to reach as far south as the central Gulf Coast. These temperatures which equate to around 20 to 30 degrees below average would challenge and/or break some daily low temperature records. Freeze Warnings have been issued and spread from eastern Texas to the Carolinas, including much of the Tennessee Valley and Deep South. Temperatures below the freezing mark could kill sensitive vegetation, as well as damage unprotected outdoor plumbing. As the high pressure system gradually slides eastward on Tuesday, slightly warmer temperatures will surge northward throughout the southern Plains and lower Mississippi Valley, but one more cold morning can be expected across the Southeast to much of the eastern U.S on Tuesday before mild air from the central U.S. arrives on Wednesday. Meanwhile, back-to-back storm systems will make for increasingly active weather to impact the western U.S. through the next couple of days. Moisture from the first system has already brought widespread rain/snow from the Pacific Northwest through the Intermountain West. The rain and snow will continue spreading east across the Rockies today before moving out into the northern High Plains tonight. A low pressure system is forecast to form along a polar front and track east across the northern Plains on Tuesday. A swath of generally 3 to 6 inches of snow is anticipated from the Dakotas to northern Minnesota just north of the track of the low pressure center, which is forecast to reach northern Minnesota by Wednesday morning. The next storm system from the Pacific is set to aim toward California on Tuesday with more potent impacts from hazardous weather mainly focusing on the southern half of the Golden State. High Winds from the central California coast to southern California could lead to tree damage and power outages as gusts reach up to 80 mph. Heavy rain is also forecast to swing inland on Tuesday and could lead to scattered instances of flooding and rapid runoff, mainly for southern California, but also potentially spreading up the central coastline and San Joaquin Valley. Into Tuesday night, an axis of locally heavy rain is also possible over central Arizona. Soils remain overly saturated for these regions and could exacerbate any flood threat. For the central/southern Sierra Nevada and Southern California mountain ranges, another round of heavy snow is on the way and could add up to several feet for some the highest terrain. By Tuesday night into Wednesday morning, widespread low-elevation rains and heavy mountain snow is forecast to expand into the Great Basin followed by the Four Corners region including Arizona as the storm center slams onshore into southern California. Kong/Snell Graphics available at https://www.wpc.ncep.noaa.gov/basicwx/basicwx_ndfd.php