Short Range Forecast Discussion NWS Weather Prediction Center College Park MD 355 AM EDT Sat May 08 2021 Valid 12Z Sat May 08 2021 - 12Z Mon May 10 2021 ...Severe weather and moderate to heavy rainfall potentially causing flash flooding are forecast across portions of the Plains and Mississippi and Ohio Valleys.... ...Some late-season snowfall is expected across the Northern Rockies to Northern High Plains... ...Colder than normal temperatures are likely in the northern U.S., while warm and dry conditions will cause Critical Risks of fire weather in California and New Mexico... A strengthening low pressure and frontal system is expected to move across the Central Plains today and toward the Ohio Valley by Sunday. Widespread rain and thunderstorms are forecast in portions of the central U.S. as abundant moisture flows into this system. Today, severe thunderstorms are likely to focus in the Central Plains, and a Slight Risk of severe weather is in place for tornado, wind, and hail threats. Widespread rainfall amounts of 1 to 2 inches are forecast for parts of the Central Plains into the Middle Mississippi Valley, and isolated to scattered flash floods are possible. Then on Sunday, the associated cold front is expected to shift southward, so storms will focus from the Ark-La-Tex into the Mid-South, and Slight Risks of severe weather and flash flooding are both in place there. Moderate to heavy rain is also expected across the Ohio Valley on Sunday and Sunday night. Farther west, snow is forecast in the Northern Rockies underneath an upper-level low, which could accumulate to around a foot in the highest elevations today through Monday morning. Snow is expected to shift southward into the Central Rockies as well on Sunday night. Additionally, late-season snow is possible in the Northern High Plains particularly on Saturday night, with accumulations of an inch or two possible. In terms of temperatures, broad upper-level troughing will keep temperatures well below normal from across the northern tier states to much of the eastern U.S. today before a warm-up in the Southeast to Carolinas on Sunday. Freeze Warnings and Frost Advisories are in effect this morning for the Upper Great Lakes region and into parts of the Ohio Valley with lows in the 30s. On the other hand, temperatures will be quite warm across the south-central U.S., rising into the 90s today over southern/central portions of the High Plains. The cold front should push the heat southward on Sunday, with temperatures in the 100s for South Texas. Warm and dry conditions in the Southwest/Southern High Plains and also interior northern California have prompted Elevated to Critical Risks of fire weather as well as Red Flag Warnings in those areas. Tate Graphics available at www.wpc.ncep.noaa.gov/basicwx/basicwx_ndfd.php