Short Range Forecast Discussion NWS Weather Prediction Center College Park MD 404 PM EDT Tue May 18 2021 Valid 00Z Wed May 19 2021 - 00Z Fri May 21 2021 ...Numerous flash floods are likely to continue across Texas and Louisiana through Thursday under Moderate Risks of excessive rainfall... ...Severe weather is also possible for the south-central U.S. through Wednesday and over northern/central parts of the High Plains Thursday... ...Late-season snow is expected for the Cascades, Northern Rockies, and higher elevations of the Intermountain West... ...Renewed fire danger is likely across the Central Great Basin and Southwest... Abundant moisture from the Gulf of Mexico will continue to flow into the central U.S. just ahead of an upper-level trough and its associated energy, which should set the stage for persistent rain and thunderstorms in the south-central U.S. over the next couple of days. At the surface, a weak frontal system and outflows from previous thunderstorms may help to provide convergent areas that storms could form along. Additional rainfall of 3 to 6 inches is forecast to be widespread across much of eastern Texas and into western Louisiana through Thursday, with locally even higher amounts possible. Flooding is already ongoing across portions of this area, and this heavy rainfall will serve to exacerbate flooding and flash flooding concerns. Moderate Risks of excessive rainfall and Flash Flood Watches are in place. Severe weather is also a possibility through tonight for much of Texas into the Ark-La-Tex region, and tornadoes, high winds, and hail are all possible under a Slight Risk of severe weather from the Storm Prediction Center. Severe storms should mainly focus in South Texas on Wednesday. A deeper upper-level low is expected to gradually move into the Northwest through Thursday, which will spread below average temperatures to the area as well as precipitation as a cold front pushes across. Another round of late-season snow is possible for higher elevations of the West, with over a foot of snow forecast for the Washington Cascades and the Northern Rockies through Thursday. Other high elevation areas in the Northern Great Basin into the Sierra Nevada could receive a few inches of snow. Rain should spread into the Northern Plains and Upper Midwest by Wednesday ahead of the cold front. Additionally, severe thunderstorms are a threat in northern/central portions of the High Plains on Thursday after a renewed dryline develops. However, south of the front and upper-level trough, dry conditions are expected to continue. Fire danger is forecast to increase Wednesday and Thursday for portions of the Central Great Basin into the Southwest, where Critical Risks of fire danger are delineated. The eastern U.S. will see mainly dry conditions under high pressure with only a few showers--though Florida could see scattered showers and thunderstorms with high temperatures a few degrees below normal. Meanwhile, the north-central and northeastern U.S. are expected to warm to above normal by 10 to 20 degrees over the next couple of days, with temperatures in the 80s in most places. The south-central U.S. should be slightly below normal given the rain and cloudiness, while below normal temperatures spread south and east underneath the trough in the West. Freeze Warnings are in effect for Wednesday morning over portions of northern Washington and Idaho. Tate Graphics available at www.wpc.ncep.noaa.gov/basicwx/basicwx_ndfd.php