Short Range Forecast Discussion NWS Weather Prediction Center College Park MD 411 PM EDT Wed May 19 2021 Valid 00Z Thu May 20 2021 - 00Z Sat May 22 2021 ...Ongoing flooding in parts of eastern Texas and Louisiana will be exacerbated by additional rainfall over the next couple of days... ...Cold temperatures and snow are expected in parts of the West, with heavy snow in the Northern Rockies... ...Severe weather is possible in the Northern/Central High Plains on Thursday... ...Critical Risks of fire weather are in place for the Southwest/Central Great Basin through Friday... Ample moisture from the Gulf of Mexico will continue to flow into the central U.S. over the next few days, and upper-level energy should help trigger even more scattered showers and thunderstorms for the region. Additional rainfall amounts of 2 to 4 inches are forecast for portions of southeastern Texas and Louisiana, with some potential for locally higher amounts. Due to heavy rain over the past few days in portions of the area, the additional rain will serve to exacerbate ongoing flooding and could lead to numerous instances of flash flooding. Moderate Risks of excessive rainfall as well as Flash Flood Watches are in place through late Thursday along the western/central Gulf Coast. A deep upper-level low is forecast to drop southward across the western U.S. tonight through Friday, leading to several hazardous weather concerns. First, temperatures are expected to be considerably below normal over the Northwest, spreading to the Great Basin on Thursday and toward parts of the Desert Southwest on Friday. These cold temperatures will lead to dropping snow levels across the West. Snow totals could be greater than 2 feet in higher elevations of the Northern Rockies in Montana through late Friday, and a Winter Storm Warning is in place there as persistent snow occurs. Lesser amounts of late-season snow are expected for portions of the Intermountain West and Cascades/Sierra Nevada, and some areas are under Winter Weather Advisories. The upper low and the associated slow-moving front as well as a tightening dryline could also cause severe thunderstorms across northern and central portions of the High Plains on Thursday, and there is a Slight Risk of severe weather in place for wind and hail threats. Rain and thunderstorms are also likely for the north-central U.S. near a frontal system, with some possible severe weather, and some rain totals could be over an inch. Meanwhile, persistent dry weather and gusty winds should combine to produce fire danger across much of the Central Great Basin and Southwest through at least Friday, and Elevated to Critical Risks of fire weather are delineated for those areas. Surface high pressure over the eastern U.S. will lead to generally dry conditions, though southern Florida could see a few showers, and so could portions of the Northeast on Thursday and Friday along a meandering front. Warmer than normal conditions are forecast to continue for the Great Lakes/Ohio Valley and Northeast/Mid-Atlantic over the next several days, though the south-central U.S. and Florida should stay slightly cooler than average. Tate Graphics available at www.wpc.ncep.noaa.gov/basicwx/basicwx_ndfd.php