Short Range Forecast Discussion NWS Weather Prediction Center College Park MD 352 AM EDT Thu May 20 2021 Valid 12Z Thu May 20 2021 - 12Z Sat May 22 2021 ...There is a Moderate Risk of excessive rainfall over the Central/Western Gulf Coast through Friday... ...There is a Slight Risk of severe thunderstorms over parts of the Northern/Central High Plains through Friday morning... ...Late-season snow is expected for the Cascades, Northern Rockies, and higher elevations of the Intermountain West... ...There is a Critical Risk of fire danger across the Great Basin and Southwest... Moisture from the Western Gulf of Mexico will continue to flow across the Plains and Mississippi Valley through Saturday. Upper-level energy over the Plains will trigger showers and thunderstorms over the region through Friday. The WPC has issued a Moderate Risk of excessive rainfall over the Central/Western Gulf Coast through Friday. The showers and thunderstorms will produce heavy rain over the region producing numerous areas of flash flooding. Additionally, the heavy rain may cause many streams and possibly larger rivers to flood. The SPC has issued a Slight Risk of severe thunderstorms over parts of the Northern/Central High Plains through Friday morning. The main threats from the severe thunderstorms are frequent lightning, severe thunderstorm wind gust, hail, and maybe a tornado. On Friday, the excessive rainfall threat will lessen to a Moderate Risk over parts of the Western/Central Gulf Coast through Saturday. Meanwhile, a deep upper-level low over the Pacific Northwest will advance southward to California and the Great Basin. The associated upper-level trough will help produce late-season snow over parts of the Pacific Northwest, Northern Rockies, Great Basin, and the higher elevations of California. The lower elevations will have rain. Winter Storm Warnings are in place over parts of the Northern Rockies, while areas of the Intermountain West and Cascades/Sierra Nevada and some areas are under Winter Weather Advisories. Additionally, persistent dry weather and gusty winds should combine to produce fire danger across parts of the Great Basin and Southwest through Friday, and Elevated to Critical Risks of fire weather are delineated for those areas. Surface high pressure and upper-level ridging over the eastern U.S. will produce generally dry conditions. However, southern Florida could see a few showers, and so could portions of the Northeast on Thursday and Friday along a meandering front. Warmer than average temperatures are forecast to continue for the Great Lakes/Ohio Valley and Northeast/Mid-Atlantic over the next few days. Ziegenfelder Graphics available at www.wpc.ncep.noaa.gov/basicwx/basicwx_ndfd.php