Short Range Forecast Discussion NWS Weather Prediction Center College Park MD 457 AM EDT Sun May 17 2020 Valid 12Z Sun May 17 2020 - 12Z Tue May 19 2020 ...There is a slight risk of severe thunderstorms over parts of the Western Ohio Valley... ...There is a slight risk of excessive rainfall over parts of the Great Lakes/Ohio Valley and over parts of the Lower Mississippi and Tennessee Valleys... ...Tropical Storm Arthur has formed and is forecast to move northeastward way from the U. S. Coast... ...Critical fire weather conditions are likely for parts of the Great Basin and Southwest... Low pressure over the Middle Mississippi Valley will slowly move eastward across the Great Lakes/Ohio Valley and stall over the Ohio Valley Monday into Tuesday morning. The system will produce rain and thunderstorms over the Ohio Valley and parts of the Great Lakes on Sunday. The SPC has issued a Slight Risk of severe thunderstorms over parts of the Western Ohio Valley with the main threat will be tornadoes and damaging thunderstorm wind through Sunday and into Sunday night. In addition, the WPC has issued a slight risk of excessive rainfall over parts of the Great Lakes/Ohio Valley and over parts of the Lower Mississippi and Tennessee Valleys. The associated heavy rain will aid in producing mainly localized areas of scattered flash flooding over those regions. On Monday the heavy rain will be over the parts of Great Lakes, Ohio Valley, Tennessee Valley, and Southern Appalachians. The National Hurricane Center has determined that the low pressure system east of Florida is now Tropical Storm Arthur and is forecast to move northeastward way from the U. S. Coast. The eastern end of the aforementioned system will be a front over the Mid-Atlantic and as Arthur moves northeastward and associated region of tropical moisture will move into the front aiding in the development of showers and thunderstorms with associated heavy rain over the Mid-Atlantic on Monday into Tuesday. Furthermore, Arthur will produce heavy rain, tropical-storm-force winds, dangerous surf, and rip currents along the North Carolina Coast on Monday. Please see the National Hurricane Center for more information on this system. A deep upper-level low is expected to approach the West Coast pushing a front eastward across the Pacific Northwest and into the Great Basin and California. This will cause increasing precipitation chances for those areas. Through Monday evening, rainfall of 1 to 3 inches is forecast for portions of Northern California and Western Oregon. Most precipitation should fall as rain, but higher elevations of the Sierra Nevada could receive a few inches of snow. In between the upper-level low in the West and the system in the eastern half of the country, upper-level ridging is expected across the Great Basin into the Rockies and Plains. This will lead to temperatures that are above average by 10 to 20 degrees in those areas underneath the ridge. The dry, hot conditions could also cause fire danger, and the Storm Prediction Center has Elevated to Critical Risks for fire weather in place on Sunday and Monday for portions of the Southwest, Central Great Basin, and Four Corners. Ziegenfelder Graphics available at www.wpc.ncep.noaa.gov/basicwx/basicwx_ndfd.php