Short Range Forecast Discussion NWS Weather Prediction Center College Park MD 400 PM EDT Sat May 16 2020 Valid 00Z Sun May 17 2020 - 00Z Tue May 19 2020 ...Heavy rain with strong to severe thunderstorms could cause flash flooding for portions of the Mississippi Valley, Ohio Valley, and Great Lakes through Monday... ...A surface low east of Florida will likely develop into a tropical or subtropical system soon... ...Precipitation is likely to increase across the Northwest... ...Critical fire weather conditions are likely for parts of the Great Basin and Southwest... A surface low pressure system is forecast to move slowly eastward across the Middle Mississippi Valley and Great Lakes region over the next couple of days. Rain and thunderstorms are expected in the vicinity of the low, as well as east along the slowly lifting warm front and ahead of the cold front moving eastward across the Mississippi, Tennessee, and Ohio Valleys. Through tonight, a Slight Risk of severe weather is in place for portions of the Lower Mississippi Valley, and through Sunday evening, that area could receive 1 to 2 inches of rain with locally higher amounts. So Slight Risks of excessive rainfall/flash flooding are also in place there tonight and into Sunday. Closer to the low, rainfall amounts of 2 to 3 inches should be widespread from the Midwest to Great Lakes and parts of the Upper Ohio Valley. Slight Risks of flash flooding are outlooked for those areas as well over the next couple days considering those rainfall amounts, and strong to severe thunderstorms cannot be ruled out. Cool temperatures are expected behind this low. The National Hurricane Center has been monitoring a low pressure system currently located east of the Florida peninsula for tropical or subtropical development, and they may initiate advisories on the system as a tropical or subtropical depression later today. The low is forecast to move north and could affect the North Carolina coast with heavy rain, gusty winds, dangerous surf, and rip currents. Please see the National Hurricane Center for updated information on this system. A deep upper-level low is expected to approach the West over the next couple of days, pushing a frontal system 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. Additionally, high temperatures are expected to be 10 to 20 degrees below normal for northern California and parts of Oregon on Sunday, spreading south and east Monday. 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 normal 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. Tate Graphics available at www.wpc.ncep.noaa.gov/basicwx/basicwx_ndfd.php