Short Range Forecast Discussion NWS Weather Prediction Center College Park MD 400 PM EDT Mon Aug 21 2017 Valid 00Z Tue Aug 22 2017 - 00Z Thu Aug 24 2017 ...Flash flooding and severe weather possible from portions the Upper/Middle Mississippi Valley to New England through Tuesday morning... ...Flash flooding and severe weather possible from portions of the Central/Southern Plains to the Mid-Atlantic morning... ...Heavy rainfall will continue across the Southern Rockies today... A surface low pressure system moving through the central U.S. will be the focus for showers and thunderstorms over the next few days. The leading area of low pressure will lift through the Upper Midwest/Great Lakes into eastern Canada by midweek while a cold front moves south and east through the central and eastern U.S. Strong to severe thunderstorms will be capable of producing heavy rainfall over portions of the Southern/Central Plains, Mississippi Valley, Mid-Atlantic and Northeast as the system passes through. Areas with heavy rainfall will have an increased risk for flash flooding. The Storm Prediction Center has highlighted parts of the Northern Plains and Upper Mississippi Valley as having a slight risk for severe weather on Tuesday... and from the Ohio Valley to the Northeast on Wednesday. Areas of excessive rainfall have been highlighted by WPC from Nebraska to Wisconsin on Tuesday... and Oklahoma and Arkansas on Wednesday. Parts of the Southern Rockies are getting showers and thunderstorms this afternoon as an upper level disturbance interacts will monsoonal moisture. Rain will be heavy at times and may lead to flash flooding. Scattered to isolated showers will spread across California and the Great Basin region as a slow-moving upper low approaches the West Coast. A slow-moving upper low off the California coast should give way to scattered to isolated shower activity across portions of California and the Central Great Basin early this week. The highest rainfall amounts are forecast for the Sierra Nevada mountain range. Afternoon thunderstorms will develop along the central and eastern Gulf Coast over the next few days. Precipitation amounts are expected to increase as an inverted trough pushes eastward toward the east coast of Florida. Expect much cooler temperatures behind the cold front as it sweeps eastward. Meanwhile, warmer than normal temperatures will occur in the Pacific Northwest and northern Rockies. Campbell Graphics available at www.wpc.ncep.noaa.gov/basicwx/basicwx_ndfd.php