Short Range Forecast Discussion NWS Weather Prediction Center College Park MD 256 PM EDT Tue Sep 16 2025 Valid 00Z Wed Sep 17 2025 - 00Z Fri Sep 19 2025 ...Slow moving coastal low to bring heavy rain potential along the Mid-Atlantic coast... ...Heavy rain and possible severe thunderstorms across the Plains Tuesday and Wednesday... ...Tropical moisture from Mario begin to push into Southern California... ...Below average temperatures likely where wet weather occurs next two days, otherwise above average temperatures expected across much of the CONUS... A well defined low pressure system sitting off the Mid-Atlantic coast continue to bring showers, gusty winds, and chances for thunderstorms along the eastern portion of North Carolina, Virginia, and southeastern parts of Maryland. With rain rates expected to reach 1-2"/hr and chances for occasional heavy downpours, there is a Slight Risk (level 2/4) for Excessive Rainfall and an increase chance for flash flooding for northeastern North Carolina and parts of Virgina. The system will continue to slowly move northwestern, but will continue to weaken as the low moves inland. An upper-level low will bring some unsettled weather across the Central Plains, as the trough will continue to form across the central CONUS. With the combination of sufficient instability, moisture, and lift, Storm Predicition Center has placed a Slight Risk (level 2/5) for severe thunderstorms across the Central Plains and Eastern Colorodo/Wyoming. Along with heavy showers and thunderstorms, other hazards supported by this system will be possible hail, strong wind gust, and risk for low-probability tornados through Wednesday. Tropical moisture associated with Mario, currently moving northwestward off the west coast of the Baja, will begin to possibly impact Southern California Tuesday night through Wednesday, before pushing farther north into Central California mid to late week. While Mario is forecast to weaken as it moves northwestward, this tropical moisture may bring scattered showers into far southern coastal California and the offshore islands Wednesday, with these showers pushing farther north into much of Southern California on Thursday. Overall, any rainfall amount across the Southwest and central Rockies will be beneficial, as these areas have been notably dry. Climate Prediction Center has highlighted that most of the Western U.S. has been drier than normal over the past month. Temperatures across much of CONUS for the next few days will be above normal, with the upper and middle Mississippi Valley seeing 10-15 degrees above normal. The exception will over the Plains, where below normal temperatures will develop due to the upper-level low building over the Central Plains. Oudit/Kong Graphics available at https://www.wpc.ncep.noaa.gov/basicwx/basicwx_ndfd.php