Short Range Forecast Discussion NWS Weather Prediction Center College Park MD 330 AM EDT Mon Sep 21 2015 Valid 12Z Mon Sep 21 2015 - 12Z Wed Sep 23 2015 ...Tropical Depression Sixteen-E to bring the possibility of flash flooding to portions of the Southwest... ...Well above average temperatures expected today across the northern/central plains and Upper Midwest... ...Cool and showery conditions expected for southern portions of the Mid-Atlantic today... Tropical Depression Sixteen-E is forecast to move across Baja California and the Gulf of California today, with the center forecast to reach southern Arizona by this evening. Refer to the latest products issued by the National Hurricane Center for the latest information on Sixteen-E. Abundant tropical moisture will spread into the southwestern U.S. in association with this system, bringing widespread showers and thunderstorms today and tonight across portions of southern California, much of Arizona, as well as portions of western New Mexico. Showers and thunderstorms will persist across these areas for Tuesday, while also spreading a little farther north into the Four Corners region. Heavy rainfall amounts of 1 to 4 inches are forecast to fall across portions of the southwestern U.S. in association with this system, leading to the possibility of flash flooding. By late Tuesday the low-level center of the system will dissipate as it encounters higher terrain, but the moisture will persist, keeping scattered showers and thunderstorms across the Four Corners region into Wednesday. High temperatures today will be well above average across the northern/central plains and the Upper Midwest, with temperatures expected to be 10 to 15 degrees above average. These warm temperatures will occur ahead of an incoming cold front, which will move into the region by later today. Scattered thunderstorms are possible ahead of the front across portions of the Upper Midwest by late this evening. The front will stall across the central plains late Tuesday and will drift slowly north as a warm front on Wednesday, keeping showers and thunderstorms a possibility. An area of surface high pressure crossing northern New England today will cause northeasterly surface flow across the Mid-Atlantic region. This combined with a frontal boundary over the Carolinas and an upper-level disturbance crossing the central Appalachians will result in cool and cloudy conditions with a good chance of showers for southern portions of the Mid-Atlantic region. High temperatures may be 10 to 15 degrees below average in this area. Ryan Graphics available at www.wpc.ncep.noaa.gov/basicwx/basicwx_wbg.php