Short Range Forecast Discussion NWS Weather Prediction Center College Park MD 358 AM EDT Mon Aug 08 2016 Valid 12Z Mon Aug 08 2016 - 12Z Wed Aug 10 2016 ...There is a slight risk of severe thunderstorms for portions of Montana and the northern Plains... ...Heavy rain possible over the Gulf Coast and Mid-Atlantic... ...Heavy rain possible over portions of Arizona and New Mexico... A near-stationary boundary will remain draped from the Carolinas, across the Gulf states and into the southern Plains. Tropical moisture will pool along the boundary with a weak upper-level low over Florida that will aid in producing showers and thunderstorms from the Southern Plains to the Southeast. Rainfall intensity will increase during the afternoon and evening hours, which will increase the risk for flash flooding, especially along the central and eastern Gulf of Mexico Coast. An upper-level impulse over the Northern Rockies will move northeastward into Canadian Prairie and merge with a boundary moving southward over Central Canada by tonight. Once they merge the front will extend from the Hudson Bay through the Upper Midwest and westward to Northern Rockies. Scattered showers and thunderstorms will develop along and ahead of this boundary- some will likely become strong to severe. Additionally, bursts of heavy rain will be possible along the International border of Washington, Idaho and Montana increasing the threat of flash flooding. Onshore flow from the Pacific Ocean will help produce rain over parts of the Pacific Northwest through Tuesday. Monsoonal moisture will continue to stream northward into the Desert Southwest. A combination of the ample moisture and daytime heating will generate scattered to widespread convection for the Southern/Central Rockies and the Southwest/Eastern Great Basin. Localized heavy rain is forecast and flash flooding will be possible. Campbell Graphics available at www.wpc.ncep.noaa.gov/basicwx/basicwx_wbg.php