Short Range Forecast Discussion NWS Weather Prediction Center College Park MD 359 AM EDT Thu Aug 11 2016 Valid 12Z Thu Aug 11 2016 - 12Z Sat Aug 13 2016 ...Severe thunderstorms and flash flooding possible across the High Plains and Upper Midwest... ...Heavy rainfall to persist across the central Gulf Coast states... ...Heavy to excessive rainfall possible across Arizona and New Mexico through tonight... A low pressure system tracking north and east through the northern states will be the focus for numerous showers and thunderstorms through the end of the week. Severe thunderstorms will be possible across portions of the northern Plains/Upper Midwest. Very moist air streaming northward from the Gulf of Mexico into the central and northern Plains will interact with the advancing boundary. With precipitable water values of 2 standard deviations or higher, the storm environment will be primed for long periods of heavy rainfall. Flash flooding will be likely, especially from Iowa to northern Michigan where WPC has identified a slight risk for excessive rainfall. A lingering surface low over the coastal plains will continue to draw in tropical moisture into the South. Numerous showers and thunderstorms will develop then linger across the Gulf states, yielding high rainfall amounts. The central Gulf Coast will likely have flash flooding - a moderate risk for excessive rainfall has been issued by WPC for the Mississippi Delta and surrounding areas. Shower and thunderstorm activity will continue from the Tennessee and Ohio valleys to the Mid-Atlantic and Northeast as moisture streams around the ridge over the Southeast. Monsoonal moisture and daytime heating will continue to trigger showers and thunderstorms. Localized heavy rain and flash flooding is possible through tonight for portions of the Desert Southwest. By Friday afternoon a cold front plunges southward into the central and southern Plains. Numerous showers and thunderstorms will develop along and ahead of the front from western Texas to the Middle Mississippi valley. Campbell Graphics available at www.wpc.ncep.noaa.gov/basicwx/basicwx_wbg.php