Short Range Forecast Discussion NWS Weather Prediction Center College Park MD 359 AM EDT Sat Aug 19 2017 Valid 12Z Sat Aug 19 2017 - 12Z Mon Aug 21 2017 ...Heavy rain and flash flooding possible over parts of the Southwest and Rockies this weekend... ...Slight risk of severe thunderstorms for the Central Plains on Saturday... ...Slight risk of flash flooding for portions of the Upper and Middle Mississippi Valley on Sunday... This weekend, an upper-level low is expected to move into the southwestern U.S. Moisture is forecast to increase as well, and this will trigger widespread showers and thunderstorms for parts of the Southwest and Southern and Central Rockies. Heavy rain is possible for these areas, and there is a slight risk of flash flooding in effect for southern New Mexico on both Saturday and Sunday. The risk will spread northward on Sunday to much of New Mexico and into southern Colorado. Widespread rainfall totals of 1-2 inches are forecast over the weekend, with locally higher amounts possible. Additionally, the Sierra is forecast to see heavy rain that could cause flash flooding. On Saturday, a weak surface and mid-level low will combine with sufficient moisture to produce thunderstorms across the Central Plains. The Storm Prediction Center has portions of Nebraska and Kansas in a slight risk of severe thunderstorms. A cold front is forecast to move through the Northern Plains Saturday evening and into the Upper Mississippi Valley on Sunday. Along and ahead of this front, showers and thunderstorms will be possible. A few storms could be strong, and since storms could be slow moving and there is plenty of available moisture, there is a slight risk of flash flooding for portions of the Upper and Middle Mississippi Valley. This front will cool down temperatures in the Northern Plains as well after Saturday's above average temperatures. Elsewhere, a stationary front is expected to linger through the weekend across the Carolinas and portions of the Southeast. This will lead to scattered showers and thunderstorms for those areas and for Florida. Additionally, some thunderstorms are possible for portions of the Ohio Valley on Saturday during the day, a few of which could be strong. Tate Graphics available at www.wpc.ncep.noaa.gov/basicwx/basicwx_ndfd.php