Short Range Forecast Discussion NWS Weather Prediction Center College Park MD 409 PM EDT Mon Jul 20 2015 Valid 00Z Tue Jul 21 2015 - 00Z Thu Jul 23 2015 ...There is a slight risk of severe thunderstorms over parts of the Middle Mississippi Valley, Ohio River Valley and central Appalachians... ...Heavy rain possible over parts of the Southern and Central Plains and Missouri... Two frontal systems will move through the eastern half of the US by midweek. The first front, which extends from the New England states to the Central High Plains, will move out by Tuesday afternoon. A secondary front slides down into the Central Plains and Upper Midwest behind the first on Tuesday and pushes east and south on Wednesday. The northern portion of the front will bring relief from the heat and higher humidity for the Mid-Atlantic states, however the southern half stalls over the southern Plains and lower Mississippi Valley. Hot and humid conditions will continue for the deep South during this time. These two systems will produce showers and thunderstorms for much of the Northeast, the Mid-Atlantic, the Tennessee Valley into the Central High Plains through Tuesday evening. Some of these storms may become severe, especially for the Central and Southern Plains through Tuesday morning and for areas along the Central Appalachians Tuesday afternoon and evening. Excessive rain and flash flooding will be possible along and ahead of the front for south-central Colorado, northeast New Mexico, Oklahoma, southeast Kansas, Missouri and western Illinois through Tuesday morning. Potential for heavy rain will continue for portions of the Central and Southern Plains through Wednesday. A cold front will push onshore over the Pacific Northwest and track across the Northern Rockies by Tuesday. Showers and thunderstorms are expected to develop along the warm front over the Northern High Plains, before moving east into the Northern Plains by Tuesday evening. In addition, monsoonal moisture and moisture associated with the remains of Dolores will aid in producing showers and thunderstorms over parts of Southern California/Great Basin into the Southern/Central Rockies through Tuesday evening. Moisture pooling over the Southeast and upper-level impulses will trigger showers and thunderstorms over parts of the Southeast/Central Gulf Coast through Tuesday. Campbell/Ziegenfelder Graphics available at www.wpc.ncep.noaa.gov/basicwx/basicwx_wbg.php