Short Range Forecast Discussion NWS Weather Prediction Center College Park MD 156 PM EDT Mon Aug 17 2015 Valid 00Z Tue Aug 18 2015 - 00Z Thu Aug 20 2015 ...Unseasonably strong low pressure forecast to develop over the central Plains to upper Mississippi Valley... ...Temperatures will be 10 to 15 degrees below average over parts of the Northern Plains and by the middle of the week the central Plains... ...Widespread showers and storms with areas of severe weather expected from the central Plains to the mid Mississippi Valley... A front extending from the Upper Great Lakes to the Central Plains will be quasi-stationary through Tuesday. A wave of low pressure will develop along the boundary over the Central High Plains on Monday night and move northeastward to the upper Mississippi Valley Tuesday night. The associated front will sweep eastward to the Middle Mississippi Valley and Great Lakes and south down to the Southern Plains. Moisture and lift ahead of the front will cause showers and thunderstorms to develop. Severe convective weather outlooks indicate areas of severe thunderstorms are possible and excessive rainfall outlooks indicate locally heavy rain is possible in these areas through Tuesday. In addition, moisture moving northward from the Gulf of Mexico will aid in producing showers and thunderstorms from the Gulf Coast across the Southeast and northward into the Tennessee Valley and southern and central Appalachians on Tuesday; continuing into the mid Atlantic on Wednesday. Monsoonal moisture will aid in developing showers and thunderstorms over parts of the Southern Rockies and Southern High Plains this afternoon and evening and again on Tuesday. Hot temperatures are expected to continue over the desert southwest and interior southern California with excessive heat warnings in effect over most of western Arizona and southeast California. Petersen Graphics available at www.wpc.ncep.noaa.gov/basicwx/basicwx_wbg.php