Short Range Forecast Discussion NWS Weather Prediction Center College Park MD 335 PM EDT Mon Jul 10 2017 Valid 00Z Tue Jul 11 2017 - 00Z Thu Jul 13 2017 ...Severe weather and heavy rainfall possible this evening across portions of the Ohio Valley and the lower Great Lakes... ...Severe weather and heavy rainfall threat to increase by Tuesday and Wednesday from the Northern Plains to the Upper Mississippi Valley and into the Great Lakes... Initially, a weak wave of low pressure along a frontal boundary will track eastward into the Ohio Valley this evening. Expect showers and thunderstorms to continue along the boundary from portions of the Ohio Valley to the Northeast. Mainly near and ahead of the low center itself, some of the storms may be capable of producing severe weather and heavy to excessive rainfall. Both WPC and SPC have highlighted slight risks in the Ohio Valley and parts of the lower Great Lakes for this evening. As this boundary weakens throughout the day on Tuesday, a second area of low pressure is forecast to drop into the Northern Plains. This will drag another boundary across the northern tier states Tuesday into Wednesday with showers and thunderstorms likely to develop initially across the northern Plains and Upper Mississippi Valley Tuesday afternoon, shifting eastward into the Upper Midwest/Great Lakes on Wednesday. Once again, severe weather and heavy to excessive rainfall is possible with this system. SPC is advertising an enhanced risk for severe thunderstorms across portions of the Northern Plains and Upper Mississippi Valley on Tuesday, and a slight risk across parts of the Upper Midwest and into the Great Lakes on Wednesday. Elsewhere, hot and dry conditions across parts of the Northwest are expected to continue into the work week with Red Flag warnings in effect for some areas. Diurnally driven monsoonal moisture will continue to bring scattered showers and thunderstorms to parts of the Southwest and into the central Rockies. Meanwhile, return flow around high pressure over the western Atlantic keeps showers and storms in the forecast across the Southeast and Gulf Coast states through the middle of the week. Santorelli Graphics available at www.wpc.ncep.noaa.gov/basicwx/basicwx_ndfd.php