Short Range Forecast Discussion NWS Weather Prediction Center College Park MD 333 AM EDT Thu Jul 21 2016 Valid 12Z Thu Jul 21 2016 - 12Z Sat Jul 23 2016 ...There is a slight risk of severe thunderstorms over the Great Lakes... ...Heavy rain possible over parts of the Northern Plains... ...Temperatures will be 10 to 15 degrees above average over Central/Northern Plains into the Upper Great Lakes... A front extending from the Upper Mississippi Valley to the Central Plains and westward to the Great Basin will move eastward to the Great Lakes by Friday evening while extending westward to a wave over low pressure over the Northern High Plains. Showers and thunderstorms will develop along and ahead of the boundary over the Upper Mississippi Valley/Upper Great Lakes that will extend into parts of the Western Ohio Valley on Thursday morning. The showers and thunderstorms will move eastward to the into the Northeast/Ohio Valley and extending westward into parts of the Middle Mississippi Valley by Friday evening. By Friday morning, showers and thunderstorms will develop along and ahead of the front associated with the wave of low pressure moving eastward out of the Northern Rockies/High Plains that will expand into parts of the Northern Plains by Friday evening. In addition, onshore flow off the Pacific will aid in producing rain over parts of the Pacific Northwest starting overnight Thursday into Friday evening. On Friday afternoon into evening, showers and thunderstorms will develop over parts of the Northern Intermountain Region and Northern Rockies. Meanwhile, tropical moisture across the Gulf Coast States and daytime heating will aid in producing showers and thunderstorms from parts of the Western Gulf Coast to the Southeast on Thursday and Friday. The storms will have their greatest areal coverage during the afternoon into the late evening hours. Additionally, showers and thunderstorms will develop over parts of the Southwest/Eastern Great Basin and parts of the Central/Southern Rockies on Thursday and Friday afternoon into late evening due to monsoonal moisture and daytime heating. Ziegenfelder Graphics available at www.wpc.ncep.noaa.gov/basicwx/basicwx_wbg.php