Short Range Forecast Discussion NWS Weather Prediction Center College Park MD 353 AM EDT Thu Jul 20 2017 Valid 12Z Thu Jul 20 2017 - 12Z Sat Jul 22 2017 ...There is a slight risk of severe thunderstorms over parts of the Lower Great Lakes/Ohio Valley and the Northern/Central High Plains ... ...Heavy rain possible over parts of the Upper/Middle Mississippi Valley into the Western Ohio Valley... ...Temperatures will average 10 degrees above average over parts of the Central Plains/Middle Mississippi Valley... A front extending from the Northeast/Northern Mid-Atlantic westward to the Northern/Central Plains will become quasi-stationary as the eastern end of the boundary dissipates overnight Thursday. The remaining parts of the boundary will linkup with the energy from another front moving southeastward from Central Canada by Friday morning. Showers and thunderstorms will develop along and ahead of the front over the Great Lakes westward into parts of the Northern/Central Plains that will move eastward to the Northeast westward to the Middle Mississippi Valley by Thursday night. The showers and thunderstorms will move off the Northeast Coast by Friday morning and continue over parts of the Ohio Valley/Middle Mississippi Valley on Friday into Friday evening. Another front will develop over the Northern Intermountain Region/Northern Rockies by Thursday evening and advance eastward to the Northern Plains/Great Basin by Friday evening. Showers and thunderstorms will develop along and ahead of the boundary over parts of the Northern High Plains/Northern Rockies by Thursday evening that will expand into the Northern Plains overnight Thursday. On Friday, the showers and thunderstorms will move into parts of the Upper Mississippi Valley/Central Plains into Friday evening. Meanwhile, monsoonal moisture and daytime heating along with upper-level energy will aid in producing showers and thunderstorms over parts of the Southwest/Great Basin eastward to the Central/Southern Rockies through Friday evening. The showers and thunderstorms will have the greatest areal coverage during the late afternoon into late evening on Thursday and Friday. In addition, moisture rich air over the Southern Mid-Atlantic/Southeast Coast and across the Gulf Coast State will interact with daytime heating and upper-level impulses to produce showers and thunderstorms along and near the coastal region through Friday evening. Similarly, the showers and thunderstorms will have the greatest areal coverage during the late afternoon into late evening on Thursday and Friday. Elsewhere, onshore flow off the Pacific will aid in producing rain over parts of the Pacific Northwest through late Thursday night. Ziegenfelder Graphics available at www.wpc.ncep.noaa.gov/basicwx/basicwx_ndfd.php