Short Range Forecast Discussion NWS Weather Prediction Center College Park MD 457 PM EDT Wed Jun 19 2013 Valid 00Z Thu Jun 20 2013 - 00Z Sat Jun 22 2013 ...Deep upper level low will bring unseasonably wet conditions from the Great Basin to the Northern Plains... ...Showers and thunderstorms will continue across the Southeast and southern Atlantic states... A deep upper level low has moved inland from the Pacific Northwest and continues to bring unsettled conditions across the northern Great Basin. This upper level low is slowly progressing eastward towards the Northern Plains; in fact, it does not exit the Northern Rockies until after the short range period. The placement of already unstable air combined with enough lift and anomalous supply of moisture, showers and thunderstorms will be triggered along the mountains and eventually spread eastward into Montana and the Dakotas by early Thursday morning. The heaviest rainfall, along with the threat of severe weather, will concentrate along the U.S.-Canada border in Idaho and Montana. As the surface frontal boundary advances into the Northern Plains by Thursday morning, most of the convection will taper off across the Northern Rockies and surrounding regions. However, due to the slow moving nature of the upper level low, showers with periods of moderate rainfall will linger across the Pacific Northwest and portions of the Great Basin through Friday. The Gulf Coast region along with southeastern Atlantic states will continue with its rounds of showers and thunderstorms. A cold front is slowly dipping southward across the Southeast. This boundary will stall out and remain along the Gulf Coast and off the coast of the Carolinas through Friday evening. Southerly winds will bestow this region with copious amounts of warm Gulf moisture and the aforementioned boundary will provide focus for scattered thunderstorms and showers. A surface low will remain adjacent to the Carolina coast and allow some of the heavier activity to concentrate around that region. By Thursday night and into Friday morning, the majority of the convection will subside. With that said, don't expect all of the convection to subside as the boundary will stick around for the beginning of the weekend. Fanning Graphics available at www.wpc.ncep.noaa.gov/basicwx/basicwx_wbg.php