Short Range Forecast Discussion NWS Weather Prediction Center College Park MD 257 PM EDT Mon Sep 12 2016 Valid 00Z Tue Sep 13 2016 - 00Z Thu Sep 15 2016 ...High pressure over the Northeast will drift eastward with a slow warmup through Wednesday... ...Showers and thundershowers will fall along a weakening cold front along the Gulf Coast and across Florida where a tropical wave is expected to cross the state... ...A large outbreak of cool air will spill southward across the Rockies with rain and mountain snow while Canadian high pressure and cooler air move eastward across the northern Plains and Midwest toward the Northeast by Thursday... ...As the cool front moves south and eastward from the Rockies into the Plains states...showers and thundershowers will fall with the front...especially across the Southern and Central Plains..where the front will become stationary and help focus possible heavy rainfall... Blue skies and lower humidity will continue across the Midwest, Ohio Valley and Northeast as high pressure drifts eastward from the Northeast into the western Atlantic overnight and into Tuesday. Temperatures will start out comfortable but warmer and more humid conditions are expected to return by midweek before the next front. The retreating cold front behind what is now an intense storm northeast of the Canadian maritimes will stall and weaken along the Gulf Coast providing a moist environment for showers and thundershowers that will peak in the afternoon and evening along the Gulf Coast. Meanwhile, a tropical wave will cross Florida, enhancing the chances of possibly heavy showers and thunderstorms on each day, especially Tuesday. An early autumnal outbreak of cool air is currently making its way south and eastward across the Northwest, northern Rockies into the Plains states. Chilly temperatures are accompanying this late summer outbreak with some upslope rains and higher elevation in Montana and Wyoming. Showers are expected to continue across the Great Basin into Tuesday while cooler air makes its way south and eastward across the east slopes of the Rockies and then eastward across the Northern Plains, the Upper Mississippi Valley, the Midwest on Wednesday and then reaching the Northeast by Thursday morning. As the cold front moves south and eastward, showers and thundershowers will fall across the Southern and Central Plains and continue as the front becomes stationary across the region, contributing to the potential for heavy rainfall. Showers and thunderstorms will accompany the more progressive portions of the front especially across the Upper Mississippi Valley and Midwest on Tuesday into Wednesday. Kocin Graphics available at www.wpc.ncep.noaa.gov/basicwx/basicwx_wbg.php