Short Range Forecast Discussion NWS Weather Prediction Center College Park MD 407 PM EDT Tue Sep 12 2017 Valid 00Z Wed Sep 13 2017 - 00Z Fri Sep 15 2017 ...Irma's remnant circulation is expected to gradually dissipate as it moves up the Mississippi Valley... ...Parts of the northern Rockies could see wet snow on Thursday... Irma, once a powerful category-5 hurricane north of the Caribbean Islands, has continued to lose tropical characteristics as it interacts with an upper-level trough and moves further inland across the southeastern U.S. Although Irma's remnant circulation remains large, a lack of replenishing cool air from Canada means that Irma will gradually dissipate over the mid-Mississippi Valley during the next couple of days. Only very modest amounts of addition rain are expected over the Mississippi Valley into the Tennessee Valley through tomorrow before the circulation dissipates on Thursday. Nevertheless, a piece of the moisture is forecast to move eastward across the Eastern Seaboard on Thursday ahead of a weak front, where some scattered showers and thunderstorms can be expected to linger. Some showers and thunderstorms are expected in Florida as well. With the expansive cloud cover associated with the remnants of Irma, temperatures will continue to be much cooler than normal from the Mississippi Valley northeastward into the Ohio Valley. Meanwhile, cooler air from the Canadian prairies is expected the slowly filter into the northern Plains and the northern Rockies through Thursday. Light rain is expected to develop behind a cold front and a low pressure wave over the Intermountain region. This should gradually develop into a steady rain on Thursday. As colder air continues to filter in, some of the highest elevations in northern Rockies could see wet snow on Thursday as temperatures fall much below normal. Farther south, scattered showers and thunderstorms are expected to linger over the Great Basin into the central Rockies as well as northern Arizona through Thursday with near normal temperatures. Kong Graphics available at www.wpc.ncep.noaa.gov/basicwx/basicwx_ndfd.php