Short Range Forecast Discussion NWS Weather Prediction Center College Park MD 330 AM EDT Mon May 13 2013 Valid 12Z Mon May 13 2013 - 12Z Wed May 15 2013 ***Unseasonably cool airmass over the Eastern U.S.*** ***Warm weather for the north central U.S.*** ***Rain showers for the Pacific Northwest and northern Rockies*** Given the trough in the East and the ridge in the West, temperatures are expected to be 10 to 20 degrees below average for the East Coast states and into the Ohio Valley through Tuesday. Frost and freeze advisories/warnings are in effect for much of the Great Lakes region, Ohio Valley, and central Appalachians. It will also be refreshingly cool for the typically humid areas of the Deep South and Southeast, before a warming trend commences later in the week. Much warmer weather is in the forecast for the central and northern Great Plains, with the highest temperatures of the season thus far expected. Some 90-degree readings are possible for parts of Montana and into the Dakotas as a strong warm front moves through the region, accompanied by a ridge aloft. A few record highs are possible. In the precipitation department, a rather uneventful pattern is expected over the continental U.S. for the next couple of days. Some organized rainfall is likely over coastal regions of the Pacific Northwest and the spine of the northern Rockies as a cold front and upper level energy pass through that region. Some scattered showers will also be possible over the Upper Midwest and western Great Lakes as a result of warm air advection from the Plains. Showers and storms are also likely over Mexico, and some of these may affect parts of southern Texas. D. Hamrick Graphics available at www.wpc.ncep.noaa.gov/basicwx/basicwx_wbg.php