Short Range Forecast Discussion NWS Weather Prediction Center College Park MD 410 AM EDT Tue May 21 2013 Valid 12Z Tue May 21 2013 - 12Z Thu May 23 2013 ...Widespread severe weather and heavy rainfall threat are expected along a slow-moving cold front migrating through the Nation's mid-section... ...Windy...cool and wet conditions are in the forecast for the pacific Northwest and northern Rockies... and ...Scattered showers and thunderstorms will continue over Florida and up into the Mid-Atlantic region... A cold front edging eastward through the Nation's mid-section will continue to be a big weather maker during the short range period. Anomalous amounts of moisture surging northward out of the Gulf...combined with strong dynamics aloft...should produce organized convection along and ahead of the slow-moving frontal boundary. Heavy rainfall may accompany the more intense showers and thunderstorms with severe weather expected from the Southern Plains to Upper Midwest/Upper Great Lakes. A moderate risk of severe storms will be located today and tonight for northeast Texas into the Ark-La-Tex and southern Ozarks. Please refer to the Storm Prediction Center for the latest information and updates for severe weather. Farther north...moisture wrapping around a slow-moving upper-level low anchored in the upper Mississippi Valley and a stationary front draped to the east of this low will be the focus for light to moderate rainfall and embedded thunderstorms from the northern Plains to the Great Lakes and into southern New England during the next few days. A vigorous upper vortex settling in over the Pacific Northwest will slowly push a cold front inland through the West and northern Rockies. Moderate moisture...instability and cold air aloft will produce scattered showers and a few thunderstorms. Windy conditions along the front should enhance precipitation amounts along the windward slopes of the higher terrain. With conditions noticeably cooler behind the front...temperatures could briefly fall below freezing at elevation with the possibility of snow showers in the Washington and Oregon Cascades. Across the East and southeast...weak energy aloft and warm advection should keep conditions ripe for scattered showers and thunderstorms over Florida and northward into the Mid-Atlantic states. Gerhardt/Vojtesak Graphics available at www.wpc.ncep.noaa.gov/basicwx/basicwx_wbg.php