Short Range Forecast Discussion NWS Weather Prediction Center College Park MD 417 PM EDT Tue May 21 2013 Valid 00Z Wed May 22 2013 - 00Z Fri May 24 2013 ...A slow moving cold front with several low pressure systems will produce heavy rain...a threat of flash flooding and continued severe weather for the next couple days... ...Much cooler conditions will affect the northwestern corner of the nation with scattered showers and high elevation snow that will persist into Thursday... ...A strong push of cooler air will make its way across the Upper Mississippi Valley into the Midwest and Ohio Valley by Thursday... Cool weather will continue over the nations midsection as a slow moving upper trough and its associated surface cold front edges slowly eastward across the eastern half of the US during the next few days. Warm humid air will cover the eastern US and flow off the Gulf of Mexico will provide lots of moisture in generating showers and thunderstorms near and ahead of the front. Farther north...cloudy and cool conditions with rain and rain showers will cover much of the Upper Midwest across northern New England. However...most of the heavy thunderstorm and a possibility of more severe weather will occur along and east of the advancing cold front. Organized convective systems will likely produce localized flash flooding while severe weather is a risk this evening across eastern Texas into the lower Mississippi Valley. These risks will likely push slowly eastward over the next couple days. Please refer to the Storm Prediction Center for the latest information and updates on any tornado and severe weather threats. With the exception of northern New England where cloudy...cool and occasionally rainy conditions Will occur over the next couple days...much of the East and Southeast Coasts...including Florida will experience warm and humid conditions with mostly scattered showers and localized thunderstorms especially in the late afternoon and evening. By Thursday...as the upper trough/surface front nears the East Coast...a secondary surge of cooler air will be moving southward across the Midwest and should help clear out much of the Central and Northern Plains/Midwest and Ohio Valley before heading toward the East Coast late in the week. Relatively cool...comfortable conditions will follow in the wake of this secondary cool outbreak. An impressive deep trough over the Pacific Northwest will continue to push a cold front slowly eastward across the Intermountain West. Snow levels will fall to about 3500 feet across the Washington Cascades and Olympic Mountains where several inches of snow will accumulate. This deep upper low will likely remain over the Northwest for the next several days and will result in breezy...cool and showery conditions to continue. Kocin Graphics available at www.wpc.ncep.noaa.gov/basicwx/basicwx_wbg.php