Short Range Forecast Discussion NWS Weather Prediction Center College Park MD 301 PM EST Wed Dec 23 2015 Valid 00Z Thu Dec 24 2015 - 00Z Sat Dec 26 2015 ...Widespread severe weather likely from the central/eastern Gulf Coast up to the Great Lakes... ...Flash flood threat exists from the central Gulf Coast up to the central Appalachians... ...Heavy snow expected over the higher terrain of the western U.S... ...Very warm temperatures in the forecast across the eastern third of the nation... Highly amplified flow across the U.S. will favor a very active weather pattern through the Christmas holiday. Such a regime will lead to the possibility of severe weather, flash flooding, wintry precipitation, and record warmth across the country. To start with, favorable vertical wind profiles in conjunction with unstable air will lead to the potential for tornadic development. There are currently tornado watches extending from areas of the mid-South up to the Ohio valley. Additionally, the latest Storm Prediction Center outlook features a moderate risk for severe thunderstorms from eastern Arkansas through northern Mississippi and into the western halves of Kentucky and Tennessee. Locations toward the Great Lakes and Gulf Coast are generally in the slight risk but still can expect a threat for damaging winds and perhaps a few tornadoes. A stalled frontal zone extending from the Mid-Atlantic southwestward back toward the Ozarks will set the focus for daily threats for heavy rainfall. As soils become further saturated by moderate/heavy rains, the potential for flash flooding will increase. Currently WPC has an excessive rainfall outlook area extending from the central/eastern Gulf Coast up across the southern/central Appalachians. Of course urbanized areas are more likely to experience issues given problems with run-off. As the upper flow begins to further amplify over the southwestern U.S., much colder air will work its way southward spreading below normal temperatures to much of the western states. On Christmas day, high temperatures should generally be 10 to 20 degrees below normal with readings generally in the 20s over interior locales. Additionally, rain is expected along the coastal and adjacent lower elevations while heavy snow blankets the local mountain ranges. The current forecast indicates the highest amounts are possible over the Sierra Nevada range along with the Colorado Rockies with 1 to 2 inches expected. Besides the cool and unsettled weather over the western states, anomalous warmth will continue from the Great Plains eastward. The largest departures from climatology are forecast over the eastern third of the U.S. Forecast highs generally range from 25 to 35 degrees Fahrenheit above normal which equates to highs in the 70s as far north as southern Vermont on Thursday with a potential for 80 degrees in southeastern Virginia. This may lead to many daily temperature records being broken. Temperatures cool a bit for Christmas given the increased threat for rain. However, highs on Christmas day should still remain in the 60s all the way up toward Boston. Rubin-Oster Graphics available at www.wpc.ncep.noaa.gov/basicwx/basicwx_wbg.php