Short Range Forecast Discussion NWS Weather Prediction Center College Park MD 258 AM EST Sat Jan 06 2018 Valid 12Z Sat Jan 06 2018 - 12Z Mon Jan 08 2018 ...Well below normal temperatures to continue across the eastern third of the nation... ...Freezing rain likely to spread from eastern Kansas into sections of the Great Lakes and Ohio/Tennessee valleys... ...Heavy precipitation possible over western Washington late in the weekend... The latest arctic surge has brought another round of well below normal temperatures to most locations east of the Mississippi River. The most anomalous departures from climatology should reside across the Great Lakes, Ohio Valley, central/northern Appalachians, and over the northeastern United States. This afternoon, high temperatures will likely be around 20 to 30 degrees below average over these locations which supports a number of daily temperature records being broken. Expected highs will be in the single digits across the lower Great Lakes down into Ohio. Meanwhile, readings in the teens are likely from Washington, D.C. up to New York City with single digits up into coastal New England. Based on the latest forecasts, overnight temperatures should go below zero degrees over most of New England with perhaps even some 5 to 10 degree numbers all the way into North Carolina. Suffice to say, it will be a brutally cold weekend but some relief is in sight heading into early next week. Until then, the frigid temperatures aloft should keep lake effect snow production going over the Great Lakes although amounts are much lighter than recent days. A series of disturbances will push into the Pacific Northwest during the next couple of days with the lead system expected to split into two while departing inland. This initial feature should bring light precipitation to the Pacific Northwest and into the upper Intermountain West. A separate upper trough to the south will also be spreading moderate rain and snow to the Sierra Nevada range on Saturday. Eventually all of these subtle features should interact across the southern/central Plains on Sunday afternoon leading to a more organized system. A pronounced frontal zone will be the site for active convection across the central Gulf Coast where 1 to 2 inch rainfall amounts are possible over eastern Louisiana. Additionally, enough low-level cold air remaining from the series of arctic blasts will afford a freezing rain risk anywhere from eastern Kansas through the Missouri valley and into much of Illinois, Indiana, as well as the Ohio and Tennessee valleys. While only light accumulations are likely, any trace amount of ice on road surfaces could cause issues to ground transportation on Sunday into Monday. Late in the weekend, a much more pronounced upper trough takes shape over the eastern Pacific. Persistent low-level southwesterly flow will usher in abundant moisture into coastal Washington. Vigorous orographic lift should result across the south/southwest facing slopes of the Olympics where over 2 inch precipitation amounts are likely during a 24-hour time period ending Monday morning. Meanwhile, some higher elevation snows are expected across the Washington Cascades. While the eastern states remain frigid for another couple of days, mild conditions are in the forecast across the western and central United States. The upper flow flattening out as Pacific origin systems move through will ensure a warmer period ahead. Westerly flow along the lee of the Rockies will lead to sufficient downsloping across the Great Plains as highs soar into the 40s as far north as South Dakota on Sunday. Also, temperatures over the Upper Midwest are likely going to be 20 degrees warmer on Sunday than the previous day as readings finally move into the mid/upper 20s. Rubin-Oster Graphics available at www.wpc.ncep.noaa.gov/basicwx/basicwx_ndfd.php