Extended Forecast Discussion NWS Weather Prediction Center College Park MD 1042 PM EST Mon Jan 14 2019 Valid 12Z Fri Jan 18 2019 - 12Z Tue Jan 22 2019 ...Frigid air from the Central U.S. through the Northeast sets the stage for another major central to eastern U.S. snowstorm... ...Guidance Evaluation/Preferences... Guidance is in good agreement throughout the medium range period over much of the nation, bolstering forecast confidence to above normal levels. WPC continuity is well maintained with the WPC product suite primarily derived from a composite blend of well clustered guidance from the 18 UTC GFS/GEFS mean and 12 UTC ECMWF/ECMWF ensemble mean. ...Weather Highlights/Hazards... Amplified southern stream mid-upper level trough energy/height falls digs through the Southwest Friday with pooled moisture and precipitation working through the Intermountain West/Great Basin/Rockies with windy conditions and valley rain/mountain snow. Snow levels will fall as heights lower which will turn some lower elevations over to snow as precipitation diminishes Saturday. Pacific storm systems reload farther to the north later for the holiday weekend to then focus an associated heavy precipitation threat into/across the Northwest. Downstream surges of frigid arctic air into the central U.S. Friday through the weekend occur as the northern stream amplifies around a Hudson Bay upper vortex. A lead system will spread some wintery weather over the northeast Friday. Upstream, a more robust system ejecting from the West organizes over the south-central Plains with increased lead Gulf of Mexico moisture and lift up through the east-central U.S. Saturday as an arctic front to the north pushes through the Northeast. As precipitation overruns the arctic airmass to the north, heavy snow will spread out of the Central Plains through the Midwest/Ohio Valley then Mid-Atlantic/Northeast through the holiday weekend along with some threat of blizzard conditions in the tight pressure gradient around a main low that lifts through the eastern U.S. and offshore. Meanwhile, heavy warm-sector rains/convection move through the South/Southeast and a transition zone between snow and rain will include significant sleet and freezing rain. Please consult WPC Day 4-7 QPF and Winter Weather Outlook for a probabilistic assessment of the significant winter weather threat. Schichtel WPC medium range 500 mb heights, surface systems, weather grids, quantitative precipitation, winter weather outlook probabilities and heat indexes are found at: https://www.wpc.ncep.noaa.gov/medr/5dayfcst500_wbg.gif https://www.wpc.ncep.noaa.gov/medr/5dayfcst_wbg_conus.gif https://www.wpc.ncep.noaa.gov/5km_grids/5km_gridsbody.html https://www.wpc.ncep.noaa.gov/qpf/day4-7.shtml https://www.wpc.ncep.noaa.gov/wwd/pwpf_d47/pwpf_medr.php?day=4 https://www.wpc.ncep.noaa.gov/heat_index.shtml