Extended Forecast Discussion NWS Weather Prediction Center College Park MD 207 AM EST Sat Feb 16 2019 Valid 12Z Tue Feb 19 2019 - 12Z Sat Feb 23 2019 ...Multi-day Threats of Heavy Rain for the Lower Mississippi/Tennessee Valleys to South-Central Appalachians and Ohio Valley/Northern Mid-Atlantic Heavy Snow/Ice... ...Western to Central U.S. Cold/Unsettled Weather to focus into the Southwest... ...Guidance/Predictability Assessment and Weather Hazards... Models and ensembles maintain a pattern with a series of potent upper troughs/height falls progressing overtop a northeast Pacific ridge that then dig sharply southward to reinforce a western US mean trough. The supports western to central U.S. cold and unsettled weather with a focus over the Southwest. Lead deep layered and anomalously moist southwest flow channeled from the southern Plains to the East meanwhile acts to sustain a Southeast ridge and fuel multi-day threats of heavy rain/training from the Lower Mississippi/Tennessee Valleys to South-Central Appalachians and Ohio Valley/Northern Mid-Atlantic heavy snow/ice. This occurs as multiple waves traverse and moisture feeds into a lingering southern to eastern U.S. surface front and into cold surface high pressure settled/dammed overtop. In this pattern main mid-upper level troughs eject from the Southwest to Northeast Tue-Thu as a main upstream trough digs from the Pacific Northwest to the Southwest Wed-Sat. This amplified pattern overall offers above normal forecast predictability next week, albeit with timing/strength variance with embedded small-mid scale systems growing gradually over time. The WPC medium range product suite was primarily derived from a composite blend of well clustered guidance from the recent GFS/ECMWF and GEFS/ECMWF ensemble means along with the National Blend of Models and WPC continuity. Schichtel WPC medium range 500mb heights, surface systems, weather grids, quantitative precipitation and winter weather outlook probabilities 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