Extended Forecast Discussion NWS Weather Prediction Center College Park MD 200 AM EST Mon Nov 05 2018 Valid 12Z Thu Nov 08 2018 - 12Z Mon Nov 12 2018 ...Guidance/Predictability Assessment... The latest few GFS/GEFS and ECMWF/ECMWF ensemble runs are now better clustered into Thu/Fri, bolstering forecast confidence a bit with acceptance of a composite blend solution that maintains decent WPC continuity. Forecast spread and uncertainty steadily increases into days 5-7 with embedded systems within a generally similar larger scale flow regime. Accordingly, prefer a more ensemble mean blend that also maintains a bit more flow amplitude consistent with upstream flow over the Pacific and WPC continuity. ...Weather Highlights/Threats... Expect occasional modest rain/snow in the West will periodically be tied to incoming shortwaves and surface fronts. System ejections from the Rockies into the Plains where ENE flow around a surface high may support a swath of snow from the central Plains northeastward. To the south, Gulf moisture will support moderate rainfall (potentially locally heavy via embedded convection) from the western Gulf Coast and lower Mississippi Valley to the Southeast with frontal progression, with additional amounts up the Appalachians/Eastern Seaboard aided by Atlantic inflow. As the front clears the east coast, lake-effect snow is likely with cold temperatures aloft atop mild lake temperatures in general NW flow. Temperatures will be most anomalously cool over the Upper Midwest/Great Lakes as well as Texas behind the cold front. Some record cold maximum temperatures are possible over the Midwest. Clipper low approach Sun/next Monday may support some snow for parts of the Upper Midwest/Great Lakes and Northeast. 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