Extended Forecast Discussion NWS Weather Prediction Center College Park MD 1100 AM EST Mon Nov 05 2018 Valid 12Z Thu Nov 08 2018 - 12Z Mon Nov 12 2018 ...Pattern Overview and Guidance Assessment... The medium range period features shortwave energy traversing the northern tier from the Northern Plains to Northern New England while a second possible shortwave drops down into the northern Rockies by Day 5 and riding builds over the coastal Eastern Pacific and West Coast. There remains good agreement between deterministic models and ensembles in the days 3-4 (Thur - Fri) period, with uncertainty increasing later in the period. There remains some question with how much, if any, shortwave energy drops down into the Northern Plains on day 5. The ECMWF has good consistency with both its previous runs and the EC and GEFS ensemble means in showing some semblance of energy ahead of more amplified ridging in the East Pacific while the GFS remains on the slightly flatter/weaker side. The biggest outlier remains the CMC and its ensemble which shows a much more defined shortwave across the West. This likely is a result of differences upstream over the central Pacific and Alaska. The blend used for this cycle of the medium range progs features a majority deterministic blend (between the latest ECMWF/GFS/UKMET runs) days 3-4, with increasing weighting of the EC and GEFS ensemble means by the end of the period. Did maintain a little weighting of the deterministic ECMWF through day 7 because it was the closest to the solution provided by the ensemble means, and this overall pattern fit very close to WPC continuity as well. ...Weather Highlights/Threats... 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. A clipper low approaching by Sun/next Monday may support some snow for parts of the Upper Midwest/Great Lakes and the Northeast. Santorelli/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