Extended Forecast Discussion NWS Weather Prediction Center College Park MD 200 AM EST Sat Dec 08 2018 Valid 12Z Tue Dec 11 2018 - 12Z Sat Dec 15 2018 ...Pattern/Weather Highlights and Hazards... A departing coastal low off the Carolinas Tuesday offers a lingering maritime gale hazard being followed by OPC. In the wake of the low, cool temperature reinforcing/dry high pressure surges dig through the central and eastern U.S. into next midweek. Out West, precipitation will periodically increase early-mid next week and into next weekend as heights fall with a succession of approaching shortwaves/frontal systems. Higher terrain of western Oregon/Washington have potential for heaviest precipitation amounts (rain and mountain snow) as shots of dynamic snows drive inland into favored north-central Great Basin/Rockies terrain. Some of this energy will progress eastward over the north-central through northeastern us to support modest northern stream snows. Potential for substantial energy infusion into an emerging southern stream later next week meanwhile offers potential for deeper system genesis and the threat for more widespread and Gulf of Mexico moisture fueled heavy precipitation over the south-central U.S. then northeastward across the eastern seaboard into next weekend including a threat of snow/ice on the colder northern periphery of an expanding and intensifying precipitation shield. ...Guidance Evaluation/Preferences... The WPC medium range product suite was primarily derived from a blend of the latest GEFS/ECMWF ensemble means. Recent deterministic runs GFS/ECMWF have been offered well less than stellar run to run consistency. The ensemble means have varied a bit more than normal, but have been much more consistent with the above mentioned systems, but ample forecast spread/uncertainty remains. Latest GFS/ECMWF runs overall trend better in line with the ensemble means, but still have some significant embedded system timing differences. 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