Extended Forecast Discussion NWS Weather Prediction Center College Park MD 128 AM EST Sun Nov 29 2020 Valid 12Z Wed Dec 02 2020 - 12Z Sun Dec 06 2020 ...Active pattern into next weekend... ...Guidance Evaluation/Preferences... Teleconnections from a strong positive anomaly at 500mb over Saskatchewan through the period favors troughing about 30 deg to its south (western Mexico) as well as up/downstream in an omega configuration. The models/ensembles have largely shown this synoptic orientation but how it gets there and by what evolution have varied wildly over the past several days. Deep system in the East early Wednesday will continue into Quebec as two systems in the West interact just east of the Rockies. Consensus takes the lead system to the east through the mid-Mississippi Valley Friday and then northeastward to the eastern Great Lakes by next Sunday in somewhat similar fashion to the short range system this Tuesday. Given the inconsistencies in all models over the past few days, course of least regret was a broad consensus of the 12Z/18Z guidance except the UKMET which was too removed from the cluster. By next weekend, ECMWF was a good middle ground somewhat near the ensemble means as the 18Z GFS was too aggressive/quick with height falls into the Northwest and the Canadian too fast in the East. ...Sensible Weather and Hazards... In the wake of the Northeast/Canadian low pressure system, lake-effect snow will continue into Wednesday before diminishing. Below normal temperatures behind the front (most pronounced over the Southeast and Florida) will moderate a bit ahead of the next system at the end of the week. In the West, upper low(s) will bring in colder than normal temperatures to Rockies and points east as the surface system takes shape in the Gulf and lifts northeastward. Modest precipitation over the northwest Gulf is likely, perhaps focused right along the coast, as low pressure travels eastward. Some snow could be possible on the northern side of the precipitation shield. As the system moves up the East coast, another round of rain is likely for areas along and east of the Appalachians with some snow on the west side. Areas that may see above normal temperatures will be the northern Plains and much of California. Fracasso Additional 3-7 Day Hazards information can be found on the WPC medium range hazards chart at: https://www.wpc.ncep.noaa.gov/threats/threats.php WPC medium range 500mb heights, surface systems, weather grids, quantitative precipitation, winter weather outlook probabilities and heat indices are 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