Extended Forecast Discussion NWS Weather Prediction Center College Park MD 1237 PM EST Sun Nov 29 2020 Valid 12Z Wed Dec 02 2020 - 12Z Sun Dec 06 2020 ...Guidance Evaluation/Preferences... Teleconnections from a strong positive anomaly at 500mb over Saskatchewan through the period favors a closed low about 20 deg to its south near the western US/Mexico border which leads to a positive tilted trough from southeast Canada into northwest Mexico. Ridging remains along the West Coast. The models/ensembles have largely shown this synoptic orientation but details remain an issue. Aloft, the 00z ECMWF burrows the ejecting Southwest system in the southern Plains/Southwest on a more easterly trajectory too far to the southeast into what should be an area of ridging. The 00z UKMET is slow with its ejection while the 00z Canadian/06z GFS are faster. Normally, faster wouldn't be better in this sort of amplified environment, but at the surface a compromise of the 00z Canadian/06z GFS has the most support of the 00z NAEFS and 00z ECMWF ensemble members. The pressures, 500 hPa heights, and winds were derived from a blend of the 00z ECMWF/00z Canadian/00z UKMET/06z GFS from Wednesday into Thursday morning before lowering percentages of the UKMET and ECMWF with time and increasing the percentages of the 00z NAEFS/00z ECMWF with time. This led to a slightly quicker system moving through the East late in the period. The remaining grids will carry more ensemble mean weighting, as usual. ...Sensible Weather and Hazards... Generally, the South and East will be the wetter areas near and east of the upper trough while the remainder of the country will be relatively dry. The West and Northern Tier will see generally above average temperatures while below average readings will be mostly across the Southern Tier, with the notable exception of the Central High Plains during Wednesday afternoon. The main system will be a low pressure area forming in the Gulf of Mexico and sweeping east and northeast up the fall line through the East. With this system, moderate to heavy precipitation is expected again over the northwest Gulf Coast early on, perhaps focused right along the coast. 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. Roth 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