Extended Forecast Discussion NWS Weather Prediction Center College Park MD 147 AM EST Thu Jan 6 2022 Valid 12Z Sun Jan 9 2022 - 12Z Thu Jan 13 2022 ...General Pattern Overview... A deep upper level trough coupled with an arctic surface high will be present across the north-central U.S. and then the East Coast through Tuesday with an amplified upper level flow pattern in place, and an upper ridge over the West Coast on Sunday. A split flow pattern develops over the eastern Pacific and this leads to a potential closed low near the Desert Southwest, and progressive shortwave impulses tracking from western Canada to the Great Lakes through the middle of the week. ...Guidance/Predictability Assessment... The 00Z model guidance suite and ensembles continue to agree quite well on the overall synoptic scale pattern, particularly through Monday. Going in early next week, the models still have a good handle on the deep trough over the East Coast region and the timing of the cold front passage. Then models and ensemble members continue to vary for specifics of how eastern Pacific shortwave energy may split as it nears the West Coast. These differences ultimately affect flow over/near the Southwest as well as locations east of the Rockies, with northern stream flow determined in part by how Pacific energy goes around the western U.S. ridge and southern tier flow influenced by the pattern to the west. The WPC forecast was based primarily on a multi-deterministic model blend through Tuesday, and then gradually increasing use of the ECENS and GEFS means through early next week while still keeping about 50 percent of a CMC/ECMWF/GFS blend.. ...Hazards/Sensible Weather Highlights... Gulf moisture advecting northward ahead of a developing Plains/Midwest cold front will support increasing coverage of showers and thunderstorms from eastern Texas and the central Gulf Coast to the central Appalachians and Mid-Atlantic region this weekend, with lighter precipitation expected farther north. There will likely be some embedded heavier rainfall across portions of the Deep South where convection is persistent, and some localized flooding is within the realm of possibility. Areas from the upper Great Lakes to the Northeast could see wintry weather, with the best snowfall prospects over Michigan and northern New York as a result of lake effect snow. Freezing rain and/or sleet may be among the hazards over and near parts of the northern half of the Appalachians for a time as moisture overruns cold air at the surface. Dry conditions will likely prevail over a majority of the country for Monday and Tuesday. Exceptions include some showers and mountain snow over western Washington and Oregon as one or more systems cross the region and some precipitation over the Southwest and southern Plains by Wednesday. The next blast of arctic air makes its presence known across the Northern Plains and Upper Midwest by Sunday in the wake of the strong cold front, and this cold weather will eventually reach the East Coast in modified form as well, bringing highs down to 10-25F below normal from the Mid-Atlantic through New England on Tuesday for one of the coldest days of the year thus far. It should still be rather mild across the Southeast U.S. ahead of the front on Sunday before a return to reality by Monday. The northern-central Plains will trend warmer next week, reaching 10-15F or so above normal over some locations by Tuesday-Wednesday. Seasonably cold conditions are likely west of the Continental Divide with readings generally within 10 degrees of climatological averages. Hamrick Additional 3-7 Day Hazard information can be found on the WPC medium range hazards outlook 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