Extended Forecast Discussion NWS Weather Prediction Center College Park MD 200 AM EST Tue Feb 22 2022 Valid 12Z Fri Feb 25 2022 - 12Z Tue Mar 01 2022 ...Heavy snow and ice threat spreads across the northern Mid-Atlantic and Northeast into Friday... ...Guidance Evaluation/Predictability Assessment... Models and ensembles still offer a reasonably similar larger scale pattern evolution through medium range time scales and a guidance composite seems ok for Friday. However, differences with the handling of smaller scale embedded systems is more varied, particularly from the weekend into next week with southern stream energies digging into the West before ejecting out across the central and eastern states. The 12 UTC ECMWF/UKMET and to a lesser extent the 12 UTC ECMWF/Canadian ensemble means are overall more amplified/less progressive than the 18 UTC GFS/GEFS mean and 12 UTC Canadian. Preferred a solution slightly on the more amplified side of the full envelope of solutions, most in line with the ECMWF ensemble mean, considering the bulk of guidance works an amplified upper ridge upstream into the West Coast. However, the 00 UTC models do not offer great run to run continuity with these suspect southern stream systems. ...Pattern Overview and Weather Highlights/Threats... A potent ejecting southern stream shortwave will interact with northern stream energies over the Great Lakes/Ohio Valley Friday. Moisture will stream over a leading front to fuel enhanced precipitation across the high pressure/cold air dammed northern Mid-Atlantic and Northeast. Frontal wave approach and coastal low reformation will favor a pronounced swath of significant snow and ice on the northern/western side of the precipitation shield that will lift enhanced in the right entrance region of a strong upper jet. Cold high pressure will settle across much of the country in the wake of this system. This will include Friday some record cold pockets both over CA/AZ and the Plains as well as lingering record pre-frontal warmth under amplified upper ridging over the Southeast. Overall, the pattern will favor a drier pattern for many. An exception may be from The South through the Southeast/Mid-Atlantic Saturday-Monday where uncertain ejecting shortwave amplitude may be sufficient to support a swath of enhanced precipitation. Another exception may be with advent of modest precipitation for the Pacific Northwest starting this weekend with the likely slow approach of northeast Pacific systems. Schichtel 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