Extended Forecast Discussion NWS Weather Prediction Center College Park MD 210 AM EST Sun Jan 16 2022 Valid 12Z Wed Jan 19 2022 - 12Z Sun Jan 23 2022 ...Pattern Overview... A mean upper ridge will amplify along/off the West Coast by mid-later week. This will allow a series of northern stream impulses carve out and reinforce a large mean trough downstream over the central to eastern U.S. later week into the weekend. Of the main shortwaves, the first should slide over the Great Lakes into the Northeast Wednesday and Thursday, with the next tending to dig more sharply into the South Friday and up off the Mid-Atlantic/Southeast coast Saturday. There is significant forecast spread and run to run uncertainty with this latter feature and associated mid-winter weather focus with frontal wave/coastal low genesis. ...Guidance/Predictability Assessment and Weather Highlights/Hazards... The WPC medium range product suite was mainly derived from a model and ensemble composite days 3-7. There is good agreement with an organized low pressure system set to dig into the north-central U.S. and subsequently track moving eastward along the U.S./Canadian border Wed/Thu. This should bring some snow to the Great Lakes then northern New England, with locally higher totals expected near typical lake enhancement areas as cold high pressure sweeps down across the central and eastern U.S. in the wake of the low in a pattern with above normal predictability for these features. The wavy trailing cold front on the leading edge of this Arctic blast will gain some Gulf moisture to fuel an emerging area of precipitation up from the South/Southeast. Guidance varies however with potential focus due to ample run to run trough track/separation uncertainty aloft later week into the weekend. The pattern offers potential into later week for an enhanced swath of overrunning snow/ice on the northern periphery of activity. A cluster of multi-model ensemble members along with in particular the 18 UTC GFS and now the latest 00 UTC ECMWF/Canadian models, are much more robust with frontal wave to coastal low/storm genesis and mid-winter precipitation extent across the region and up the East Coast at these longer time periods. However, the 00 UTC GFS has backed off. The preferred model and composite trends WPC product continuity toward more organized and closer to the coast genesis and track, but now at this point as strong as some of the models. Meanwhile, The West could see some light precipitation through the period, particularly over the Pacific Northwest and into the Northern Rockies as weakening systems cross the region, with mainly dry conditions elsewhere. 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