Extended Forecast Discussion NWS Weather Prediction Center College Park MD 150 AM EST Tue Feb 16 2021 Valid 12Z Fri Feb 19 2021 - 12Z Tue Feb 23 2021 ...Much below normal temperatures continuing through Saturday from the Plains to the East... ...Active weather expected across the Pacific Northwest and northern Rockies through the period... ...Overview and Guidance Evaluation... Following a very active short range period, the medium range should finally begin transitioning towards a less amplified/less active weather regime into early next week. The exception to this will be in the Pacific Northwest where multiple shortwaves will keep the weather active with several opportunities for heavy mountain snow and lower elevation rain. Synoptically, the latest guidance continues to show very good agreement through the period, with mainly typical timing and detail differences needing to still be resolved. In the East, the CMC/UKMET are faster with the surface low exiting the Northeast on Friday, while the GFS/ECMWF show better agreement with the ensemble means for low position. The next system ejecting out of the Rockies on Sunday also has some minor timing differences, but a blend of the CMC/ECMWF seems to agree best with the ensemble means. Given this assessment, the WPC blend relied heavily on the ECMWF/GFS for days 3-4, replacing the GFS with the CMC thereafter while also increasing contributions from the ensemble means. This maintains good continuity with the previous forecast. ...Weather/Threats Highlights... Lingering heavy snow across interior and northern New England will continue through Friday associated with the storm system exiting the East Coast. The heaviest rainfall will have pushed off the coast by the start of the period, although some lingering showers are possible across the Outer Banks and Florida along the trailing cold front. The West should stay active through the entire period as multiple fronts pass through the region. These will each bring the potential for additional focused rainfall along coastal portions of Washington/Oregon with heavy mountain snow in the Cascades, Northern Rockies, and Northern California. Precipitation should begin to break out across the Plains this weekend as a frontal system moves through, with wintry precipitation possible on the northern side of the system across the Upper Great Lakes region. Temperatures will remain much below normal Friday into Saturday from much of the Southern Plains to the East, with departures from normal as much as 20-30F for some areas. By Sunday, temperatures should finally begin to moderate back close to normal into early next week. Meanwhile, expect a warming trend across especially the Southwest and Northern Plains, with above normal temperatures maybe creeping into parts of the southern/central Plains as well by next Tuesday. Santorelli 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