Extended Forecast Discussion NWS Weather Prediction Center College Park MD 208 AM EST Wed Feb 19 2020 Valid 12Z Sat Feb 22 2020 - 12Z Wed Feb 26 2020 ...Dynamic Southwest to Northeast U.S. then Wintry Northwest to Midwest Lows... ...Guidance/Predictability Assessment... Latest model and ensemble solution spread slowly increases over time, but remains at below normal values overall through medium range time scales. This bolsters forecast confidence. WPC medium range products were based mainly from a composite blend of well clustered guidance from the 12 UTC GFS/ECMWF, 12 UTC GEFS/ECMWF ensemble means, and the National Blend of Models. Blend emphasis was gradually transitioned from the models toward the ensemble means days 3-7 to address lingering system timing and emphasis differences. WPC continuity was well maintained and the newer 00 UTC models and ensembles now overall seem in line. ...Weather Pattern and Hazard Highlights... System #1: Mainly dry high pressure will linger over the East this weekend in anticipation of an approaching southern stream system set to progress from southern California and the Southwest U.S. to the south-central U.S. A moderate precipitation swath from the Southwest/Four Corners/Rockies Saturday will include terrain enhanced snows. Precipitation will develop more in ernest into the Mid-Lower MS and TN Valleys Sun and spread across the eastern states through early next week as height falls and main surface system tracks east-northeastward. Gulf of Mexico return flow will promote locally moderate to heavy rainfall over parts of the mid-lower Mississippi and Tennessee Valleys/southern Appalachians, areas that will be sensitive to additional rainfall given ongoing runoff issues. This will be a fairly warm system, but there is a risk for snow/ice on the northern periphery (particularly for the Northeast) of the growing precipitation shield as the ambient/cold high pressure dome recedes and with coastal low development. System #2: Upstream, a more northern stream upper trough/surface system moving into the Northwest Sunday will dig through the Great Basin and Rockies Sunday will bring enhanced rain and higher elevation snow and unsettled flow to the Pacific Northwest, with some heavy snow risk over the north-central Great Basin/Rockies/Plains with slow system progression and reinforcement. Downstream progression over the east-central states into next midweek offers an emerging pattern for moderate lead precipitation, but there would especially be a threat of heavy wrapback snows over the cooled n-central U.S. considering upper support. Schichtel Additional 3-7 Day Hazards information can be found on the WPC medium range hazards 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