Extended Forecast Discussion NWS Weather Prediction Center College Park MD 207 AM EST Sun Feb 16 2020 Valid 12Z Wed Feb 19 2020 - 12Z Sun Feb 23 2020 ...Guidance/Predictability Assessment... Model and ensemble mass field forecast spread remains below normal through medium range time scales and lingering system timing/emphasis differences seem well mitigated by blending guidance. The WPC medium range product suite was based mainly from a blend of the latest GFS/ECMWF/UKMET and GEFS/ECMWF ensemble means. However, increased blend weighting was applied to the ECMWF/UKMET Wed-Fri then ECMWF ensemble mean next weekend amid growing variance. Overall, the ECMWF/UKMET and ECMWF ensemble mean offer more suppressed QPF for the U.S. southern tier than the GFS/Canadian and GEFS mean that seem overdone considering varying support aloft and the predominance of surface high pressure and limited moisture. ...Weather Pattern and Hazard Highlights... The upcoming medium range pattern will feature cold post-frontal high pressure that will settle over much of the lower 48. A northern stream mid-upper level trough will progress from the n-central U.S. to off the East Coast Wed-Fri in response to the steady deamplification of upstream ridging aloft over Canada. Organized precipitation potential will be mainly limited to the U.S. southern tier from the southern Rockies/Plains through the South/Southeast closer to and overrunning a trailing frontal zone. This may include some wintry activity on the northern periphery of precipitation, with most potential over the southern Rockies/High Plains midweek aided by ejecting southern stream impulses and upslope fetch. The models also show a favorable trend to develop an amplified upper trough/low into an emerging southern stream flow off the West Coast later week. It remains uncertain the effect of this system with potential inland progression with modest precipitation potential next weekend into the Southwest then s-central states in increasingly split flow. Meanwhile, development and weekend approach of an amplified northern stream mid-upper level trough and surface front seems to also support potential for an increasingly wet flow focus into the Pacific Northwest. 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