Extended Forecast Discussion NWS Weather Prediction Center College Park MD 138 PM EST Tue Jan 21 2020 Valid 12Z Fri Jan 24 2020 - 12Z Tue Jan 28 2020 ...Overview... The medium range period will start Fri with a closed upper low over the central U.S., moving eastward across the Ohio Valley and the Northeast over the weekend. A series of Pacific systems will progress into the West, and troughing may become more consolidated there early next week. ...Guidance/Predictability Assessment... The upper low in the central/eastern U.S. seems to be handled pretty well by model guidance, with the 00Z/06Z GFS and 00Z ECMWF and UKMET clustering well through Sat. The 00Z Canadian as well as some of its ensemble members were slower with the upper low over the weekend, which led to a slower surface low as well, so leaned away from that solution as it was not particularly supported by other model systems. By Sun the GFS runs were a bit faster with the track compared to the closely clustered ECMWF and UKMET. But overall a multi-model blend worked well for this system given the close model consensus. Ridging is expected to build in behind the upper low. As a series of shortwave troughs and surface fronts approach the West, a multi-model consensus was used for now through Sun, without major differences in the models and allowing for blending to smooth out the minor ones. By Mon, deterministic models diverge as GFS runs split northern and southern stream energy coming into the West which creates a faster progression through Tue, while the 00Z ECMWF consolidates the energy and builds a slower upper low in the Four Corners region. The 06Z GFS even had a faster trough axis than its mean, so heavily weighted the EC and GEFS means by Mon/Tue. ...Weather/Hazard Highlights... An occluded low pressure system will move in conjunction with the upper low across the central/eastern U.S., leading to modest to locally rain ahead of the system. There is also potential for wintry weather on the backside of the low across parts of the Midwest/Ohio Valley into the Great Lakes and the interior Northeast. Snowfall could be enhanced in higher elevations, including the Endless Mountains of northeastern Pennsylvania and Poconos, then into the Catskills and Berkshires, and finally into the Green/White mountains and Maine. Snow is also expected for the Central Appalachians. Given the active pattern in the West, rounds of precipitation will continue. Higher elevations can expect snow with lower elevation rain, but snow levels will be near or above normal given the overall milder pattern. Speaking of which, most of the CONUS will remain near or above average temperature-wise in the medium range, with the highest anomalies of 10 to 25 degrees across the north-central tier of the U.S. Tate 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