Extended Forecast Discussion NWS Weather Prediction Center College Park MD 148 AM EST Thu Jan 30 2020 Valid 12Z Sun Feb 02 2020 - 12Z Thu Feb 06 2020 ...Overview and Guidance/Predictability Assessment... An upper-level trough is forecast to move off the Eastern Seaboard on Sun (day 3) as a deepening surface low moves along the east coast of Canada. The western and central U.S. will be the more active regions of the CONUS through much of the remainder of the extended forecast period. Models show good consensus around a positively-tilted but amplified shortwave forecast to reach the Northwest Sat night-Sun. The wave is forecast to further amplify as it crosses the Great Basin Sun night-Mon and crosses the Rockies approaching the central U.S. Mon night-Tue. Model consensus with this features has been better than farther east the past several days, but differences do emerge as the feature crosses the interior West. The ECMWF/CMC show the wave undergoing more amplification relative to the GFS. This eventually results in a timing difference for the low pressure system expected to develop across the Southern/Central Plains and move northeastward Mon-Wed (eventually reaching the eastern states). Based on the ensemble means, observed spread/clustering among ensemble members, and typical biases, opted to lean away from the faster GFS timing with the central/eastern U.S. trough, and associated low pressure system by the middle of next week. Otherwise, the WPC forecast was initially based on a multi-model deterministic blend (12Z UKMET/ECMWF/18Z GFS) for days 3-5 (Sun-Tue). The forecast for days 6-7 (Wed-Thu) was based on increased ensemble mean weighting (ECENS/NAEFS), and more weight on the ECMWF relative to the GFS. ...Weather/Hazard Highlights... Onshore flow persisting across the Pacific Northwest will keep rain/mountain snow in place across western Oregon/Washington on Sun before potentially (briefly) drying out on Mon. Farther inland, the shortwave/cold front will bring rain/snow to much of the interior West Sun-Mon, from the Great Basin to the central/northern Rockies. Additional rain/snow, potentially heavy at times, is forecast to reach the Pacific Northwest next Wed-Thu as a low pressure system moves from the North Pacific into western Canada, bringing a plume of increased moisture to Washington/Oregon and eventually the interior Northwest. Farther east, moisture return ahead of the upper trough and surface front will bring showers and possibly thunderstorms from the lower Mississippi Valley to the Southeast and Mid-Atlantic Tue-Thu. Farther north, sufficient cold air may be in place for some wintry precipitation Tue-Wed from the Midwest/Mid-Mississippi Valley to the Northeast. Temperatures are forecast to be well above average across the central U.S. Sun-Mon, and the eastern U.S. well into next week. High temperatures of 15 to 30 deg F above average are possible across the Plains on Sun, shifting toward the eastern U.S. by Mon. Meanwhile, the trough/cold front expected to reach the western U.S. this weekend will bring an end to above average temperatures, with highs 5 to 15 deg below average forecast to spread across the West Sun-Mon and persisting into the middle of next week for the interior west. Ryan 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