Extended Forecast Discussion NWS Weather Prediction Center College Park MD 200 AM EST Mon Jan 04 2021 Valid 12Z Thu Jan 07 2021 - 12Z Mon Jan 11 2021 ...Overview... A progressive synoptic pattern will persist over the CONUS through next weekend with activity focused on the Pacific Northwest. On Thursday there will be a southern system over the south-central Plains that will move east, lifting northeastward along/off the Carolina/Mid-Atlantic coast Friday/Saturday, respectively. In the West, a series of systems persists, producing continued/additional coastal rain and mountain snow for northern California and western Oregon/Washington. By the weekend into next Monday, a system off the Texas coast may move across the Gulf with another focus for rainfall. ...Guidance/Predictability Assessment... Global guidance continues to depict varied solutions with the succession of shortwave features out of the Pacific and how the northern/southern portions of the waves will evolve. A blended solution couched mostly in the 12Z ECMWF offered a good starting point. The GFSp paired better with the ECMWF than did its operational version (current GFS), though the pattern suggests any agreement between models means less than normal. By later in the period, preferred a majority ensemble weighting which takes the southern trough to the Gulf of Mexico with potential surface cyclogenesis along the central Gulf Coast. ...Weather/Threats Highlights... The Pacific Northwest will continue to see systems arrive about every other day through the period though the best focus for heavier amounts will be in Canada and the Alaska panhandle. Low pressure in the lower Mississippi Valley Thursday will move eastward as an expanding area of rain precedes the front (and some snow on the north side of the system in the marginally cold air mass). As the system reaches the coast, it will turn northeastward and spread some rain/snow over the Carolinas and Mid-Atlantic region Fri-Sat and perhaps into New England Sat-Sun (if it remains close enough). Next system out of the Interior West will tap the Gulf for moisture into the Texas and Louisiana coasts next Sunday into Monday. This could lead to a heavy rain threat for east-central Texas Sunday into Monday. Temperatures will be well above normal along the Canadian border by about 10-25 degrees, especially for overnight lows, through next week. Modestly above normal temperatures can be expected for most of the rest of the CONUS into late next week with a general cooling pattern toward modestly below normal temperatures, especially over Texas, as successive lows track farther south. Fracasso/Jackson 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