Extended Forecast Discussion NWS Weather Prediction Center College Park MD 158 AM EST Tue Jan 05 2021 Valid 12Z Fri Jan 08 2021 - 12Z Tue Jan 12 2021 ...Overview... A progressive synoptic pattern will persist over the CONUS through the period with systems affecting the Northwest, South, and Southeast. Western systems will primarily track into Canada with daily light to modest precipitation for especially coastal Washington and Oregon. Lead system in the Southeast Friday will move off the coast and out to sea as a southern Rockies system heads for the Texas coast. Modest to heavy rain could accompany the system near the TX/LA coast. That front will move eastward through the Gulf and perhaps off the Southeast/Mid-Atlantic coast by next Mon-Tue. Wavy west-to-east flow will keep any arctic air in Canada for the next week, but troughing into the southern Plains will promote cooler than normal temperatures by next week. ...Guidance/Predictability Assessment... Global guidance continues to depict varied solutions with the succession of shortwave features out of the Pacific and struggle with how the northern/southern portions of the waves will evolve. Preference remains closer to the 12Z ECMWF though confidence was no better than average as no model has had great continuity. The rather agreeable GEFS/ECENS means served as a best guide by next week with uncertainty off the Southeast coast. Recent GFS runs remained a bit on the quicker side but the consensus has trended quicker at times for some systems, perhaps a function of differing wave interactions rather than longwave progression. ...Weather/Threats Highlights... The Pacific Northwest will continue to see periods of precipitation about every other day Fri-Tue with the heaviest amounts perhaps next week. Low pressure over South Carolina early Friday will turn northeastward and spread some rain and elevation snow over the Carolinas and southern Mid-Atlantic region Fri-Sat and perhaps into far eastern New England this weekend. Next system out of the southern Rockies will tap the Gulf for moisture into the Texas and Louisiana coasts late Saturday/early Sunday into Monday. This could lead to a heavy rain threat for east-central Texas to the central Gulf Coast though the heaviest rainfall may be just offshore. To the north, temperatures may be cold enough for some light wintry weather near the ArkLaTex. Temperatures will be well above normal along the Canadian border by about 10-20 degrees, especially for overnight lows, through the period. Near normal temperatures can be expected from the central Plains eastward and over California. Below normal temperatures are expected over the central Rockies southeastward to Texas behind the cold front and with the upper trough. Highs may be 5-10 degrees below normal. Fracasso 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