Extended Forecast Discussion NWS Weather Prediction Center College Park MD 201 PM EST Thu Jan 12 2023 Valid 12Z Sun Jan 15 2023 - 12Z Thu Jan 19 2023 ...Unsettled and Active Pattern Continues for Western U.S. with focus on California Atmospheric Rivers... ...Overview and Guidance/Predictability Assessment... A series of shortwaves will split from their parent along the West Coast and swing across the midsection of the CONUS through next week. ...Weather/Hazard Highlights... The West will remain active as a series of shortwaves continues to direct unneeded additional heavy rainfall and mountain snows towards particularly California, but also the Pacific Northwest. The first in this series of extended range storms will arrive on Saturday just before the start of this forecast period, and the heaviest of the precipitation should be over by Sunday as the overall upper system moves inland. Still, any lingering rainfall over an already very over-saturated California may continue to worsen flooding or delay improvement of ongoing issues. Rain and higher elevation snows are possible in the Southwest on Sunday, and eventually return flow out of the Gulf of Mexico may increase precipitation chances into the Plains/Midwest as well early next week. The next in the series should arrive early next week again possibly exacerbating problems across California as it delivers more moisture into the region. Heavy rainfall could develop out into the Plains-Mississippi Valley-Midwest again along the attendant cold front next Wednesday, possibly heavy if a stronger storm manifests. There could be a chance for some snow/ice too in the northern periphery of the storm, amounts again highly dependent on storm strength. Above normal temperatures will move east with time from the Central U.S. this weekend into the Midwest and eventually the East early next week. The greatest anomalies should focus across the Deep South into the Midwest with daytime highs 15 to 20 degrees F above normal. Even more impressive will be the very warm nighttime lows, with readings 20 to 25 degrees F above normal generally across the same region from Sunday onward. Daytime highs across the West and Southwest should be near or below normal amidst plenty of clouds and rainy conditions. Santorelli 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, experimental excessive rainfall outlook, 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/#page=ero https://www.wpc.ncep.noaa.gov/wwd/pwpf_d47/pwpf_medr.php?day=4 https://www.wpc.ncep.noaa.gov/heat_index.shtml