Extended Forecast Discussion NWS Weather Prediction Center College Park MD 156 AM EST Fri Nov 6 2020 Valid 12Z Mon Nov 9 2020 - 12Z Fri Nov 13 2020 ***Cold across the West and mild for the Eastern U.S., and Eta likely affects southern Florida*** ...Overall Synopsis... A deep upper level trough will become anchored in place across the western U.S. for most of the upcoming week, with three identifiable shortwave perturbations rotating around it and then ejecting over the High Plains. This amplified pattern will sustain an anomalous ridge centered over the western Atlantic, and this is not expected to move much during this forecast period. Meanwhile, tropical cyclone Eta is expected to eventually enter the Gulf of Mexico. ...Guidance Evaluation/Preferences... Similar to the past few days, the deterministic guidance is in excellent agreement through Wednesday on the synoptic evolution of the trough and the first two shortwaves, with the GFS slightly faster across the Great Lakes region. The CMC becomes more amplified with the second disturbance crossing the Intermountain West, and the GFS is also slightly faster with this system. By the end of the week, the CMC and ECMWF are both slower and more amplified with the third disturbance near the West Coast, and the GFS not as strong and more in line with the ensemble means. Taking these factors into account, the WPC forecast was primarily derived from a GFS/ECMWF/CMC/ensemble mean blend through Wednesday, and then slightly more of the ensemble means for next Thursday and Friday. ...Weather/Hazard Highlights... Heavy rainfall is becoming increasingly likely for portions of southern Florida from both prolonged easterly flow and the arrival of Eta, which is currently forecast by the NHC to track near the Florida Keys on Monday and into Tuesday. The potential exists for high winds and several inches of rainfall, along with some flooding. The persistent western U.S. trough will result in much colder temperatures for much of the interior western U.S. next week, with widespread high temperatures of 10 to 20 degrees below normal. This will easily be a 30+ degree drop for some areas compared to the recent warm spell. Heavy snow will be possible for portions of the Colorado Rockies and the Cascades. The opposite will hold true across the eastern U.S. through much of next week, with temperatures that are expected to be 10 to 20 degrees above normal from the Midwest and Great Lakes region, and extending to the East Coast. Some daily record high temperatures will be challenged, especially over the Ohio Valley. As the trough axis slowly advances eastward across the High Plains by early next week, moisture interacting with the front will likely bring locally heavy rainfall to some locations across the central Plains to the Midwest, with a swath of wintry precipitation possible for the northern portion of the area. Noteworthy rainfall is also possible for portions of the Southeast and Mid-Atlantic region towards the end of the week as the front slowly approaches this region. Hamrick 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