Extended Forecast Discussion NWS Weather Prediction Center College Park MD 111 AM EST Sat Nov 7 2020 Valid 12Z Tue Nov 10 2020 - 12Z Sat Nov 14 2020 ***Tropical Storm Eta expected to affect the eastern Gulf Coast region, heavy rain for portions of the Southeast, and unsettled weather for the Pacific Northwest*** ...Overall Synopsis... A broad upper level trough over the west-central U.S. next week is expected to be anchored in place through this forecast period, with three separate shortwaves/low pressure systems pivoting around it. The Bermuda high and the anomalous upper ridge near the East Coast will limit the eastward extent of the trough. Meanwhile, the Tropics remain active with tropical cyclone Eta expected to visit the eastern Gulf of Mexico by the middle of next week. ...Guidance Evaluation/Preferences... The deterministic guidance is in good agreement on the overall pattern for the early to middle portion of next week, mainly owing to the trough/ridge magnitude. The 00Z GFS is a little slower with the low crossing the Great Lakes region, whilst the non-NCEP guidance is indicating a more progressive trend. The second system emerging over the Plains by the end of the week appears to be weaker and the GFS is faster than the model consensus by the time the low reaches the Ohio Valley region. The details are more uncertain regarding the third system arriving across the West Coast, with the 00Z CMC considerably stronger, and the ECMWF/EC mean are faster than the flatter GFS. For the WPC fronts/pressures forecast, there was a gradual trend from a GFS/CMC/ECMWF blend to more of a NAEFS/EC mean blend by next Saturday to mitigate the increasing model differences. ...Weather/Hazard Highlights... Tropical storm Eta is forecast to slowly track north over the eastern Gulf, bringing heavy rain and tropical-storm-force winds for portions of the western Florida Peninsula coast, but the worst conditions will likely remain offshore until the system eventually makes landfall, and both the timing and location of that remains highly uncertain. Meanwhile, 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. An extended period of unsettled weather is forecast to move across the Pacific Northwest by the end of the week, with heavy mountain snows spreading eastward to the northern Rockies with over a foot of snow possible. Persistent rain, heavy at times, will also be likely west of the Cascades through much of next week under an active upper-level pattern across the northeastern Pacific. 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 region. 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 Upper Midwest, with a good chance of a swath of mixed precipitation for the northwest portion of the area. Noteworthy rainfall, possibly heavy, is also possible for portions of the Southeast and Mid-Atlantic states towards the end of the week as Atlantic moisture will be ingested into the region ahead of the slow moving front. 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