Extended Forecast Discussion NWS Weather Prediction Center College Park MD 259 AM EDT Tue Oct 8 2024 Valid 12Z Fri Oct 11 2024 - 12Z Tue Oct 15 2024 ...Overview... An initial Northeast/Mid-Atlantic upper trough should push off the coast on Friday, while a central U.S. ridge will continue to bring much above normal temperatures but with northern stream energy dampening the northern periphery. This energy should amplify as it reaches the East Coast this weekend setting up another round of Eastern U.S. troughing early next week. Meanwhile out west, one shortwave into the Northwest this weekend will be followed by a much more amplified trough into the West Coast next week which will also act to amplify upper ridging downstream and another round of much above normal temperatures to the northern High Plains/Plains. ...Guidance/Predictability Assessment... Models show good agreement on the overall pattern evolution across the CONUS during the medium range period, but with some typical details differences especially into early next week. One initial area of uncertainty still lies with the first shortwave into the West this weekend and the CMC is still fastest with this feature and stronger with it as it moves into the south-central U.S. while the rest of the guidance shows stronger riding over this region. The CMC is also not as amplified and much faster with the shortwave into the Northeast late weekend/early next week, and is also a little more muted/faster with the next trough into the West next Tuesday. The WPC forecast for tonight leaned heavily towards the ECMWF and GFS for the first half of the period, increasing the ensemble means late period, but still maintaining a slightly majority deterministic blend on Day 7. ...Weather/Hazards Highlights... A large part of the lower 48 will see fairly dry weather for a majority of the period. A compact eastern Pacific upper trough/low may bring a brief period of mostly light rainfall to the central West Coast around Friday-Saturday, with a little light precipitation possibly reaching farther eastward into the West thereafter. Then a front approaching the Pacific Northwest may bring some moisture into the region by the start of next week. The amplifying upper trough and accompanying surface evolution should bring some areas of rainfall to parts of the Great Lakes/Northeast by late weekend into the early part of next work week, though with fairly low confidence in specifics at this time. A central U.S. upper ridge will continue to promote an extended period of well above normal temperatures with northern stream troughing and a cold front pushing the greatest warm anomalies southeast with time from the central Plains and Mid/Upper Mississippi Valley to the Southeast Friday- Saturday. Temperatures around 10 degrees above normal in the Southwest could set additional daily records though the temperatures have moderated compared to recent days and the short range. The northern Rockies/High Plains may see temperatures reach up to 10-20F above normal by early next week. Meanwhile, some near to slightly above normal temperatures in the East this weekend should be replaced by temperatures generally 5-10 degrees below normal next week underneath amplified troughing. 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 forecast (QPF), excessive rainfall outlook (ERO), winter weather outlook (WWO) probabilities, heat indices, and Key Messages can be accessed from: 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 https://www.wpc.ncep.noaa.gov/#page=ovw