Extended Forecast Discussion NWS Weather Prediction Center College Park MD 1151 PM EDT Mon Oct 05 2020 Valid 12Z Fri Oct 09 2020 - 12Z Tue Oct 13 2020 ...Heavy rainfall from Hurricane Delta and the remains of Gamma headed for Gulf states and the Southeast... ...Strong winds, storm surge and coastal flooding likely to impact parts of the Gulf Coast as Delta approaches and then makes landfall... ...Major pattern change expected for the western U.S. with cooler temperatures and increasing precipitation into early next week... ...Overview... Much of the extended period will be in a progressive pattern with a trough over the East that slowly weakens, while a trough moves through the West and amplifies over the Plains with a storm taking shape across the Northern Plains early next week. Outside the 00z Canadian, there was fair clustering of the 12z UKMET, 12z ECMWF, 18z GFS, and the 12z ECMWF/GEFS/NAEFS ensemble means. A combination of the 18Z GFS/12Z ECWMF/12z UKMET was preferred early on to deal with lingering progression spread (UKMET slower and GFS quicker), and for the rest of the periods increasing amounts of the 12z ECMWF/NAEFS ensemble means were used for the pressures/winds/500 hPa heights. ...Weather/Hazard Highlights... Hurricane Delta is expected move through southeast Mexico into the Gulf of Mexico before re-curving northward while either absorbing Gamma or flinging its remains around its southern and southeast side. Delta is expected to make landfall late on Friday and then continue to track north/northeast, spreading heavy rainfall across the Gulf states/Tennessee Valley and into the Appalachians and Mid-Atlantic regions over the weekend. Strong winds, storm surge and coastal flooding will impact stretches of the Gulf Coast as Delta draws closer to the southern U.S. Localized intense rainfall may cause scattered/widespread urban and river flooding along/near its track. Across the West, a potent trough will favor a period of cooler than average temperatures along the West Coast and into the Great Basin by Sunday. Additionally, precipitation will increase through the end of the week and this weekend across the West with snow possible in the higher terrain of the Cascades and the Northern/Central Rockies. This very much needed precipitation should provide some relief from ongoing fire weather concerns. Due to the relatively zonal flow/progressive pattern, areas east of the Rockies are expected to near to above average temperatures due to downslope flow offsetting the cold advection, even in the wake of a cold front early next week. Record highs could be threatened across portions of NM/TX on Friday and Saturday before the cold front/upper trough advance into the region. Roth 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