Extended Forecast Discussion NWS Weather Prediction Center College Park MD 243 PM EDT Tue Oct 06 2020 Valid 12Z Fri Oct 09 2020 - 12Z Tue Oct 13 2020 ...Heavy rainfall, strong winds, and coastal flooding likely from from Hurricane Delta over parts of the central Gulf coast later this week into the weekend... ...Major pattern change expected for the western U.S. with cooler temperatures and increasing precipitation into early next week... ...Overview and Guidance Evaluation/Preferences... Much of the extended period will be in a modestly amplified but still progressive pattern with a trough over the East that slowly weakens, while a trough moves through the West and amplifies over the Plains. Hurricane Delta is forecast to make landfall along the Gulf coast and into the Southeast as a robust cold front moves across the Plains early next week. The deterministic and ensemble guidance was less than desirable over the CONUS, due in part by timing differences off/into the West Fri-Sat as well as with the track of Delta into the Gulf Coast and inland. Latest 15Z NHC track was best represented by a 06Z GFS and 00Z UKMET/Canadian blended solution in the medium range as the ECMWF/ECMWF ensembles were slower and farther southwest (and weaker). For the West, opted to stay nearer to continuity via the 00Z ECMWF/UKMET/Canadian vs the slower GFS and ensembles. Another model/ensemble cycle may clarify some timing issues as the 12Z deterministic trend has been a bit slower. ...Weather/Hazard Highlights... Hurricane Delta is forecast to make landfall late Friday/early Saturday over the Gulf coast and then continue to track northward/northeastward. This will spread heavy rainfall across the Gulf states/Tennessee Valley and into the Appalachians and perhaps 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 flooding along/near its track especially in areas that have seen an abundance of rainfall the past few weeks (central LA/MS where 14-day rainfall is 2-4X normal despite a recent dry period). 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 see 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 the Southwest to central Plains Friday and NM/TX this weekend before the cold front/upper trough advance into the region. Mild temperatures for mid-October are also expected into the Great Lakes ahead of the central states system. Fracasso/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