Extended Forecast Discussion NWS Weather Prediction Center College Park MD 1150 AM EDT Sat Sep 07 2019 Valid 12Z Tue Sep 10 2019 - 12Z Sat Sep 14 2019 ...Record heat to continue for the Lower Mississippi Valley/Gulf Coast next week... ...Overview and Guidance Evaluation/Preferences... The synoptic pattern across the CONUS at the beginning of the medium range period (Wednesday) is expected to feature an anomalously strong ridge over the southeast U.S. while troughing deepens in the west. As this trough advances toward the northern Plains mid to late week, the southeast ridge weakens and is shunted to mainly the Gulf Coast region. The northern Plains shortwave will deepen considerably by Thursday-Friday and force an area of low pressure and associated frontal system across the Upper Midwest and Great Lakes regions. Finally, as upper flow consolidates by mid to late next week, models show some consensus that another shortwave should dig toward the Pacific Northwest by next Friday, with an associated surface frontal system pressing inland, reaching the Great Basin/Rockies by Saturday. For this forecast cycle, the 00Z ECMWF, 06Z GFS, and 00Z CMC/UKMET were used as a starting point for Day 3, with the greatest weight placed on the ECMWF and GFS solutions. For Day 4 onward, the CMC and UKMET solutions were increasingly out of consistency with continuity and the ensemble means and therefore were not included. The preference was for a general blend of the 00Z ECMWF/ECENS and 06Z GFS/GEFS, gradually increasing the weight of the ensemble means toward Day 6-7 although the deterministic ECMWF and GFS did offer some utility through Day 7 and was incorporated in the model blend. ...Weather Highlights/Threats... Through the medium range period, heavy rainfall potential will be focused across the northern tier of the US, from portions of eastern Montana eastward through the northern Plains, Upper Midwest, and Great Lakes as a series of low pressure systems track through the area. Another area of heavy rainfall may accompany a cold frontal passage across the central Plains on Day 5-6 (Thur-Fri). The other weather headline will the continuation of much above normal temperatures across the southeast U.S. High temperatures are forecast to be 5 to 15 degrees F above average much of next week from the Gulf Coast region through the Tennessee, lower Ohio Valley, and Southeast. Taylor 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