Extended Forecast Discussion NWS Weather Prediction Center College Park MD 1203 PM EDT Wed Oct 02 2019 Valid 12Z Sat Oct 05 2019 - 12Z Wed Oct 09 2019 ...Overview and model uncertainty assessment... Global deterministic guidance has variability in the pattern beginning this weekend with the strength of the ridge up the BC to AK coast and the downstream north-central CONUS trough ejecting northeast across the western Great Lakes. The ECMWF remains more amplified than other guidance both this weekend and into the middle of next week for all troughs and ridges over North America. The strong ridging over the Aleutians has a teleconnection favoring a multi-day mean of ridging over the eastern CONUS, so the operational 00Z ECMWF was limited starting on Day 5 in favor of ensemble means. Another area of uncertainty is an upper trough approaching the Pacific Northwest Tuesday into Wednesday. The ECMWF continues to favor an upper low to form near the shore while the GFS is much more progressive with an open trough pushing inland. As the 06Z GFS/GEFS was even more progressive with this feature than the 00Z, the 00Z NAEFS was used. The WPC forecast package was primarily derived from a composite blend of the 06Z GFS and the 00Z ECMWF through Day 4 with increasing weight on the 00Z ECENS and NAEFS means for Days 5 to 7. ...Weather Pattern Highlights/Threats... A cold front progresses from the Plains to across the Midwest Saturday into Sunday before slowing down and not reaching the East Coast until Monday night. This slowing causes an increased chance for heavier rain to linger across the Tennessee Valley into the Northeast. A decrease in forcing looks to bring more general rain through the East Coast Monday. Record high temperatures will be limited to the Deep South by Saturday as a cold front progresses east while well below normal temperatures spread in behind the front. The western U.S. upper trough will bring scattered rain/high elevation snow to the Pacific Northwest and northern Rockies Monday into the middle of next week. Meanwhile, tropical moisture will bring a good chance of thunderstorms across Florida starting Monday. The heaviest rains are expected to stay in the Gulf of Mexico through the middle of next week. Jackson 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