Extended Forecast Discussion NWS Weather Prediction Center College Park MD 313 AM EDT Tue Oct 22 2019 Valid 12Z Fri Oct 25 2019 - 12Z Tue Oct 29 2019 ...Guidance/Uncertainty Assessment and Weather Highlights/Threats... Models and ensembles continue to show quite varied medium range solutions that mainly stem from the extent of short range shortwave digging down through the w-central U.S. and subsequent southern stream flow separation. Forecast confidence is not stellar. Recent ECMWF and to a slighly lesser extent ECMWF ensemble mean and Canadian/Canadian ensembles and to some extent the UKMET continue to show max digging within the full envelope of solutions. This leads to the most separated southern stream and most westward/amplified closed low development and slowest/wettest subsequent northeastward system track over the central then eastern U.S. at medium range time scales as a new upstream upper trough amplifies sharply back over the West and upper ridging builds over the Southeast. Recent GFS and to a lesser extent GEFS runs instead show the least short range digging over the West that subsequently offers much less downstream southern stream separation, no closed low development, and way more progressive and eastward flow over the central to eastern U.S. that offers a significantly less heavy rainfall threat. Still suspect that the sharp upper ridge amplitude building into the West coast over the next couple of days and sufficient wavelength spacing from subsequent upstream upper trough approach from the Pacific should favor a solution well on the more amplified and southern stream/closed low separated side of the aforementioned full envelope of guidance solutions. Given the GFS/GEFS have not trended significantly in that direction with the latest 00 UTC runs, opted to not jump all the way to the ECMWF at this point given lingering uncertainty. However, suggest preference of the still stormy ECMWF ensemble mean and the Canadian/Canadian ensemble mean that were primarily used as a starting point for the WPC medium range product suite. This solution offers a threat of widespread heavy rainfall/convection centered over the South Fri into the weekend from the main lead system and substantial cooling upstream over the West/Rockies to include a threat of heavy mountain snows to occur by early next week upper trough amplification. Schichtel 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