Extended Forecast Discussion NWS Weather Prediction Center College Park MD 311 AM EDT Sat Oct 22 2022 Valid 12Z Tue Oct 25 2022 - 12Z Sat Oct 29 2022 ...Model and Predictability Assessment and Weather/Hazard Highlights... Model and ensemble solutions have trended towards better agreement recently and show fairly good agreement on the overall pattern, but increasingly have run to run variability and forecast spread on the small-mid scale interactions/details through next week. The WPC product suite was primarily derived from a composite blend of the GFS/ECMWF/UKMET/Canadian Tuesday along with the compatible 01 UTC National Blend of Models. Switched to a blend of still reasonably compatible GFS/ECMWF and GEFS/ECMWF ensemble means Wed-Saturday to smooth out component detail consistent with predictability. A potent upper trough/closed low is slated to lift/shear northeastward across the central U.S. and Great Lakes/Midwest/Northeast though early-mid week. Timing and amplitude issues remain in the guidance, but forecast spread has steadily decreased over the past few days. The pattern should focus Gulf moisture and instability into the developing lead frontal system where strong to severe thunderstorms are possible along with increasingly progressive convective rains over time. The best potential for multiple inches of rainfall may be over the Mid-South and vicinity Tuesday coincident with any closed signature aloft. Adjusted NBM QPF that seems underdone with afternoon/evening trailing cold frontal convective rainfall potential in deeper moisture and favorable support aloft. Periodic uper trough energy flow into the West Coast by early next week and as renewed later next week continue to be handled differently by the models despite some recent improving agreement, mainly on digging/amplitude. Even so, the pattern does show a decent signal for a period of much below normal cold over the West/Rockies and composite system amplitudes should still favor a decent and repeatable moderate QPF coverage response to include additional heavy snow threats with focus over favored terrain from the West Coast states through the Great Basin and the Rockies. A main and possibly closed southern stream system remains slated to emerge over the south-central to southern U.S. late next week into next weekend to renew rain/convection, although uncertainty on placement/amounts remain highly variable. Elsewhere, the evolution associated with pesky/lingering upper troughing over the Mid-Atlantic and troughing focus/intercation with a blocking ridge offshore the Northeast through at least early next week remains uncertain and run to run inconsistent in guidance. However, the pattern does offer support for coastal effects and broad scale modest QPF with protracted inflow, albeit with diminshing influence through medium range time scales. Schichtel Additional 3-7 Day Hazard information can be found on the WPC medium range hazards outlook chart at: https://www.wpc.ncep.noaa.gov/threats/threats.php WPC medium range 500mb heights, surface systems, weather grids, quantitative precipitation, experimental excessive rainfall outlook, 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/#page=ero https://www.wpc.ncep.noaa.gov/wwd/pwpf_d47/pwpf_medr.php?day=4 https://www.wpc.ncep.noaa.gov/heat_index.shtml