Extended Forecast Discussion NWS Weather Prediction Center College Park MD 126 PM 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 continue to trend towards better agreement on the overall pattern, but do still show some 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 Tuesday and Wednesday. By day 5/Thursday, incorporated increasing parts of the ensemble means along with reasonably compatible GFS/ECMWF Thursday-Saturday to smooth out some of the lingering differences. This also maintained good continuity with the previous WPC forecast. A potent upper trough/closed low is slated to lift/shear northeastward across the central U.S. and Midwest/Great Lakes/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 00z CMC seems too quick to lift the system north and was not included in todays blend. The ECMWF/UKMET are a nice compromise, with the 06z GFS a little slow (but the 12z run came in faster). 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 parts of the middle Mississippi Valley/Midwest on Tuesday into Wednesday coincident with any closed signature aloft. This area has been very dry recently and so much of this rainfall may be more beneficial than particularly hazardous. Needed a noticeable increase from the 13z NBM QPF across this region, and north into Michigan, where the NBM seemed underdone with afternoon/evening trailing cold frontal convective rainfall potential in deeper moisture and favorable support aloft. Light and more scattered precipitation should quickly race off into the Great Lakes and Northeast by later Wednesday and into Thursday, with some lake enhancement possible after the upper low moves through. Periodic upper trough energy flow into the West Coast by early next week and as renewed later in the week continue to exhibit some differences mainly with amplitude/timing although with some recent improving agreement. Even so, the pattern does show a good 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 higher terrain heavy snow threats from the West Coast states through the Great Basin and the Rockies. A main and possibly closed southern stream system remains slated to again 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 weak upper troughing over 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 diminishing influence through medium range time scales. Santorelli/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