Extended Forecast Discussion NWS Weather Prediction Center College Park MD 204 PM EDT Sun Oct 23 2022 Valid 12Z Wed Oct 26 2022 - 12Z Sun Oct 30 2022 ...Guidance and Predictability Assessment... Model and ensemble solutions continue to trend towards better agreement, bolstering forecast confidence longer into medium range time scales. The WPC product suite was mainly derived from a blend of the best clustered deterministic model guidance Wednesday-Thursday (with input from the 13z NBM). Beyond day 4/Thursday, there is increasing uncertainty in timing of the next southern stream possible closed low across the southern Plains, with the GFS seeming to show more run to run variability and a little faster progression with the system into the weekend. WPC preferred the better clustered and slightly slower ECMWF/CMC and UKMET (through 5), and after the forecast was generated, the 12z GFS did come in a little slower than it's 06z run. The late period forecast is low confidence though because the ensembles do show a wide variety of differences both with timing and strength/amplitude leading to the mean solutions quite washed out compared to what will likely happen in reality. Was able to pair the ECMWF/CMC models with more EC mean though late period because the EC mean was more amplified than the remainder of the ensemble mean guidance. The next shortwave into the West next weekend also shows plenty of uncertainty in terms of timing and amplitude and a more ensemble heavy blend by then seems to work well. ...Pattern Overview and Weather/Hazard Highlights... A dynamic upper trough/closed low will lift/shear northeastward from the Midwest to eastern Canada Wednesday into Thursday. This should continue to direct some Gulf of Mexico and Atlantic moisture into the leading frontal system across a broad region, but progression should mostly favor an increasingly more scattered precipitation pattern compared to the short range, albeit with some Great Lake enhancement possible after the upper low moves through. Ample midweek upper trough energy into the West Coast and subsequent southern stream flow amplification inland across the Interior to the Rockies sets the stage for some much below normal cold temperatures and a moderate QPF coverage response to include terrain enhanced heavy snow threats from the Great Basin to the Rockies Wednesday into Thursday. Late week additional flow/digging of upstream Pacific system/upper energies into the West become too chaotic in the models to offer sure focus, but the less defined ensemble means at least show potential energy available along with a modest model, ensemble and NBM QPF signature back across mainly the Northwest and inland into the north-central Great Basin and Rockies next weekend. Meanwhile, the downstream ejection of a main and possibly closed/well separated southern stream system in this active pattern 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, The signal/potential for modest to heavy rainfall has increased some with this cycle, compared to the previous forecast, which is more consistent with current model trends for this low. 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