Extended Forecast Discussion NWS Weather Prediction Center College Park MD 318 AM EDT Fri Oct 21 2022 Valid 12Z Mon Oct 24 2022 - 12Z Fri Oct 28 2022 ...Model and Predictability Assessment and Weather/Hazard Highlights... Model and ensemble solutions seem in reasonably good overall agreement Monday, but rapidly exhibit run to run variabilty and increasing forecast spread through the rest of next week in an active pattern with lowering forecast confidence. The WPC medium range surface and 500 mb progs were mainly derived from a composite blend of the 00 UTC GFS/ECMWF/UKMET/Canadian Monday into early Tuesday before rapidly transitioning to a blend of the compatible GEFS/ECMWF ensemble means for the rest of the period. In this scenario, an exiting upper trough/low and deepened surface low/system over the north-central U.S. Monday offers windy/wrapping precipitation including lead strong to severe convection as per SPC and some wrapping backside snow. Lead early week pre-frontal warmth moderates through the rest of the week over the east-central U.S. Upstream, system energy pushing inland across the Northwest to the Rockies will produce a swath of precipitation including elevation snows enhanced by terrain before reaching the northern Plains. Potent trailing upper trough energies in this stream across an unsettled Southwest Monday may tap modestly with some moisture from Mexican landfalling and decaying Roslyn. The driving upper trough is slated to then eject from the Southwest and lift northeastard across the central U.S. and Great Lakes/Midwet though midweek, but guidance is varied with stream separation and timing issues. The pattern though should focus Gulf moisture and instability into the developing front and WPC has issued an experimental "Slight" risk of excessive rainfall centered over the Southern Plains Monday where multiple inches of convective rains may focus. Subsequent renewed upper trough energy flow into the West Coast into mid-later week was been handled differently by the models, but the 00 UTC runs are more in agreement with an overall trend for digging. This should prolong a quite cold period over the West/Rockies and system amplitude should 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. This system is slated to energe over the central U.S. late period to renew rain/convectiion. Elsewhere, lingering upper troughing over the Mid-Atlantic and offshore troughing focus through at least early next week has proven highly uncertain in guidance from run to run. However, the pattern does offer protracted support for coastal affect with prehaps best flow focus over New England. Targeted changes to the 01 UTC NBM 4.0 QPF were mainly to increase afternoon/evening convective rainfall trailing over the south-central U.S. early in the week given favorable upper support and frontal pooling moisture/instability, to modestly increase amounts and coverage downstream into mid-late week with sweep across the east-central states given low NBM bias at these time frames with organized systems and given forecast spread consolidate/expand overall areal coverage of mid-later week precipitation over the West/Rockies given favorable flow. 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