Extended Forecast Discussion NWS Weather Prediction Center College Park MD 253 AM EDT Fri Oct 7 2022 Valid 12Z Mon Oct 10 2022 - 12Z Fri Oct 14 2022 ...General Pattern Overview... An anomalous mid-upper ridge axis across the eastern Pacific and Gulf of Alaska is expected to be nearly anchored in place for much of next week, and this will tend to result in an amplifying downstream trough over central Canada and into the north-central U.S. going into the middle of the week. This will help reinforce the autumnal airmass across much of the eastern U.S., while still remaining mild to warm across the northwestern U.S. and the southern tier states. ...Model and Predictability Assessment... In terms of the building northern stream upper trough for the middle of next week, there has been a definitive trend over the past 36 hours for less of a cut-off low developing over the Intermountain West and the main trough axis developing over the north-central U.S. with a positively tilted trough extending southwest from it. The ECMWF and GFS, along with the JMA, have trended in this direction, whereas both the 12Z/00Z CMC continues to show the upper low breaking away across the Intermountain West with not much in the way of support from the ensemble means. The ECMWF is faster in taking the cold front towards the East Coast by the end of the week, compared to the GFS. Teleconnections with the positive height anomaly over the Gulf of Alaska and the negative height anomaly north of Hawaii suggest a non-CMC solution, and this would not support a well-defined upper low breaking off from the main trough. The forecast was primarily derived from a UKMET/GFS/ECMWF/WPC continuity composite through Tuesday, and then some of the GFS/ECMWF and increased use of the ensemble means for the Wednesday through Friday time period with generally below average forecast confidence at this juncture owing to the model variability noted above. ...Sensible Weather and Potential Hazards... An amplifying upper trough and a strong cold front reaching the Northern Plains and Upper Midwest by Wednesday will likely produce showers and some thunderstorms from the Central Plains to the Great Lakes, although rainfall totals should be light to moderate. There may be an uptick in rainfall coverage as the front approaches the Northeast U.S. towards the end of the week, and also for the Gulf Coast region as the front taps into deeper moisture. Elsewhere, the convection across the southern Rockies and Arizona is finally expected to subside going into the middle of the week as the upper low/trough weakens. Some high elevation snow showers are also possible for the highest terrain of the central and northern Rockies on Tuesday and Wednesday. Much of the northwestern U.S. should have above normal temperatures next week with the upper ridge just off the coast, and things have trended milder compared to earlier forecasts. Farther east, temperatures should be moderating going into early in the week after a relatively chilly weekend for most locations. Readings should still be warm across most of the Plains and Midwest states through Wednesday before the front passes through the region, followed by highs about 5-15 degrees below average to close out the work week for the Ohio Valley and Great Lakes, and potential for frost at night. Hamrick 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