Extended Forecast Discussion NWS Weather Prediction Center College Park MD 258 AM EDT Tue Oct 11 2022 Valid 12Z Fri Oct 14 2022 - 12Z Tue Oct 18 2022 ...Pattern Overview... A more active fall weather pattern is expected to evolve by the end of this week and continuing into the weekend as a couple of cold fronts associated with an Eastern U.S. amplifying upper level trough (and embedded shortwaves) move across the central and eastern states. The first cold front will be exiting the East Coast by early Friday with widespread showers and storms likely ahead of it across New England, and lake effect precipitation behind it. By this weekend, a second cold front dropping southward from Canada is expected to reinforce the cool airmass across the eastern half of the nation and likely lasting into early next week. The opposite is expected to be the case across the West Coast region as an upper ridge brings a period of well above normal temperatures from California to the Pacific Northwest as summer tries to hang on a little longer ...Model and Predictability Assessment... The 00Z model guidance suite continues to strongly support a deep and expansive closed low over southern Ontario and the northern Great Lakes for basically the entire forecast period with multiple shortwave perturbations pivoting around it, which will govern overall frontal progression across the central/eastern states. At the time of the fronts/pressures compilation, the 12Z CMC was an outlier solution for the Sunday-Tuesday time period by having the core of the upper low much farther south across the Ohio Valley, whereas the 00Z CMC has trended closer to the consensus, so the 12Z CMC was not used. For the closed low over the Desert Southwest/northwestern Mexico, model agreement is good through Sunday as it drifts eastward, although the GFS does tend to have the low linger a little longer than the ECMWF/CMC solutions. In terms of QPF, amounts were raised from the NBM across the Great Lakes to better account for lake effect precip, and a 75% ECMWF/25% GFS blend was used as a starting point for this region, and also across the Ohio Valley to better account for lighter precip near the front. A slight increase of the ensemble means was used for the latter half of the forecast period for fronts/pressures. ...Sensible Weather and Potential Hazards... The first strong cold front of this series and the associated upper trough will result in moderate to locally heavy rain across central and eastern New England on Friday, with the potential for some 2+ inch totals. This area will continue to be monitored for possible flood potential, but for now the risk appears to be below Slight Risk criteria, in part owing to recent dry conditions. Strong and gusty winds are also a concern there as the trough becomes negatively tilted and the pressure gradient tightens. Elsewhere, lake enhanced rain and snow showers are likely across the Great Lakes for the Friday through Saturday time period, and showers could become more widespread with another frontal system by Sunday. Out West, showers and thunderstorms are forecast to increase in coverage going into Sunday and even more so by Monday as moisture is advected northward ahead of the slow moving upper low across Arizona, New Mexico, and much of Texas. Much of the northwestern U.S. and California should have above normal temperatures each day with the upper ridge remaining nearly anchored in place near the coast. The opposite will hold true across the north-central U.S. and extending to the East Coast, with highs about 5-15+ degrees below average to close out the workweek and going into next weekend and beyond, with highs only in the 40s and 50s from the Great Lakes to the Northeast on most days. 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