Extended Forecast Discussion NWS Weather Prediction Center College Park MD 144 PM EST Tue Nov 08 2022 Valid 12Z Fri Nov 11 2022 - 12Z Tue Nov 15 2022 ...Heavy rains from Nicole will continue to spread inland across the Appalachians Friday and across the Northeast Friday night into Saturday... ...Overview... A low ejecting northeast out of the Southwest through midweek is forecast develop into a mean long wave trough over central and eastern states with an upper low developing and lingering this weekend over the Great Lakes. Nicole will eject north ahead of this trough, currently on an interior East Coast track as it becomes post-tropical Friday night/Saturday. Heavy rain along and well east of the track is forecast for the Appalachians/Upper Ohio Valley and across the Northeast Friday night into Saturday. An amplifying upper ridge over the Northeast Pacific/northwestern North America will help promote the central/eastern troughing and below normal temperatures over much of the country into next week. ...Guidance and Predictability Assessment... The 00Z/12Z consensus is for a less potent low/more of a sharp trough over the northern Plains Friday than then still develops into a deep upper low/large eastern trough this weekend with an upper ridge building up the West Coast up to the Yukon/Alaska area into next week which maintains the central/eastern troughing. The GFS has been strongest with the Friday low over the northern Plains, but since 00Z the ECM and CMC have been weaker with now the 12Z GFS/UKMET on board with that progression. In order to maintain some continuity with the previous forecast, the 06Z GFS was favored in the blend through Day 5 before focusing more on input from ensemble means, but the 12Z GFS has come in more in line with the 00Z/12Z consensus, so continued movement to a stronger ridge/trough pattern from the general consensus is anticipated. East of the developing trough/low, guidance continues trend west and somewhat faster as it gets swept up by the trough from the Plains, with some spread still among the latest guidance. The WPC QPF for Day 4 was generally a blend of the NBM with the 06Z GFS and 00Z ECMWF that was then updated for the farther west shift from the 12Z GFS. General agreement is with a fairly quiet stretch precip-wise after the remnants of Nicole lift north though lake effect snow is expected across typical snow levels off the Great Lakes into next week and shortwave impulses riding the ridge will result in localized precip for the central/potentially southeast parts of the country. There is also general agreement on the mean ridge building/lifting farther north with potential for a trough/low getting in under the ridge off the southern CA coast early next week. However, timing/placement/strength shortwave troughs/lows approaching the West Coast this weekend is noted among the most recent consensus. Blending in some GEFS/ECENS into the forecast did bring some precip to CA this weekend and portions of The West early next week. ...Weather/Hazard Highlights... A more progressive/less closed low reduces the threat for lingering snow bands west of Lake Superior Friday night. Under the upper low will be a lake effect snow threat for typical snow belts into next week. The greatest threat now for the medium range period will be Nicole as it tracks quickly inland from the East Coast Friday night into Saturday. Moisture ahead of Nicole will spread inland across the Appalachians and the approaching cold front from the developing Great Lakes low will help to enhance rainfall. There is a threat for a predecessor rainfall event somewhere in the Northeast even with the quicker guidance. Given the farther inland trend in QPF guidance, the Slight Risk in the day 4 experimental ERO was nudged west and north, away from much of the Mid-Atlantic coast, but still for the I-95 corridor north from Richmond and west to the upper Ohio River and to the shore of Lake Ontario. Given the combination of tropical moisture and frontal convergence, embedded Moderate Risks may be necessary for the high rainfall rates that are possible despite much of the area being rather dry over the past week. Below normal temperatures spread across the country through early next week under the developing trough and offshore ridge axis out west. The coldest air will spread from the northern Rockies and across the northern Great Plains Friday and linger into next week. Min temp anomalies of 15 to 25 degrees below normal are forecast with several days of subzero mins in portions of the Dakotas, eastern Montana and northern Minnesota. Min temp anomalies of 10 to 15 degrees below normal will persist over the northern Rockies/Great Basin and spread down the Mississippi Valley through the Southeast Sunday through early next week. Much above normal temperatures returning to the East Coast ahead of Nicole will become slightly below normal by early next week. Jackson 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