Extended Forecast Discussion NWS Weather Prediction Center College Park MD 204 PM EST Fri Nov 11 2022 Valid 12Z Mon Nov 14 2022 - 12Z Fri Nov 18 2022 ...Overview... A chilly pattern is in store for a large portion of the nation for this coming week with broad cyclonic flow aloft around a deep upper level trough centered near the Northern Plains/Midwest states. During this period, multiple reinforcing cold fronts/shortwaves will help to maintain this pattern. A shortwave within the southern stream will spread rain from the Gulf Coast, across the Deep South and then to the East Coast. There is some potential for this to develop further as it emerges off the East Coast late in the week. ...Guidance and Predictability Assessment... The latest guidance is showing an energetic pattern with multiple shortwaves initially within the northern and southern streams that transition to a very broad, phased trough over much of the contiguous states. Overall there is good synoptic scale agreement with th broad cyclonic flow expected over the north-central states both there is notable spread on the timing, location and strength of individual features that increase beyond day 4/5, especially with northern and southern stream shortwaves diving into the Western/Central U.S. on the east side of a building ridge over the East Pacific. The potential remains with this system to phase with a northern stream shortwave across the north-central states around the same time. Near the end of the extended period models hint that a shortwave may track near the West Coast. The WPC forecast used an initial blend of the GFS, ECWMF, UKMET, and CMC then reduced the weighting of the UKMET and CMC beyond day 4 while increasing the inclusion and weighting of the GEFS means and ECWMF ensemble means to account for the to greater model differences. ...Weather/Hazard Highlights... An upper trough crossing the Northeast states on Monday, along with cold low level cyclonic flow, will support some lake effect snow to the areas east of the Upper and Lower Great Lakes, mainly early in the week. Light precipitation is expected to spread across the Intermountain West and portions of the Rockies, mainly falling as snow into the middle of the week. The disturbance exiting the Rockies and emerging across the Southern Plains on Monday is expected to result in broader coverage of precipitation from the southern half of the Plains to the East Coast. Locally heavy rainfall may develop, especially along the western and central portions of the Gulf Coast. On the northern periphery, there is the potential for some wintry precipitation from northern Oklahoma/Kansas to southern Illinois. It will take additional time to resolve important system details that will determine the coverage/intensity/type of precipitation. Broad upper troughing in response to the strong ridge offshore the West Coast should keep a cold pattern in place through all of next week, especially west of the Appalachians. The coldest readings should be over parts of Montana and the Dakotas, with some temperatures on the order of 20-30 degrees below normal, including locally subzero morning lows. Coldest anomalies over the West should tend to be over the Great Basin with multiple days of highs 10-20F below normal. The Midwest to East Coast are also expected to be below normal all week, though with slightly less extreme anomalies. Maine and Florida could be exceptions with near to slightly above normal temperatures. Campbell/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