Extended Forecast Discussion NWS Weather Prediction Center College Park MD 157 PM EST Wed Nov 16 2022 Valid 12Z Sat Nov 19 2022 - 12Z Wed Nov 23 2022 ...Winter-like temperatures accross the U.S. along with continued lake effect snow... ...Synoptic Overview... A highly amplified upper-level flow pattern continues across the country to start the period with a deep trough extending from Hudson Bay to the Upper Midwest forecast to gradually shift to the east as another trough begins to dig in the West later in the period. Temperatures will remain quite chilly and well below average initially across a wide swath of the country after the passage of an arctic front and high pressure remains in place. Precipitation chances will persist in Florida and begin to increase in the Pacific Northwest by the start of next week with the passage of the western trough. ...Guidance and Predictability Assessment... The overnight guidance showed slightly above average predictability particularly through the early half of the period when most of the deterministic guidance was in good agreement on the overall pattern. The guidance depicted an amplified trough in the Midwest/Northeast and southern stream shortwave over the Southern Plains early in the period followed by another trough amplifying in the West with a ridge along the West Coast. The 00 UTC ECMWF showed good consistency with past recent runs and both the 00 UTC and 06 UTC GFS began to converge towards this same solution, with the 00 UTC UKMET also in general agreement. The deterministic runs, specifically the 00 UTC ECMWF, also showed good agreement with the ensemble guidance later in the period with respect to the evolution of the western trough and possible stream seperation. The 00 UTC CMC showed a more amplified pattern overall which diverged more significantly from the solutions in the other guidance. The WPC blend for the first half of the period was a combination of the 00 UTC ECMWF and UKMET and 06 UTC GFS. The 06 UTC GEFS mean and 00 UTC EC mean were incorporated for the latter half of the period with the 00 UTC ECMWF included to provide a more amplified pattern. For the precipitation forecasts, some of the 00 UTC ECMWF was incorporated with the NBM to increase QPF in the lake-effect regimes of the Lower Great Lakes as well as along the Atlantic Coast of Florida early in the period. The QPF from the NBM was notably lower for the West Coast from southern Oregon into California later in the period compared to the prior WPC forecast, but this was generally consistent with the other model guidance. The 00 ECMWF was used to increase amounts a bit to provide more continuity, although the amounts still remain lower overall. ...Weather/Hazard Highlights... Widespread well below average temperatures are forecast to continue into the weekend across a majority of the country, with the coldest readings expected across Minnesota, North Dakota and northern Wisconsin where highs will only reach into the middle 10s to lower 20s with lows in the 0s or even slightly below zero for this same general area. The frigid temperatures will begin to shift into the Great Lakes region and Ohio Valley Sunday into Monday. It will also be quite chilly extending southward to Texas and the central Gulf Coast through Monday, with highs generally running 10 to 20 degrees below mid-late November averages. Downslope flow should help to moderate temperatures over the Central and Southern Plains by early next week. In terms of precipitation, much of the nation should be relatively dry as the noted surface high pressure dominates the overall weather pattern. Lake effect snow is likely to be persistent downwind of the Lower Great Lakes through Sunday owing to strong cold air advection over the warmer waters. Some light showers are possible in Texas Sunday as the southern stream shortwave moves through. Daily chances for heavier showers and thunderstorms will persist along the Atlantic Coast of Florida. Lower elevation showers and higher elevation snow will begin in the Pacific Northwest Sunday and expand into the Northern Rockies by Tuesday as a trough digs into the West. Rain chances also look to increase ahead of this trough on Wednesday across portions of Texas and the Lower Mississippi Valley. Putnam/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