Extended Forecast Discussion NWS Weather Prediction Center College Park MD 247 PM EDT Mon Apr 04 2022 Valid 12Z Thu Apr 07 2022 - 12Z Mon Apr 11 2022 ...Overview... Overall, the large scale regime from late this week into early next week will remain amplified but progression/evolution during the period will essentially lead to a flip of the upper level pattern, with an initial western ridge/east-central U.S. trough ultimately trending toward a western trough/eastern ridge. Precipitation will steadily decrease in coverage and intensity over the eastern half of the country while chilly temperatures will progress from the Plains through East late week through the weekend. Meanwhile the West will see much above normal temperatures late this week, with some daily records possible over and near California, followed by a cooler trend during the weekend into early next week while areas of precipitation spread across the region. As this occurs, above normal temperatures will shift into the Plains and eventually parts of the East. ...Guidance Evaluation/Predictability Assessment... Based on 00/06 UTC guidance, best clustered guidance from the latest GFS/ECMWF/CMC and GEFS/ECMWF ensemble means provided a good depiction of consensus days 3-7. This remains true for most of the latest 12 UTC guidance. However, a noteable exception is the 12 UTC GFS that is a stark outlier in delaying by 1-2 days significant upper trough amplification over the West from the weekend to early next week with the next major shortwave. This trend is not supported by other guidance including the 12 UTC GEFS. Continuity adjustments were again fairly modest and represented typical run-to-run detail refinements. The overall forecast of the deep eastern upper trough and associated surface evolution is fairly consistent. The majority cluster maintains good definition of the embedded upper low into day 4 Friday, followed by solutions showing varying ways in which it may weaken/open up. UKMET runs have been the fast extreme with shortwave energy on the east side of the trough and thus with the Mid-Atlantic through New England coastal wave, but is beginning to trend favorably. The ECMWF/ECMWF ensemble mean are a bit on the slower side. An intermediate solution continues to look good for depicting the specifics of the upper trough and surface reflection. Forecasts of the upper trough reaching the West have been a bit more varied, due in part to involvement of separate shortwaves. However, but with the aforementioned exception of the 12 UTC GFS, recent GFS/ECMWF/CMC runs still overall compare favorably to each other and the ensemble means. ...Weather Highlights/Threats... Heaviest rainfall with the system affecting the eastern half of the country should be Thursday into Friday and focused by the triple point wave lifting from the Mid-Atlantic into New England. Specifics within this area of potentially enhanced rain are still uncertain, with additional time needed to resolve important details. Some pockets of locally moderate to heavy rainfall could extend along the trailing front as far south as Florida, and the Storm Prediction Center is monitoring severe potential over parts of the Mid-Atlantic. Check SPC's outlooks for the latest information on severe threats. Precipitation in the vicinity of the Great Lakes low should trend lighter after midweek. However cold air aloft associated with the upper trough will likely promote areas of diurnally enhanced showers from the Midwest into the northern half to two-thirds of the East into Friday-Saturday. Some precipitation could be in the form of snow between the Midwest and Appalachians. The upper trough amplifying over the West will gradually increase the coverage of mostly light to moderate rain and higher elevation snow from late week onward. Most of this precipitation should be over the northern half of the region into early Monday but may push farther south thereafter. The upper ridge over the West late this week will produce well above normal temperatures across the region. Forecasts continue to show highs reaching 15-25F above normal Thursday-Friday from parts of California and Oregon into the Great Basin along with some daily records for highs/warm lows. Then the upper trough arriving from the Pacific will bring in cooler air, with the Northwest trending below normal during the weekend and much of the West likely to see highs 5-15F below normal by next Monday. Meanwhile highs of 5-15F or slightly more below normal will progress from the Plains/Mississippi Valley into the East late week into the weekend. A trailing warming trend will bring plus 10-20F anomalies into the Plains for the weekend and persisting over some areas into Monday while eastern U.S. readings rebound closer to or slightly above normal by early next week. Rausch/Schichtel 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