Extended Forecast Discussion NWS Weather Prediction Center College Park MD 256 AM EDT Sun Apr 03 2022 Valid 12Z Wed Apr 06 2022 - 12Z Sun Apr 10 2022 ...Overview... The lower 48 will see an amplified upper pattern during the period. During the mid to late week time frame the dominant features will be a deep east-central U.S. trough anchored by an Upper Midwest into Great Lakes low, and a western U.S. ridge. The upper low/trough and associated surface evolution will produce a broad area of precipitation across the northern Plains and eastern half of the country (with some pockets of locally heavy totals possible) while the western ridge will support much above normal temperatures, including potential for some record highs/warm lows over California and vicinity. By the weekend expect a Pacific trough to move into the West, leading to a cooling trend and some precipitation, while progression of the eastern trough to East Coast should favor drier weather over the East. ...Guidance Evaluation/Predictability Assessment... A blend of 12Z/18Z operational models followed by a transition to the 18Z GFS/GEFS mean and 12Z ECMWF provided a reasonable depiction of consensus ideas through the period along with fairly good continuity. The ECMWF mean was comparable to the GEFS mean but was not available for including in the blend due to a local data issue. For the wave forecast to be over/near the Mid-Atlantic early Wednesday, consensus through the 18Z cycle was consistent with a number of previous runs but new 00Z runs actually seem to enlarge the spread. The new UKMET/CMC actually show a track into the Upper Ohio Valley before the CMC develops a separate wave that tracks offshore like the 12Z ECMWF and faster GFS. Upstream the guidance had stabilized/converged for the northern tier upper low and surrounding trough, plus the triple point coastal wave, though by late week into the weekend some uncertainty develops over whether the upper low may open up and how much southwestward elongation of the trough may occur. The 00Z UKMET is quickest to open up the low, ultimately leading to a fast progression of the Thursday-Friday coastal wave. GFS runs have been on the amplified side with the southwestern part of the trough but the new 00Z run has toned down that trait somewhat. The new 00Z ECMWF is consistent with its prior run. For the upper trough moving into the West by the weekend, the CMC continues to run on the fast/deep side of the spread so it has not been included in the forecast blend. GFS runs have been a little inconsistent with potential flow separation. Overall the 18Z run was closest to the similar and consistent GEFS/ECMWF means while the 00Z run has adjusted faster and flatter with its northern stream. Detail differences among model runs and ensemble members continue to suggest lower predictability for this overall trough versus the ridge/trough configuration farther east. ...Weather Highlights/Threats... The deep-layer low tracking over the Upper Midwest into Great Lakes, along with a leading triple point wave that may become the primary system by the end of the week--plus the trailing cold front--should support multiple areas of enhanced precipitation mid-late week. Specifics for heaviest totals are still fairly uncertain though. One area of focus may be for some combination of rain and/or snow over or a little west/south of Lake Superior, just north of the parent low's track. Meanwhile the wave expected to track from the Mid-Atlantic northeastward may produce some locally moderate to heavy rainfall. Far interior sections of New England may see some wintry weather on the leading side of the moisture. More localized pockets of enhanced rainfall are possible farther south along the trailing cold front. The Storm Prediction Center is monitoring potential for severe threats across the southern tier. Check their latest outlooks for more information. Expect lingering showery precipitation, possibly including some snow from the Midwest into the Appalachians, under the cold upper trough into Saturday. The upper trough pushing into the West by the weekend should bring mostly light to moderate rain and high elevation snow into the Northwest starting Friday or Saturday. The upper ridge building into the West will spread a broad area of well above normal temperatures across the region mid-late week. Highest temperatures will likely be on Thursday-Friday when parts of California and Oregon into the Great Basin could see readings 15-25F above normal. Some daily records for highs/warm lows will be possible. The upper trough arriving from the Pacific will bring a rapid cooling trend during the weekend, with much of the West seeing near to below normal highs by Sunday. Farther east, highs generally 5-15F or so below normal will progress from the northern Plains/northern-central Rockies into the East during Wednesday-Saturday under the deep upper trough. Expect temperatures to moderate noticeably by next Sunday. Flow ahead of the upper trough will bring a couple days of above normal readings (especially for morning lows) to the East around Wednesday-Thursday. Rausch 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