Extended Forecast Discussion NWS Weather Prediction Center College Park MD 236 PM 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 medium range period (Wed-Sun). 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... In the East, the 00z CMC and UKMET continued to be farther west with it's track than consensus with the initial wave in the Mid-Atlantic on Wednesday. Upstream, concerning the Midwest closed low, the 00z UKMET is quickest to open up the low, leading to a faster progression of the system as a whole. Later 12z runs of the CMC and UKMET seem to show better consistency with the GFS and ECMWF for both features. Later in the period, the trough in the East should linger/become elongated as ridging amplifies into the Central U.S.. There are some timing concerns for the front late period, but mostly not until it's well off the coast. Out West, plenty of uncertainty continues to surround the evolution of troughing into the region by next weekend. Models show an initial wave moving through on Friday, with a bigger closed low dropping down from the Gulf of Alaska by Sunday. Biggest outlier was the 00z CMC which was quite a bit deeper/amplified with the first system resulting in another building ridge over the West Coast next weekend and less progressive Gulf of Alaska low. The GFS and ECMWF were a little bit more in line, racing the initial shortwave off into central Canada as the next low reached the coast by Sunday. This general evolution was also better supported in the ensembles. The 12z run however of the CMC has abandoned this idea and seems to have come much more into line with the GFS/ECMWF and ensemble means. But detail differences among model runs and ensemble members continue to suggest lower predictability for this overall trough versus the ridge/trough configuration farther east. The WPC blend for today utilized a non-UKMET consensus for the first half of the period in the East. Out West, the CMC was left out in favor of increasing weighting towards the ensemble means to help mitigate the Western U.S. uncertainties. This provided very good continuity with the previous WPC forecast as well. ...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. Santorelli/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