Extended Forecast Discussion NWS Weather Prediction Center College Park MD 139 PM EST Fri Feb 25 2022 Valid 12Z Mon Feb 28 2022 - 12Z Fri Mar 04 2022 ...Overview... Most guidance expects flow across the lower 48 to have moderate amplitude next Monday-Friday. A general western ridge/broad eastern mean trough pattern through at least midweek should progress eastward thereafter as a Pacific trough moves into the western U.S. Moisture ahead of the Pacific trough will likely bring meaningful precipitation into the Pacific Northwest with somewhat lighter amounts eventually spreading across other parts of the West. Many areas east of the Rockies will be fairly dry, with any precipitation generally light and confined to northern areas with one or more waves and possibly southern parts of the Plains mid-late week. Near to above normal temperatures will be most common next week. Best potential for below normal readings will be over/near the southern Plains early in the week and in northern parts of the eastern U.S. on some days. ...Guidance Evaluation/Predictability Assessment... Model blends consisting of deterministic guidance from days 3-5 then ensemble means on days 6 & 7 provided a reasonable solution for the medium range. For Monday, a greater weighting was given to the 00z EC/CMC due to the uncertainty around an impulse moving through the West. The GFS amplified this shortwave into a closed low and had it move at a slow pace compared to the rest of the deterministic suite so it was excluded from Tuesday's blend. The 00z UK and CMC join the 06z GFS in losing weighting on Wednesday, due to difficulties and spread in handling a trough approaching the Pacific Northwest. Therefore, a blend of 00z EC and the ensemble means were utilized through Thursday. The EC was dropped and a full ensemble blend was used by Friday. ...Weather Highlights/Threats... Expect the heaviest precipitation next week to be over the Pacific Northwest and northern Rockies. A series of systems embedded in moist flow ahead of an initially slow-moving eastern Pacific upper trough may produce an atmospheric river event over these regions early-mid week. Eventual progression of the upper trough should bring a lighter trend to the Northwest and spread precipitation farther south and east later in the week. Exactly how far south the moisture reaches into California and the Great Basin/Rockies will depend on the amplitude of the upper trough. Farther east, a couple clipper systems may bring mostly light snow from the Upper Midwest through the Great Lakes and Northeast. Additional northern tier snow will be possible late in the week ahead of low pressure organizing over the north-central Plains. A weak shortwave crossing the Southeast Monday may produce some light rain before departing. Another weak upper feature may generate light/scattered rain over the southern Plains around mid-late week. Aside from chilly morning lows over the southern Plains on Monday (up to 10-15F below normal), the forecast pattern will support above normal temperatures over a majority of the western and central U.S. Monday-Wednesday followed by a cooling trend over the West and a warmer trend over the East. Plus 10-20F anomalies will be possible for max and/or min temperatures for one or more days over the Great Basin/Southwest and parts of the Rockies/Plains. Areas from the Upper Midwest to the Northeast will tend to stay below normal though, with some locations in the Northeast 10-20F below normal early in the week. Kebede/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, 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/wwd/pwpf_d47/pwpf_medr.php?day=4 https://www.wpc.ncep.noaa.gov/heat_index.shtml