Extended Forecast Discussion NWS Weather Prediction Center College Park MD 158 AM 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... Models and ensemble means offer similar ideas for the overall pattern evolution through the period but there are some embedded uncertainties. Solutions are similar for a leading wave tracking from the northern Plains through the Great Lakes Monday-Tuesday but there has been greater spread and run-to-run variability for the pattern behind it, due to differences in the handling of central-southern Canada shortwave energy. Faster progression of the energy leads to more Midwest/eastern U.S. high pressure by Wednesday-Thursday while slower progression allows for a more defined surface wave and farther north front. The preferred starting point of a 12Z/18Z model composite transitioning to a model/ensemble mean blend mid-late period introduced a hint of such a surface wave. New 00Z runs support existence of this second wave but with a decent amount of spread. The other large-scale consideration is the amplitude and timing of the upper trough moving into the West. GFS runs have tended to be on the flatter/faster side of the spectrum. The 18Z run was closer to other models and means (including the GEFS) than the 12Z or new 00Z runs. The new 00Z ECMWF has trended a little weaker/faster though. A number of model runs are suggesting that a trailing small-scale/low-predictability feature may drop into the mean trough toward Friday and this would add some complexity to the forecast. An intermediate depiction of this trough looks reasonable at this time. There will also be a couple southern tier features with relatively low predictability for specifics, a weak shortwave crossing the Southeast early in the week and energy that could briefly close off a low over/near Arizona before shearing eastward. ...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 focus periods of locally moderate to heavy rain and higher elevation snow 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. 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