Extended Forecast Discussion NWS Weather Prediction Center College Park MD 249 AM EDT Sat Aug 27 2022 Valid 12Z Tue Aug 30 2022 - 12Z Sat Sep 03 2022 ...Overview... The mid to upper level pattern over the CONUS is expected to remain amplified next week into early next weekend, featuring a strong ridge through the interior West with troughing across the eastern Pacific and portions of the northeastern U.S.. A sweeping cold front will move across much of the central to eastern U.S. mid to late week, ushering in drier and more Fall-like temperatures to portions of the eastern CONUS. Meanwhile, warm and dry conditions are expected for the interior West into the Northwest where a few daily temperature records could be challenged. The greatest precipitation coverage and amounts are expected to be tied to the frontal passage across the central and eastern U.S. with some moderate to locally heavy rainfall possible. ...Guidance Evaluation/Predictability Assessment... With the more amplified pattern, the latest model guidance showed average to above average agreement and consistency with the large scale pattern. The deterministic runs used in the blend (18Z GFS, 12Z ECMWF, 12Z UKMET, 12Z CMC) showed fairly strong agreement with the shortwave trough deepening over the Great Lakes with the upstream ridge over the interior West building northward into the Canadian Rockies and a 594dm center over the Four Corners. This amplified pattern now supports the cold front passage to sweep much of the central to eastern U.S. mid to late week, with the surface front likely to settle along the Gulf Coast before washing out late next week into next weekend. Toward the end of the week into next weekend, a weakness in the upper ridge may form over the southern Plains to lower Mississippi Valley in combination with the surface front settling in the region. This could be the focus for additional precipitation, enhancing totals along the Gulf Coast somewhat. The WPC blend this cycle began with a near equal weighting of the latest available deterministic guidance then transitioned into using about 50 percent of ensemble means (ECENS and GEFS) and 18Z GFS and 12Z ECMWF making up the other half. This seemed to adjust well to the latest model trends while maintaining continuity. ...Weather/Hazards Highlights... The main weather feature through the period will be a cold front that progresses across the central to eastern U.S. mid to late week. Ahead of that feature, enough warm and moist air will support scattered to numerous showers and thunderstorms, some of which could be locally heavy. The greatest chances for seeing a few stronger storms and locally heavy rainfall look to be across the eastern Great Lakes into the Northeast mid-week tied to the better forcing/lift with the frontal passage as well as the Southern Plains into the Mississippi Valley where the better instability/moisture will be found mid to late week. The West is expected to be mainly dry though by the end of the work week into next week, precipitation is possible across the Southern Rockies and High Plains. A frontal passage may clip the Pacific Northwest bringing some precipitation to the Olympics and northern Cascades. The warmest temperature anomalies will be found across the Pacific Northwest into the Northern Plains next week, underneath the building upper ridge and ahead of a cold front that slips through later in the week. Highs could reach 10-20F above normal each of those days. Meanwhile, the Northeast will also see much above normal temperatures on Tuesday ahead of the stronger cold front that is slated to sweep through much of the central and eastern U.S., bringing in some early fall seasonable temperatures in its wake. As the calendar turns to Meteorological Fall, much of the Upper Midwest, Great Lakes and even into the portions of the South should see at or slightly below normal highs. Lows in the 40s to 50s will be found across the Upper Midwest into the interior Northeast. Taylor 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