Extended Forecast Discussion NWS Weather Prediction Center College Park MD 300 PM EDT Sat Mar 26 2022 Valid 12Z Tue Mar 29 2022 - 12Z Sat Apr 02 2022 ...A deepening low pressure system presents a mid-late next week heavy rain/severe weather threat across the South while heavy snow/ice and high wind threat focus across the Upper Midwest/Great Lakes... ...Overview... A rapidly intensifying cyclone is forecast to track across the central/southern Plains through the Great Lakes mid-late next week. The unsettled and wet pattern initially over the Southwest will be followed by an outbreak of heavy rain and severe weather to sweep across the southern tier states through Thursday. Meanwhile, heavy snow and ice are forecast for the upper Midwest/upper Great Lakes region where high winds are also expected. The high winds could also extend well to the west of the low track across much of the northern and central Plains. ...Guidance Evaluation/Predictability Assessment... Model guidance this morning has come into general agreement for a rapidly intensifying cyclone to track across the central/southern Plains through the Great Lakes mid-late next week under an upper-level pattern that favors phasing of the cold northern stream flow with a resurgence of moist southern stream flow from the Gulf of Mexico. A composite blend of 40% 00Z ECMWF/EC mean, 40% 06Z GFS/GEFS and 20% from the 00Z CMC/CMC mean was used to compose the Days 3-6 forecasts. Toward the end of next week, models begin to diverge regarding the amplitude of next upper trough forecast to dive across the western U.S. The CMC was most enthusiastic with the trough amplification while the GFS/GEFS indicated a much flatter evolution. The ECMWF/EC mean was in between these extremes. An intermediate solution was adopted for Day 7 by incorporating a higher weighting from the ensemble means. The solutions maintained very good continuity with the previous WPC forecast package. ...Weather Highlights/Threats... An upper low ejecting across southern CA/Southwest will support a spread of enhanced rain and higher elevation snow through the south-central Intermountain West/Rockies and the Southwest Tuesday. As a surface low pressure system strengthens in the Plains and tracks northeast, increasingly widespread rain and threat for severe weather with heavy downpours are forecast to develop over the southern Plains late Tuesday and then move across the South by Wednesday before reaching the Southeast on Thursday. The heaviest rains are forecast to break out Tuesday night over eastern portion of the southern Plains and then sweep through the Mid-South/Gulf Coast states through Thursday where areas of flash flooding are possible. An emerging "slight" risk area is depicted on the new experimental WPC day 5 ERO given favorable system ingredients and antecedent conditions. Meanwhile, light rain and some thunderstorms are also expected farther north from the central Plains through the Mid-Atlantic. On the northern side of the precipitation shield, the potential for a swath of heavy wintry mix and accumulating deep low wrapping snows have continued to increase across the Upper Midwest to the Great Lakes later Tuesday into Wednesday-Thursday given much model consensus on developing a rather intense cyclone. High winds appear to likely impact near and well to the west of the low track during this time frame as well given the impressive rate of cyclogenesis. Some wintry precipitation is also forecast for interior New England late Thursday/early Friday ahead of a warm front, while pockets of heavy rain are possible down the East Coast ahead of a cold front. Over the central Rockies to the nearby High Plains, a period of heavy snow is possible from the central Rockies to the central High Plains on Tuesday behind a reinforcing cold front. By late next week, another upper trough is forecast to dig southeastward from the Pacific Northwest through the western U.S. and could provide another opportunity for an enhanced round of wintry mix from the northern to central Rockies to the nearby High Plains. Some heavy rainfall could linger across the eastern Gulf Coast by next weekend as a front becomes nearly stationary offshore. Kong 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 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