Extended Forecast Discussion NWS Weather Prediction Center College Park MD 300 PM EDT Fri Mar 25 2022 Valid 12Z Mon Mar 28 2022 - 12Z Fri Apr 01 2022 ...Wet weather moving through southern California early next week will be followed by low pressure system intensifying over the Plains mid-late week to bring heavy rain/severe weather across the South and increasing potential of heavy snow/ice across the upper Great Lakes to upper Midwest... ...Overview... An amplified upper trough and lingering wintry weather will exit the northeastern U.S. by early next week, followed by a gradual moderation of a polar airmass across the north-central through eastern states. The main weather focus across the nation will then shift to the West as a strong upper trough and embedded closed low progress into and through the southwestern states early next week. As the system lifts across the south-central Rockies/Plains midweek, model guidance continues to trend toward supporting additional phasing with northern stream trough energies digging into the northern Plains mid to late week that would promote more solid intensification of a surface low and associated frontal systems. Overall, this will favor rather unsettled and wet pattern from CA and the Southwest to the south-central Rockies early next week (including mountain snows) that will emerge/ expand in magnitude and spread from the Plains to the east-central and eastern/southeastern U.S. later next week as Gulf moisture increasing feeds into the system. ...Guidance Evaluation/Predictability Assessment... Since yesterday, model guidance has continued the trend of increasing interaction/phasing between a developing surface low over the southern Plains on Wednesday and a surge of colder air down the northern and central Plains. The GFS took the most decisive shift of tracking a rather robust cyclone into the upper Midwest by Thursday morning. The 00Z ECMWF and, to the lesser extent, the 00Z CMC have trended toward a more robust cyclogenesis. The 12Z ECMWF, CMC, as well as the GFS have now agreed to this scenario. ...Weather Highlights/Threats... The medium-range period will begin with a vigorous upper low moving onshore over the southwestern U.S. on Monday. The heaviest rain totals for southern California will likely be enhanced by higher terrain and could cause flooding issues if heavy rain falls over burn scar areas. Rain and higher elevation snow will spread across the Intermountain West and Rockies Monday and Tuesday. As surface low pressure strengthens in the Plains and tracks east, more widespread rain and possibly severe thunderstorms are forecast to develop over the southern Plains late Tuesday and then move across the South on Wednesday before reaching the Southeast on Thursday. 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 snows have increased across the upper Great Lakes into the upper Midwest Wednesday-Thursday. Depending on the strength and size of the intensifying cyclone, high winds could also impact a large portion of the northern U.S. during this time frame. Some wintry precipitation is also forecast for interior New England late Thursday/early Friday ahead of a warm front, while pockets of heavy rain is possible down the East Coast ahead of a cold front. Kong/Schichtel 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