Extended Forecast Discussion NWS Weather Prediction Center College Park MD 300 AM EDT Sun Mar 27 2022 Valid 12Z Wed Mar 30 2022 - 12Z Sun Apr 03 2022 ...A deepening low pressure system presents a mid-late next week heavy rain/severe weather threat focus across the South while heavy snow/ice and high wind threat focus across the Upper Midwest/Great Lakes... ...Guidance Evaluation/Predictability Assessment... A composite of reasonably well clustered guidance from the 18 UTC GFS and 12 UTC ECMWF/UKMET/Canadian along with the 01 UTC NBM seems to offer a run to run consistent forecast Wednesday- into Friday that enjoys good GEFS/NAEFS/ECMWF ensemble support. The 12 UTC ECMWF ensemble mean seems best in line best in line with WPC continuity heading into next weekend, so have adjusted NBM guidance toward this guidance. Lingering guidance difference in this time frame concerns upper trough amplification back over the West and subsequent downstream frontal wave weather impact with ejection downstream back over the South. Overall, the ECMWF/UKMET/Canadian and ECMWF/Canadian ensemble means still develop a more amplified eastern Pacific upper ridge than the GFS/GEFS mean. This allows for deeper trough digging back into the West late next week. ...Overview and Weather Highlights/Threats... As a main surface low pressure system over the Plains strengthens and tracks northeast, increasingly widespread rain with heavy downpours and a threat for severe weather are forecast across the South into Wednesday before spreading over the Southeast/Mid-Atlantic Thursday. A "slight" risk area remains depicted on the WPC experimental medium range excessive rainfall outlook (ERO) for Wednesday given favorable system ingredients and antecedent conditions. Meanwhile, rain and thunderstorms are also expected farther north from the central Plains through the East with wavy frontal progression across the region. On the northern side of the precipitation shield, expect a swath of heavy wintry mix and accumulating snows from the Upper Midwest to the Great Lakes into Wednesday-Thursday given model consensus on developing a rather intense cyclone. In addition, high winds appear to likely impact near and well to the west of the low track given the impressive rate of cyclogenesis. Some wintry precipitation is also forecast for northern New England in this flow. Late week, additional upper trough energies forecast to dig with some uncertainty southeastward from the Pacific Northwest through the West could provide another opportunity for an enhanced round of wintry weather, mainly for the northern to central Intermountain West/Rockies to the High Plains. Potential system amplitude and progression into next weekend would favor return moisture flow into an increasingly wavy/lifting front. This may support renewed heavy rainfall potential across the central/eastern Gulf Coast states and Southeast next weekend. 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