Extended Forecast Discussion NWS Weather Prediction Center College Park MD 346 PM EST Fri Mar 11 2022 Valid 12Z Mon Mar 14 2022 - 12Z Fri Mar 18 2022 ...Overview... Two systems in progressive flow are noted over the Lower 48 next week. The first system shifts east from the southern Plains and through Southeast Monday night through Wednesday before turning northeast, pushing off the southern Mid-Atlantic coast Thursday. Meanwhile, an ongoing atmospheric river into the Pacific Northwest shifts down to the northern California coast Monday night ahead of the next wave that crosses the Pacific Northwest coast Tuesday. Much above normal temperatures will shift east over the central and eastern U.S. between these two waves mid to late week, offering spring-like temperatures reaching 10-20 above normal. ...Guidance Evaluation/Predictability Assessment... Excellent agreement among the latest deterministic guidance is noted in the in the main surface and 500mb features and evolution through Wednesday. North-south waffling between guidance on the progression/amplitude of the closed mid-level low over the Southeast Tues-Wed have diminished, particularly with the 12Z GFS that is a bit deeper and slower with the mid-level low compared to the 06Z GFS which is in excellent agreement with the 00Z ECMWF/CMC. The 00Z CMC is still slower starting Wednesday night with the low tracking over the Carolina Coast, so a fairly evenly distributed blend among the 00Z ECMWF/UKMET/CMC and 06Z GFS into Day 5 favors the 00Z CMC less with the addition of ensemble means for Days 6/7 to replace the UKMET (which we only get 5 days worth of data). Furthermore, the GFS is more amplified with the next wave out West Wednesday night/Thursday while the ECMWF is less amplified, so they are now in better agreement with each other. ...Weather Highlights/Threats... Low pressure over the southern Great Plains Monday night shifts to the Gulf coast shifts across the lower MS Valley into Tuesday and over the Gulf Coast/Southeast mid-week. This system should draw up ample Gulf moisture ahead of it and could combine with sufficient instability to bring widespread thunderstorms capable of producing heavy rainfall, especially along/near the Gulf Coast region. With a bit of a slower solution to the low, there is now a marginal threat for excessive rain over north Florida Tuesday/Tuesday night which is an area currently receiving heavy rain and already had above normal rainfall over the past week going into today. The atmospheric river is fairly progressive Monday night into Tuesday as it pushes across northern California, bringing beneficial rainfall and heavy elevation snowfall. A taste of spring-like temperatures is generally expected for much of the central to eastern U.S. next week under the ridge between the two systems. Daytime highs reach 10 to 20 degrees above normal on Tuesday over the Northern Plains, slowly shifting across the Great Lakes to the Northeast through Friday. Jackson 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 Hazards: - Heavy precipitation across portions of the Pacific Northwest and the Northern Great Basin, Mon-Tue, Mar 14-Mar 15. - Heavy rain across portions of California and the Pacific Northwest, Mon, Mar 14. - Heavy rain across portions of the Southeast, Tue, Mar 15. - Heavy snow across portions of the Northern Rockies and the Northern Great Basin, Mon-Tue, Mar 14-Mar 15. - Severe weather across portions of the Lower Mississippi Valley and the Southern Plains, Mon, Mar 14. - Severe weather across portions of the Southeast, the Lower Mississippi Valley, and the Tennessee Valley, Tue, Mar 15. - Flooding occurring or imminent across portions of the Middle Mississippi Valley, the Lower Mississippi Valley, and the Ohio Valley. 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