Extended Forecast Discussion NWS Weather Prediction Center College Park MD 251 PM EDT Thu Mar 24 2022 Valid 12Z Sun Mar 27 2022 - 12Z Thu Mar 31 2022 ...Record warmth and cold likely next week for different parts of the Lower 48 in dynamic springtime pattern... ...Overview... A strong upper trough and embedded closed low will progress into/through the Southwestern states early next week before lifting into the central Plains/Great Lakes by next Wed/Thu. This will promote a rather wet pattern for the Southwest/Four Corners region into the Plains and eventually the Southeast through the week. Colder than normal temperatures within the trough may feature record cold temperatures for parts of the Great Lakes and Northeast (with snow over the northern tier) while ridging ahead of the incoming western trough may feature record warmth over the Interior West into the southern Plains. ...Guidance Evaluation/Predictability Assessment... Though the upper pattern falls in the usually more predictable phase between zonal and blocky flow (inherently less predictable for different reasons), there was an added complication to the forecast; namely, separate northern and southern stream flow out of the Pacific into the West. The 00Z/06Z GFS runs were quite different than the preferred cluster of the 00Z ECMWF/Canadian/UKMET/ECMWF ensemble mean in their handling of the northern stream (much slower) so that it resulted in a stronger and much slower system next week through the Plains. This was evidenced by many 06Z GEFS members on the slower side but with perhaps just as many quicker members nearer to the ECMWF/CMCE consensus, which was near the largest overlap among the three ensemble systems. Note that the 12Z GFS did quicken its pace toward the ECMWF/Canadian-led cluster. By the end of the period, a positively-tilted trough between the northern and southern streams should move east of the Plains as a weaker shortwave comes into the Pac NW. Despite the good agreement between the ECMWF and Canadian even into next Thursday, increased the weighting of the 00Z ECMWF ensemble mean with time to account for uncertainty as the system could still trend a bit deeper/slower as shown by some of its ensemble members. ...Weather Highlights/Threats... Light precipitation could linger across the Great Lakes region and Northeast early in the period given strong cyclonic flow and coastal low pressure systems. As the next system moves into the western U.S. early next week, unsettled and active weather is expected for the West Coast states Sunday, which could bring mostly beneficial and welcome rains to the valleys. Higher elevation areas of the Sierra could see see several inches or more of snow. Current model guidance shows the heaviest rain totals for southern California Sunday and Monday especially enhanced by higher terrain, which 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 thunderstorms are likely for the southern Plains/Lower Mississippi Valley Tuesday and Wednesday. Meanwhile on the northern side of the precipitation shield, a wintry mix and accumulating snow are possible for the northern tier around the Great Lakes and potentially into the Northeast. Rainfall could remain heavy through the Southeast into next Thursday. Unseasonably warm temperatures are likely underneath upper ridging from the western states into the Plains early next week, and temperatures of 10-25F above normal will be common. Though expansive record-breaking warmth will occur in the short range, some record highs and high minimum temperatures could be set or tied Sunday and Monday. Temperatures in the West will be near to below normal as the cold front moves through. Much of the East will see below normal temperatures early in the week, perhaps by as much as 10-25F. Freezing temperatures overnight may dip into parts of the Carolinas. A moderation in temperatures should commence by Wednesday ahead of the storm in the Plains. Fracasso/Tate 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