Extended Forecast Discussion NWS Weather Prediction Center College Park MD 241 AM EDT Sat Apr 13 2019 Valid 12Z Tue Apr 16 2019 - 12Z Sat Apr 20 2019 ...Another in a series of dynamic spring storms next week... ...Overview... Troughing will push through the West early in the week and dive through the Plains and into the Midwest as ridging comes back to both coasts temporarily. This supports a strong/robust system lifting out of the southern Plains into the Great Lakes with a threat of heavy rain, strong winds, and some wintry weather. ...Guidance Preferences and Predictability Assessment... Most of the models/ensembles show reasonable clustering to start the period (Tue) so that a blended/consensus solution sufficed. By Wed the east-west timing spread remained in place from 24 hrs ago though it was not quite the dog's breakfast of yesterday as there has been some contraction westward in the quicker ECMWF members and eastward in the slower Canadian/GEFS members. However, parent model and children members (both deterministic and ensemble) remained separate in each system. Again favored a mostly middle ground solution very near the 18Z FV3-GFS. As the system should deepen and turn eastward then northeastward Thu, ECMWF ensemble members continued to lead the pack with a quicker exit to the northeast, though the trend has been slower. Opted to discount the 12Z ECMWF ensemble mean in favor of the slower solutions near the 12Z ECMWF/GFS as the low pushes through Michigan Friday. By next Saturday, the front will push to the coast and perhaps continue eastward, but with the possibility of sfc wave development that would slow its eastward progress. The west will be comparatively quieter, with a weak frontal passage Wednesday then another late Friday. Consensus positioning sufficed via the blend preference in the east, which was close to continuity. ...Weather Highlights/Hazards... Significant precipitation will again increase starting Wednesday and continuing into Thursday across the Mississippi/Missouri Valleys into the Great Lakes as low pressure strengthens over Kansas. Multi-inch rainfall totals are probable (enhanced in embedded convection) in some locations of the warm sector and perhaps to the north/northeast of the low with additional northern stream support. Temperatures to the north/northwest of the low may only be marginally cold enough for snow depending on the amount of cooler air available. Temperatures will largely be within 10-15 degrees of average values for mid-April. The northern/central Rockies into the northern Plains and Upper Midwest will generally be cooler than average while the west and east coasts will generally be milder than average. Fracasso Additional 3-7 Day Hazards information can be found on the WPC medium range hazards chart at: https://www.wpc.ncep.noaa.gov/threats/threats.php WPC medium range 500mb heights, surface systems, weather grids, quantitative precipitation, winter weather outlook probabilities and heat indices are at: 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