Extended Forecast Discussion NWS Weather Prediction Center College Park MD 228 AM EDT Fri Apr 12 2019 Valid 12Z Mon Apr 15 2019 - 12Z Fri Apr 19 2019 ...Active pattern to continue through next week for much of the lower 48... ...Overview... Upper ridging pushed out of the northeastern Pacific will surge back toward the west coast of North America which favors renewed downstream troughing in the central/eastern states late next week. A lead system out of the short range will exit through New England Monday as a couple more push through the west. By midweek, low pressure will deepen out of the southern Plains and lift toward the Great Lakes/southern Canada with another round of rain, convection, and some wintry weather on the colder northwest side. ...Guidance Preferences and Predictability Assessment... Models/ensembles align with the longwave pattern through next week, but differ mostly on timing/depth/track of especially the late-week system. At the start of the period, models have struggle with the quick flow south of the Gulf of Alaska between southern ridging and northern troughing, so a consensus position in both depth and speed was preferred as run-to-run changes will continue. Trend has been for a bit weaker/flatter flow but northern flow across the U.S./Canadian border was unclear as well. By 12Z Wed, split in the guidance was evident (and mostly mimicked in their parent ensemble systems)--GFS/UKMET were slower than the ECMWF/Canadian/FV3-GFS as the trough digs through the Great Basin/Four Corners region. ECMWF has trended quicker while the GFS trended slower, away from a common solution 24 hrs ago, but the ensembles overlapping most just a bit slower than the 12Z ECMWF. As the low lifts northeastward, 12Z GFS/ECMWF offered reasonable clustering near the 12Z NAEFS mean which was not as quick as the ECMWF ensemble mean but not as slow as the 18Z GEFS mean. This paired well with continuity which was preferred until another cycle or two of runs can be reviewed for short term changes that may influence the late week system's exit speed (i.e., upstream kicker and northern stream affects). ...Weather Highlights/Hazards... Precipitation will again increase by Wednesday into Thursday across the Mississippi/Missouri Valleys into the Great Lakes as low pressure strengthens over Oklahoma/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 (and perhaps only at night) depending on the amount of cooler air behind a weakening Canadian cold front Wednesday. Temperatures will largely be within 10 degrees of average values for mid-April but with a slower moderation over parts of the Dakotas/Minnesota owing to the near-term snow cover that will take at least several days to melt. 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