Extended Forecast Discussion NWS Weather Prediction Center College Park MD 1232 PM EDT Sat Jun 01 2019 Valid 12Z Tue Jun 04 2019 - 12Z Sat Jun 08 2019 ...Heavy rainfall threat spreading northeastward next week from the Texas coast into south-central Plains, followed by the lower and mid Mississippi Valley, Tennessee Valley and into the lower Ohio Valley... ...Overview and Weather/Threats Highlights with guidance/uncertainty assessment... An upper-level trough moving relatively slowly across the Plains next week together with tropical moisture currently consolidating over the southern Gulf of Mexico will appear to be the recipe for potentially heavy rainfall to spread from southern Texas toward the Ohio Valley next week. Models and ensembles are in decent agreement on the slow eastward progression of the upper-level trough. This pattern by itself would represent a heavy rain threat for the Deep South into the Mississippi Valley. The more uncertain part of the forecast has to do with a tropical system that is currently consolidating over the Bay of Campeche and how much of the associated moisture will be drawn northward into the southern Plains. The GFS takes the tropical system on a more northwest track toward the Mexican mountains and deposits much of the moisture in Mexico before drawing the remaining moisture northward into the Deep South. The ECMWF appears to take the system on a more northerly track near or just off northern Mexico and toward the Texas coast. The Canadian model represents the most convective solution with the eastern-most extreme track, taking the system faster and stronger along the Texas coast next Wednesday and across Louisiana next Thursday. With the consideration of the upper-level trough moving slowly eastward across the Plains next week and the convective nature of the tropical system, the eastern solutions indicated by the ECMWF and the Canadian models cannot be ruled out. For the rest of the country, the more uncertain part of the forecast will be from the Pacific Northwest into the northern Rockies for late next week. Models are still showing a great deal of run-to-run variability regarding an amplifying upper trough and the placement and intensity of the surface cyclone moving across the region. The ECMWF has been more consistent on forecasting this upper-level trough and thus more of the 00Z ECMWF was incorporated into the Day 6 and 7 model blend. The WPC medium range product suite was mainly derived from a composite blend of well clustered 00/06 UTC GFS combining with the 06Z GEFS mean and the 00 UTC ECMWF/ECMWF ensemble mean guidance in a pattern with average to below average mass field forecast spread. The main heavy convective rainfall focus is less predictable within this pattern, but there is a growing signal supporting a threat from the south-central Plains to the mid-lower Mississippi Valley, Tennessee Valley and lower Ohio Valley in a region already inundated with heavy rainfall and flooding issues. Kong 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