Extended Forecast Discussion NWS Weather Prediction Center College Park MD 300 AM EDT Sun May 31 2020 Valid 12Z Wed Jun 03 2020 - 12Z Sun Jun 07 2020 ...Hot temperatures for the West-Central U.S. and a Gulf of Mexico feature to monitor... ...Overview and Guidance/Predictability Assessment... A composite of reasonably well-clustered GFS/ECMWF/UKMET seems reasonable over the nation Wed into Thu. However, prefer to quickly switch to an ensemble mean blend later Thu through next weekend in an effort to mitigate growing smaller-scale model timing and detail differences. Zonal northern stream flow amplifies significantly into next weekend with development of West Coast and Northeast U.S. upper troughs and the blocky nature at mid-lower latitudes seems to favor the slower side of guidance spread. The models also continue to overall trend a bit slower with ejection of closed southern CA upper trough energy late week, but the GFS/GEFS remain on the faster side of the full solution envelope. Accordingly, applied much greater weighting in the WPC blend to the overall less progressive ECMWF ensemble mean in a pattern with lowering forecast predictability and continuity over time. ...Weather/Hazard Highlights... Maximum temperatures will remain hot across much of the west-central U.S. with a broad area of plus 10-15F anomalies and spotty record values in advance of an approaching cold front. The pattern should favor showers/thunderstorms mid-late week with best potential of locally moderate to heavy downpours from the Mid MS/OH Valleys to the central Appalachians/Mid-Atlantic in advance of a front. Upstream, a wavy front extending back across the Northern Plains/Rockies will also provide a focus for convection. Srn CA closed low ejection through the West will meanwhile increase rainfall coverage and height falls/moisture will weekend West Coast upper trough amplification will further enhance activity. There is some potential to monitor for moisture working northward from the unsettled tropics to enhance rainfall late next week over the Gulf of Mexico/vicinity with approach of a ridge penetrating upper trough slated to drop down from the southern Plains. Schichtel/Ryan 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