Extended Forecast Discussion NWS Weather Prediction Center College Park MD 104 AM EDT Tue Jun 18 2019 Valid 12Z Fri Jun 21 2019 - 12Z Tue Jun 25 2019 ...Weather Highlights/Threats... Several rounds of showers and thunderstorms are possible from the southern Plains across the MS Valley, Oh Valley and Great Lakes. Pockets of severe convection and heavy rainfall are possible. Rainfall Thu night and Fri over the northeast departs and conditions improve over the weekend. The upper trough over the northern Rockies and Plains brings much colder than normal temperatures across the regions days 3 and 4, spreading south into CO day 5, while moderating over the northern Rockies. With the upper low departing CO and WY moderate back towards normal early next week. The new trough in the Pacific northwest to the Great Basin brings more below normal temperatures to the region early next week, extending down into the southwest. The continued high heights across the southern mid Atlantic and southeast coastal areas brings a prolonged period of above normal temperatures. ...Guidance/Predictability Assessment... The days 4-7 forecasts were derived from a blend of the 12z ECMWF Ensemble Mean and 18z GEFS Mean, with less weighting on the 12z operational ECMWF and 18z GFS. The 12z ECMWF Ensemble Mean and 18z GEFS Mean continuity to show better than average run to run continuity and overlap/agreement with each other, in contrast to the significant run to run changes in the 18z GFS and 12z ECMWF. The overall pattern remains in place to have an initial northern Plains upper trough and embedded closed low that eventually moves up into southern Canada. A succeeding upper trough develops in the Pacific northwest and then expands inland into the Rockies and Great Basin early next week. The departure of the cyclone off the New England coast Fri is followed by rising heights and approach of a deep layer ridge over the weekend into early next week. Petersen 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