Extended Forecast Discussion NWS Weather Prediction Center College Park MD 138 AM EDT Fri Jun 19 2020 Valid 12Z Mon Jun 22 2020 - 12Z Fri Jun 26 2020 ...Overview and Weather/Hazard Highlights... The medium range period begins Monday with one upper level low exiting the Northeast coast, while a stronger and slow moving low settles south of Hudson Bay and drifts only slightly eastward through the week. This should bring height falls and a cold front working itā€s way across the Midwest and eventually into the Northeast. Ahead of this front, high temperatures early to middle of next week should remain 10 to 15 degrees above average from the Great Lakes to northern New England. The trailing end of this frontal boundary is expected to stall across the warmed central/southern Plains and linger through much of next week, serving as a focus for shower and thunderstorm development. Precipitation should slowly shift farther south and east, from the Southern Plains/Lower Mississippi Valley to the Ohio Valley/Appalachians and the Eastern Seaboard middle to latter part of next week. Models continue to highlight the south-central Plains and Lower Mississippi Valley states as the greatest potential for locally heavy rainfall and runoff issues under additional influence of a broad upper-level weakness. Meanwhile, out west, upper-level ridging should maintain itself over the Desert Southwest through much of next week. Initial upper ridging in the Northwestern states should keep conditions dry, though height falls and a weak cold front look to move it by mid to late next week. This may bring some showers to the region by next Thursday, with any organized activity likely focusing along a lingering boundary in the northern Rockies/High Plains region. Temperatures across much of the west are forecast to stay above normal, with daytime highs ranging 10 to 15 degrees above average, especially across the Great Basin and into parts of the interior Northwest. ...Guidance/Predictability Assessment... Overall, guidance spread through next week was relatively good. A blend of the deterministic GFS/ECMWF was preferred Monday-Tuesday, though a slow increase of the ensemble means was incorporated later in the period to account for continued run to run differences on placement/strength/evolution of the eastern Canadian upper low. In the northwest, the ECMWF remains a bit more amplified with the troughing moving in next Thursday-Friday, so a blend of the ensemble means seemed reasonable for that system. Some deterministic model guidance was maintained even into Day 7 just for definition of systems. This maintains good continuity with the previous WPC shift. Santorelli 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