Extended Forecast Discussion NWS Weather Prediction Center College Park MD 141 PM EDT Tue Jun 30 2020 Valid 12Z Fri Jul 03 2020 - 12Z Tue Jul 07 2020 ...Overview and Guidance Assessment... The current general pattern of troughing/closed low development over western Canada into the northwest CONUS, an upper ridge looks extending southeast from the Northwest Territories of Canada to western Ontario then southwest to Texas will generally hold into this weekend as the southern portion of central ridge expands both into the Southwest and Northeast CONUS with troughing persisting over eastern Canada. The complex structure of the low/trough over western Canada/Northwest CONUS presents uncertainty among global guidance. Global guidance still indicates a weak upper trough persisting over the Southeast/Gulf Coast into next week. Uncertainty increases by Friday with evolution of a closed low currently developing over southern BC/Alberta. While it is unknown how long the low will remain closed or how positively tilted the resulting trough will be (and how far it will extend into the Pacific), there is general agreement among global guidance. Preference was given to the 00Z ECMWF given consistency and a more compact low/positively tilted trough into the Pacific Northwest (compared to the 06z GFS) through this weekend as well as a narrower trough over the central Gulf Coast. This solution is similar to the 00Z CMC which was given second preference. The 06Z GFS is unique with a stronger trough off the southern BC coast and a broader trough over the Southeast. The 00Z ECENS mean was mixed with the 06Z GEFS mean and 00Z NAEFS mean for Days 6/7 with a preference given to the 00Z ECENS for its less positively tilted trough in the Northwest and weaker trough in the Southeast. ...Weather/Hazard Highlights... Continued trends toward a weak upper trough persisting over the Southeast/Gulf Coast have further increased the rainfall threat near the Gulf Coast Days 4/5, expanding into the Southeast/southern Carolinas Days 6/7. Given the mesoscale factors deciding where the heaviest rain will occur, uncertainty is still the case for precip in the Southeast. Persistence of a wavy front over the extreme northern part of the Plains may lead to higher rainfall totals from Northern Plains showers and thunderstorms with some training/repeat activity possible. Expect diurnal convection over the central/southern Rockies during the period. The upper trough and surface front over the Northeast to Mid-Atlantic should promote showers/thunderstorms to shift south with the cold front on Friday/Saturday, then return north with a warm front Sunday into next week. A broad swath of temperatures 10 to 15 degrees above normal are expected to spread east under the ridge from the Northern Plains to the Northeast through the Day 3-7 time frame, keeping the Great Lakes above normal through this time. A few daily hi max temperature records are possible over northern Minnesota Friday and Saturday with max temperatures in the low 90s. Elsewhere expect anomalies to be in the single digits. The persistent upper trough over the Pacific Northwest keeping coastal temperatures just below normal while clouds/precipitation should keep the South near to somewhat below normal though the Florida Peninsula, south of the main precip area will likely stay a little above normal. Jackson 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