Extended Forecast Discussion NWS Weather Prediction Center College Park MD 259 AM EDT Fri Jun 03 2022 Valid 12Z Mon Jun 06 2022 - 12Z Fri Jun 10 2022 ...Overview... Potential Tropical Cyclone One is forecast by the National Hurricane Center to develop into a tropical storm that by the start of this medium range period Monday should be tracking well offshore the Carolinas and pulling away from the U.S. as a maritime threat. Meanwhile, much of the rest of the lower 48 should see a fairly zonal pattern, but with shortwaves and surface frontal boundaries providing foci for thunderstorms and potential for heavy rainfall over a broad region from the Rockies/central U.S. into the East next week. ...Model Guidance Evaluation/Preferences... Please see National Hurricane Center advisories for Potential Tropical Cyclone One for the most recent information. Guidance is overall trending to show better than normal agreement/predictability with the mid-larger scale flow evolution for much of next week in a pattern with relatively zonal flow. A blend of best clustered guidance of the latest GFS/ECMWF and GEFS/ECMWF ensemble means along with the 01 UTC National Blend of Models should tend to mitigate the more ample smaller scale embedded system differences at the cost of less predictable detail. There remains some signal that a more amplified pattern could develop late next week, but recent guidance has exhibited more pronounced run to run continuity issues at these longer time frames. Accordingly, greater blend weighting applied to the models for early-mid next week was switched to the still compatible ensemble means into later next week amid growing uncertainty. ...Sensible Weather/Threat Highlights... Next week should offer an active weather pattern primarily from the Rockies to the East as multiple chances for local heavy downpours and strong thunderstorms try to focus fueling moisture and instability near a wavy frontal boundary, as locally induced with impluses passages and additionally with terrain/upslope flow as well as with harder to pinpoint convectively induced meso-boundaries. Convective clusters and repeat/training cells could produce local runoff issues with perhaps the strongest signal week from the High Plains/Central Plains to the mid-Mississippi Valley along with a lead region with some potential with training convection from the upper Ohio Valley to the Northeast, especially if the main fronts slow due to the downstream well offshore track of "One" over the western Atlantic. Schichtel Additional 3-7 Day Hazard information can be found on the WPC medium range hazards outlook chart at: https://www.wpc.ncep.noaa.gov/threats/threats.php WPC medium range 500mb heights, surface systems, weather grids, quantitative precipitation, experimental excessive rainfall outlook, 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/#page=ero https://www.wpc.ncep.noaa.gov/wwd/pwpf_d47/pwpf_medr.php?day=4 https://www.wpc.ncep.noaa.gov/heat_index.shtml