Extended Forecast Discussion NWS Weather Prediction Center College Park MD 259 PM 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... The guidance continues to show above average agreement and predictability with the mid-larger scale flow evolution through much of next week in a patter with relatively zonal flow. There remain some questions in the smaller scale details which likely will take until the short range to resolve. A general model blend using the latest deterministic runs served as a good starting point for days 3-5. Models and ensembles are hinting at a more amplified flow pattern by later next week, but with plenty of run to run continuity issues leading to much greater uncertainty at these longer lead times. WPCs blend for days 6-7 incorporated more of the compatible ECENS/GEFS means, though still with at least half deterministic guidance (ECMWF, CMC, GFS) for added system definition. This maintained good continuity with the previous forecast. ...Sensible Weather/Threat Highlights... Despite zonal flow, next week should offer a somewhat active weather pattern primarily from the Rockies to the East as locally heavy rainfall and strong thunderstorms tend to focus near and along a wavy frontal boundary, with plenty of moisture and instability available. Exact locations of heaviest rain will remain extremely difficult to pinpoint given the convective nature of this activity. Convective clusters and repeat/training cells could produce local runoff issues with perhaps the strongest signal next week from the High Plains/Central Plains to the mid-Mississippi Valley along with a lead region from the upper Ohio Valley to the Northeast. Much of the west should stay dry next week until later in the week when a Pacific system approaching the coast brings a period of rainfall to the Pacific Northwest. General troughing over the northern tier and into the East will keep temperatures near or modestly below normal with the greatest anomalies (near 10 degrees below normal) over the northern Plains/Upper Midwest. Texas remains warm, with near record daytime highs as much as 15 to 20 degrees above normal, through much of the week, with some relief on Thursday before ridging amplifies again on Friday. From California, across the central Great Basin and the Southwest, temperatures will trend warmer throughout the week, with daytime highs 10 to 15 degrees and possible excessive heat concerns for some in the interior valley region of California and the Desert Southwest by later next week Santorelli/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