Extended Forecast Discussion NWS Weather Prediction Center College Park MD 322 PM EDT Fri Jun 17 2022 Valid 12Z Mon Jun 20 2022 - 12Z Fri Jun 24 2022 ...Expansive area of heat to shift from the Northern Plains/Midwest into the South next week... ...Overview and Guidance/Predictability Evaluation... The overall pattern of troughing in the West and northern tier and persistent ridging in the Mississippi Valley and Deep South is captured reasonably well by the latest guidance. A general model blend of 00z EC/CMC/UK and 06z GFS was utilized on days 3 and 4 with the inclusion of the 00z GFS as it was fairly consistent with the overall synoptic pattern. Some small scale differences with respect to the upper trough over the Plains prompted the introduction of the 06z GEFS to the GMB on day 5. With a fairly consistent signal for zonal flow across much of the northern tier states, focus shifts to an upper low approaching from the British Columbia coast on days 6 & 7. While the ensembles are agreeable with respect to timing and intensity details of the upper low, the deterministic suites, particularly the 06z GFS and 00z EC have notable timing differences with the EC being a bit more progressive than the GFS. The latest model trends have tucked the low farther inland as it glides down the BC coast. ...Sensible Weather/Threat Highlights... The biggest weather hazard during the medium range period will be a dome of heat and anomalous warmth expanding from the Upper Midwest on Monday into the Southern states by Wednesday-Friday. The greatest anomalies are expected from parts of the central Plains to the Upper Midwest with daytime highs as much as 20 to 25 degrees above normal. This equates to high temperatures in the mid to upper 90s and low 100s with overnight lows in the mid to upper 70s struggling to provide much relief. Record high max and min temperatures are likely in many places. By Tuesday to Friday, the heat suppresses south with the upper ridge into the Midwest and eventually the south with several days of high temperatures near or exceeding 100F from central Texas to the Southeast and widespread high temperature records likely to be challenged. To the north, systems moving through the northern tier will focus some areas of locally moderate to heavy precipitation, with the best potential over/near the northern Rockies and Plains on Monday. Highest elevations may see some light snow as well with this system. Northward streaming anomalous moisture west of the ridge will bring an unusually early monsoon type pattern to parts of the Four Corners states and vicinity, mainly early in the week, supporting an increase in coverage and intensity of rainfall across the region. By mid week, there are still mixed signals over how much rainfall the interaction of this moisture with the western front advancing into the Plains will produce. However the potential for some training/repeat activity may have to be monitored as consensus shows this Plains front becoming aligned west-east along the southern edge of the westerlies by Wednesday-Thursday. Farther east, an area of showers and thunderstorms may push across the Great Lakes and possibly into the Northeast ahead of an advancing warm front, with some activity possibly on the heavy side. The Florida Peninsula should see multiple days of diurnal showers/storms from the weekend into next week as a front pushing into area decelerates and eventually dissipates. Santorelli/Kebede 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 Hazards: - Heavy rain across portions of the Southern Rockies, the Southern Plains, and the Southwest, Mon-Tue, Jun 20-Jun 21. - Heavy rain across portions of the Northern Plains and the Northern Rockies, Mon, Jun 20. - Flooding occurring or imminent across portions of the Upper Mississippi Valley, the Northern Plains, and the Northern Rockies. - Flooding likely across portions of the Northern Plains and the Northern Rockies. - Excessive heat across portions of the Central Plains, the Lower Mississippi Valley, the Tennessee Valley, the Middle Mississippi Valley, the Southern Appalachians, the Southeast, the Southern Plains, and the Ohio Valley, Mon-Fri, Jun 20-Jun 24. - Excessive heat across portions of the Central Plains, the Middle Mississippi Valley, the Great Lakes, the Upper Mississippi Valley, and the Northern Plains, Mon, Jun 20. - Excessive heat across portions of the Central Plains, the Middle Mississippi Valley, the Great Lakes, and the Upper Mississippi Valley, Mon-Tue, Jun 20-Jun 21. - Excessive heat across portions of the Central Appalachians, the Middle Mississippi Valley, the Mid-Atlantic, the Southern Appalachians, the Great Lakes, and the Ohio Valley, Tue-Wed, Jun 21-Jun 22. - Excessive heat across portions of the Central Appalachians, the Tennessee Valley, the Mid-Atlantic, the Southern Appalachians, the Southeast, and the Ohio Valley, Tue-Fri, Jun 21-Jun 24. 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