802 FXUS02 KWBC 230751 PMDEPD Extended Forecast Discussion NWS Weather Prediction Center College Park MD 351 AM EDT Tue Jun 23 2026 Valid 12Z Fri Jun 26 2026 - 12Z Tue Jun 30 2026 ***Additional heavy rain for the Midwest and Ohio Valley*** ***Heat and humidity increases across the Central and Southern U.S. starting this weekend*** ...General Overview... After a zonal upper level flow pattern during the middle of the week, the upper ridge over the Southwest states weakens due to an amplifying trough over the northwestern quadrant of the country over the weekend, bringing a welcomed cool down after a hot week. This strong trough will support an organized low pressure system that will emerge from the Rockies to the central/northern Plains with a relatively potent cold front crossing the Pacific northwest and Intermountain West for this time of year. This will result in a downstream upper ridge developing over the east-central U.S. towards early next week with a return to hotter temperatures for much of that region. ...Guidance/Predictability Assessment... The 00Z model guidance suite featured good overall synoptic scale agreement overall for the end of the week, with good overall consensus on the developing upper trough/closed low dropping south across the Pacific Northwest. More model differences are apparent by Sunday and beyond as the trough reaches the northern Rockies and the downstream ridge that builds ahead of it across the Midwest states. In particular, recent runs of the CMC have maintained a trough cutting the northern portion of the ridge across the Great Lakes region late Sunday into Monday, and this differs considerably from the ensembles and other guidance, so a non-CMC blend was used for early next week. The ensemble means were increased to about 40-50% by this time. The NBM was a reasonable starting point for most areas of the country, although QPF was raised across portions of the interior Southwest U.S. and the Rockies for Friday, and temperatures lowered for coastal areas of the Mid-Atlantic, Northeast, and the Great Lakes. ...Weather/Hazards Highlights... Multiple mesoscale convective systems are likely to affect much of the Midwest and extending eastward to include the Ohio Valley through the end of the week and into Saturday, with some areas getting an additional 1-3 inches of rain over already saturated grounds from recent heavy rainfall. A lingering frontal boundary with shortwave energy aloft and strong moisture convergence will provide enough instability and lift to sustain these thunderstorm complexes, and some of these storms could produce flash flooding. This also includes the potential for some strong to severe thunderstorms. Elsewhere across the nation, rainfall increases for Washington and Oregon to close out the work week with the storm system moving through the region, and a larger area of heavier rainfall develops across Montana and then the Dakotas as the main surface low ejects eastward over the northern Plains by the weekend. High elevation snow is likely for the highest ranges of the northern Rockies as the colder upper low moves in. Scattered showers and thunderstorms are also expected for the East Coast through Saturday with increasing low level moisture in place. The widespread above average heat levels across the western third of the nation are expected to abate considerably going into the weekend. A strong cold front brings relief from the heat starting Friday and becoming even more noticeable going into the weekend as highs return to below average by late June standards, whereas overnight lows should be less anomalous. The opposite holds true for the southern High Plains where temperatures are likely to increase by the weekend with highs well into the 100s for western Texas, and building heat and humidity for much of the central and Eastern U.S. going into Sunday and Monday as the upper ridge dominates the weather pattern. Widespread major heat risk is currently depicted across much of the Central and Southeast U.S. for early next week, and heat advisories are likely for many areas. Hamrick 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 forecast, excessive rainfall outlook, winter weather outlook probabilities, heat indices and Key Messages 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 https://www.wpc.ncep.noaa.gov/#page=ovw $$