484 FXUS02 KWBC 250745 PMDEPD Extended Forecast Discussion NWS Weather Prediction Center College Park MD 345 AM EDT Sat Jul 25 2026 Valid 12Z Tue Jul 28 2026 - 12Z Sat Aug 1 2026 ***Lengthy heat wave expected for much of the Western and Southern U.S. along with active monsoonal pattern over the Rockies*** ...Pattern Overview... The main theme going into the middle of the week will be a large upper ridge situated across the Rockies and western High Plains, and extending northward into south-central Canada. A broad upper trough is expected over the Northeast Pacific, and a more amplified ridge over the Northeast states will likely support periods of heavy rainfall Tuesday into Wednesday. This general pattern holds true going into the end of the week as the ridge expands farther to the west to include the Intermountain West, and general troughing likely continues for the East Coast with some abatement in rainfall coverage. Daily afternoon and evening thunderstorms are expected from the central Rockies to the Desert Southwest with plenty of monsoonal moisture in place. ...Guidance/Predictability Assessment... The 00Z model guidance suite is in good overall agreement on the synoptic scale pattern across the Continental U.S. through the middle of the week, with a general deterministic model compromise serving as a starting point in the forecast process. Looking ahead to the end of the week, the models agree best on the upper ridge expanding across the West (with potential for a 600dm high centered over Utah by late Friday). The greatest differences are noted across southern Canada with shortwave energy tracking around the northern periphery of the high, and the degree of downstream troughing across the East Coast region. The AIFS and CMC are more amplified with the trough over the central Appalachians by Saturday compared to the GFS and ECMWF. The ensemble means were gradually increased to about 50% by Saturday. ...Weather/Hazards Highlights... Extreme heat will continue to make weather headlines across a large expanse of the country going into next week. Widespread upper 90s and low 100s are expected from Montana to the Dakotas, which is 10-15 degrees above average in many cases. It will also be very hot and humid from Texas to the Gulf Coast states with highs ranging from 95 to 105 degrees on most days, with some areas of extreme heat risk given the longevity of the heat and expected heat indices exceeding 110 degrees at times. It will also be quite hot from the Desert Southwest and extending north across the Intermountain West with the upper ridge exerting its influence, with 110s for the lower elevations of southern Arizona and southern interior California, and near 100 degrees northward to the greater Salt Lake City area. Overnight lows will also be above normal for many of these same areas. The opposite will likely be the case for the East Coast with readings near average or slightly below. An organized low pressure system crossing the Northeast and Mid- Atlantic region on Tuesday, in combination with an amplifying upper level shortwave trough, will fuel the development of numerous showers and storms from Virginia to New England. A Marginal Risk of excessive rainfall will be valid for portions of this region given the potential for 1-2 inches of rainfall with the stronger storms, which could be enough to produce flooding for some areas. There is also a threat of severe weather across portions of the Mid-Atlantic in the warm sector of the low pressure system, with damaging winds being the primary hazard with the strongest storms. Elsewhere across the country, monsoonal moisture will remain entrenched across the Four Corners region and including the central and southern Rockies. Scattered to numerous showers and storms are expected most days, with the greatest coverage expected across northern New Mexico into central Colorado. Farther east across the Plains and Midwest, northwest flow aloft around the northern periphery of the upper ridge should support the development of some mesoscale convective complexes, but the timing and placement of these remain uncertain at this time. 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 $$