642 FXUS02 KWBC 010718 PMDEPD Extended Forecast Discussion NWS Weather Prediction Center College Park MD 318 AM EDT Sat Aug 1 2026 Valid 12Z Tue Aug 04 2026 - 12Z Sat Aug 08 2026 ...Heat wave likely to continue across the Southwest and Intermountain West into next week... ...Overview... The upper ridge dominating the weather pattern across the western half of the country will weaken slightly and get suppressed south early next week as a strong cold front is forecast to bring much cooler air through the Northwest and into the northern Plains the first half of the week. Meanwhile, a slowly dissipating front merging with a wave lifting from the Midwest to the Northeast will trigger scattered showers and thunderstorms, which will gradually edge toward the East Coast through much of the week. Excessive heat will be persistent across the southwestern quadrant of the country, and should gradually spread northeast into the central Rockies/Plains as the upper ridge re-intensifies, as well as farther east across the South as it could join with subtropical Atlantic ridging coming in for later week. ...Guidance/Predictability Assessment... There is general agreement on the overall synoptic scale pattern and evolution through the period featuring progressive energy through the northern tier, and an expanding ridge building from the Southwest into the South and Southeast. Uncertainties lie mainly with energy timing within the broader central Canada to northern tier U.S. trough which leads to differences at the surface as well, and has implications for QPF coverage and intensity along associated frontal boundaries. There are differences early period over the Mid-South as energy looks to get left behind by a departingNortheast trough and how quickly that energy weakens or gets absorbed by the next shortwave reaching the Great Lakes around Thursday. Out West, additional weak energy moves into the Northwest, though the ECMWF seems to want to hold on to a stronger ridge than consensus would suggest. Either way, differences during the medium range period are plentiful, but more or less all within the realm of possibilities. A general model compromise, with more ensemble mean weighting for the latter half of the period, seemed to work as a good starting point for the WPC progs and maintains good consistency with the previous shift. ...Weather/Hazards Highlights... Though much more suppressed compared to the short range, widespread Major to Extreme HeatRisk will continue for much of the Southwest through much of next week. Then, heat should build again gradually northward across the Intermountain West and Rockies to the High Plains, as well as eastward in the Mid-South and Southeast as the upper ridge expands. See Key Messages issued by WPC for this event for additional information regarding this long lasting and dangerous heat wave. Temperatures across the East should be generally near average. Showers and thunderstorms look to linger across the East for much of next week as moisture streams northward ahead of the northern stream shortwaves and interacts with weak frontal boundary draped across the region. Locally heavy to excessive rainfall is possible. Elsewhere across the contiguous U.S., most of the monsoonal rainfall should be confined to eastern Arizona and into central New Mexico, with scattered convection reaching into portions of Utah and Colorado. A corridor of showers and storms is likely ahead of the front that crosses the Dakotas and into Minnesota early in the week, and this may also be accompanied with some severe weather. Heavy rain seems possible in the central Plains/Mid-Mississippi Valley into Tuesday- Wednesday with that front. Santorelli 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 $$