703 FXUS02 KWBC 020703 PMDEPD Extended Forecast Discussion NWS Weather Prediction Center College Park MD 303 AM EDT Sun Aug 2 2026 Valid 12Z Wed Aug 05 2026 - 12Z Sun Aug 09 2026 ...Heat wave likely to continue across the Southwest and Intermountain West through next week, expanding eastward with time... ...Overview... The upper ridge currently dominating the weather pattern across the western half of the country will weaken slightly and get suppressed south by the start of the medium range period 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. However, 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. Meanwhile, a handful of frontal systems in the central and eastern U.S. will trigger scattered showers and thunderstorms through the week with monsoon convection in the Southwest as well. ...Guidance/Predictability Assessment... Models show good agreement on the large scale pattern evolution through the period which features a northern stream trough through the north-central U.S. and a sprawling southern tier ridge. The main focus of uncertainty continues to be with the positions of various energies aloft within the broader trough, especially the latter part of the week and into the weekend. Weak energy moving into the Northwest also shows some variability. The ECMWF/ECENS seems a bit faster than consensus in the Northwest late week. There is agreement for the southern ridge to expand and possibly connect up with the subtropical Atlantic ridge, but uncertainty on any embedded weaknesses over the Southeast/Mid-South which may act to keep the two more separate features. Across the board, there are not any real clear outliers, so a general blend of the deterministic guidance worked well for the first half of the period, increasing the weighting of the ensemble means a bit later in the period to help smooth out increasing uncertainty. ...Weather/Hazards Highlights... Though much more suppressed compared to the short range, some Major to Extreme HeatRisk will continue for 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 northern tier and into the East should be generally near average most of the period. A reasonably strong front will push into the Midwest and Central Plains by Wednesday and trigger a corridor of potentially heavy rain and thunderstorms along and ahead of it. Meanwhile, weak frontal boundaries will allow for showers and thunderstorms to be scattered across the East, with some locally heavy to excessive rainfall possible there as well. These interacting features should allow for additional rounds of rain and storms across the north- central to eastern U.S. through late week as the mean frontal boundary may stall for a bit. Elsewhere, monsoonal convection is likely for Arizona and New Mexico in particular, with scattered convection occasionally reaching portions of Utah and Colorado. The remainder of the West into the Northern Plains should be mostly dry during the period. 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 $$