Prognostic Meteorological Discussion
Issued by NWS
Issued by NWS
986 FXUS02 KWBC 231859 PMDEPD Extended Forecast Discussion NWS Weather Prediction Center College Park MD 259 PM EDT Thu Jul 23 2026 Valid 12Z Sun Jul 26 2026 - 12Z Thu Jul 30 2026 ...West-Central to Southern U.S. Hazardous Heat this weekend into next week as monsoonal rains focus over the Four Corners states... ...Heavy convection/rain pattern focus into the East next week... ...Pattern Overview and Guidance/Predictability Assessment... Models depict the overall synoptic pattern evolution very well during the medium range. The expanding ridge from the central U.S. into the West, as well as mean troughing over the Northwest and East were captured well by the available model guidance. There continues to be some uncertainty around the timing of a southern Canada/Great Lakes/Ohio Valley shortwave later next week, but the ensemble means resolve that reasonably well. A general model blend consisting of the available deterministic and Ai guidance was used through day 6 followed by a majority of ensemble means on day 7. ...Weather/Hazards Highlights... Upper ridge influence offers Major to Extreme HeatRisk threats to shift this weekend and next week from the Southwest/Intermountain West/Rockies and the Northern Plains down through the South- Central U.S. and the South. Expect spotty record highs and more widespread record overnight lows to limit relief from the heatwave. Some moderating flow within and around the western periphery of the upper ridge will occur as significant monsoonal moisture feeds into the Southwest and Intermountain West/Rockies/Plains this week, with the next influx of moisture from Mexico possible early next week. Scattered to numerous showers and thunderstorms are expected with heavy rainfall and localized flash flooding potential. Sensitive places such as burn scars, steep terrain, slot canyons etc. would be the most vulnerable to possible flooding concerns. WPC Excessive Rainfall Outlook (ERO) Marginal Risks areas are for Sunday/Monday. Ample northern stream system energies set to dig into the upper trough position over the East will support organized enhanced to heavy convective rainfall potential from the Great Lakes/Ohio Valley Sunday to the Eastern Seaboard through early-mid next week. ERO Marginal Risk areas have been introduced for Sunday/Monday. Kebede/Schichtel 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 $$