Preliminary Forecasts
Issued by NWS
Issued by NWS
522 FXUS02 KWNH 060635 PREEPD Extended Forecast Discussion NWS Weather Prediction Center College Park MD 234 AM EDT Sun Jul 6 2025 Valid 12Z Wed Jul 09 2025 - 12Z Sun Jul 13 2025 ...Hazardous heat and humidity continues for parts of the East while the heat builds over the West... ...Pattern Overview... The large scale pattern will transition from being quasi-zonal to having an upper ridge over of the West/Southwest with troughing into the Northeast. This change will limit monsoonal flow to the Southwest while bolstering widespread heat. A low pressure system will advance through the northern/central states toward the Northeast and will be the focus for scattered showers and thunderstorms. ...Guidance/Predictability Assessment The latest guidance has above average confidence for hazardous heat with the upper ridge building over the west and for multiple impulses to track through the flow as troughing setups up over the Northeast. The main feature tracking from the eastern Pacific to the Northeast remains faster with the GFS/GEFS mean whereas the CMC is deeper with the closed low/trough exiting the Dakotas. The spread was still acceptable however weighting of those solutions were reduced later in the extended period. WPC utilized a combination of the OOZ ECMWF/GFS/Canadian/UKMET/ECMWF ensemble mean/GEFS mean, continuity and the NBM. ...Weather/Hazards Highlights... Showers and thunderstorms are expected to be focused in proximity to progressive cold fronts, stalled boundaries and round the upper high in the Southern Rockies. The wavy front into the eastern U.S. may be a focus for heavier rain and thunderstorms. This includes areas from the Corn Belt into the Midwest and Ohio Valley, Appalachians, Mid-Atlantic, and Northeast. There are Marginal Risks in place (level 1 of 4) for the Central Plains/Midwest for Day 4, for the parts of the Dakota/Upper Mississippi Valley on Day 5 and for portions of the Mid-Atlantic/coastal Carolinas for Day 4/5 for an axis of heavier rainfall possible south of a frontal boundary. Many locations will have daily maximums climbing well into the 100s at lower elevations across the Southwest, which will greatly limit rain except for perhaps far southeastern Arizona into New Mexico early in the week. Experimental HeatRisk values may rise to Major or Extreme levels (3 out of 4 or 4 out of 4) from the California deserts into southern Nevada, Utah, and Arizona. Extreme Heat Watches have been raised for parts of Arizona through at least Thursday. Campbell 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 (QPF), excessive rainfall outlook (ERO), winter weather outlook (WWO) probabilities, heat indices, and Key Messages can be accessed from: 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 $$