Preliminary Forecasts
Issued by NWS
Issued by NWS
813 FXUS02 KWNH 050644 PREEPD Extended Forecast Discussion NWS Weather Prediction Center College Park MD 243 AM EDT Sat Jul 5 2025 Valid 12Z Tue Jul 08 2025 - 12Z Sat Jul 12 2025 ...Hazardous heat and humidity over parts of the East; building over the West... ...Pattern Overview... Quasi-zonal flow over most of the CONUS to start the week will transition toward an upper high starting to take residence near Las Vegas and increased troughing into the Northeast. This will favor a fairly typical summertime pattern but without much, if any, monsoon signal into the Southwest. ...Guidance/Predictability Assessment The large scale pattern remains in good agreement through the extended period. Like its previous runs, the GFS and the GEFS mean were persistent in being the faster solutions from the Northeast Pacific into western North America than the other models therefore had limited inclusion in the forecast. The preferred blend was a comprise of the 12Z ECMWF/Canadian/UKMET/ECMWF ensemble mean 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 Southwest, Central Plains/Midwest to the Upper Mississippi Valley/Upper Great Lakes region and portions of the Northeast for Day 4 and for the Mid-Mississippi Valley/Midwest for Day 5. Heights across the Northeast and Mid-Atlantic regions will gradually lower as troughing moves in. With the higher heights shifting southward the heat will increase as well as begin to build to the west as the upper high strengthens over the Southwest. Many locations will have daily maximums climbing well into the 100s at lower elevations which will greatly limit rain except for perhaps far southeastern AZ into NM 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. Campbell/Fracasso 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 $$