964 FXUS02 KWBC 080625 PMDEPD Extended Forecast Discussion NWS Weather Prediction Center College Park MD 225 AM EDT Tue Jul 8 2025 Valid 12Z Fri Jul 11 2025 - 12Z Tue Jul 15 2025 ***Heavy rain and storms expected for the Midwest and portions of the East Coast, and high heat continues for the Southwest states*** ...Pattern Overview... An upper level low will track from Southwest Canada into the Great Lakes region bringing a surface cold front from the Central/Northern Rockies through the north-central states in the coming days. Upper ridging will keep hot conditions in place for much of the Southwest and surrounding locations. Daily showers will pop up in proximity to a stationary boundary lingering near the Mid- Atlantic region. A separate complex of organized convection is also likely for the upper Midwest Thursday into Friday ahead of the front. ...Guidance/Predictability Assessment The large scale pattern begins with high pressure over the Southwest and a closed low/trough passing through western Canada and a trough passing through the Great Lakes/Hudson Bay/Ohio and Tennessee Valleys. The first day or so has very good agreement therefore a multi-model blend was used for initialization. As both troughs advance eastward through the weekend and into early next week the spread increases among the solutions resulting in timing and location differences of the QPF and amounts. The ensemble means were gradually increased to account for these model differences. ...Weather/Hazards Highlights... Scattered convection anticipated to fire ahead of, and along progressive cold fronts, stalled boundaries and round the upper high in the Southern Rockies. The exact location of anticipated higher QPF amounts remain a bit uncertain given persistent model differences, nevertheless, there is potential for isolated instances of excessive rainfall and localized flash flooding-- including areas from the Corn Belt into the Midwest and Ohio Valley, Appalachians, and Mid-Atlantic. For Day 4, there is broad Marginal Risk area for the Upper Mississippi Valley/Midwest, a broad Marginal Risk stretching from interior portions of the Deep south to the Mid- Atlantic coast, and a Marginal Risk covering portions of eastern Colorado, Kansas, Oklahoma and Texas Panhandle. For Day 5, there is a Marginal Risk for eastern New Mexico and parts of the Oklahoma/Texas Panhandles and from the Central/Southern Plains to southern portions of the Northeast/Maryland. Many locations will have daily maximums climbing well into the 100s at lower elevations across the Southwest and mainly dry conditions, except for perhaps far southeastern Arizona into New Mexico where some monsoonal moisture may be present. 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 and Nevada through at least Thursday and several Extreme Heat Warnings are in effect from southern California to eastern Arizona. Campbell/Hamrick 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 $$