Preliminary Forecasts
Issued by NWS
Issued by NWS
088 FXUS02 KWNH 270759 PREEPD Extended Forecast Discussion NWS Weather Prediction Center College Park MD 358 AM EDT Wed Aug 27 2025 Valid 12Z Sat Aug 30 2025 - 12Z Wed Sep 03 2025 ...Overview... Mean troughing over the East is expected to persist through the medium range period with blocky ridging over the Interior West. Weak disturbances sliding down the western side of the upper trough will interact with a stationary surface front to generate heavy rain threats across the Plains this weekend. Heavy rain potential will also exist across the southern U.S. as a slow-moving frontal boundary sinks into the northern Gulf through early next week. A digging upper trough in the Eastern Pacific may increase monsoon activity across the Four Corners next week. ...Guidance/Predictability Assessment... A non-deterministic Canadian blend sufficiently captured the overall synoptic evolution across the lower 48 during the medium range period. Heavy weighting was placed on the deterministic Euro and GFS this weekend since they resolve the large scale features similarly well. The Euro has a more amplified shortwave propagating through the Western ridge on Sunday while, the GFS has a more progressive shortwave cutting through the Northern Plains/Upper Midwest. The ensemble means make up a majority of the blend beginning on day 5 and continuing through the end of the period. On day 5, the Euro suite is more suppressed than the GFS and Canadian suites, which cluster well together, with QPF over the Southern High Plains/Southwest. ...Weather/Hazards Highlights... A stationary front over the High Plains and a slow moving cold front across the Gulf Coast states will be the focus for showers and thunderstorms late this week. Sufficient moisture along these boundaries will support heavy rain threats in these regions. There is a broad Marginal Risk of excessive rainfall from the Great Plains down and across the Gulf Coast states and Southeast on Saturday and Sunday. On Saturday, there is an embedded Slight Risk of excessive rainfall for parts of the Texas/Oklahoma Panhandles and eastern New Mexico, where primed surfaces caused by storms on Friday could result in scattered instances of flash flooding. A slight risk was introduced over southern New Mexico into far western Texas on Sunday, due to an increasing QPF trend in the latest guidance over those areas. The current slight remains close to the border zones but could expand north if recent trends in the GFS and Canadian continue. Elsewhere, the downstream section of the front will produce additional thunderstorm activity across the Gulf Coast this weekend. A convergence axis beneath a weak disturbance aloft could refocus monsoon moisture over much of New Mexico and the Four Corners region later this weekend and into next week. Showers and storms may also return to the northern tier next week as a cold front sinks south across the Northern Rockies, Plains, and Upper Midwest. There may be potential for isolated heavy rain threats with this front, though it is very uncertain at this time. Surface high pressure from Canada will descend over much of the Eastern U.S. beginning this weekend. This will bring a cool and dry continental airmass to the Midwest and East Coast, making for a very comfortable Labor Day weekend. Cloudy and stormy conditions over the Plains will likely contribute to well below average temperatures this weekend. Kebede 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 $$