Extended Forecast Discussion NWS Weather Prediction Center College Park MD 359 PM EDT Sat Sep 13 2025 Valid 12Z Tue Sep 16 2025 - 12Z Sat Sep 20 2025 ...Overview... The most prominent upper-air feature next week is troughing over the north-central states that shifts to the Great Lakes by next weekend. Ridges and above normal temperatures are on either side of this trough with further troughing over the Southeast that brings rain chances as it lifts over or off the Mid- Atlantic through midweek and an approaching trough over the northeast Pacific that likely closes into a low over Washington state in the mid to late week timeframe. Troughing in the East with the potential for a lingering closed low would bring increasing rain chances along at least coastal areas of the Carolinas/southern Mid- Atlantic. ...Guidance/Predictability Assessment... The 12Z model guidance suite agrees on most aspects of the synoptic scale pattern across the Continental U.S. to start the forecast period Tuesday. The low that is likely to develop along the stalled frontal boundary off the East Coast has trended more to the north compared to last night's forecast, and the low over Manitoba has trended a little more to the south. There is also a slightly faster progression of the cold front crossing the Central Plains and Midwest Tuesday into Wednesday. The overall weather pattern gets more complicated going into the end of the week, particularly across the northern tier states with a trough over the Pacific Northwest, closed low over the Midwest, and a narrow ridge axis extending north across the Rockies and into central Canada, and a weaker trough over New England. The models still have substantial mesoscale differences by this time, and therefore an increase in the ensemble means was used by Friday and Saturday. ...Weather/Hazards Highlights... Upper troughing over the northern Plains Tuesday and Wednesday will encourage enhanced Gulf moisture transport up the Plains with convergence ahead of a slow moving frontal system. Patchy areas of heavy rain is likely over the central Plains both days. The Marginal Risk areas across this region have been maintained with just minor adjustments. Another area to watch will be the southern Rockies, where monsoonal moisture gets into southwest New Mexico on Tuesday and then into western Texas, which warrants inclusion of an enlarged Day 4 Marginal Risk ERO from southeast Arizona to northern New Mexico, and a Day 5 Marginal has been introduced a little to the east of the Day 4 outlook with additional convection likely on Wednesday. Otherwise, the low moving up near the Outer Banks of NC and the DelMarVa should bring some onshore flow and rain. There has been a trend over the past few model cycles for more substantial rainfall moving inland across NC and VA, so this will continue to be closely monitored in the days ahead, but not warranting any ERO risk areas at this time. Meanwhile, the trailing portion of the stationary front will linger over or near South Florida Tuesday through the rest of the week, and a Marginal Risk for Wednesday has been introduced here. Elsewhere, the ridge axis over the Southwest shifts east starting Wednesday which will send anomalous moisture north over southern CA later in the week and potentially excessive rainfall. An upper ridge will promote hot temperatures centered on the Midwest and Mississippi Valley through at least mid-next week, with anomalies of 10-20 degrees above average. Temperatures well in the 90s will be common, and a handful of record highs are possible but currently do not look to be widespread. Recent model trends continue to favor some warmer than average temperatures to move into the Northeast as the week progresses. Initially cooler than average temperatures in the Northwest look to moderate as the week progresses. Jackson/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