488 FXUS02 KWBC 190756 PMDEPD Extended Forecast Discussion NWS Weather Prediction Center College Park MD 356 AM EDT Tue May 19 2026 Valid 12Z Fri May 22 2026 - 12Z Tue May 26 2026 ***Multiple days of heavy rainfall expected for the south-central U.S. through the weekend*** ...General Overview... An unsettled weather pattern is expected to be place across much of the south-central U.S. through the end of the week and into the upcoming weekend with multiple rounds of showers and thunderstorms expected. Meanwhile, an upper trough crossing the northern Plains and Upper Midwest will generate a separate area of showers and storms for Friday, followed by drier conditions for the weekend. A potentially stronger trough arrives across the Pacific Northwest for the beginning of next week. ...Guidance/Predictability Assessment... The 00Z model guidance suite has average agreement for the beginning of the forecast period Friday, with differences apparent in the evolution of shortwave energy in the northern stream flow over the Dakotas and Upper Midwest, and with the southern stream trough over the Desert Southwest. Model spread increases further by Sunday with noteworthy timing and amplitude differences, and recent runs of the GFS have been faster with bringing in the next upper trough/closed low to the Pacific Northwest late in the period, with the slower and better clustered ECMWF/AIFS/CMC guidance preferred over the more progressive GFS for days 6 and 7. The ensemble means were increased to about half by next Tuesday. ...Weather/Hazards Highlights... Heavy rainfall is expected to make weather headlines going into the end of the work week from central Texas to the Ohio Valley. The highest QPF should be across east-central Texas this weekend where multiple mesoscale convective systems will likely develop and affect the same areas. Both Day 4/Friday and Day 5/Saturday feature broad Marginal Risk areas, with a good chance that a Slight Risk could eventually be needed for portions of central and eastern Texas as the event gets closer in time. Elsewhere across the country, lighter precipitation is expected farther to the east across the Carolinas into Virginia with overrunning flow north of the frontal boundary, and moderate rainfall for interior portions of the Northeast. There should also be corridors of moderate rainfall across portions of the Upper Midwest on Friday. The potential exists for this region to see an upward trend in rainfall totals in future forecasts based on recent model trends. In terms of temperatures, a cold air damming type event will likely become established east of the Appalachians with overcast skies and periods of mainly light rain at times to close out the work week, and warm and humid conditions continuing south of the boundary. Elsewhere, relatively cool conditions across the central/northern Plains are expected to gradually warm through the forecast period. 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, excessive rainfall outlook, winter weather outlook probabilities, heat indices and Key Messages are at: 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 $$