477 FXUS02 KWBC 250713 PMDEPD Extended Forecast Discussion NWS Weather Prediction Center College Park MD 313 AM EDT Mon May 25 2026 Valid 12Z Thu May 28 2026 - 12Z Mon Jun 01 2026 ...Heavy rain and thunderstorms expected to continue across much of the Southern U.S... ...Overview... Multiple pieces of energy within a southern stream shortwave will pass through the south-central U.S. later this week, providing lift for widespread rain and thunderstorms in a moist and unstable environment stretching through the Southeast as well. Heavy rain is likely to focus more into the Middle to Lower Mississippi Valley midweek, potentially over areas that will already have wet antecedent conditions, leading to some concern for flooding. Out West, a closed upper low should be atop the Great Basin mid to late week, resulting in cooler temperatures and precipitation for the West as it meanders while weakening. A blocky upper ridge is set to stretch across the north- central U.S. and bring above average temperatures through much of the period. Meanwhile a couple of upper troughs/lows should push through the Northeast and allow for precipitation chances. ...Guidance/Predictability Assessment... Models continue to show good agreement on the overall large scale pattern evolution through the period, but with fairly typical differences in the details, which affect sensible weather. Good agreement continues with the upper low initially centered over the central Great Basin, which should gradually weaken into the weekend while joining with a northeastern Pacific trough. Downstream, upper ridging stretches from the Southeast into the north-central U.S., with southern stream energy undercutting it across the south- central U.S.. Eventually, this ridge should reform with a more neutral tile and an omega block type of look with reinforced troughing over the Northeast. This troughing over the Northeast does continue to show some uncertainty, but the new 00z guidance have trended more in line with each other especially as it pertains to the speed of a compact upper low singing through the Northeast this weekend. The WPC forecast was based on a blend of the ECMWF, EC-AIFS, and GFS (with minor ECENS) through Day 5. After this, increased the weighting of the ensemble means to help mitigate some of the smaller scale details differences. ...Weather/Hazards Highlights... Persistent southern stream energy will continue to keep much of the South active and unsettled into the weekend within a very moist and unstable environment and daily thunderstorm chances. Both the Day 4/Thursday and Day 5/Friday EROs show broad Marginal Risks across the middle-lower Mississippi Valley and into parts of the Tennessee Valley and Deep South where moisture anomalies are high and instability will not be lacking. There remains a lot of model uncertainty still on where the heaviest QPF may focus, so held off on any Slight Risks for now but it's possible a Slight Risk may be needed eventually. Wet weather is likely across the Southeast into Florida as well, with a Marginal Risk for parts of southern Florida Thursday and Friday in a favorable pattern for heavy rainfall. After what has been a very wet period for much of Texas, conditions should finally settle across the region later this week as the overall pattern shifts slightly east. However, rainfall may be renewed again across Texas by the weekend. Upper troughing meandering around the Great Basin with a frontal system ahead of it will allow for increased precipitation across the Pacific Northwest to Intermountain West for multiple days. Snow is possible across higher elevations, with highest amounts now most likely in the Sierra Nevada. Combining energies will allow rain chances to stretch east into the central Plains and Midwest for midweek and beyond. Rainfall is also possible across the Northeast underneath the upper low. With the closed upper low over the West, temperatures should be below normal through about Friday, with some moderating back towards normal as the trough weakens and drifts next weekend. The upper ridge to its east will allow for warmer than average temperatures across the north- central U.S. through much of next week, with daytime highs 10-20 degrees above normal, with greatest anomalies through around mid to late week. Renewed troughing over the East may bring slightly below normal temperatures there as well. Santorelli 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 $$