486 FXUS02 KWBC 241959 PMDEPD Extended Forecast Discussion NWS Weather Prediction Center College Park MD 359 PM EDT Sun May 24 2026 Valid 12Z Wed May 27 2026 - 12Z Sun May 31 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. during the 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 in Texas and the Lower Mississippi Valley midweek, potentially over areas that will already have wet antecedent conditions, leading to flooding concerns. 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... Model guidance is agreeable in showing an upper low centered over the central Great Basin through late week. The low is forecast to gradually weaken and track northeast Friday into next weekend while joining with a northeastern Pacific trough. To the east, upper ridging will stretch from the Southeast northwestward into the Midwest as southern stream energy cuts into it in the south-central U.S., with typical model differences in the details. As the southern energy weakens and moves east, the ridge looks to reform with a neutral tilt across the Plains late week into the weekend. The pattern starts to look more like an omega block as troughing retrogrades into the Northeast. There continues to be quite a bit of uncertainty with the Northeast trough, with the complicating factor of likely two different vort maxes moving through. GFS and AI-GFS runs are on the faster side with both, with the non-NCEP guidance slower. The WPC forecast was based on a multi-model blend early in the forecast period, with increasing proportions of the ensemble means to about half by the end of the period to mitigate the individual model differences. ...Weather/Hazards Highlights... Persistent southern stream energy will continue to keep much of the Southern Plains to the Southeast active and unsettled well into next week within a very moist and unstable environment and daily thunderstorm chances. This could be especially impactful for parts of Texas and the Lower Mississippi Valley where recent rains and additional rain in the short term has lead to rather saturated grounds. For the Day 4/Wednesday ERO, a broad Marginal Risk is in place across much of the Southern U.S., and continue to highlight an embedded Slight Risk for southeast Texas to western Louisiana. A broad Marginal Risk is in place on the Day 5/Thursday ERO for the lower and middle Mississippi Valley back into the central Plains. An upgrade to a Slight Risk for parts of the central Gulf Coast is not out of the question, depending on previous days' rainfall, but uncertainties in the position of heavy rain (including the potential for max amounts to be offshore) preclude an upgrade for now. The exact locations of heavier rainfall on both days will likely change as models come into better agreement, but the pattern overall favors heavy rainfall potential with flooding still a concern given the potentially concerning antecedent conditions. The pattern evolution may gradually support drier conditions for Texas by next weekend, but the wet pattern looks to continue along the Gulf Coast and especially Florida through next weekend. A Marginal Risk remains in place for the urban corridor of southeast Florida on Thursday, with heavy rainfall potential trending upwards beyond as well. Upper troughing across the Northwest and 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. With the closed upper low over the West, temperatures should trend cooler in this region through Thursday, with some moderating back towards normal as the trough weakens and drifts. 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. Tate/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 $$