748 FXUS02 KWBC 270719 PMDEPD Extended Forecast Discussion NWS Weather Prediction Center College Park MD 319 AM EDT Wed May 27 2026 Valid 12Z Sat May 30 2026 - 12Z Wed Jun 03 2026 ...Heavy rain/thunderstorms for parts of the Southern U.S... ...Overview... A blocky upper flow pattern will be in place to start the period on Saturday featuring troughing over both the West and East, with ridging in between over the Central U.S.. The trough over the West will weaken as it lifts northeastward bringing heavy rain potential to parts of the northern Rockies/High Plains this weekend. Another shortwave will move into the Pacific Northwest early next week. Troughing over the East will be reinforced through the period, with a frontal boundary draped across the southern edge of it across the South. This, combined with forcing from southern stream energy in the region, will allow for a generally continued wet pattern across much of the South where things have been very wet as of late, and will continue to be in the short range period as well. ...Guidance/Predictability Assessment... Models show good agreement on the overall large scale pattern evolution through the period, but with plenty of variability in the smaller scale details. Out West, the guidance shows good timing consensus with the upper low/trough lifting northeastward out of the Great Basin by the weekend, but a lot of uncertainty on subsequent energies into the overall trough. Overall though, the pattern should become less amplified over this region with time. In the East, lots of uncertainty still with a variety of shortwaves as they drop down the western side of the trough to reinforce and deepen mean troughing over the East. There is some indication is guidance for a possible cut off low over the East by the middle of next week too, but plenty of run to run variability on this evolution to buy into any one solution at this point. The WPC forecast for tonight used a majority blend of the deterministic guidance for the first half of the period, increasing weighting of the ensembles to 60 percent of the blend by Days 6 and 7 given increasing pattern variability and uncertainty. ...Weather/Hazards Highlights... It generally remains the case that persistent shortwave energies and a couple of wavy frontal boundaries will continue to keep much of the South active and unsettled into the weekend within a moist and unstable environment and daily thunderstorm chances. Combined with what has already been a wet pattern across this region, isolated flooding could be a concern. For Day 4/Saturday, did maintain a marginal risk for parts of the Southeast along the frontal boundary. Previous Marginal Risks for central Texas and south Florida were removed for Day 4 because the QPF support seemed to have diminished with recent model runs. Showers and storms will continue into Sunday as well across the Southern Plains and Gulf Coast/Florida, but a lack of appreciable QPF precluded any Marginal Risk areas yet for the Day 5 ERO. However, given how wet its been in many areas across the South, localized flooding is not out of the question and so its possible risk areas may be needed in future updates if the signal for heavy rainfall increases. To the north over the Northeast, a vigorous vort moving through late this week may result in a period of moderate to heavier rainfall for parts of New England given windy offshore low genesis which may last into Saturday. Out west...upper troughing lifting out of the Great Basin with a wavy frontal system ahead of it will allow for increased precipitation across the Intermountain West for the end of this week. Snow is possible across the highest elevations, though with minimal accumulation. The signal for heavy rainfall has increased over parts of western Montana and vicinity so a Marginal Risk was added to the Day 4/Saturday ERO tonight. Rain will continue into Sunday, but with less intensity, so no risk areas are depicted at this time for this region. Rainfall chances also increase this weekend and into next week for parts of the northern and central Plains ahead of general weak troughing over the West. With the closed upper low over the West during the short range working to lift out by this weekend, below normal temperatures should moderate back towards normal. Some ridging building back into the region late in the period may bring temperatures above average by then. 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 early in the period. Persistent troughing over the East may bring slightly below normal temperatures through the period, which may extend westward with time into the Southern Plains. 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 $$