662 FXUS02 KWBC 241934 PMDEPD Extended Forecast Discussion NWS Weather Prediction Center College Park MD 334 PM EDT Fri Apr 24 2026 Valid 12Z Mon Apr 27 2026 - 12Z Fri May 01 2026 ...A deepening low pressure system will produce heavy rain and severe weather across the east-central U.S. Monday/Tuesday... ...Overview... It is still the case that an active pattern continues across the CONUS next week, beginning with a strengthening low pressure system that is set to bring heavy rain and severe weather across portions of the Mississippi Valley on Monday. As the main low pushes across the Great Lakes into southern Canada, the trailing cold front will press across the East Tuesday into Wednesday and bring varying rain chances there. The southern portion of the front will sag into the southeastern U.S. before stalling out, supporting numerous showers and storms and potentially another heavy rain risk. Meanwhile, a Pacific system will likely slide across southern California and the Southwest mid to late week, bringing chances for low elevation rain and mountain snow across the windy Intermountain West, Rockies and Plains. There is a growing guidance signal that this may then lead to a downstream heavy rain/runoff and strong convective development and expansion threat broadly over the south-central U.S. to monitor for next Thursday/Friday. ...Guidance/Predictability Assessment... The latest guidance has a fairly decent handle on the large scale pattern through most of the medium range period, featuring broad troughing from the central to eastern U.S., ridging over the Pacific Northwest, and an upper low moving across the southwest U.S. With that being said, the smaller scale details remain more uncertain. This has particularly been the case recently with the forecast track and evolution of a Pacific to Southwest U.S. upper low, as the timing and amplitude of downstream shortwaves on the backside of broad upper troughing lead to significant run-to-run differences of the upper low's forward speed, positioning, and sensible weather. The WPC product suite was derived with favor toward a slower than concensus progression of this system into later next week given stream separation and closed nature. The good news is that new 12 UTC guidance has strongly trended in this slower direction, bolstering forecast confidence. The 12 Canadian is now in particular much less progressive with this system, trending toward our favored blend of the GFS/ECMWF and GEFS/ECMWF ensemble means and more in line with the National Blend of Models. ...Weather/Hazards Highlights... A potent negatively-tilted shortwave ejecting out of the central Rockies and across the central Plains and Upper Midwest will support the rapid strengthening of a surface low pressure system on Monday. Flow around the low will draw anomalous moisture and instability northward from the Gulf, setting the stage for numerous showers and thunderstorms across the Mississippi Valley Monday afternoon and evening with the potential for heavy rain and severe weather. The Storm Prediction Center has highlighted the Mid- Mississippi Valley as having the greatest threat from thunderstorms that could produce damaging winds, large hail, and even a few tornadoes. Heavy rain that can lead to flash flooding will also be a concern, especially as clusters of thunderstorms with high rainfall rates merge and repeatedly train over the same areas. A Marginal Risk remains in place from the Upper Midwest to the Lower Mississippi Valley for the Day 4/Monday ERO. As the strong surface low lifts across the Great Lakes and tracks into southern Canada, the cold front trailing in the wake of the low will slide to the south and east Tuesday into Wednesday, spreading showers and thunderstorms into the eastern U.S. The front will begin to lose steam and stall out over the south-central to southeastern U.S. into Tuesday, becoming the focus for another round of heavy rain and possible severe weather. Significant moisture and instability pooling along the stalling boundary could lead to clusters of storms with high rainfall rates, supporting the potential for isolated instances of flash flooding. As a result, a Marginal Risk ERO was introduced from the ArkLaTex region eastward to the Mid-South and Tennessee Valley for Day 5/Tuesday. By mid to late week, a Pacific system will likely push inland across southern California, the Southwest, and the Four Corners states, spreading light to moderate low elevation rain and higher elevation mountain snow into the region. There is a growing signal for significant rainfall will develop and expand/intensify with system approach and lead return Gulf inflow over the south-central U.S. for Thursday/Friday to monitor. Warmer than average temperatures are likely to continue across the southern Plains through midweek, and ahead of the cold front into the Mississippi and Ohio Valleys through early next week. Temperatures in the 90s will be common across Texas. Meanwhile, below average temperatures will continue for much of the West and northern/central Plains under the broad troughing through Monday before shifting into the north-central U.S. through midweek. Cooler than normal temperatures in the wake of the cold front will then continue to expand to the south and east Thursday into Friday, while the Pacific Northwest warms back closer to or slightly above normal. Miller/Schichtel 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 $$