806 FXUS02 KWBC 030528 PMDEPD Extended Forecast Discussion NWS Weather Prediction Center College Park MD 128 AM EDT Sun May 3 2026 Valid 12Z Wed May 06 2026 - 12Z Sun May 10 2026 ...General Overview... The amplified and slow moving upper-level closed low over southeastern Canada continues to drive broad cyclonic flow and repeated trough reinforcement across central/eastern U.S. next week. This will bring a stretch of cool, unsettled weather across the area. The associated cold front will continue to move south- southeast and will produce showers and thunderstorms across eastern U.S., with potential flooding concerns. Furthermore, a southern stream upper trough/closed low moves across the Southwest into the Plains, bringing chances for storms across the Plains/Mississippi Valley. By midweek, below normal temperatures will continue across much of northern and central U.S., before moderating by the end of the week. ...Guidance/Predictability Assessment... The latest model guidance continues to show good agreement with the large- scale features through Day 5, with differences in regard to timing and amplitude of the shortwave features associated with the trough/low over West/Southwest. The deterministic models seem to show some improvement with the smaller scale features with the trough/low over southeastern Canada. Later in the period, CMC and ECMWF seems to show better agreement, where as the GFS seemed to show faster progression with some of the large-scale features, especially over the West. Therefore, the WPC forecast consisted of a even multi-model blend with CMC/GFS/ECMWF/UKMET and EC-AIFS for the first portion of the period, while phasing in more weight on the ensemble means to smooth out some of the differences. ...Weather/Hazards Highlights... The prolonged upper-level low will continue to hover over central to southeastern Canada through the medium-range period, bringing a series of shortwaves rotating around the base of the mean trough. This will support multiple frontal passages and waves of precipitation across Central/Eastern U.S. through the week. Ahead of the cold front, expect showers and thunderstorms across the Mississippi Valley, Ohio/Tennessee Valley, Great Lakes and Northeast on Wednesday. In addition, gusty winds may develop along frontal passes over the Southeast, Mid-Atlantic, Ohio/Tennessee Valley, and Northeast. The cold front will continue to move southeastward and will pull warm Gulf moisture along the boundary, which will support showers and thunderstorms across the Mid- South, Mid- Atlantic, and Southeast by Wednesday. With the combination of upper-level forcing/instability, an influx of moisture, and organized thunderstorms producing heavy rainfall along the front, localized flooding may be possible across the lower Mississippi Valley into the Ohio/Tennessee Valley Wednesday into Thursday. This flood threat is represented by the Marginal Risk on the Day 4/Wednesday ERO. Going into Thursday, the front pushes closer to the East Coast with a trailing front stretching across the Mid-Atlantic and Southeast. This will bring some additional showers and thunderstorms along the boundary, with higher rainfall totals over Southeast. The cold air pushes into the Northern and Central U.S. behind the cold front and cyclonic flow, which will bring below normal temperatures across the northern/central Plains into much of the eastern U.S., with frost/freeze conditions across northern/central Plains into the Upper Midwest/Great Lakes. With the cold temperatures, there is a slight chance for some mixed precipitation over some isolated higher- elevation areas near the Upper Midwest/Great Lakes but impacts will be minimal. Over northern/central Plains into the Great Lakes, temperatures will drop 15-20 degrees below average by midweek. By late week, the below normal temperatures pushes towards eastern U.S., while temperatures moderate for central U.S. Over the western U.S., the Pacific upper low/trough will continue to move across the Southwest early in the period, then gradually ejects into the Plains. This will be bring some low elevation showers and possible thunderstorms, as well as some high elevation snow across parts of Rockies/Plains on Wednesday. The cold front will bring 15-25 degrees below normal temperatures across the Four Corners on Wednesday. This will facilitate cold rain for the Front Range of Colorado to southern Wyoming and heavy snow for the Colorado Rockies. The frontal system and shortwave energy will also bring some gusty winds across Rockies/Plains on Wednesday. Over the Pacific Northwest, a ridge will push inland, bringing a warming trend. As the ridge continues to move eastward, above normal temperatures will return across much of western U.S. later next week. Oudit 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 $$