773 FXUS02 KWBC 010522 PMDEPD Extended Forecast Discussion NWS Weather Prediction Center College Park MD 122 AM EDT Fri May 1 2026 Valid 12Z Mon May 04 2026 - 12Z Fri May 08 2026 ...Overview... The persistent amplified upper-level low over southeast Canada continues to bring shortwave energy across central/eastern U.S. into next week. This pattern will bring multiple rounds of precipitation and cooler than normal conditions across Upper Midwest, Mid- Atlantic, Great Lakes, and Northeast through midweek. As the front moves southeastward, showers and thunderstorms are expected to expand into Lower Mississippi Valley into Southeast. Another low/trough off the Pacific will bring precipitation across parts of the West early next week. The ridge moves inland over the West by midweek, bringing above seasonal temperatures. ...Guidance/Predictability Assessment... The latest model guidance provides an overall decent agreement on the large-scale features, with the deterministic models showing some small-scale difference with timing and structure. The large- scale differences become notable around Day 5, with the most disagreement on the upper low/trough over the Pacific. Although the models continue to show good agreement with the upper low/trough over southeastern Canada through the period, the deterministic models continue to show discrepancy with the shortwave energy embedded at the base of the low. Therefore, the WPC forecast consisted of a multi- model blend of the GFS/ECMWF/CMC/UKMET/EC- AIFS for the first half of the period. The later portion incorporated the ensemble means to help smooth out some of the amplitude and timing differences amongst the models. ...Weather/Hazards Highlights... The persistent upper-level trough over southeastern Canada continues to slowly move eastward, ejecting multiple embedded shortwave disturbances through the period. The trough will push a few frontal passages across central and eastern U.S., which will reinforce unsettled weather. By Monday, expect showers and thunderstorms across Upper Midwest, Ohio Valley, Great Lakes and Northeast. With the tightening pressure gradient, gusty winds may develop along the front across Southern Plains into Ohio Valley and Northeast. As the front slowly moves southward and interacts with warm Gulf moisture, showers and thunderstorms will develop over parts of the mid/lower Mississippi Valley, Mid- Atlantic, and Southeast by midweek. With the combination of upper- level forcing and organized thunderstorms producing heavy rainfall, localized flooding may be possible across mid/lower Mississippi Valley into Ohio/Tennessee Valley. This flood threat is represented by the Marginal Risk on Day 5/Tuesday ERO. Additionally, the cold front will bring below normal temperatures behind the front, especially over parts of northern/central Plains, California, and Southwest, where temperatures will drop 10-15 degrees below average through midweek. With the colder temperatures, chances for some mixed precipitation over the northern parts of the upper Great Lakes/Midwest will be possible Tuesday through Thursday. Over the western U.S., a upper low/trough approaching the coast will bring precipitation over the area for the first portion of next week. With sufficient moisture and instability, expect low elevation showers and possible thunderstorms, as well as some high elevation snow across California and Great Basin. A secondary cold front will drop into the Rockies/Plains by Tuesday, expanding the chance for showers and thunderstorms across the area. Expect flooding potential to increase as training may develop along the slow-moving front. Over the Pacific Northwest, possible record breaking warm temperatures may develop on Tuesday as an ridge pushes inland. As the ridge continues to move eastward, above normal temperatures will return across much of western U.S. by Thursday. 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 $$