903 FXUS02 KWBC 050453 PMDEPD Extended Forecast Discussion NWS Weather Prediction Center College Park MD 1253 AM EDT Tue May 5 2026 Valid 12Z Fri May 08 2026 - 12Z Tue May 12 2026 ...General Overview... A broad upper-level closed low over eastern Canada will continue to drive broad cyclonic flow and repeated trough reinforcement through the period. This pattern will bring unsettled weather across central/eastern U.S. The series of frontal passages will continue to move across central U.S. into eastern U.S through Monday, bringing showers and thunderstorms along the boundaries. The remnants of a prior front will linger across the Lower Mississippi Valley into the Southeast, bringing additional rainfall to the area. Below normal temperatures will continue across the Great Lakes into the Northeast through the weekend, while a warming trend ensues across much of Western/Central U.S. ...Guidance/Predictability Assessment... Latest model guidance continues to show agreement with the large- scale features of the broad trough over eastern U.S. from the low that sits over eastern Canada and the ridging pattern building over western U.S. The small-scale differences for the troughing over eastern U.S. remain minor until day 6, where model shows discrepancies for the shortwave troughs. Over into western U.S., deterministic models show timing differences for the ridge by day 5. CMC seems to show faster eastward progression of the ridge than the GFS and ECMWF. As a trough begins to form over east Pacific, model difference increases through the remainder of the time period. Therefore, the WPC forecast was based on a model blend of the CMC/ECMWF/GFS/ECAIFS/UKMET. Later in the period, the ensemble means were phased in with heavier weight on the model means compared to the deterministic to help smooth out some of the timing and amplitude differences. ...Weather/Hazards Highlights... The broad upper-level low hovering over eastern Canada will serve as anchor for cyclonic flow and multiple shortwave energies near the base of the mean trough. The trailing end of a previous cold front will stall over/near the Gulf Coast and Southeast and will interact with warm Gulf moisture early in the period. This will bring additional showers and thunderstorms across parts of the Southern Plains and Southeast through the weekend. On Friday, there is a signal for some instability that may cause moments of heavy rainfall. A Marginal Risk was considered for southern portions of the Southeast, but there is low confidence at this moment due to model spread and conditions not meeting flash flooding guidance. Furthermore, as the front exits off the coast, wraparound moisture and embedded shortwaves will bring occasional showers across the Great Lakes, Interior Northeast, and Central Appalachian through the weekend. In addition, a few frontal passages will move through Central U.S. into eastern U.S. through Monday, bringing widespread showers and thunderstorms across the Northeast into the lower Mississippi Valley/Southern Plains along the frontal boundaries. Meanwhile, below average temperatures will continue across eastern U.S. behind the cold front through Friday. Frost/freeze conditions will continue across the Upper Midwest/Great Lakes and Northeast through Saturday morning. With the cold temperatures, there is a slight chance for some mixed precipitation over isolated high- elevation areas over the Northeast, but impacts will be minimal. High temperatures moderate across much of eastern U.S. by Saturday afternoon through the rest of the period. Over western U.S., a shortwave energy will push a frontal boundary into Northern-Central Rockies/Plains early in the period, bringing a chance for showers, thunderstorms, and high- elevation snow through the weekend. In addition, deep boundary layer mixing will bring gusty winds across the area through the weekend. The front will continue to strengthen as the surface low moves into the Great Lakes the cold front drapes across the Plains/Rockies into the Southwest. This will expand the chances for precipitation across Central U.S. through Sunday. A ridging pattern continues to move further inland over western U.S. bringing 10-15 degrees above average temperatures across western and central U.S. with highs mostly in the 80s and 90s through Saturday. On Sunday, temperatures moderate over central U.S. but western U.S. may experience record breaking highs with 15-20 degrees above normal. 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 $$