545 FXUS02 KWBC 061816 PMDEPD Extended Forecast Discussion NWS Weather Prediction Center College Park MD 216 PM EDT Wed May 6 2026 Valid 12Z Sat May 09 2026 - 12Z Wed May 13 2026 ...General Overview... The deep cyclonic flow regime tied to a closed low over eastern Canada will facilitate a continuation of unsettled conditions for the East. The system will eject shortwave energies across the central/eastern U.S., supporting a series of frontal passages, which will bring showers and thunderstorms along the boundaries. The remnants of a prior front will linger across the Lower Mississippi Valley into the Southeast, with instability and anomalous moisture supporting moderate to heavy rainfall Saturday into Sunday. Below normal temperatures will continue across the Great Lakes into the Northeast through the weekend into early next week, while a warming trend continues to build across much of the Western U.S. and eventually Central U.S. by early next week. ...Guidance/Predictability Assessment... The latest model guidance for today remains in decent agreement for the large-scale forecast over the CONUS during the period, with some notable differences in the details of smaller systems moving through the flow. There are a few minor differences with systems as they reload into the trough over the East, but a general model compromise seemed to serve as a good starting point. After this, there are some differences with a shortwave riding the top of the Western U.S. ridge mid-period, with the ECMWF notably stronger with this system (and the resulting QPF). Late in the period, there is some uncertainty with the placement and structure of the Western U.S. ridge, owing to greater differences in an upper low located well off the West Coast. The WPC forecast trended more towards the ensemble means for the latter half of the forecast period, with also maintained good agreement with the previous WPC forecast. For the most part, the NBM served as a decent starting point for the sensible weather grids, with only minor edits needed. ...Weather/Hazards Highlights... The closed upper-level low over eastern Canada will continue to bring cyclonic flow and multiple shortwave energies near the base of the mean trough. This will facilitate the progression of a strong cold front that will sweep through the eastern half of the country early in the period. The frontal passage will bring widespread showers and thunderstorms across portions of the Great Lakes, Lower Mississippi Valley/Southern Plains, Ohio Valley into the Northwest and Mid- Atlantic, with locally heavy rainfall possible along the boundary through Monday. In addition, the southern extend of a previous front will continue to stall across the Gulf Coast region, where persistent moisture pooling and weak impulses embedded in the subtropical flow could support occasional convection and heavy rainfall along the Southeast through Sunday. With flooding concerns over the area, a Marginal Risk has been maintained for Day 4/Saturday ERO across across the Lower Mississippi Valley into the Deep South, and Day 5/Sunday ERO for parts of the Southeast. As the primary cold front moves closer to the East Coast, much of the Plains and Mississippi Valley will see a short- lived drying trend by Monday with the front clearing the East Coast by Tuesday. Over the western/central U.S., shortwave energy will push a frontal boundary over parts of the Northern-Central Rockies/Plains, which will bring a chance for low- elevation showers and thunderstorms. With temperatures dropping during the overnight hours, there is a chance for high- elevation snow across the Rockies on Saturday. In addition, deep boundary layer mixing may bring somewhat gusty winds across the area through the weekend. On Monday, another frontal boundary begins to form over the Northern Tier as a potential clipper system, bringing chances for showers and thunderstorms across the northern Plains into the Upper Midwest, and eventually the Great Lakes and Northeast. As the cold front over the Northern Tier moves southeastward, it will usher a return of below- average temperatures across the northeastern U.S. with moderating temperatures across central U.S. by Sunday. A ridging pattern will continue to move further inland over the western U.S. early in the period, bringing increasingly well above average highs through early next week. Some record- tying/breaking highs will be possible as heat reaches Moderate to Major HeatRisk levels across portions of the central California Valleys and the Desert Southwest by Monday into Tuesday. Well above normal temperatures push eastward into the central U.S. by Tuesday. Santorelli/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 $$