249 FXUS02 KWBC 290823 PMDEPD Extended Forecast Discussion NWS Weather Prediction Center College Park MD 423 AM EDT Fri May 29 2026 Valid 12Z Mon Jun 01 2026 - 12Z Fri Jun 05 2026 ...Overview... The medium range period, beginning Monday, will feature an amplified pattern with a digging trough in the East Coast as well as a closed mid-level low over the Rockies/Northwest. The Northwest vort max will slip north into southern Canada before propagating into the Canadian Maritime by late next week. The East Coast trough will be reinforced by waves of shortwave energy out of eastern Canada before quickly retreating back north and out into the North Atlantic by late next week. Zonal flow develops across the northern tier of the CONUS on the backside of the departing Rockies/Western U.S. low. ...Guidance/Predictability Assessment... Models are in reasonably good agreement regarding the evolution of the Western U.S. pattern, while notably diverging on the Eastern U.S. trough evolution. In the East, the GFS develops a deep cut off low over the Mid-Atlantic by mid-week and has it slowly move out to sea while the Euro is notably weaker and more progressive, and the Canadian is much slower and weaker than both. A general model blend consisting of the available deterministic and Ai guidance were used in the day 3 blend with equal weighting across the board. The variance along the East Coast is the greatest on day 4 where the deterministic Euro GFS and Canadian all have different solutions. A composite of all 3 was used to find an average. The ensemble means make up a majority of the blend beginning on day 5 due to the developing zonal flow and uncertainty in the Western Atlantic. ...Weather/Hazards Highlights... Troughing over the Intermountain West above a decaying low pressure system will promote scattered showers and thunderstorm activity across the Central U.S. next week. Some storms over portions of the Southern High Plains could produce isolated instances of flash flooding next Tuesday, which is reflected in our day 4 marginal risk (at least 5% chance) of excessive rainfall. Warm and humid air will continue to surge north throughout these areas, leading to muggy conditions through mid-week when conditions begin to improve a bit as warm air shifts into the Eastern U.S.. Troughing over the East will support slightly below average temperatures until mid-week when the aforementioned seasonal air begins to work its way back into the region. Elsewhere, temperatures remain around average. A plume of tropical moisture may impact portions of the Gulf Coast late next week, but there's still plenty of uncertainty regarding where exactly the maximum QPF footprint will organize at this time. Kebede 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 $$