441 FXUS02 KWBC 280722 PMDEPD Extended Forecast Discussion NWS Weather Prediction Center College Park MD 322 AM EDT Thu May 28 2026 Valid 12Z Sun May 31 2026 - 12Z Thu Jun 04 2026 ...Heavy rain and thunderstorm threats continue for the Southeast and the northern Rockies late weekend into early next week... ...Overview... An amplified upper-level synoptic pattern will remain in place into early next week, before turning more zonal mid to late week. Overall, the general pattern will feature troughing over both the West and East with ridging in between. The trough over the West will close off into a broad upper low and spin over the northern Rockies, bringing low elevation heavy rain and mountain snow Sunday into Monday. Unseasonably low heights over the East will be reinforced through early to midweek as several disturbances rotate within and around a parent trough/closed low over Atlantic Canada. The relatively cool air mass across the northeast and east- central U.S. will keep heat and humidity suppressed to the south. The resulting frontal boundary draped across the Southeast combined with southern stream energy will allow for the persistence of a generally wet and stormy pattern across much of the region. Later in the period, stormy weather from parts of the West builds into the Plains before advancing eastward with time. ...Guidance/Predictability Assessment... The latest models are in good agreement of their depictions of the large scale pattern through the medium range period, highlighting an amplified solution that slowly becomes more zonal. Smaller spatial and temporal differences, particularly with respect to the transition away from a blocky pattern mid to late week, leads to some lingering uncertainty with system/frontal placement and sensible weather impacts. However, for the most part, a blend of the deterministic models and ensemble means seemed to provide a solid forecast basis that retained continuity and mitigated any larger differences. This solution is generally in line with the NBM and also fits with National Hurricane Center insight that continues to discount tropical moisture feed and development potential by recent GFS runs northward from the Caribbean. ...Weather/Hazards Highlights... A very warm, humid, and unstable airmass south of a wavy frontal boundary will keep much of the South and Southeast active with daily rain and thunderstorm chances from late weekend into early next week. The potential for scattered clusters of thunderstorms containing high rainfall rates combined with what has already been a wet pattern across this region indicates that isolated flash flooding could be a concern, particularly for flood prone areas. As a result, for Day 4/Sunday and Day 5/Monday, marginal risk areas have been introduced for parts of the Southeast into Florida. Meanwhile, an upper trough that is forecast to close off into a cut-off low over the northern Rockies will bring widespread low elevation heavy rain and some high elevation mountain snow from late weekend into early next week. The signal for heavy rainfall remains robust enough to maintain the Day 4/Sunday marginal risk across a large portion of Montana and a part of northern Wyoming, with intensity waning heading into Monday and Tuesday. Rainfall and thunderstorm chances also increase across the Plains mid to late week as the cut-off low opens back up into a wave and begins to move eastward. Moderating temperatures are expected across the West into next week following a period of cooler than normal temperatures associated with increased cloud cover and precipitation. Above normal warmth will generally be confined to the central U.S. where upper level ridging is most persistent. In contrast, near to slightly below normal temperatures are expected across the Northeast and Mid- Atlantic as periodic systems bring rain chances and reinforcing pushes of cool air. Miller 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 $$