046 FXUS02 KWBC 310754 PMDEPD Extended Forecast Discussion NWS Weather Prediction Center College Park MD 354 AM EDT Sun May 31 2026 Valid 12Z Wed Jun 03 2026 - 12Z Sun Jun 07 2026 ...Overview... Transient shortwave energy will propagate across the northern tier and into Ontario during the medium range. This system will likely generate storms across the Northern Plains and Upper Midwest late-week. Downstream ridging will spread above average temperatures from the Central U.S. late next week into the East by the weekend. Shortwave impulses out of Mexico will generate additional shower and thunderstorm activity across portions of the Southern/Central Plains during the medium range. A potent mid-level low enters the Pacific Northwest on Friday, bringing renewed chances for rain to the region next weekend. ...Guidance/Predictability Assessment... Non Canadian models are in reasonably good agreement regarding the evolution of the overall synoptic pattern across the lower 48 between Wednesday and next Sunday. The Canadian mainly deviates from consensus regarding the evolution of the East Coast trough mid-to-late next week. Models are a bit uncertain as to the intensity of the approaching East Pacific low late-week, but tend to agree on the timing of it. A general model blend consisting of the available non-CMC deterministic and Ai guidance was used in the blend on day 3. The GEFS was introduced on day 4 to mitigate some of the differences in the amplitude of the Southwest energy. The Euro and GFS suites are favored in the blend through the rest of the medium range period due to good clustering on the synoptic pattern. ...Weather/Hazards Highlights... A slow moving surface low pressure system will focus scattered to isolated showers and thunderstorms over portions of the Northern Plains and Upper Midwest/Great Lakes on Wednesday and Thursday. Some storms may produce isolated instances of flash flooding, which is why a marginal risk (at least 5% chance) of excessive rainfall is in effect for portions of the Plains and Upper Midwest. Meanwhile, a weak mid- level disturbance propagating northward across the Southern High Plains will also act as a forcing mechanism for more thunderstorm activity across portions of the Central and Southern Plains. A slight risk (at least 15% chance) of excessive rainfall leading to flash flooding is in effect for portions of southeastern New Mexico and into west Texas on Wednesday. A deep upper-level low will bring rain to the Pacific Northwest late this week and into the weekend. Some showers may spill over into the Northern Rockies/High Plains by Saturday. Elsewhere, a weak quasi-stationary front draped across Florida will generate daily showers and thunderstorms over the peninsula. A ridge centered over the Midwest will promote broad southerly flow into the Eastern half of the country late next week. Temperatures will gradually increase over portions of the Midwest and East Coast as the ridge shifts eastward, with much of the Mid-Atlantic Coast, in particular, possibly experiencing some heat risk impacts by the weekend as lows struggle to drop into the 60s in some places. 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 $$