746 FXUS21 KWNC 011933 PMDTHR US Hazards Outlook NWS Climate Prediction Center College Park MD 300 PM EDT June 01 2026 SYNOPSIS: Mid-level high pressure forecast over southern Canada is expected to bring above-normal temperatures for much of the lower 48, with a lingering potential for extreme heat conditions over parts of the Great Plains, Mississippi and Ohio Valleys, and Great Lakes heading into next week. The combination of unseasonable late spring warmth and inadequate rainfall amounts supports the continuation of a Rapid Onset Drought (ROD) risk over portions of the Mississippi and Ohio Valleys and Great Lakes. HAZARDS Slight risk of extreme heat for portions of the Northern and Central Plains, Upper and Middle Mississippi and Ohio Valleys, and Great Lakes region, Tue-Thu, June 9-11. Possible Rapid Onset Drought for parts of the Upper and Middle Mississippi Valley, Ohio Valley, and Great Lakes region. DETAILED SUMMARY FOR THURSDAY JUNE 04 - MONDAY JUNE 08: https://www.wpc.ncep.noaa.gov/threats/threats.php FOR TUESDAY JUNE 09 - MONDAY JUNE 15: By early next week, there continues to be good model agreement featuring an amplifying 500-hPa ridge center positioned to the south of Hudson Bay, with a broad coverage of positive height departures overspreading much of the entire CONUS. While some troughing is favored over the eastern Pacific and West Coast, much of the anomalous ridging is expected to promote widespread above-normal late spring temperatures with the potential for the development of extreme heat conditions over portions of the Midwest in proximity to the ridge center. Based on both the GEFS and ECWMF ensembles, the strength of the anomalous ridge center looks to peak on days 7 and 8 (Jun 8-9), followed by a gradual deamplification of the anomalous ridge center to allay any associated heat risks later next week. However, it is at these leads where the ECMWF and GEFS ensembles also diverge in regards to the evolution of the pattern, leading to added uncertainty in the updated outlook. The ECMWF ensemble continues to favor building a strong ridge center over the northwestern CONUS, where the coupling of more troughing over the northern Pacific and southeastern CONUS looks to become more consistent with a positive Pacific North America (+PNA) pattern towards the middle of June. By contrast, the GEFS maintains much of the troughing (ridging) over the West Coast (central CONUS), along with a fairly deep, but weak mean trough over much of eastern North America later in week-2. For temperatures, a slight risk of extreme heat remains posted for the north-central CONUS where the GEFS and ECMWF Probabilistic Extreme Tools (PETs) most agree in their depiction of increased chances (20-40%) for maximum temperatures exceeding the 85th climatological percentile, and remains valid through Jun 11 as the ridging aloft deamplifies. The highlighted slight risk area captures the strongest positive temperature departures favored among the dynamical models, with the heat index values potentially reaching 100 deg F. Over time, the ECWMF PET features a split of the warm signals, with one maxima in percentile space advancing eastward into the northeastern CONUS, and another building across the West Coast and Interior West by days 9 and 10. This development is less supported by the GEFS PET which maintains increased heat signals over the northern two thirds of the CONUS, likely tied to the persistent, but weaker ridging favored. Based on the GEFS AI and Canadian ensembles which feature more troughing over the western CONUS, this better aligns with the cooler GEFS guidance. Therefore, no additional temperature hazards are posted but this potential will be closely monitored in upcoming outlooks. Over the past several weeks, precipitation has been quite limited over portions of the Great Lakes region and Middle and Upper Mississippi Valley following a wet spring in these regions. The U.S. Drought Monitor shows an expansion of abnormally dry conditions into portions of Minnesota, Wisconsin, eastern Iowa, northern Illinois, and adjacent Indiana in its latest update. Although near to slightly above-normal precipitation is favored during week-2, the lack of total precipitation forecast combined with favored above-normal temperatures to drive increased evaporation rates supports the continuation of Rapid Onset Drought (ROD) risk. This risk has been expanded to now include parts of northwestern Indiana based on poor soil moisture percentiles forecast. For precipitation, moist return flow from the Gulf is expected to keep much of the southern tier of the U.S. above-normal during week-2. While the uncalibrated GEFS and ECMWF feature increased chances for 3-day amounts exceeding an inch over the Florida peninsula through the middle of week-2, these tools, as well as the PETs are at odds with the timing of a heavy precipitation risk, prompting the removal of the slight risk of heavy precipitation in the outlook. Moreover, the potential for enhanced rainfall may serve to be more beneficial for parts of Florida and the Southeast which continue to register severe to exceptional drought conditions. Any advection of tropical moisture over the southern CONUS appears more likely to be sourced from the eastern Pacific tied to potential tropical cyclone development. As of 11am PDT, the National Hurricane Center (NHC) is currently eyeing two areas for formation in the eastern Pacific, with one located to the south of Mexico (30% chances for development during the next seven days). Should any development occur next week associated with the area south of Mexico, a northwestward track nearing the Gulf of California could bring enhanced moisture and increased precipitation into the lower Four Corners. In Alaska, river ice breakup season is ending, but many rivers north of the Brooks Range remain icebound. River breakup flooding can occur with little or no notice as conditions on frozen rivers can change quickly, so please check with the Alaska Pacific River Forecast Center for the latest conditions and advisories. In addition, there is some model support for an influx of tropical moisture over parts of coastal Gulf of Alaska during week-2 associated with the recurving of tropical cyclone Jangmi (currently at Tropical Storm strength in the western Pacific). No hazards are issued at this time, but this potential will continue to be monitored. FORECASTER: Nick Novella $$