700 FXUS21 KWNC 031939 PMDTHR US Hazards Outlook NWS Climate Prediction Center College Park MD 300 PM EDT June 03 2026 SYNOPSIS: Mid-level high pressure forecast over south-central or southeastern Canada is expected to be slowly deamplifying early in week-2, with a lingering potential for extreme heat across parts of the central and northeastern Contiguous United States (CONUS) early in the period. The above-normal temperatures, in combination with deficient rainfall and antecedent short-term dryness, increases the potential for Rapid Onset Drought (ROD) over the southwestern Great Lakes Region and Upper Midwest. Farther south, a low pressure system is expected to slowly drift from near southern Florida toward the Southeast and Gulf Coast, bringing a risk of heavy precipitation to most of Florida and adjacent areas through the middle of week-2. Meanwhile, a mid-level ridge is forecast to slowly amplify near the West Coast, accompanied by gradually increasing temperatures and an elevated risk of extreme heat in the Southwest and the California Valleys by the middle of week-2. HAZARDS Slight risk of extreme heat across the central northern Plains, parts of the Upper and Middle Mississippi and Ohio Valleys, the Great Lakes Region, and parts of the Mid-Atlantic and Northeast, Thu-Fri, Jun 11-12, 2026. Slight risk of extreme heat in the Desert Southwest and the California Valleys, Sat-Wed, Jun 13-17, 2026. Slight risk of High Winds for portions of coastal California and the Pacific Northwest, Thu-Fri, Jun 11-12, 2026. Slight risk of heavy precipitation over most of Florida, southern Georgia, and adjacent areas, Thu-Mon, Jun 11-15, 2026. Rapid onset drought possible for parts of the Upper and Middle Mississippi Valley, Ohio Valley, and Great Lakes region. DETAILED SUMMARY FOR SATURDAY JUNE 06 - WEDNESDAY JUNE 10: https://www.wpc.ncep.noaa.gov/threats/threats.php FOR THURSDAY JUNE 11 - WEDNESDAY JUNE 17: At the start of week-2, the models all depict a mid level ridge stretching from Canada southward into the interior CONUS that is in the process of deamplifying and pushing eastward. As a result, unusually hot weather that built into the central CONUS during week-1 will be on the wane, but a lingering risk of extreme heat is expected to continue into the first few days of week-2. Forecast uncertainty is introduced by poor model agreement on the location and evolution of this mid-level ridge, which lowers forecast confidence in any specific area. The 0z GEFS mean shows the deamplifying ridge axis considerably farther west across the Plains or Mississippi Valley while the Canadian ensemble (CMCE) and European ensemble (ECENS) means place the axis farther east at the outset of week-2. In addition, the ECENS and GEFS means maintain a bit more amplitude than the CMCE mean, which flattens the ridge and shears it eastward more quickly. These pattern discrepancies have a significant impact on temperature forecasts over the central and eastern CONUS. Surface temperature anomaly forecasts and the Probabilistic Extremes Tools (PETs) from the GEFS start week-2 with a risk of extreme heat centered over the Plains or Mississippi Valley early week-2 while the tools derived from the ECENS center the greatest risk significantly farther east, over the eastern Great Lakes and interior Northeast. These patterns are considerably out of phase. Internal excessive heat guidance derived from the GEFS places the greatest chances for extreme heat over the north-central Great Plains and adjacent Mississippi Valley, which is near where the same tool based on the ECENS shows relatively lower chances there than in areas farther east and west. The bottom line is that there is broad agreement among the tools supporting an enhanced risk of extreme heat, but little agreement on exactly where this will occur. Officially, a slight risk of extreme heat is posted across a broad area covering much of the central and eastern CONUS for the first two days of week-2 before 500-hPa heights drop to near normal, ending the risk. The coverage essentially combines the higher risk areas identified by the disparate tools, as there is no overriding reason to favor one solution over another at this time. Over the past several weeks, precipitation has been significantly below normal over portions of the western Great Lakes region and adjacent portions of the Mississippi Valley. The U.S. Drought Monitor highlights abnormally dry conditions in this region. The week-2 precipitation outlook depicts marginally enhanced chances for above-normal precipitation across this area, but the expected hot weather and associated increases in evaporative moisture losses, in conjunction with the elevated human and ecological demand for surface water inherent to summertime, makes it likely that the precipitation will not be sufficient to offset surface moisture losses. As a result, a potential for rapid-onset drought (ROD) is maintained across southeastern Minnesota, northeastern Iowa, southwestern Wisconsin, northern Illinois, and northwestern Indiana. The Drought Monitor will be updated tomorrow, at which time the chances for ROD will be re-assessed. Models remain in good agreement favoring mid-level troughing over the West Coast early week-2. This is expected to establish low surface pressure over the interior West while surface high pressure builds eastward from the North Pacific. The resulting pressure gradient supports a slight risk of high winds over parts of coastal California and the Pacific Northwest early week-2 (Jun 11-12). Surface pressure forecasts from the ensemble means highlight this potential, and the PETs derived from the GEFS and ECENS show enhanced chances for winds to reach the top 15 percent of the climatological envelope. PETs, which have come into better agreement depicting increased chances for wind speeds exceeding the 85th percentile, along with 20 to locally 60 percent chances for wind speeds topping 20 mph, with the highest odds along the immediate coast. Chances for winds above 25 mph reach as high as 50 percent northwest of Santa Rosa, CA in the ECENS PET. Over the western Atlantic, guidance increasingly supports the potential for a wave of low pressure to develop. The models have been inconsistent in handling the evolution of this potential system, which is not unexpected given the relatively subtle mid-level features that determine the eventual evolution of low pressure in lower latitudes during summer. Today, there is general agreement that this system will be affecting south Florida at the outset of week-2, moving slowly northward toward southern Georgia or the northeastern Gulf Coast over the next several days. This consensus is longer-lived and farther west than the consensus of tools yesterday. The PETs are not too enthusiastic on the potential for heavy precipitation, but the ECENS, GEFS, and especially the dynamical European model (ECMWF) all show enhanced chances for a few inches of rain to fall on some areas affected by this system. A slight risk of heavy precipitation is posted for most of Florida, southern Georgia, and some adjacent areas which could be affected by this feature, but there remains a lot of uncertainty as indicated by the wide array of potential scenarios indicated by the individual members of the ensembles. A mid-level trough over the western CONUS will be pulling away from the region early week-2. In its wake, most tools depict a mid-level ridge amplifying in the eastern North Pacific that builds slowly into the western CONUS. As this evolves, temperatures are expected to slowly increase across the western CONUS, resulting in a slight risk of extreme heat across the Desert Southwest and California Valleys during the middle and latter parts of week-2. The ECENS mean is considerably more robust with this solution than the GEFS and CMCE means, but the mean solution from the new GEFS artificial intelligence ensemble (AIGEFS) supports the ECENS scenario, along with the European artificial intelligence model (ECMWF-AI) ensemble mean. Temperatures are expected to climb into the low to middle 100's F after the first couple days of week-2, with the ECENS mean forecasting temperatures of 110 to 115 deg. F in the most arid locations near the lower Colorado River and near the Mexican border. 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. FORECASTER: Rich Tinker $$