580 FXUS21 KWNC 041944 PMDTHR US Hazards Outlook NWS Climate Prediction Center College Park MD 300 PM EDT June 04 2026 SYNOPSIS: Mid-level high pressure initially over interior eastern North America is expected to deamplify while pushing northeastward early week-2, leaving a lingering potential for extreme heat across parts of the central and eastern Contiguous United States (CONUS) in its wake. Meanwhile, prevailing above-normal temperatures, in combination with insufficient rainfall and antecedent dryness, increases the potential for Rapid Onset Drought (ROD) over the southwestern Great Lakes Region. Farther south, a persistent influx of tropical moisture is expected along with the potential for slow-moving low pressure development in the eastern Gulf. This enhances the risk of heavy precipitation across most of Florida and adjacent areas through most of week-2. At the same time, a slowly-amplifying mid-level ridge is expected to bring gradually increasing temperatures and an increasing risk of extreme heat to the Southwest, California Valleys, and some adjacent areas which is expected to continue through most of week-2. HAZARDS Slight risk of extreme heat across much of the Plains, the Mississippi and Lower Ohio Valleys, the southern Great Lakes region, and the central Appalachians, Fri, Jun 12, 2026. Slight risk of extreme heat in much of the Mid-Atlantic and lower Northeast, Fri-Sat, Jun 12-13, 2026. Slight risk of extreme heat in the Desert Southwest, California Valleys, and some adjacent areas, Sat-Thu, Jun 13-18, 2026. Slight risk of High Winds along the northern California and southern Oregon coastline, Fri, Jun 12, 2026.. Slight risk of heavy precipitation over most of Florida, southern Georgia, southeastern Alabama, and some adjacent areas, Thu-Tue, Jun 13-18, 2026. Rapid onset drought possible for parts of northeastern Illinois and northwestern Indiana. DETAILED SUMMARY FOR SUNDAY JUNE 07 - THURSDAY JUNE 11: https://www.wpc.ncep.noaa.gov/threats/threats.php FOR FRIDAY JUNE 12 - THURSDAY JUNE 18: 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 and eastern CONUS during week-1 is expected to moderate early week-2, but a lingering risk of extreme heat is anticipated during the first day or two of the period from the central CONUS through portions of the East Coast. Forecast uncertainty is introduced by poor model agreement on the location and evolution of this mid-level ridge, which results in differences in the placement of the greatest heat risk. The 0z GEFS mean depicts a mid-level ridge axis extending from Canada through the western Great Lakes while the Canadian ensemble (CMCE) mean and European ensemble (ECENS) mean place the axis closer to the Northeast at the outset of week-2. Today there is less spread between the GEFS and the other ensemble means, and there good agreement on the strength of the mid-level ridge as it dissipates, but the GEFS still shows the hottest weather and greatest temperature anomalies over the Great Plains and Mississippi Valley on day 8 (Fri Jun 12) while the ECENS and to a lesser degree the CMCE place the largest anomalies farther east over the Great Lakes, Mid-Atlantic, and lower Northeast. The Probabilistic Extremes Tools (PETs) from the GEFS and ECENS show similar differences in the forecast location of the greatest chances for extreme heat. The likelihood that temperatures will be among the warmest 15 percent of recorded history exceed 40 percent in the GEFS PET from the Upper Mississippi Valley into the central Great Lakes Region while the ECENS PET depicts chances exceeding 60 percent from Upstate New York through the central Appalachians. Because of these discrepancies, a broad area with a slight risk of extreme heat is posted from portions of the Great Plains eastward through the Mid-Atlantic and lower Northeast. The extreme heat risk is removed from the Appalachians, where none of the guidance indicates a significant potential for extreme heat. West of the Appalachians, the slight risk is removed after the first day of the period. Farther east, closer to the decaying mid-level ridge, the slight risk of extreme heat continues for an additional day. Also, while the best odds for highly anomalous temperatures cover the northern tier of the eastern CONUS, the slight risk of extreme heat has been removed since there seems to be little chance for temperatures to rise much above 90 deg. F there. In contrast, there are low but non-trivial chances for temperatures to reach 100 deg. F farther south across the central tier of the eastern CONUS. 500-hPa heights return to near normal by the third day of the period (Sun Jun 14), ending the extreme heat threat. For the past several weeks, precipitation has been significantly below normal over portions of the western Great Lakes region and adjacent parts of the Mississippi Valley. Recently, the U.S. Drought Monitor has highlighted abnormally dry conditions across this region, and the weekly issue released this morning introduced some moderate drought in portions of this area. 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 much of northern Illinois and northwestern Indiana. Farther in the areas where drought was introduced this week, some relatively quick deterioration into more severe drought classifications is possible. Elevated ROD potential was removed from areas farther west in parts of Iowa and Minnesota, where heavy short-term rains (1.5 to 2.5 inches) over the next several days should be enough to preclude rapid drought development there, although less dramatic deterioration over the next few weeks is possible. A departing mid-level trough is expected to leave low surface pressure in its wake over the interior West. Meanwhile, mid-level ridging is forecast to build toward or into the West Coast, resulting in higher surface pressures. The resulting pressure gradient supports a slight risk of high winds over parts of northern coastal California and the Pacific Northwest early week-2 (Jun 12). Surface pressure forecasts from the ensemble means highlight this potential, and the PETs derived from the GEFS and ECENS show somewhat enhanced chances for winds to reach the top 15 percent of the climatological range. Models have trended a bit farther north relative to yesterday, placing the greatest positive 500-hPa height anomalies near the Pacific Northwest. This reduces the chances for high winds farther south, and the slight risk of high winds is removed from central and southern sections of the California Coast. Some guidance continues to highlight the potential for a wave of low pressure to develop west or southwest of Florida in conjunction with a potent flow of tropical moisture from into the Gulf and adjacent southeastern CONUS. 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 evolution of low pressure in lower latitudes during summer. Today, the preponderance of models agree that this system will form and increase chances for heavy precipitation across most of Florida and nearby portions of the Southeast, with the best chances across southern Florida. This system is forecast to drift northward over the course of week-2, but after mid-week, models significantly diverge from each other on the timing, placement, and intensity of the heaviest rainfall as well as the track of any surface low pressure that develops. The dynamical European model (ECMWF) drops 4 to 6 inches of rain on southern Florida through the middle of week-2, and forecasts 2 or more inches into the central Florida Peninsula. The dynamical GEFS Artificial Intelligence model is similar, but restricts amounts over 4 inches to the southwestern coastline, and brings more than 2 inches through almost all of the Florida Peninsula. The ECENS mean and the ECENS Artificial Intelligence ensemble mean depict maximum amounts of 2-3 inches south of Lakes Okeechobee or along the southwestern Florida coast, respectively, with amounts of an inch or more expected across the rest of the state. During the last half of week-2, the models diverge even further, bringing the heaviest rainfall farther north, anywhere from the central Gulf Coast to the South Atlantic Coastline. Most models eventually bring an additional 1 to 2 inches of rain to northern Florida and anywhere from the central Gulf Coast to the interior Southeast to the South Atlantic coastline, depending on the model. Regardless of the specifics, there are enough indicators favoring heavy precipitation to support a slight risk of heavy precipitation across most of Florida and adjacent parts of the Deep South. The risk extends through most of week-2, but the timing, location, and magnitude of any heavy rainfall is highly uncertain. Most tools depict a mid-level ridge amplifying in the eastern North Pacific that builds slowly toward or 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 most of week-2. The ECENS mean is more robust with this solution than the GEFS and CMCE means, but there is less model disparity than yesterday. The mean solution from the new GEFS artificial intelligence ensemble (AIGEFS) generally supports the ECENS scenario, as does dynamical European artificial intelligence model (ECMWF-AI) ensemble mean. Temperatures are expected to reach 100 to 105 deg. F for several days during the middle 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 Mexican border. Today, the GEFS and ECENS forecast the mid-level ridge to retrograde toward the central Pacific later in the period, potentially bringing temperatures a little closer to normal. The CMCE, however, locks the ridge in place along or near the West Coast. These divergent solutions lower confidence in the forecast end of the slight risk of extreme heat. 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 $$