985 FXUS21 KWNC 281827 PMDTHR US Hazards Outlook NWS Climate Prediction Center College Park MD 300 PM EDT May 28 2026 SYNOPSIS: Todays primary hazard concern is the increased potential of extreme heat across parts of the central and east-central contiguous U.S. (CONUS) associated with strong mid-level high pressure across these regions. A moderate risk (40-60% chance) of extreme heat is designated for parts of the Northern and Central Plains, Upper and Middle Mississippi Valley, and Great Lakes region at the beginning of week-2, with a slightly broader area of slight risk through June 11. Anomalously warm temperatures, and antecedent and anticipated dry conditions across the Upper Midwest increases the likelihood of Rapid Onset Drought (ROD) for the Upper and Middle Mississippi Valley and Great Lakes region. Mid-level high pressure is predicted to linger across the West Coast and Southwest from the end of week-1 into the onset of week-2 before shifting eastward to the central CONUS, continuing the risk of extreme heat for the Central Valley of California and parts of the Desert Southwest for June 5. High winds are possible across parts of the California Coast from beginning to mid week-2. HAZARDS Moderate risk of extreme heat across parts of the Northern and Central Plains, Upper and Middle Mississippi Valley, and Great Lakes region, Sat-Mon, June 6-8. Slight risk of extreme heat for portions of the Northern and Central Plains, Upper and Middle Mississippi and Ohio Valleys, and Great Lakes region, Sat-Thu, June 6-11. Slight risk of extreme heat for the central Valley of California and parts of the Desert Southwest, Fri, June 5. Slight risk of high winds for parts of the California coast, Thu-Mon, June 4-8. Possible Rapid Onset Drought for parts of the Upper and Middle Mississippi Valley and Great Lakes region. DETAILED SUMMARY FOR SUNDAY MAY 31 - THURSDAY JUNE 04: https://www.wpc.ncep.noaa.gov/threats/threats.php FOR FRIDAY JUNE 05 - THURSDAY JUNE 11: Mid-level ridging continues to be expected to linger across the West Coast and Southwest from the end of week-1 into the onset of week-2. This favors continuance of the slight risk of extreme heat for the central Valley of California and parts of the Desert Southwest, June 5. The Probabilistic Extremes Tools (PETs) indicate at least a 20 to 30% chance of temperatures exceeding the 85th percentile climatologically and 95-100 deg F. The Weather Prediction Centers (WPC) experimental Probabilistic HeatRisk tool shows enhanced potential for major or higher heat risk levels. The mid-level ridge across the West at the start of week-2 is anticipated to shift eastward to the central CONUS early in the period, accompanied by the shift in enhanced potential for extreme heat. Multiple model ensemble means indicate more amplified ridging developing across the central CONUS compared to yesterday. Recent deterministic GFS and ECMWF model solutions indicate positive 500 hPa height normalized anomalies reaching greater than 3 standard deviations across the Northern Plains and Upper Mississippi Valley early in the period. This pattern amplification translates to increased signals for heat across the north-central CONUS in the model solutions and associated tools. Therefore a moderate risk (40-60% chance) of extreme heat is designated for parts of the Northern and Central Plains, Upper and Middle Mississippi Valley, and Great Lakes region, June 6-8. The PETs indicate at least a 20 to 30% chance of temperatures exceeding the 85th percentile climatologically and 90 deg F (85 deg F across more northern regions), with uncalibrated guidance indicating areas further north exceeding 90 deg F. A broader area of slight risk is highlighted for these regions in addition to the Ohio Valley, June 6-11. Southerly enhanced moist flow is possible as surface high pressure forms across the East, resulting in higher relative humidity which could result in higher heat index temperatures across the risk area. Recent model guidance shows 2-m dewpoint temperatures reaching the 70s (deg F) in the extreme temperature risk areas. The experimental WPC HeatRisk tool indicates increased potential of major or higher heat risk levels across the highlighted risk regions. Following a very wet spring across the Great Lakes and Upper Mississippi Valley, precipitation has been limited over the past several weeks. The most recent release of the U.S. Drought Monitor shows expansion of abnormally dry conditions across parts of the region. With anticipated anomalous warm temperatures combined with dry soils, and antecedent and anticipated dry conditions there are elevated chances for Rapid Onset Drought (ROD). A possible risk of ROD is posted for parts of the Upper and Middle Mississippi Valley and Great Lakes region. A tight pressure gradient may set up across parts of coastal California due to a thermal low developing across Baja California and the Desert Southwest due to intense solar heating and adjacent surface high pressure off the shore of coastal California. This set up supports a slight risk of episodic high winds for parts of coastal California June 4-8. The PETs indicate at least a 20% chance of wind speeds exceeding the 85th percentile and 25 mph, further supported by uncalibrated guidance showing increased potential for wind gusts exceeding 34 mph. The heavy precipitation risk is discontinued in todays outlook across the Southeast due to timing out of the hazard and uncertainty of where enhanced rainfall may occur during week-2. 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: Melissa Ou $$