296 FXUS21 KWNC 281806 PMDTHR US Hazards Outlook NWS Climate Prediction Center College Park MD 300 PM EDT June 28 2026 SYNOPSIS: Extreme heat is likely to continue into week-2 across many areas of the central and eastern contiguous U.S. (CONUS) associated with anomalous mid-level high pressure. Anticipated high dewpoints favor heat index values exceeding 100 to 105 deg F over many areas with warm nights limiting overnight relief. As the mid-level high shifts westward, some heat relief is forecast across the Eastern Seaboard, but with extreme heat potential increasing across parts of the western CONUS. Surface high pressure off the West Coast in week-2 increases chances for episodes of high winds across the Pacific Northwest and California through much of the period. HAZARDS Moderate risk of extreme heat for the eastern Central and Southern Plains, Central and Lower Mississippi Valley, Southeast Atlantic states, and Mid-Atlantic, Mon, Jul 6. Slight risk of extreme heat across much of the central and eastern CONUS, Mon-Wed, Jul 6-8. Slight risk of extreme heat across much of the Great Basin, Northern Intermountain, Southwest, and Rockies, Mon-Fri, Jul 6-10. Slight risk of high winds for portions of California and the Pacific Northwest, Mon-Sun, Jul 6-12. DETAILED SUMMARY FOR WEDNESDAY JULY 01 - SUNDAY JULY 05: https://www.wpc.ncep.noaa.gov/threats/threats.php FOR MONDAY JULY 06 - SUNDAY JULY 12: A major heat wave is forecast to be ongoing across much of the central and eastern CONUS at the start of week-2. For the Eastern Seaboard, the peak of the heat is likely to occur during the late week-1 timeframe, with mid-level ridging retrograding farther to the west at the beginning of week-2. Despite these height trends, the surface temperature forecast from the ECENS and GEFS Probabilistic Extremes Tools (PETs) still highlight elevated chances for maximum temperatures to exceed the 85th climatological percentile. The GEFS PET has a more robust signal for Jul 6 relative to yesterday's forecast. Separately, a skill weighted heat risk tool indicates greater than 40% chances for heat index values to exceed 105 deg F and the 90th percentile. The overnight minimum temperature forecast from the National Blend of Models (NBM) continues to highlight a significant number of records by the beginning of week-2. The deterministic ECMWF and GFS forecast maximum apparent temperatures near 105+ deg F for the Mid-Atlantic and Southeast Atlantic states, and 105 to 110 deg F over the eastern Central and Southern Plains and Middle and Lower Mississippi Valley. As such, a moderate risk of heat is forecast for the Mid-Atlantic and Southeast Atlantic Coast for Jul 6. A separate risk is designated for the eastern Central and Southern Plains into the Middle and Lower Mississippi Valley, also for Jul 6. A small area of Georgia and Alabama was removed from the moderate risk today with continued weakening of the heat signal across this region. However, a broader slight risk remains valid through Jul 8 across much of the central and eastern CONUS. By day-8, the 0z ECMWF, GEFS, and Canadian ensembles all depict a 594-596 dm ridge across the Four Corners, which could result in extreme heat conditions emerging across portions of the Interior West and persisting through at least the middle of week-2. There is still a fair amount of uncertainty regarding the surface reflection of the mid-level height pattern with PET tools still not bringing moderate risk chances into the region. However, the Weather Prediction Center (WPC) Probabilistic HeatRisk tool shows increasing signals for major HeatRisk across the West by the beginning of week-2. Therefore, an additional slight risk (20-40 percent chance) of extreme heat is valid July 6-10, across much of the interior western US, excluding most areas west of the Sierra Nevada and the Northern Rockies. Surface high pressure off the West Coast and mid-level low pressure, along with thermal low pressure over the Great Basin increase chances for episodes of high winds during week-2. The GEFS and ECMWF PETs indicate at least a 20 percent chance of wind speeds exceeding the 85th climatological percentile and 25-mph. Therefore, a slight risk of high winds is posted across this region. Across the southwestern CONUS, the ridge axis is forecast to move towards a more favorable position for enhanced monsoonal moisture advection and increased precipitation over parts of the Desert Southwest. Although PETs show increased chances of 3-day precipitation exceeding the 85th climatological percentile over the Desert Southwest and into the Central Rockies during the second half of week-2, both raw and calibrated precipitation amounts in the ensemble means remain fairly low, precluding a corresponding precipitation hazard at this time. Localized thunderstorms are still possible and this area will continue to be monitored with ensemble guidance indicating precipitable water increasing during the week-2 period. Transient shortwaves moving across Alaska favor periods of enhanced precipitation across much of the state, along with a tilt toward below-average temperatures. However, precipitation and temperature values are expected to remain below hazardous thresholds. FORECASTER: Ryan Bolt $$