150 FXUS21 KWNC 151801 PMDTHR US Hazards Outlook NWS Climate Prediction Center College Park MD 300 PM EDT July 15 2026 SYNOPSIS: Persistent mid-level high pressure over the Four Corners provides a good set up for monsoon rains over the Southwest, particularly early in the period, leading to a risk of heavy precipitation and flooding. A more progressive area of mid-level high pressure remains forecast over the south-central contiguous U.S. (CONUS) occurring near the peak of summer bringing the risk of extreme heat to the region. Above normal temperatures bring a continued risk of Rapid Onset Drought to parts of the Northern Plains. HAZARDS Moderate risk of extreme heat for parts of the Southern Plains and the Lower Mississippi Valley, Thu-Fri, Jul 23-24. Slight risk of extreme heat for parts of the Central and Southern Plains, Lower Mississippi and Tenneesee Valleys, and Southeast U.S., Thu-Wed, Jul 23-29. Slight risk of extreme heat for Interior Washington, Thu-Sat, Jul 23-25. Moderate risk of heavy precipitation for parts of western Colorado and the Mogollon Rim of Arizona, Thu-Fri, Jul 23-24. Slight risk of heavy precipitation for much of the Desert Southwest and southern Great Basin, Thu-Mon, Jul 23-27. Flooding Possible for parts of western Colorado and the Mogollon Rim. Rapid onset drought (ROD) possible for portions of the Dakotas. DETAILED SUMMARY FOR SATURDAY JULY 18 - WEDNESDAY JULY 22: https://www.wpc.ncep.noaa.gov/threats/threats.php FOR THURSDAY JULY 23 - WEDNESDAY JULY 29: Multiple model ensembles depict anomalous mid-level ridging persisting over the western and central CONUS through much of week-2, with a closed 594-dm contour remaining near the Four Corners. There is increased support for a period of transient subtropical ridging to build into the south-central CONUS at the end of week-1 and into week-2. This particularly stands out in the normalized 500-hPa height anomalies where 1 to 2 standard deviation anomalies are forecast at the climatological peak of summer. Generally southerly flow off the Gulf of America is favored to boost dewpoints east of the Rockies, resulting in potentially hazardous heat index values for much of the Great Plains and along the Gulf Coast. The potential for extreme heat continues to be supported by a variety of forecast tools with elevated forecast confidence over parts of the Southern Plains and Lower Mississippi Valley. The GEFS-ECWMF combined extreme heat tool shows widespread 20 to 40% chances of either maximum temperatures or heat index values to exceed the 90th percentile at some point during the week-2 period for most of the CONUS except along the Northern Tier. Additionally, probabilities exceed 40% and as high as 60% for the same threshold across parts of Texas and the Lower Mississippi Valley. When considered individually the two models disagree somewhat with respect to regions affected and signal strength but have good agreement where the signal is strongest across this region. Given all this, a moderate risk of extreme heat is posted for parts of the Southern Plains and the Lower Mississippi Valley covering Jul 23-24. A broader slight risk of extreme heat remains posted for much of Central and Southern Plains, Middle and Lower Mississippi Valley, Tennessee Valley, and Southeast for all of week-2. A slight risk of extreme heat remains posted for Interior Washington for Jul 23-25, consistent with increased signal from the extreme heat tools. Guidance from the uncalibrated and PET tools show elevated signals across the Pacific Northwest early in the week-2 period. Above normal temperatures are likely to persist across the Northern Plains, although these temperatures are less likely to reach hazardous thresholds. However, the combination of anomalous warmth, near to below normal precipitation favored during week-2, and antecedent dryness supports an enhanced risk of ROD across portions of the Northern Plains. Model ensembles are showing continued enhanced signals of enhanced precipitation stemming from the southwestern monsoon. Dynamical models are depicting a potential enhancement of monsoon convection through the middle of week-2, with uncalibrated probabilities from the ECWMF and GEFS indicating widespread 50% chances of 3-day precipitation totals to exceed half an inch, with some locations seeing 20% chances of 1 inch accumulations along with higher probabilities centered over the Central Rockies and Mogollon Rim. A moderate risk of heavy precipitation remains posted for portions of the Central Rockies valid Jul 23-24. A corresponding moderate risk was added today for portions of the Mogollon Rim across Arizona. A slight risk of heavy precipitation remains valid for much of the Desert Southwest and southern Great Basin and is forecast for Jul 23-27. This region is prone to flash flooding with relatively small precipitation accumulations especially along dry creek beds and in canyons and extreme caution should be exercised in such areas should thunderstorm activity initiate nearby. As such, a pair of flooding possible shapes have been added corresponding to the moderate risk area. Monsoonal thunderstorms can also produce dry lightning, resulting in increased wildfire risk. FORECASTER: Ryan Bolt $$