227 FXUS01 KWBC 290424 PMDSPD Short Range Forecast Discussion NWS Weather Prediction Center College Park MD 1223 AM EDT Mon Jun 29 2026 Valid 12Z Mon Jun 29 2026 - 12Z Wed Jul 01 2026 ...Showers and thunderstorms will continue for Northern Plains into Upper Midwest on Monday... ...Showers and thunderstorms will move into the Northeast and Great Lakes by Tuesday... ...Persistent Dryline will bring flooding concerns over portions of west Texas through Tuesday... ...Dangerous Heat builds across much of Central and Eastern U.S., while below normal temperatures persist over the West... Shortwave impulses embedded within a northwesterly flow will interact with a frontal boundary that stretches across the Northern/Central Plains through the Upper Midwest and Great Lakes, which will facilitate repeated episodes of organized convective development along the boundary. Moist air mass, combined with moderate to strong instability, will support showers and thunderstorms that may produce heavy rainfall rates. Therefore, WPC has highlighted a Marginal Risk of excessive rainfall across parts of the Northern Plains and Upper Mississippi Valley for Monday. In addition, Storm Prediction Center continues to highlight portions of the Northern/Central Plains and Upper Midwest with a Slight Risk of severe thunderstorms, gusty winds, and hail. The shortwave troughs behind the frontal boundary will bring mixed precipitation over the highest elevations across the Intermountain West/Northern Rockies. The frontal boundary will gradually split with the lower portion heading into the Southeast, bringing showers and thunderstorms over the area. On Tuesday, the warm frontal boundary will lift and stretch into the Northeast and the associated cold front will move eastward, bringing chances for organized showers and thunderstorms to develop ahead and north of the boundary. With the chances for heavy rain rates, a Marginal Risk of excessive rainfall have been placed for Tuesday over Northern New England and the Great Lakes, with a chance for severe thunderstorms to develop across portions of the Central Plains into the Great Lakes and Northeast as well. Furthermore, the slow moving frontal boundary across the Southeast, will continue to bring a risk of localized flooding, while shortwave troughs will continue to bring showers and thunderstorms across the Northern/Central Rockies and Plains. Also, a persistent dryline in west Texas will produce showers and thunderstorms bringing isolated flooding concerns through Tuesday. A strengthening upper-level ridge will bring dangerous heat with temperatures in the 90s and lower 100s across much of central and eastern U.S. The combination of high humidity values will produce heat indices between 105-115 degrees across portions of the southern Plains, Mid-Mississippi Valley, and eventually into parts of the Mid-Atlantic. Much of central and eastern U.S. will be under a Moderate to Major HeatRisk for Monday and Major to Extreme HeatRisk for Tuesday. Overnight cooling will also be limited, while many locations will see lows in the mid to upper 70s. The combination of prolonged daytime heating and limited nighttime relief will increase the risk of heat-related illnesses, especially for vulnerable populations and those without adequate cooling. Farther west, persistent troughing over the Pacific Northwest will continue bringing below normal temperatures across much of western U.S. Oudit Graphics available at https://www.wpc.ncep.noaa.gov/basicwx/basicwx_ndfd.php $$