Short Range Forecast Discussion NWS Weather Prediction Center College Park MD 338 AM EDT Sat Jul 27 2024 Valid 12Z Sat Jul 27 2024 - 12Z Mon Jul 29 2024 ...Scattered showers and thunderstorms continue across portions of the South and Mississippi Valley this weekend with the risk for some flash flooding... ...Hot weather is in store across portions of the Northern Plains and Upper Midwest ahead of a cold front bringing the threat of severe thunderstorms on Saturday and heavy downpours on Sunday... ...Monsoonal thunderstorms continue for portions of the Intermountain West with isolated flash flooding possible... Scattered showers and thunderstorms will continue across portions of the South and Mississippi Valley this weekend in the presence of very moist, southerly Gulf flow. An upper-level wave over the Plains on Saturday will encourage storms over the Middle and Lower Mississippi Valley and along the Gulf Coast. A Slight Risk of Excessive Rainfall (level 2/4) is in effect for portions of the Gulf Coast of Texas where recent heavy rainfall over the past few days has left wetter antecedent conditions more susceptible to scattered instances of flash flooding, though an isolated flash flood risk will exist elsewhere. The wave will move eastward on Sunday, helping to focus storm development over portions of the Middle Mississippi/Lower Ohio Valley southeastward into the Tennessee Valley and south to the Gulf Coast. The greatest concentration of storms/storm clusters is expected along the leading edge of the wave over the Tennessee Valley, where a Slight Risk of Excessive rainfall is in place for another threat of some scattered flash flooding. The unsettled weather will help keep temperatures down across the region this weekend, with temperatures at or below Summer-time averages, especially for portions of central and eastern Texas. Forecast highs are generally in the mid- to upper 80s, with low 90s possible closer to the central Gulf/Atlantic coasts and into Florida. To the north, a slow moving frontal system will bring shower and storm chances to the Northern Plains/Upper Midwest Saturday. Plentiful moisture with sufficient instability, as well as stronger upper-level flow arriving over the region helping to strengthen deep-layer shear, will promote some more intense thunderstorms. The Storm Prediction Center has issued a Slight Risk of severe weather (level 2/5) over portions of eastern North Dakota into northwestern Minnesota for the threat of large hail and damaging winds. Some isolated flash flooding will also be possible. Then, on Sunday, the front is expected to slow as it approaches Minnesota. Increasing storm coverage along the front will lead to a greater chance of heavier rain totals and flash flooding, with a Slight Risk of Excessive rainfall over northern Minnesota. Further to the southwest, more isolated storms ahead of the front over central South Dakota will continue to pose a threat of severe weather, with a Slight Risk in place for some large hail and damaging winds. Forecast highs ahead of the front will continue to remain well above average, with highs in the mid-80s to low 90s for the Northern Plains/Upper Midwest and mid- to upper 90s into the Central Plains. More Monsoonal storms are expected on Saturday across portions of the Great Basin, Rockies, and Southwest. Lingering moisture across the region may lead to some locally heavy downpours, with isolated flash flooding possible, particularly for terrain sensitive areas such as burn scars. Storm chances will come down as upper-level heights begin to rise over the region on Sunday, with a lingering chance over southeastern Arizona/southwestern New Mexico. Forecast highs broadly across the West will be at or a bit below average with an upper-level trough in place. Highs will be in the 60s and 70s along the Pacific Coast, the 70s and 80s for the Pacific Northwest, the 80s and 90s for interior California and the Great Basin/Rockies, and 100s in the Desert Southwest. Elsewhere, conditions will be rather tranquil from the Great Lakes east to the East Coast between weather systems. Some showers may begin to spread into the Great Lakes region later Sunday as the Plains system approaches from the west, while a coastal low could bring some showers to southern New England. Forecast highs will generally be at or above average, with highs in the mid- to upper 80s. Putnam Graphics available at https://www.wpc.ncep.noaa.gov/basicwx/basicwx_ndfd.php