Short Range Forecast Discussion NWS Weather Prediction Center College Park MD 340 PM EDT Tue Aug 13 2024 Valid 00Z Wed Aug 14 2024 - 00Z Fri Aug 16 2024 ...Flash flooding and severe weather threat forecast to stretch from the central Plains to the Midwest over the next few days... ...Potentially dangerous heat anticipated across the southern Plains, lower Mississippi Valley, and Gulf Coast... ...Fire weather concerns and poor air quality continues for portions of the Pacific Northwest, Northern Rockies, and Great Basin... A mid-August weather pattern continues this week with numerous areas of scattered thunderstorms impacting the Nation. A quasi-stationary front currently stretching from the Southeast to the central High Plains will be the focus for much of this activity, with the boundary eventually forecast to lift northeast into the Midwest by Wednesday night due to a deepening low pressure system in the central Plains. The most likely weather hazard over the next few days with developing thunderstorms is expected to be associated with heavy rainfall creating instances of flash flooding, as well as the potential for some severe weather. Specifically, three separate areas along the front stand out today (Tuesday) as having the greatest chances for scattered flash floods. Parts of South Carolina remain sensitive to locally heavy rain as the area continues to contain saturated ground conditions, leading to a continued threat for flash flooding due to slow-moving thunderstorms, with a Slight Risk of Excessive Rainfall (level 2/4) in effect. Further west into the Midwest/central Plains, another organized convective system is expected Tuesday evening/overnight, with a narrow corridor of impressive rainfall totals expected within a few hours centered over south-central Missouri, covered by an associated Slight Risk of Excessive Rainfall. Additionally, a Slight Risk of Excessive Rainfall is in place for northeast Colorado with another round of storms containing intense rainfall rates Tuesday evening as activity forms along the leeward side of the Rockies and pushes eastward. The Storm Prediction Center has also included a Slight Risk of severe weather (level 2/5) mainly for some isolated damaging winds gusts. Residents and visitors are advised to have multiple ways of receiving warnings, have a plan should flash flooding occur, and never drive through flooded roadways. The heavy rain and thunderstorm activity is anticipated to gradually shift eastward into the Midwest on Wednesday along with the strengthening low pressure system and lifting warm front. The focus for heaviest rainfall is currently expected with ongoing storms Wednesday morning over Missouri, and then another round of storms Wednesday afternoon/evening along the lifting warm front in Iowa and southern Minnesota, with a Slight Risk of Excessive Rainfall covering these regions. Some severe weather will also be possible given strengthening wind fields with an approaching upper-level wave, with a Slight Risk over the Middle Missouri Valley for the threat of large hail and damaging winds. Then, on Thursday, the system will push further eastward, with a similar flash flooding/severe weather scenario expected. Storms over the Middle Mississippi Valley/Great Lakes will initially pose a severe weather threat with some large hail possible before transitioning into more of a flash flood threat Thursday evening/overnight downstream further into the Great Lakes and Lower Ohio Valley. Dangerous summer heat will be confined to the southern U.S. this week as highs into the upper 90s and triple digits span from the Southwest to the Gulf Coast. The most anomalous and potentially dangerous heat is forecast across the southern Plains and Gulf Coast States through the end of the week as highs reach up to 10 degrees above the climatological average for mid-August. Elevated humidity levels will lead to maximum heat indices up to 110 degrees during the day and low temperatures only dipping into the upper 70s and low 80s at night. People spending greater time or effort outdoors, or in a building without effective cooling, are at an increased risk of heat-related illnesses. Elsewhere, temperatures will actually be rather pleasant for mid-August, with many locations near or below average. Highs in the 80s (and even some 70s) will be common across the northern tier of the country. Locations further south from the Great Basin into the central Plains and Ohio Valley/Mid-Atlantic will tend to be warmer, with highs in the mid-80s to low 90s. A persistent pattern supporting fire weather concerns across much of the central and northern Great Basin is forecast to continue today and Wednesday with the threat of lightning with dry thunderstorms, dry terrain, and periods of gusty winds. Red Flag Warnings remain in place from eastern Oregon to Idaho. Ongoing wildfires also continue to spread smoke into the atmosphere, leading to poor air quality. Putnam/Snell Graphics available at https://www.wpc.ncep.noaa.gov/basicwx/basicwx_ndfd.php