Short Range Forecast Discussion NWS Weather Prediction Center College Park MD 400 AM EDT Sun Jun 23 2024 Valid 12Z Sun Jun 23 2024 - 12Z Tue Jun 25 2024 ...Heat wave focus shifts from the Mid-Atlantic to portions of the Southeast/Southern Plains by Monday... ...Widespread storms will bring the threat of flash flooding, damaging winds, and tornadoes to New England Sunday... ...Severe storms for portions of the Upper Midwest on Monday... ...Monsoon-like conditions persist for the Southwest... Broad long-wave upper-level ridging over the East Coast and western U.S. Sunday will keep hot Summer temperatures in the forecast for much of the country. Highs are forecast into the upper-90s from the Mid-Atlantic to the Southeast/Lower Mississippi Valley/Southern Plains and west through the High Plains into the Great Basin and California. Humidity helping to push heat index values into the low 100s as well as warm low temperatures generally in the mid-70s, providing little relief from the heat overnight, will make this heat most dangerous for portions of the Mid-Atlantic, Southeast, Lower Mississippi Valley, and Southern Plains, with heat-related advisories and warnings in effect for some areas. Numerous record-tying/breaking highs are possible for the Mid-Atlantic. In the West, heat-related advisories/warnings are also in effect where temperatures will push past 100 over northern Utah and portions of central/southern interior California. An approaching upper-level trough/surface cold front later Sunday will bring temperatures down closer to average Monday for the Mid-Atlantic, while the Southeast/Lower Mississippi Valley/Southern Plains continue to simmer. The upper-level ridge over the West will also begin to move eastward over the central U.S., bringing highs into the upper 90s and low 100s more broadly over the Central/Southern Plains. The noted upper-level trough and accompanying surface low pressure/frontal system pushing eastward will bring storm chances from New England southwestward through the Mid-Atlantic into the Upper Ohio/Tennessee Valleys Sunday with moderate to locally heavy rainfall possible. The greatest chance for some potentially more significant rainfall will fall ahead of the surface low track over northern New England where anomalously high moisture values and strong forcing could lead to downpours upwards of 2"/hour. A Slight Risk of Excessive Rainfall (level 2/4) is in effect for the risk of some scattered instances of flash flooding. In addition, strengthening upper-level and low-level winds as well as strong instability given the high moisture and warming temperatures will promote some more intense thunderstorms. The Storm Prediction Center has added an Enhanced Risk of severe weather (level 3/5) over central New England where these conditions are most favorable for the threat of damaging winds and a few tornadoes. A broader Slight Risk (level 2/5) is in place across the region and southwest through the northern Mid-Atlantic into the Upper Ohio Valley for a more isolated threat of damaging winds. The system is expected to reach the coast by Monday morning, bringing drier conditions into the day Monday, though some storms may linger over northern New England. To the West, an upper-level shortwave/surface frontal system moving eastward along the northern tier of the West/southern Canada Sunday will approach the Upper-Midwest by Monday afternoon. Warm, moist air flowing northward ahead of the system will help to lead to the chance for some storms along and ahead of an eastward moving cold front. A Slight Risk of severe weather remains in place for portions of northern Minnesota/Wisconsin for the threat of some damaging winds and large hail. The chance for some more widespread/organized convection and locally heavy downpours may lead to an isolated instance or two of flash flooding as well. Monsoon-like conditions will persist over the Southwest through at least Monday, with daily shower and thunderstorm chances. Anomalously high moisture over the region will lead to some locally heavy downpours and an isolated risk for flash flooding. Daily storm chances will also persist over Florida and south Texas. Putnam Graphics available at https://www.wpc.ncep.noaa.gov/basicwx/basicwx_ndfd.php