Short Range Forecast Discussion NWS Weather Prediction Center College Park MD 346 PM EDT Tue Aug 20 2024 Valid 00Z Wed Aug 21 2024 - 00Z Fri Aug 23 2024 ...Severe thunderstorms possible across the central to northern High Plains through Wednesday with flash flood potential continuing over the Southwest... ...Record breaking heat continues across Texas... A cold front is expected to slow its eastward progression offshore the East Coast while the southern tail becomes nearly stationary across Florida, Gulf of Mexico and into the Southern High Plains/Rockies. In its wake high pressure will anchor over much of the Great Lakes region through the East, bringing much drier conditions and generally below normal temperatures for the next couple of days. Over the next few days daily high temperatures are forecast to be 10 to nearly 20 degrees cooler for mid-August for Great Lakes and Northeast. Afternoon highs are expected to top out in the 60s and 70s for many areas from the Midwest to northern Mid-Atlantic and Northeast. This high pressure is expected to dominate a majority of the region from the Mississippi River to the Appalachians for at least a few days. Underneath a strong upper level ridge, record breaking heat will continue for at least a couple more days across portions of Texas and southern Oklahoma. Excessive Heat Warnings and Heat Advisories remain in effect and many daily record high temperatures will be possible as temperatures soar into the 90s and triple digits. Combined with the oppressive humidity, daily maximum heat indices up to 110F will be possible. This will create a dangerous situation for some groups, particularly anyone spending large amounts of time outdoors. They will be at a heightened risk of heat-related illness. Some of the heat is expected to spread into eastern New Mexico by the middle/end of the week. The western periphery of the high pressure axis where the stalled front boundary will be setup up, along with interactions with another passing weather system passing through the Northern Rockies, will have threats for severe thunderstorms across the Central and Northern High Plains through Wednesday. The Storm Prediction Center is advertising a Slight Risk (Level 2 of 5) for severe weather including damaging winds and large hail. Deep monsoonal moisture will persist over the Southwest U.S. bringing a daily threat of localized and isolated flash flooding. Slow moving but intense rainfall producing thunderstorms are possible across portions of Arizona, Utah, Colorado, and New Mexico. For today, the threat appears to be fairly localized, a greater threat will exist for Wednesday across northern Arizona where a Slight Risk (Level 2 of 4) of excessive rainfall and flash flooding exists. Campbell Graphics available at https://www.wpc.ncep.noaa.gov/basicwx/basicwx_ndfd.php