Short Range Forecast Discussion NWS Weather Prediction Center College Park MD 322 PM EDT Mon Aug 26 2024 Valid 00Z Tue Aug 27 2024 - 00Z Thu Aug 29 2024 ...Much above average temperatures/record heat to stretch from the Mid West to the East coast... ...Active showers and thunderstorms expected around the peripheries of the Mid West to eastern heat with heavy rains, flash flooding and severe weather possible... The closed upper high currently centered over the Mid Mississippi Valley/Ohio Valley region will be expanding eastward over the next two days, spreading into large portions of the east coast from the Mid-Atlantic southward. This will support an eastward expansions of much above average temperatures into the middle part of this week with high temperatures Tuesday and Wednesday anywhere from 10 to 15 degrees above average. This will support the potential for record high temperatures in the middle to upper 90s over the next several days from the Mid West, into the Ohio Valley, Tennessee Valley, Southern to Central Appalachians and into the Mid- Atlantic. The combination of hot temperatures and high humidity levels will produce maximum daily heat indices of between 105 and 115 degrees F across these regions with major to extreme heat risks. Excessive Heat Warnings and Heat advisories are currently in effect across the Mid to Upper Mississippi Valley, the Mid West and southern New England, affecting nearly 61 million people, with further expansion of these warnings and advisories possible into portions of the Mid-Atlantic over the next two days. Around the peripheries of the above mentioned upper high, precipitation is likely to be active across the Gulf Coast and from portions of the Southwest, northeastward into the Central Plains, Upper Mississippi Valley, Upper Great Lakes into Northern New England. In these regions, moisture values are forecast to remain above average, supporting the potential for areas of active thunderstorms, heavy rains and flash flooding. In addition, these thunderstorms will also support potential for severe weather, especially across eastern portions of the Central to Northern Plains, Upper Mississippi Valley and Upper Lakes Monday night into early Tuesday and across portions of the Lower Great Lakes Tuesday afternoon into Tuesday evening/night. While much above to record highs dominate portions of the central to eastern U.S. into mid week, a strong front will be pushing inland into the Pacific Northwest tonight into Tuesday, through the Northern Rockies and into the Northern High Plains by Tuesday evening. Much below average temperatures likely in the wake of this front across the Pacific Northwest on Tuesday and into the Northern Rockies/Northern High Plains on Wednesday, with high temperatures 10 to 20 degrees below average. There is not expected to be a lot of precipitation with this front over the northwest, but the falling temperatures will support at least some light snowfall amounts across the Northern Rockies of Montana. Oravec Graphics available at https://www.wpc.ncep.noaa.gov/basicwx/basicwx_ndfd.php