Looking ahead to tomorrow, the weather pattern and setup for heat really doesn`t change with high pressure both at the surface and aloft dominating. The main difficulty is forecasting the areas that keep upper 70s to near 80 dewpoint temperatures in the afternoon while also experiencing the mid 90s temperatures. While that cannot be ruled out again tomorrow, the majority of the forecast points are forecast to remain in Heat Advisory criteria, so a new Heat Advisory has been issued for tomorrow, again from 10 am to 8 pm which should encompass most of the 105+ heat index readings. While shower and thunderstorm coverage has come up a bit short/delayed from what was expected again today, that could change tomorrow as a series of shortwave troughs continue to move around the ridge to the south and southeast. Depending on how much and the size of any storm system, there should be some additional surface boundaries to work with along with very unstable low level lapse rates. Most of the area is in a Marginal Risk of severe thunderstorms on Monday and Monday night.
The expansive mid/upper ridge anchored across the southwest to south central U.S./northern Mexico area early in the week will start to extend east to east-northeast across the lower Mississippi valley to the interior southeast U.S. during the mid to latter part of the week. The chances of showers and thunderstorms will start to ramp up each day as the central Gulf coast starts to become under more influence from moist easterlies. Until the rain chances increase, high heat indices will remain a concern and additional heat advisories will likely be necessary through mid week.