 Amidst the heat, thunderstorms are expected in the early part of this week. In addition, tomorrow's excessive heat watch is for the same conditions with heat index values up to 110 degrees possible. Much of the D.C. area is also under a cold orange air quality alert today, meaning it is possibly unhealthy for certain sensitive groups, such as children, the elderly, or those suffering from heart disease, asthma, or other lung diseases.