7dayWest_Sat_Rad_Large_PacWe have another hazy and hot day ahead before we import enough moisture up from the south to bring scattered thundershowers back into the region. For Thursday, highs in the low 100s will help produce some afternoon clouds, but most of any thunderstorms will likely still remain to our south. By Friday clouds will form earlier, and we have a slight chance in the Reno area of getting a thunderstorm, but those chances increase regionally as we go through the weekend as the airmass continues to destabilize. High temperatures drop from 103 on Thursday down into the 90s through the weekend, but could return to the low 100s by the middle of next week.

Thermal Thunderstorms

I mentioned that as time goes by the airmass will continue to stabilize… a very common occurrence. Why would this be? Before the first thunderstorm occurs, the air in the lower part of the atmosphere is generally very dry, which is more stable than moist air. But once you get one thunderstorm to form, any precipitation it produces will evaporate in good part (if not completely) on the way down to the ground. That additional moisture in the lower part of the atmosphere increases the instability of the airmass for the next day, which increase the likelihood of more thunderstorms. This feedback mechanism continues until a front or other weather system comes in to knock the stagnant pool of atmosphere out of the region.