We continue to heat things up. The ridge of high pressure will slowly build into western Nevada, keeping our skies mostly sunny most of the day, but still allowing some afternoon cloud development. High temperatures will peak in the upper 80s Friday and will have a real shot at 90 on Saturday. A mild cooling trend comes in at the end of the weekend, with the 70s back in the picture most of next week.
Last week during the chilly but unstable weather, Donna asked: “WHY would there be thunderstorms with this kind of weather we’ve been having? It’s so cold! There is no sunshine and daytime heating to precipitate thunderstorms.”
It is true; thunderstorms are much more common during the hot summer months when the sun can heat the ground. In addition, thunderstorms have a hard time developing if there isn’t a phase change from snow to rain as the precipitation falls through the cloud. But having said that; thunderstorms can still form in cooler weather. In over-simplified terms, the chance of thunderstorms increases as the difference in temperature between the surface and the mid-levels of the troposphere (lower layer of the atmosphere) increases. If the ground is warm, that can increase that difference, increasing the instability. But you can also increase the instability by cooling down the air aloft. And these cold-core lows can do that, causing a rare cold thunderstorm.