Today and Sunday will be hot with a chance for isolated storms each afternoon. Highs in the 90s will also linger into the first part of next week.
This is a persistent pattern. Often times when we have a pattern that is stagnant or persistent as is the case at the moment, we need to look above the surface to find out the reason why. If you look at the forecast pattern at the surface, we have an area of high pressure overhead that is keeping a lid on the vertical motion of the rising air. It helps to reduce the development of storms as it restricts the parcels of air from rising too high in the atmosphere and introducing what we refer to as an unstable environment…meaning rising air and convective development or storms.
If the high has a weak point and some of the parcels of air break through the cap… then we have a large towering cloud that will produce a good deal of rain as well as gusty winds and some hail. That is what happened over Covington Thursday evening and earlier in the day just west of Bedford. The isolated nature of the storms helps them pull a good deal of energy from the capped locations and we get the quick developing storms in a very small region. There usually is very little movement to the storms as well, since there are no real steering currents under the high pressure cell. The result is a good chance for heavy rain and localized flooding.
The storms over the next few days will take on the characteristics named above. Obviously, there are several ways to get a storm to pop up in the afternoon of a hot day, but once the cap is broken, the pop really begins. It usually takes about an hour or so for the storms to rain themselves out, so if you are under the heavy rain and slow moving storm that just popped up, keep an eye on flood prone regions at your location. The mountains also can produce flash flooding, so that is something you need to be concerned about as well. Flooding that occurs quickly and intensely due to a variety of factors, but in the mountains, it is usually topography.