A number of people have commented on the rather dramatic line of thunderstorms that rolled across Galveston County on Monday night. They were particularly curious about the fact that most forecasts put the chances of thunderstorm development at only 20-30% and a few media outlets called for no storms at all locally.
So what happened? The explanation is rather simple, though the dynamics of forecasting these events is rather rare. Monday we had an atmospheric cap in place….that is a layer of warm air a few thousand feet in the atmosphere. This is not that uncommon for Southeast Texas this time of year, especially near the coast. At any rate, a cap will either prevent thunderstorm formation or even suppress storms as they near the coast (leading to the common comment that storms seem to “fall apart” as they near Galveston County). Below is a link to a concise explanation of atmospheric caps.
At any rate, there was some chance that the cap would erode late in the day….hence the low chance for storms. However, if the cap does erode, then rapid, intense thunderstorm formation can occur and that is precisely what happened on Monday.
Meanwhile, looking ahead, the weak cold front that pushed through Monday night has led to another round of near ideal spring weather. Unfortunately, this not likely to persist for long, as deeper Gulf moisture begins returning to our area by Friday and a decent chance of rain appearing this weekend as a somewhat more vigorous push of cooler air reaches the coast late Saturday into Sunday.
The cold front will result in fairly chilly temperatures as we begin April, with minimum temperatures due to drop to the low to mid-50’s on the Island and the low to upper-40’s in northwest parts of the County.
To complicate things, weak disturbances tracking from west to east across the upper-levels of the atmosphere may keep clouds and rain chances around for much of next week.
In other words, early April may seem a little less like spring than many would prefer!