A wave in the upper level wind flow over the Big Bend is associated with cooler air aloft, and rising air aloft. The colder air aloft makes warm air, lifted from the surface tend to remain warmer than surrounding air as it rises. The air is, as result, less dense than surrounding air, and will rise, perhaps forming tall rain clouds. The rising air ahead of the upper level wave also helps produce the tall clouds. The wave is going by mostly to our north, and showers will be most widespread from Eagle Pass northward to the Hill Country, and eastward from there. We may catch the south edge of this system overnight, and I will watch the radars. After slight shower chances Tuesday and Wednesday (breaks in the clouds will lead to temperatures higher above 80 than today), hotter weather will expand northeastward out of Mexico.
I'm expecting a chance of a shower or thundershower overnight, low around 70. Mostly cloudy Tuesday and Wednesday, a slight chance of a shower, highs in the mid to high 80's. Partly cloudy Thursday through Saturday, high in the low to mid 90's. Mostly sunny afternoons Sunday and Monday, high in the high 90's to around 100.