For the past several weeks, the jet stream (as shown by the red line on the image below) has resided well to the North of Texas and the remainder of the southcentral U.S., steering the majority of precipitation producing systems along with it, leaving the Lone Star State (among parts of some adjacent others) hot and dry:
GFS Computer Model Analysis valid 1pm CDT 6-18-11
For the past several days, computer forecast models have been hinting that a change in the overall flow pattern will come about this coming week, such that the jet stream will travel further Southward over time, bringing at least a chance of precipitation to a large portion of Texas by mid-week next week:
GFS Computer Model Forecast valid 7pm CDT 6-21-11
The latest precipitation forecast from the HPC for next week indeed shows widespread rainfall of one-quarter to one-half inch across the central & Eastern two-thirds of Texas, with some pockets of 1+ inches of rain across portions of the Eastern one-third of the state:
Of course, along with any increase in cloud cover and rain chances would also come lower temperatures, suggesting that the string of 100+ degree days that much of Texas has seen for the past week or so would also come to an end at least for a time next week (in the central & eastern parts of the state at least).
I am still of the opinion that the best chance for widespread, significant rain in central & east Texas this summer will have to come from some sort of tropical system (i.e., a tropical storm or hurricane), however even a brief break in the hot, dry pattern such as the one that looks to be in line for mid-week next week will be very, very welcome indeed!