Will Houston (and the rest of Texas, for that matter) beat the famed "Curse Of The Dry Star State"? While I am not certain about the advance of Tropical Storm Don, which has had more hiccups and false development than any storm since Marco (2008), there are some hopeful signs that this feature could organize further and make an approach a bit closer to the Bayou City than current NHC forecasts would seem to indicate.
The two big knocks against an important rainfall event from Don are the upper level weakness to its northeast (siphoning off moisture) and the lack of enthusiasm shown by the various numerical models for either strengthening or a northward track adjustment. Still, the expansion of the vast heat ridge complex gives us hope that outflow issues will be resolved, enough to allow for strengthening in the remaining time over the warm water of the Gulf of Mexico. But given the fast forward speed, and rising 500MB heights, intensification may be offset by a track through South Texas late Friday into Saturday morning. In other words, I am not very excited about rainfall chances from Don reaching into Houston.
What we must concern ourselves with is heat, high relative humidity, and poor air quality. The vast subtropical high will be strong, and encompassing Texas from now through at least August 13 (I am not kidding). Once any vestiges of Don are out of the way (possibly as early as Saturday afternoon), the potential for significant rainfall will decrease as temperatures start to rise. The profound stability of the air mass is going to allow allergens and other particulates to meld with emissions and produce a photochemical smog. Yes,a two-week stretch of hard-to-breath, fetid air with little chance for a cleaning out from thunderstorms.