Cpv17 wrote:What kind of pattern would we need to get rain for the southern half of Texas?
For Texas in general, preferably a Super Typhoon in the west Pacific, a major hurricane in the east Pacific, a roaring subtropical jet with OLR (longwave radiation) screaming from the international dateline to the state. This all happened May of 2015 (STY NOUL and cat 4 Andres). Seemingly everyday someone somewhere had flood watches. Oh and a Super El Nino to boot...
The maps for 5-7 day qpf basically was just this constantly

DFW, Austin, Houston, SA all were near or close to record monthly rainfall.
May be another 50 years until we see something like that again (1957-2015)