The Tucson National Weather Service is yet again fascinated and fixated on forecasting days ahead of time record-breaking highs, confidently predicting that Sunday's high will be not just 4 degrees warmer than today's (Wednesday's) 107, but precisely 7 degrees warmer. Dismissed is the more important point that unlike the last several afternoons, which have been just hot, the next several afternoons will be both hot and humid.
I have become fascinated with the "Forecast Soundings" option on the National Weather Service Model Analyses and Guidance page. It's fascinating to watch—not just every 12 hours, but every 3 hours—Tucson's capping inversion at around 400-500 mb evolve diurnally, and from day to day. That inversion rules out nearby thunderstorms today. But the mid-level inhibition becomes much weaker possibly as early as tomorrow afternoon, more consistently by Friday afternoon, along with a flow that would steer isolated, high-based, borderline thunderstorms from the east or southeast. The odds of measurable precipitation reaching the ground any of the next several days are low. But the record or near record
hot environment will enhance negative bouyancy of any downdraft. Maybe by the end of the weekend the surface parameter that will have been observed to break a record will not be temperature.
