Tuesday, July 11, 2006

Where have all the thunderstorms gone?

On Monday the 26th of June, Katie and I flew from O'Hare back to Tucson, arriving at dusk. In route from DFW the pilot came on the intercom and said that Tucson was reporting some light showers in the area. We had a very long and turbulent approach because of a last minute runway change as a strong gust front moved over the airport. The weather during the landing was a thunderstorm with light rainshower (my observation - NOT the official TUS observation!) and strong winds from the east.

About a year and a half ago I circulated an e-mail commenting on the dramatic decrease in thunderstorm events that had occurred in the official NWS current weather observations at Tucson International Airport since 2001. A number of people in NOAA and other organizations expressed concern, but the observations seem not to have improved at all. I feel that inaccurate current weather observations at TUS constitute a real and serious threat to aviation operations. Of course, the climatology of thunderstorm events at TUS has been badly distorted also.

I have just taken a look at the July 2006 observations to date at both TUS and also at DMA (Davis Monthan AFB). These two surface observation sites are separated by only about 8 km. During the first 10 days of July the current weather observations at TUS indicated that two thunderstorms had occurred at the airport, while the observations at DMA indicated that nine different thunderstorms had occurred at the air force observing site. Thunder was reported on two different days at TUS but was reported on six different days at DMA.

Perhaps the most interesting observation at TUS this month occurred when rainshowers with gusts to 51 mph and visibility of 2.5 miles (in HAZE!) were reported on the Fourth. During the same period at the nearby AFB, a thunderstorm was observed continuously for well over two hours.

I will be gradually preparing a paper focused on this topic at the new website that Katie and I are setting up. I will link to the paper from the blog as figures and expanded background are posted on the website.

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