Dramatic Downburst in Amarillo This Afternoon

The National Weather Service's Amarillo office took quite a picture of a downburst at 4:02pm CDT this afternoon (hat tip: Mark Fox).

Here is the raw image.

It becomes even more impressive when the air flow is superimposed.

A downburst, discovered by Dr. Ted Fujita after his examination of the crash of Eastern Airlines Flight 66 in 1975, is an extreme hazard to aviation due to wind shear in both the horizontal and vertical.

On radar, nothing ominous is present on radar at 3:52pm.
click to enlarge
The black circle is the location of the radar at the airport. That is the location of the photo.
  • The left is the "reflectivity data" which depicts how hard it is raining. This is the type of radar display you typically see on television. 
  • On the right is the Doppler wind velocity data. Nothing unusual there, either. 
At 3:57, a core of intense rain, with some hail, makes its presence known (black oval, left). It is rapidly descending through the thunderstorm toward the ground. The rain may just be touching the ground at this time.
At right, the first sign of diverging winds (orange circle) is present. Green winds are winds blowing toward the radar and reds are winds blowing away from it. 

At 4:01pm, the downburst has struck the ground and is spreading out (wind flow shown by arrows at right). There is 69 mph of wind shear which would be enough to cause a plane crash if the downburst was near the end of a runway and a plane happened to be in the wrong place at the wrong time. 
The photo was taken one minute after the radar collected this data. 

The downburst is fully mature at 4:06pm.
Downbursts used to cause a crash every 18 months or so from the late 1960's to the 1985 (Delta 191). Fujita published his findings in 1977 but the aviation and meteorological communities were slow to accept the results, resulting in hundreds of needless fatalities.  

Fortunately, through the work of Dr. Fujita, Dr. John McCarthy, NW Airlines' Patrick Clyne and others, the last downburst-related airliner crash in the United States was nearly 26 years ago. However, they continue in other nations, including one in Mexico two years ago. 

The conquering of the downburst is another of the amazing successes of weather science the last 30 years. 


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