Regarding the Southwest Airlines Flight #4069 in Oklahoma

You've probably heard about the Southwest (SWA) flight from Las Vegas to Oklahoma City that dropped to ~500 feet altitude over the suburb of Yukon Tuesday night. The plane landed safely at Will Rogers World Airport at 12:21am Wednesday (19th). 

It came to my attention that there are some speculating that it was downburst or a "gust front" that caused the plane to drop. There was one comment that said it looked like the 1985 crash of Delta Flight 191 in Dallas. 

As the meteorological expert in one of the trials involving Delta 191, I can say with certainty that it was not a downburst or microburst that caused the loss of altitude. In fact, weather doesn't appear to have played any part in the incident. Here's my evidence:

The Sky Was Non-Threatening 

Above is a screen capture from a video showing the SWA flight (arrow) near Yukon. At left are a few cumulus clouds possibly associated with the 68°F dew point at Will Rogers (WR). There was a level jet stream as the wind at WR was out of the southeast at 13 mph and Doppler radar shows southeast winds at about 40 mph over Yukon at 1,200 feet. But, that is common in the Great Plains at night so there is no reason to believe there was anything unusual. 

There Were No Thunderstorms in the Area

I have circled Yukon and the runway diagram at Will Rogers World Airport. The nearest thunderstorms were more than 100 miles to the west. This is an image of the WR Terminal Doppler Weather Radar. It is blank. There are no rain showers, let alone thunderstorms. No thunderstorms = no downburst or microburst.  

No Front in the Area

Above is the Doppler wind data. Both Doppler radars in the area indicate the winds in the low levels of the atmosphere were quiescent. There is no wind shift or front in the area that would have caused an uncontrolled drop in altitude. 

My conclusion is that there was no obvious meteorological reason for a drop in altitude over Yukon.