The Weather Junkie

On Aug. 2, 1985, a Delta airlines jet on approach to Dallas-Fort Worth airport flew through what was thought to be a typical summertime thunderstorm.

Minutes later, a microburst caused the jet to crash, killing 135 people.

The tragedy was one of several that aviation safety experts said was caused by microbursts, which at the time were not well known, and the tools to detect them were not in widespread use.

In 1988 the network of NEXRAD radars (NEXt generation RADars) was complete, but it did not have the precision needed to detect microbursts close to airports, where jets flying low on approach or takeoff could be vulnerable.

By 1994, a network of high resolution doppler radars were installed near some of the nation’s busiest airports. Called TDWR, for Terminal Doppler Weather Radar, the images were clearer than the NEXRAD units used by the National Weather Service and provided refreshes every minute, as opposed to every six-minutes from NEXRAD.

In 2007 access to those TDWR radar images was released to the public, allowing storms within 50 miles of the radar dome to be scrutinized for everything from tornado vortex signatures (TVS) to the type of wind shear that crashed the Delta flight in Dallas.

Amateur weather enthusiasts and professionals alike can now use TDWR radar data to get higher resolution peeks inside severe thunderstorms. Hook echoes can be examined at resolutions not seen outside of portable units like the Doppler On Wheels (see right). And with some product updates generated every minute, better loops can help derive storm motion, possibly spotting a right-turning mesocyclone before the WSR-88D (Weather Service Radar 1988 Doppler) can pick up on it. (Although the National Weather Service has not provided those rapid updates to the public, yet, and available TDWR data refreshes at six-minute intervals, just like NEXRAD.)

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There are caveats to following storms via TDWR sites. Range folding often obscures large chunks of data, leaving gust fronts and even tornado vortex signatures invisible in some conditions. Heavy precipitation over the radar dome itself can also cause attenuation, which can make some storm activity seem to weaken further out from the radar until the storm leaves the immediate TDWR area.