Combination of factors uncannily timed into ‘perfect storm’

Sudden ice storm envelops Austin metro area by 7 a.m.
Sudden ice storm envelops Austin metro area by 7 a.m.

In a way, it was the perfect storm. A combination of factors so uncannily timed, we may not see them come together in such a way again for years to come.

Thousands of drivers and many school buses were already on the road Tuesday morning when a sudden onslaught of freezing rain made travel treacherous. Some school superintendents, who had announced school would only be delayed, soon realized cancellation was necessary to protect parents, teachers and students from dangerous, icy roads.

While the National Weather Service and the First Warning Weather team continued to broadcast a Winter Weather Advisory, with the possibility of icing on roadways, the school districts’ initial decision, like those of thousands of commuters, was based on the fact that roads were reported to be only wet, with little significant precipitation falling before 6 a.m.

Patchy freezing rain 4 a.m. Tuesday morning

Patchy freezing rain 4 a.m. Tuesday morning

But then, between 5 a.m. and 7 a.m., the last in a series of upper level impulses combined with moist air aloft, and rapidly formed an area of freezing rain, encompassing most of the Austin metro area, and some surrounding counties. It continued for another two hours.

 

Sudden ice storm envelops Austin metro area by 7 a.m.

Sudden ice storm envelops Austin metro area by 7 a.m.

The sudden precipitation falling through dry air resulted in a phenomenon known as “evaporative cooling,” which dropped the surface temperature from 30º to 28º at ABIA in about an hour, and a little later, to 27º at Camp Mabry. These temperatures are what we call the “magic” numbers–the level at which, over the years, we have observed ice suddenly develops on Austin area bridges and elevated roads when even the lightest drizzle or rain is falling.

Unfortunately, this sequence of events couldn’t have come together at a worse time. Many parents had taken their children to school, or put them on school buses, only to find out moments later school had been canceled. Needless to say, many were very unhappy.

Austin Police responded to more than 270 accidents, some with injuries, though none were reported serious. Four patrol cars in Austin and Williamson County were involved in accidents. The Travis County’s Sheriff’s Department worked more than 80 accidents. Round Rock police reported 70 wrecks. Thousands of motorists were caught in stand-still traffic.

It would be easy to assign blame to those who didn’t heed the Winter Weather Advisory. However, that wouldn’t be fair. If schools closed every time an Advisory was issued, students would be unnecessarily making up snow days into the summer.

Realistically, these decisions have to be based on the best information you have in real time. So, while it was a huge headache for many folks, I think we have to chalk this one up to bad luck, and hope Mother Nature is a little kinder with scheduling next time.

blog comments powered by Disqus