On This Day 1999- Oklahoma City EF-5 Tornado

Growing up as a kid I was rarely afraid of the weather.  I'd run to the windows to watch big wind take down trees and branches.  I could sit outside in a blizzard for 8 hours at time.  Hurricane Bertha? Yup I was running outside in the pouring rain.  One thing that did make me run to the basement was tornadoes.  Now we never had one in Northbridge but there were tornado watches in May of 1998 (May 31 to be exact) that brought some nasty hail and winds that had me running for cover.  But I still wanted to see a tornado up until May 3, 1999.  

On May 3, 1999 a massive F5 tornado struck Southern Oklahoma City and its surrounding suburbs.  Up until the Tuscaloosa-Birmingham tornado of the April 27. 2011 outbreak  and then the Joplin tornado of May 2011(review coming in a few weeks) this was the only tornado to cause $1 billion in damage on its own.  It was the deadliest tornado since 1979 at the time and showed how vulnerable urban areas are to tornadoes.
ABC News photo of 1999 OKC tornado
At 7 AM local time on May 3 warm humid air was present from Central Texas up through Central Oklahoma into Kansas.  Unlike some of the recent big severe weather outbreaks the threat was initially not judged to be high.  
NWS Norman May 3-4, 1999 tornado outbreak summary 
At the upper levels there was a lot going on.  A board 500 mb trough was moving west.  Embedded in this flow were several shortwaves.   Notice the 130 kt jet streak near Oregon.  As this jet streak dove south towards Arizona the shortwaves in New Mexico and Colorado accelerated into this unstable air mass.  First the 500 mb chart alone with the shortwave circled
5-3-1999 500 mb obs heights temps from NWS Norman event review
Adding in some other levels we see a lot going on in the west.  The purple line shows the 250 mb upper level jet diving through Western Oklahoma and Kansas intersecting the surface dry line which extends from the Dakota's into Texas.  As the shortwave crossed the dry line and the upper level jet into the warm moist air storms were able to explode.  Don't worry if you can't read this graphic- I have my degree and it took me a half hour to realize what is going on in this picture.
Surface and Upper Air Features May 3, 1999 
By 345 PM local time dew points were now 70-75 F over central OK as storms began to fire.
NWS Norman reanalysis 345 PM 5-3-1999
Here is the radar loop of the thunderstorms that day.  The tornado devastated the community of Bridge Creek, OK shortly after 630 PM.  
Norman, OK NWS radar loop 5/3/99
The NWS  issued a tornado emergency around 7 PM for Moore, OK and Southern Oklahoma City.  
NWS Norman tornado emergency 5/3/1999
A total of 40 people died in Oklahoma and there was $1 billion in damage.  Please check out the NWS official page for damage photos and more information about this storm.  I am happy to report I no longer run from tornadoes and in fact will chase them if I am able to.  I have yet to see one.  The fact remains no meteorological event can destroy a community faster than a tornado (earthquakes, tsunamis are natural disasters).

-Zack Green



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