Sunday, May 12, 2013

Arkansas Tornado History & 2013 So Far


We've made it to the middle of May and our primary severe weather season is almost over.  While severe weather and tornadoes can happen any month of the year, the months of March, April, and May are considered our main severe weather season.  So far this year, Arkansas has had 12 tornadoes.  6 of those occurred in Winter (5 in January and 1 in February) while the other 6 were in Spring (April).  There's more good news so far this year.  We have not had a fatality in the state related to tornadoes, thunderstorms winds, flooding, or lightning.  Let's keep this going!

I want to urge caution though.  Don't ever let your guard down even though we're going into the summer months.  Meteorologist Brian Smith at the National Weather Service office in North Little Rock reminded me one of the worst tornado outbreaks in state history was in JUNE!   On June 5th, 1916, we had 34 tornadoes and 87 fatalities.  This was the biggest outbreak in recorded state history until January 21st, 1999 when 56 tornadoes swept through the state.  According to the tornadoproject.com, at 4PM on the 5th, a tornado killed 25 people and injured 150 on the west and north side of Heber Springs.  There's a discrepancy on the number of injuries that day so I'll have to do some more research on that.   I find it interesting 2 of the biggest outbreaks happened OUTSIDE of the "traditional" severe weather season.  That brings me to my next point.

While we are well under the yearly state tornado average of 33, there's still a lot of time and much can happen.  Remnant tropical systems can bring tornadic activity later in the summer into fall.  Also, during the fall and early winter months, we usually experience an increase in activity as our secondary severe weather season ramps up.  In some years, this has been more active than the spring.

Our somewhat quiet year has been shared all over the country.  While we have had a cool spring so far and some didn't like that, it has kept the potential violence from Mother Nature to a minimum. 

Below are some statistics as well as a look back at that horrible outbreak in 1916


While a lot can change between now and the end of the year, our tornado count is well below average.  2012 was below average as well.  We deserve this considering the violent weather of 2011.

Check out the average number of tornadoes over the past 3 years across the country for each month.  You can really see the spike from March through May.  Also notice the tiny spike in October.  This is most likely due to tropical activity and the secondary severe weather season.  In some years, this spike in tornadoes is much more noticeable.
This is the surface map from June 5th, 1916 early in the morning.  You can see a surface low is analyzed over southwest Oklahoma at 29.40'' of mercury.  A low this far south in June is not typical.  Usually the jet stream (storm track) has retreated well north of this latitude.  In this set-up, Arkansas is exposed to the warm sector of the storm with temperatures well into the 70s at 7AM.
By 7AM the next day, June 6th, 1916, the surface low has moved northeast and strengthened.  This easily explains the violent outbreak of tornadoes that early June day.  The surface low is located near St. Louis and the pressure has dropped to 29.25'' of mercury.

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