Friday, November 15, 2013

Severe Storms On Sunday

For this post, I am only going to be focusing on the severe weather potential on Sunday, since today and tomorrow will be fairly quiet with warming temps.

I have watched the models converge on an increasing idea of severe weather on Sunday.  A few of the things meteorologists look at to predict severe weather events are things such as wind shear and instability.  Let's dive in. 

WIND SHEAR
This looks impressive on Sunday.  This indicates that Sunday will be a windy day - storms or not, but this high wind shear aloft also means that storms could easily tap into it, and produce damaging winds here at the surface.  This can also aid in the development in tornadoes if these winds are turning enough in direction with height - also known as directional shear for the weather nerds out there.  The map below shows the 500 mb winds for 8pm Sunday evening.  That purple indicates winds over 100 knots blowing above our heads on Sunday!


The European shows a very similar set-up, although it does not indicate wind shear as extreme as the GFS.  

INSTABILITY
This appears to be slightly higher than the Halloween storm only because of timing.  GFS on the left and NAM on the right. Both images are 4pm Sunday.



MOISTURE
This looks impressive for mid-November with 60 degree dewpoints in many areas.  I am just showing the GFS model here.



TORNADO INDEX
One cool thing about the NAM model is that it can give tornado probs unlike other models.  It shows the best tornado potential to our west, but certainly showing a threat here too.



TIMING
It looks like most of the severe weather will be pushing through the region between 4pm and 10pm.  Before the main line pushes through, there may be some super cell storms that could become severe.  Something to watch.  

SPC SEVERE WEATHER OUTLOOK
The SPC has placed much of Indiana in a 30% risk for severe storms.  For SPC, that is a pretty high risk for 3 days out.



MY THOUGHTS:
I have no doubt that there will be some severe weather on Sunday, based on all the parameters we just discussed.  One thing that could hamper the risk slightly is if rain and clouds hold on Sunday - which I think has a decent chance of happening.  This would help keep instability levels in check.  However EVEN if we get no sun or dry time Sunday, the wind shear is high enough to compensate for that, and we would still have a risk for severe weather.  The highest threat Sunday evening is damaging winds without a doubt, with strong winds like that aloft.  I think we have a moderate risk for a few tornadoes.  Lower risks would include hail and flooding.  The Weather Channel gives tornado TOR-CON'S for regions when there is a potential for severe storms.  They are giving Indiana a 4 which means there is a 40% chance of a tornado within a 50 mile radius.  I want to stress I do not think this is a major outbreak like a March 2nd, 2012 event.  However, everyone in Indiana stands a chance for severe weather.  

I will have updates throughout the weekend on my Facebook page.  If you have not "LIKED" it yet on Facebook, you should go ahead and do that.  That way you will get my updates on what to expect.  

Have a great day, and stay safe.  





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