Friday, April 13, 2012

Stormy Sunday Could Roll Into Monday


It's going to be a busy weekend for severe weather initially across the plains, then Arkansas Sunday afternoon and evening.

The WeatherNinja will travel to Oklahoma Friday and chase this weekend.  He will stream his live video here so check back.  His chase team will start somewhere within the high risk area in northern Oklahoma, but specifics are still to be determined.  I may open the chat room as well so you can interact and watch his chase.

These storms will move into Arkansas, but hopefully in a weakened state since instability will lessen and shear shouldn't be as high either.  The worst from this storm system will be over the plains of Oklahoma and Kansas.  However, I still think there's a strong possibility for a line of storms with wind and hail here in the Natural State.  An isolated tornado can't be ruled out.  The timing of this is in question as well.  The NAM wants to slow it down once it's in Arkansas while the GFS speeds it up.  I'll explain in the maps below.

By 1PM Sunday, the GFS shows an axis of instability through western AR northward.  This will be enough to produce storms, but it's not extreme instability.  Hopefully clouds and rain will limit this potential
By Sunday at 7 PM, the instability is located across the eastern half of the state and are definitely high enough to keep a line of storms strong to severe.
This shows the lifted index and the surface pressure by Monday morning.  The low is over the Great Lakes with the front pushing along the Mississippi River.  This is a faster solution compared to the NAM.
The NAM has the front entering central AR Monday AM at 7.  Any heating ahead of the front could produce more strong to severe storms across the east through Monday morning and afternoon.  Again, this is the slower solution compared to the GFS.  You can see the axis of elevated lifted index levels along and ahead of the front.
The index which combines shear and instability called the EHI shows elevated values late Sunday across western Arkansas.  This means there will be a chance for these storms to not only be severe, but an isolated tornado can't be ruled out.
The NAM simulated radar shows the line of storms pushing into western Arkansas Sunday afternoon around 1 PM.  This line will have the potential to produce wind and hail along with the threat for isolated tornadoes.
The SPC has outlined much of AR under a slight risk for severe weather Sunday.  Again, the worst of this will be over the plains, but we'll have to watch for some rough weather here as well.

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