Saturday, April 14, 2012

Chasing In Tornado Alley and Our Sunday Storms

Ninja's "Chase Pod" in tornado alley
I continue to expect a line of storms to affect the state Sunday afternoon and evening.  In my previous blog post, I expressed concern about the front slowing down once it was in Arkansas.  I thought there was the possibility storms could regenerate across southeastern Arkansas Monday.  At one time, there was model support for that idea, but now most agree this line will move rapidly through the state and most of it should come to an end by early Monday morning.

As I have said, the worst of this outbreak will be across the plains of tornado alley.  The storms will fire late Saturday out there and eventually organize into a squall line.  I fully expect those storms to remain organized and march across Arkansas Sunday afternoon and evening.

Here are my concerns... The biggest threat with a line like this will be wind damage.  Some hail may also be possible.  I know many are wondering about tornadoes.  That threat will exist, but it will be a low threat.  We can't rule out an isolated tornado and I'll explain.

If any storms form ahead of the main line, those may be able to rotate.  Also, I'll be watching the winds at the surface carefully.  If they begin to veer more out of the southeast, this COULD enhance the tornado potential.  This creates more spin with height.  Sometimes small, mesoscale waves of low pressure can form along the front which helps promote this backing of the wind.  Like I said, the tornado threat is low, but it can't be ruled out.  The main threat will be high winds and some hail.  Also, heavy rainfall could bring localized flooding.

Check out the maps below for timing...

This is simulated radar from the NAM valid at 4 PM Sunday.  Look at the line of storms moving into central Arkansas.  Some of these could be severe.

By 7 PM, the line is moving through central Arkansas into eastern areas of the state.  Wind and hail will be the main threat, but isolated tornadoes can't be ruled out.
This is the line at 1 AM Monday morning, it shows some weakening and is beginning to push across the Mississippi River.
The Storm Prediction Center has outlined most of Arkansas under a slight risk for severe weather Sunday.
The SPC has most of the state in an area outlined with "30%".  This means there's a 30% of severe weather within 25 miles of any given point.

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