Wednesday, April 13, 2011

Severe Threat Thursday Night Into Friday Morning

10 AM Wednesday Update... Thanks to the WeatherNinja for pointing this out with the new data this morning (NAM).  The pattern this spring is for severe weather to ramp up west of the state, move into Arkansas during the overnight with some weakening, then ramp up again once east of central Arkansas.  The latest NAM model really shows that COULD happen again with an enhanced severe weather risk for eastern Arkansas later Friday morning into the afternoon.  Check out the map below.

This is the NAM for early Friday afternoon showing high levels of instability over the eastern portions of the state.  This will be monitored closely over the the next 24-36 hours.    
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We have been following the chance for some severe weather for late Thursday for quite awhile here on the blog and it does appear the storm system is coming together.

Once again, this is coming into central Arkansas in the middle of the night which is much better than the heating of the day.  However, there will still be strong to severe thunderstorms, especially across eastern Oklahoma into western Arkansas late Thursday afternoon and evening.  The Storm Prediction Center has placed portions of the Sooner state in a moderate risk for severe thunderstorms.  Check out the models below.

This is the GFS valid at 1AM Friday.  The surface low is located in Kansas with plenty of moisture surging north into it.  The wind barbs show the direction the wind is coming from.  Notice how they are coming from the southeast across northern Arkansas.  This is the backing of the wind close to the surface low.  This along with strong winds aloft coming out of a different direction can enhance the tornado threat.
The GFS valid Friday at 1 AM shows plenty of instability  for the SW half of the state as the unstable air gets drawn into the low.
This is the EHI (Energy Helicity Index) for the same time period.  This index can help pinpoint where the best chance for tornadoes will exist.  It combines the instability parameters and the amount of spin in the air into one index.  Notice it paints a bullseye at 1 AM in eastern Oklahoma along the dry line.  The threat for severe weather will spread across AR during the overnight.
SPC has most of Arkansas under a slight risk for severe weather with the moderate risk over eastern OK into KS.

2 comments:

Anonymous said...

Thank you for keeping us posted. I love this.

nlrweatherman said...

Is the pattern really going to stay as oklahoma gets tornadoes, arkansas gets nothing bad, then mississippi gets tornadoes? I hate this pattern! we get nothing. will it change? please tell me it will, I remember in the springs of 06 and 07 it didnt. Never had a tornado warning even close to central arkansas.