Welcome to La Nina everyone. It's marked by an early and active severe weather season. I'm not sure if you can call this "early" since March is only about a week away. Last fall, I was thinking this could start in January like the 2008 season in Appleton, Arkansas. Anyway, that doesn't matter now, it's going to get active for sure with two rounds of thunderstorms. One Thursday and another possible Monday.
The main event should occur during the afternoon and evening Thursday as rain and a few thunderstorms will march from west to east across the state. The levels of instability are not very high, but there will be quite a bit of shear. It's also worth noting the model disagreement when it comes to the track of the low. The GFS shows a more southerly track which would limit the northward progression of the warm and potentially unstable sector of the system. The NAM, Euro, and UKMET indicates a track further to the north which would bring a severe weather potential to most of the state. At this point in time, it appears severe thunderstorms and heavy rainfall will be likely, but to what degree will the severity reach? Strong winds look like a good bet and we'll have to watch for the potential for isolated tornadoes as well.
You will be hearing a lot about instability and CAPE values during severe weather season. CAPE stands for Convective Available Potential Energy and is measured in Joules/Kilogram. This event will mostly be in the 0-1000 j/kg range providing for only marginal instability. This could still change as this event is a couple of days away.
Here's a guide from SPC...
0-1000 ( Marginal Instability )
1000-2500 ( Moderate Instability )
2500 - 4000 ( Very Unstable )
4000 + (Extreme Instability )
The main long range models indicate a strong area of low pressure aloft coming into Arkansas next Monday. This too will bring a severe weather potential, but it's too early to get specific with the next feature.
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|Slight risk for sever weather across all of Arkansas from the SPC.|
|The greatest risk extends from Arkansas into far western Kentucky and Tennessee|