Mid-Week Severe Thunderstorms

It's the first day of May, and as a warming gift, May is bringing us our next chance for severe weather. There is a couple of rounds possible, both which could hold potential for stronger thunderstorms. We don't expect this to be a large scale event, or widespread over the entire state, but rather isolated to certain areas. There are numerous factors which could elevate the threat, and also diminish it. As usual we have several questions that simply won't be answered until the event actually occurs. We can however do our best in analyzing the data we have and bring you the best possible forecast. Let's dive into it.

• We currently have a pretty significant severe weather event that will occur just to our north and west in Oklahoma and Kansas today (Tuesday) and tomorrow (Wednesday). These storms will remain west of here, and not impact Arkansas for the most part. 
• We have no chances for severe weather today, but Wednesday our chances begin to go up. This will be a late evening threat.
• The question of if storms will even produce Wednesday night is still something we don't know, and likely won't know until Wednesday night. This is due to a capping inversion, or warm air aloft. 
• Wednesday evening will be a wait and see event, the atmosphere certainly looks amplified and conducive for stronger thunderstorms. 
• Thursday is our next chance for any severe thunderstorm development. As a slow moving cold front tracks east thunderstorms could form along the boundary. There are a few factors which could alter this chance as well.
• Prefrontal convection could help inhibit thunderstorms Thursday afternoon from maturing. Models have suggested an initial round of showers prior to any stronger thunderstorm development. As we all know this will help aid in stabilization, thus lowering our chances for severe weather.
• Overall, the threat level is not very high. However, any of these storms could hold a fairly high damaging wind threat. Isolated tornadoes, as with any Spring severe weather occurrence, is certainly possible.  

SPC outlook for Wednesday

The storm prediction center has portions of western and northwest Arkansas under a slight risk of severe storms for Wednesday. Confidence is high that any storms that do develop near our western border will diminish quickly. A marginal risk is included to border the slight risk, this will account for any storms that do progress further east than expected.

With rather warm temperatures and abundant low level moisture the atmosphere will certainly be conducive for thunderstorm development Wednesday evening. CAPE values shown here in the NAM 3km model exceed 2,100 J/kg, which is plenty of instability for thunderstorm development. 

With all of that being said, it wouldn't be right without a couple of kinks thrown in right? You've heard us speak of "capping inversions" or better known as "the cap" before. This simply put is a lid on the atmosphere, a warm layer of air aloft that prevents air parcels from rising. To help put this into more simplistic terms, take a 2-liter bottle of soda and shake it up. If you leave the bottle cap on, nothing happens and everything is fine. However, the moment you unscrew the bottle cap, the coke explodes out of the top causing a huge mess. This is the same exact thing in relation to thunderstorm development. There is a possibility this cap could be removed tomorrow evening, but we simply won't know until tomorrow evening.

Once we make it through Wednesday, it's onto Thursday's thunderstorm chances. The SPC has highlighted areas across western, northwest, and north central Arkansas into a "slight" risk area.

Prior to any severe thunderstorm chances Thursday, we could likely experience pre-frontal showers well ahead of the boundary. This morning convection could ultimately help aid the atmosphere in stabilization. The question remains how much the atmosphere will need to recover due to the rain and cloud cover Thursday morning. At this time, confidence in a larger scale severe weather event is not high.

By Thursday afternoon a large complex of thunderstorms will begin to track east into western Arkansas. These storms will likely be more linear in nature, this could elevate the damaging wind threat along the outflow of the storms. Models have been adamant that these storms do however weaken significantly once they move into western Arkansas, thus the reason for the slim slight risk area. 

Thunderstorms slowly dying off

By Thursday evening the thunderstorms are slowly dying off. While some weaker thunderstorms and heavier rain could be on-going, the threat of severe weather will be lower. Time frame, intensity, and how far east these storms progress is one of our main concerns. Once again, we simply won't know until Thursday. 

Ultimately the threat for Wednesday and Thursday is not extremely high. This being said, do not let your guard down regarding these storms, especially Wednesday evening. Our main concerns for now is damaging winds, a few isolated tornadoes and hail. We will monitor the storms closely and have coverage during both events. Any changes to this forecast will be brought to your attention, stay tuned!

-AW Team

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