As you know by now the southern plains and especially the western southern plains has been in a drought and while drought is a long term condition it impacts the day to day forecast as well. In other words, climate matters no matter what!
As I write this, weather patterns could be changing or maybe not. I can't predict when this latest drought will end if it ever ends at all. Simply, I don't know and nobody else does either.
So lets talk about how this drought might affect the 2015 southern plains severe weather season. Well lets start off by first establishing that on average our severe weather season here in Oklahoma is roughly March 15 - June 15 give or take a 500 mb trough. Off course severe weather happens anytime of year and anytime of day depending on the weather pattern but usually we have a spike in severe weather during our severe weather season in the Spring. There is another smaller spike in severe weather during the Fall. I'm not really a stat guy, but since 1950 Oklahoma averages 54.9 tornadoes a year. If you take the city of Moore out of the equation then it's significantly lower.
Here's how I think the drought might impact the storm season assuming the drought more or less continues through our severe weather season. However, you all know what happens when you assume. If you don't understand then google the 1970s hit television show the Odd Couple or click here. There's no guarantee on the weather. See my post on predictably unpredictable!
You can make some obvious conclusions right off the bat. Since we are in a drought then there will be less thunderstorms and less thunderstorms means less severe weather, right? Well, yes and no. You see only the western half of Oklahoma is in drought so that logic doesn't fully apply to the entire state of Oklahoma. I think western Oklahoma is going to have less severe weather chances with less rainfall but the central and eastern parts of Oklahoma may actually have increased severe weather opportunities. Hmmm.
Let me try to explain this. Because the southern western high plains has been in an extended drought the dry line could set up more east compared to non drought years. This subtle shift in the average position of the dry line could have an impact on the amount of severe weather experienced in Oklahoma this year. But more importantly, IMO it will likely have an impact on the location for the best chances for severe weather this year!
The dry line is the boundary between hot dry air to the west and warm moist air to the east. The dry line moves and evolves back and fourth depending on weather patterns that dictate our sensible weather. Many times this is the focus of thunderstorm development and when storms develop near the dry line they move east and producer severe weather. So where the dry line sets up often times determines where the most likely chances for severe weather will occur. Off course the general synoptic weather pattern with upper troughs, surface lows and so on comes into play but all things being equal in a drought Spring the dry line mixes out to the east and may very well set up more across central and eastern Oklahoma compared to western Oklahoma. This would increase the chances for severe weather this Spring in central and eastern Oklahoma and perhaps lessen the threat to the west.
However, this is an average forecast!! All I'm saying here is that the dry line on "average" could mix out more east this Spring due to drought and this could increase opportunities for severe weather east and lessen to some degree west. Depending on the over all weather set up obviously there will be rain and severe weather chances out west but on average the dry line might set up more east and this could be a factor this Spring.
That's my take on the 2015 Spring Severe Weather Season. Stay safe folks!