May 192012
 

Saturday, 19 May 2012

 

It’s been a month to the day since I made a post on this blog! And while that’s shameful given it’s already approaching late May, it’s not without reason. The spring has been flying by really fast for me, and that’s mostly because I’ve been working a lot (don’t we all?). But also and more to the point of this blog, I’ve been waiting for the weather pattern to turn active again for severe storms and tornadoes. Well – it appears likely the weather pattern is about to do just that. And barring some unforeseen change, my wife and I will be making the long drive from western PA out to the Great Plains this upcoming week for our annual storm chasing trip!

For anyone that has monitored the weather pattern as of late they’d probably notice the low frequency of tornado reports over the past two to three weeks. Following the tornadoes (one of which I managed to document) in Kansas/Oklahoma back on April 14, there have been very few severe storms setups across the Great Plains. Things did pick up in frequency somewhat during the first week of May, but due to a persistent strong CAP (warm layer above the surface that suppresses t-storm/tornado growth) the severe events that unfolded yielded few tornadoes and rather insignificant supercell storms in general. Honestly, all the setups were marginal and frustrating for any storm chasers out there. You basically had to be in southeast Texas near the Gulf coast to view a tornado so far this month.

(Although, a waterspout did make landfall in Louisiana on May 9. But when a waterspout making landfall is all there is to talk about in the severe weather community in May, the weather pattern is probably not great if you are a storm chaser. Just ‘sayin :) )

Following the largely pathetic severe storm period in early May, a ridge of high pressure developed over the Great Plains and Rockies – making an already crappy pattern even worse! As a result, storm systems and strong jet stream winds (owing to adequate wind shear for supercells and tornadoes) were essentially blocked from reaching the plains during the second week of of May. So needless to say, May of 2012 has thus far been the worst May for storm chasing since 2009 and 2006!

But it appears that the atmosphere is finally recharging and severe storm setups are returning for the last ten days of May extending into early June. But there are two major factors that could cause problems in regards to tornado formation beyond mid-week – the strong CAP and a strong ridge of high pressure that will be returning to the Plains quickly. To combat that, there is a powerful upper level ‘jet’ (strong jet stream winds) over the northern Pacific Ocean that is poised to crash into the western U.S. in just a couple days, with more energy coming behind it later. As this ‘energy’ ejects into the Great Plains there will undoubtedly be severe storm setups from Kansas into Nebraska/South Dakota and perhaps as far south as Oklahoma depending on CAP issues. A couple of these setups could be big tornado producers if enough forcing is present before the ridge rebuilds in earnest.

The details are sketchy and I’m concerned about how quickly the ridge re-builds over the plains later in the week on into Memorial Day weekend. But I’m hoping there will be setups extending into the weekend and early or mid the following week.

All weather talk aside, we have a LOT of driving to do in a couple days.

 

- Jim

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