Tornado Alley Outbreaks and Severe Weather Worldwide

[Jimmy Deguara]

It seems that the 2006 US storm season would be remembered as the most frustrating for storm chasers.

Consider the following thoughts: in 2001, David Croan and I traversed only 3 states in our chase expedition - the Texas Panhandle revealed its true colours

See http://www.australiasevereweather.com/storm_news/2001/docs/200105-03.htm
http://www.australiasevereweather.com/storm_news/2001/docs/200105-04.htm
http://www.australiasevereweather.com/storm_news/2001/docs/200105-05.htm

In 2002, Matt Piper and I added 2 more states in what we thought was a slightly frustrating year. We enjoyed traversing the traditional states of Kansas, Texas and Oklahoma including the Tecas Panhandle.

In 2003, David Croan and I witnessed a two and half week death ridge. If you missed the first week of record tornado occurrences, then very few opportunities presented themselves. Once again, the states of Nebraska, Colorado, even Arkansas, Missouri, and Illinois were traversed on a chase or two.

More tornadoes associated with this discussion here:

http://www.australiasevereweather.com/tornado.htm

After an early frustrating death ridge, 2004 was one of the best years for tornado chasing - Nebraska dominated. We touched South Dakota, Iowa and even Wyoming for the first time. For the first time we did not even visit the Texas Panhandle - let alone chase the sacred heartland! Approximately 20 tornadoes intercepted in basically 3 weeks.

2005 saw once again a more northern bias to our chasing. Frustration set in with a lack of tornadoes throughout May. June 5 and 7 saved the trip with a tornado in Oklahoma and an LP supercell with tornado in the Badlands of South Dakota. Colorado saw one of the most impressive structured HP supercells progress along highway I-70.

2006? We traversed 15 states to obtain a couple of tornadoes. The states covered or travelled include Texas, Oklahoma, Kansas, Nebraska, South Dakota, North Dakota, New Mexico, Colorado, Wyoming, Montana, Mississipi, Louisianna, Arkansas, Missouri, and Iowa. There were supercells, but the positioning of the jet or lack of it, the lack of deep quality moisture, the persistent ridge and heat wave, and in some cases the less than average lower level wind shear contributed to what is now believed the worst 'storm chasing' season ever.

Current discussion seem to be concerned with shifting patterns in recent years. What are your thoughts? Given that Sydney and other parts of NSW had the worst severe storm season in many years, it raises the question: is this an evolving long term pattern or just a hickup?

Regards,

Jimmy Deguara

[Brad Hannon]

Great post Jimmy!  Comparing the states visited certainly puts 2006 into perspective as far as tornadoes go.  Putting aside any complex meteorological evidence to the contrary that may exist (most likely too complex for me!), I would have to say that I'm leaning towards a statistical hiccup in the patterns rather than a long term shift.  Yes, 2005 and 2006 were disapointing years, and granted there was an extended ridge in 2003 but there simply hasnt been a long enough period of 'poor' years to back up the theory of a long term change.  Bring on USA2007!

[Jimmy Deguara]

Statistically Brad you are correct but bear in mind what Gene Moore suggested to us - Texas seemed to be year after year raking tornadoes particularly early in the season. The general progression is to have tornadoes / severe weather at lower latitudes and then gradually progressing north with increasing temperatures and shift in the upper level jet.

That did not happen this year and not much at all last year. In fact the jet in the past few years has remained well north. One of the reasoning behind eastward dominance of severe weather and especially tornadoes was the drought furtuer in the traditional Tornado Alley" states. Greater heating related to this drought made for higher based storms. The positioning of the systems also cut off the usually deep moist air originating from the southern part of the Gulf of Mexico. All that was transported was recycled air from the eastern states.

Incidently, not much had improved after our trip in mid June.

Regards,

Jimmy Deguara

[Jeff Brislane]

I would say it would have to be a hiccup. But in saying that nobody has enough statistical evidence of the climate going back far enough to really tell. It could be part of a general warming and drying of the atmosphere over tornado alley or maybe not.

Don't forget the dustbowl drought. It was certainly much worse than anything else that has ever been seen and yet the moisture returned after those years.

I tend to think that the USA gets as many devastating years as we do good years tornadically!

[Geoff Thurtell]

I agree that it may just be a hiccup.

As it now appears that I will not be able to afford to go in 2007, I am hoping to see an improvement in 2007 - followed by a bumper tornado alley year in 2008  :D

We do need a large number of years of records to be able to spot any trends. The very obvious thing that I noticed about this year was that the moisture from the Gulf of Mexico was not penetrating into tornado alley for long periods of time. There was a very definite shift in the systems over North America this year.

Geoff

[nzstorm]

Yes, seemed to be a blocking pattern there this year and last which had Tornado Alley in an unfavourable pattern of higher pressure and drier air. 

My gut feeling for 2006 was always for a below average season following on from 2005.  For 2007 you would think the odds are on for an improvement. 

[David C]

How many years in a hiccup? - we are only afforded so many decades to live this dream. I hate wasted years.
 >
Glaciers are retreating and, equally disturbing (!), our backyard 'rainforest' that sustained itself through the 70s and 80s is now barren  - you'd think you are in Schofields in fact. USA chasing has recently been more crap and north than one expects. Storms are quickly becoming an unusual occurance in Sydney. There is a disturbing trend in the opposite direction to what we storm chasers would prefer.

Whether this (ie storm chasing aspects in particular) are the result of a general warming of the earth's atmosphere, a short term fluctuation or a combination of both...who knows.

Looking forward to spring!!

[zacaroo]

Reading Jimmy's reports from 2001 Tornado Alley season sounds great. Alot more reading to do :D. Very good!