Other tornado hotspots outside of tornado alley

[Keith Mullen]

maps

The climatology/frequeny map above basically sums it up.

Taking Billy's post one step further, the corridor itself has two very concentrated areas of interest: an area around Maple valley S to the Pierce Co line and N to the Snohomish line, and the other runs from N Vancouver WA to near central Willamette Valley.

Both areas have had F3's and one caused WA to lead the nation in annual Tornado Fatalities in 1972 I believe. April 14, 1972? We had 3 F3 tornadoes on that day in King, Clark, and Spokane Counties if I am not mistaken.

 

[Josh Murfield]

The climatology/frequeny map above basically sums it up.

Taking Billy's post one step further, the corridor itself has two very concentrated areas of interest: an area around Maple valley S to the Pierce Co line and N to the Snohomish line, and the other runs from N Vancouver WA to near central Willamette Valley.

Both areas have had F3's and one caused WA to lead the nation in annual Tornado Fatalities in 1972 I believe. April 14, 1972? We had 3 F3 tornadoes on that day in King, Clark, and Spokane Counties if I am not mistaken.

Very interesting! When I was in high school back in the early 90's my family lived in Oregon- in the Willamette Valley about 80 miles south of Portland, and that area must be just outside of the zone you are referring to (appears to be so according to the map)- in the two years we lived there I never once heard thunder or saw any lightning. But yet other relatives had lived for years up in Seattle and would talk about occasional severe weather, and even getting at least a couple thunderstorms per year, so I had to figure not ALL of the northwest was as quiet weather-wise as the area we were living in.

 

[Rich Thompson]

One reason you may not see so many watches in Indiana is this. A lot of the tornadic storms that occur in Indiana initiate in Iowa or Illiniois and race to the East into Indiana. Most fizzle before they get here but some don't.
Sorry I don't have stats just personal observation. Usually our watches seem to occur because of ongoing storms in those states.Please correct me if I'm wrong anyone. I don't want to give incorrect information.
Melissa

A relatively high fraction of tornadoes (possibly 40-50%) in Indiana seem to be produced by linear convective systems and not discrete supercells. That, combined with them not necessarily occurring during daylight, and you have a tough situation for chasing. Never mind the greater number of trees and more common cloud cover/haze.

 

[Jeff Snyder]

There is a conference preprint from Broyles and Crosbie called [URL="http://www.spc.noaa.gov/publications/broyles/longtrak.pdf"]Evidence of Smaller Tornado Alleys Across the United States Based on a Long Track F3-F5 Tornado Climatology Study from 1880-2003[/url] that has a few contour maps of just what the title of the paper suggests... For example, see the full-page Figure 1 on page 2... I imagine that having a length-based analysis (i.e. 25-mile or longer track lengths) may bias the results to those areas that see a faster mean storm motion, so it would be interesting to me to see also a contour map of long-lived (time-wise) tornadoes (e.g. something like tornadoes with a lifetime longer than 15 minutes). Of course, the usual disclaimers about biasing towards population centers also exists (no damage means it's tough to rate F3 and greater).

 

[GlennMartin]

For the "chaser", while many smaller tornado alleys exist outside the plains and compare quite well in terms of tornado frequency and intensity the greatest opportunity is given by number of tornado days and that is highest in the plains. The road network, terrain and nature of the convection come into play as well of course. My personal favorite area to chase "outside the plains" is the eastern Illinois prarie which extends from parts of central and northern Illinois into northwest Indiana, this area is perfectly flat, few trees and a gridded road network.

 

[ccrosbie]

There is a conference preprint from Broyles and Crosbie called [URL="http://www.spc.noaa.gov/publications/broyles/longtrak.pdf"]Evidence of Smaller Tornado Alleys Across the United States Based on a Long Track F3-F5 Tornado Climatology Study from 1880-2003[/url] that has a few contour maps of just what the title of the paper suggests... For example, see the full-page Figure 1 on page 2... I imagine that having a length-based analysis (i.e. 25-mile or longer track lengths) may bias the results to those areas that see a faster mean storm motion, so it would be interesting to me to see also a contour map of long-lived (time-wise) tornadoes (e.g. something like tornadoes with a lifetime longer than 15 minutes). Of course, the usual disclaimers about biasing towards population centers also exists (no damage means it's tough to rate F3 and greater).

Hi Jeff,

Since I am one of the co-authors of that paper, I thought I should chime in. There does in my opinion exist many "mini" tornado alleys across the United States, based on the research that Chris Brolyes and myself conducted, and that some are related to population density, and others are not. Similar work was done by Tom Grazulis in his Significant Tornado book (his work was the inspiration for our research). In addition to their existence, we believe there is a strong relationship between these alleys and topographical influences (as well as synoptic scale patterns). It is our intention to do a second part of this research towards this theory (once I get done with my M.S).

Also, I agree with Rich that the a large percentage of Indiana tornadoes are associated with QLCS's, and not supercells. Additionally, the stats from our paper show that a majority of Indiana significant tornadoes are early Spring events that are associated with outbreaks (as opposed to later spring/early summer cluster or isolated supercell events).

Interestingly enough, I now live in Central Indiana. One of the "mini" tornado alleys exists from S-E of Indianapolis (population bias is not a factor).

See http://www.crh.noaa.gov/images/ind/IDHS_Indiana_tornado_map.jpg
for that image I am referring to.

I specifically moved to a location that was not in this corridor, and when I got here everyone that lives in that corridor told me accounts of close encounters with tornadoes over the years. Unfortunately, I did move into the hail capitol of the Indianapolis area, proven again as I received 2.5 inch hail at my house 2 weeks ago, and the roof was only 3 years old!

Casey Crosbie

 

[Melissa Jablonski]

For the "chaser", while many smaller tornado alleys exist outside the plains and compare quite well in terms of tornado frequency and intensity the greatest opportunity is given by number of tornado days and that is highest in the plains. The road network, terrain and nature of the convection come into play as well of course. My personal favorite area to chase "outside the plains" is the eastern Illinois prarie which extends from parts of central and northern Illinois into northwest Indiana, this area is perfectly flat, few trees and a gridded road network.

Glenn
I second that. The area you describe is my non plains favorite chase area.
Melissa

 

[Kevin Myatt]

Eastern Arkansas/SE Missouri can be a hot spot for tornadoes early in the season in flat, largely cleared terrain ... one of my 3 or 4 best chases was on Jan. 17, 1999, in NE Arkansas, though March-April-early May tends to be the more conducive time ... problem is river crossings (especially the sparse crossings over the Mississippi headed eastbound) and how quickly the terrain becomes terra incognita headed west into the Ozarks.

 

[Billy Griffin]

Definitely true in regards to tornado intensity in the "little Pacific Northwest alley."
While not as infrequent as one would think, intensity > EF1 is rare. However, as with anywhere, the occasional rogue strong tornado can skew statistics.