Hey Andrew,
I live in the heart of "Landspout Alley" about 80 miles northeast of Denver. What I can tell you as far as landspout reporting goes is that there are not very many people out here. Once you get northeast of Hudson( small town about 20 miles northeast of Denver that is fast becoming a suburb) there are only three towns of 5,000 or more people along I-76 all the way to Nebraska. There is a lot of open space (especially in northeastern Weld County, where there is more than 12,000 square miles of land with less than 600 people living on it) People out here tend to ignore landspouts, as they are so common that everyone is used to them and knows that as a whole, they generally don't do much damage. Also, there are very few storm spotters out here, and the general public rarely bothers to report them.
As far as formation, there are several factors which come into play. First, we have a semi-arid climate and rarely have dewpoints above 60 degrees except for near the Kansas border, and then once you cross into Kansas you'll immediately run into much deeper moisture. It seems that the 60 + dewpoints just cannot hurdle the state line. Therefore, without the deep moisture, it is difficult to get the extreme instability required for a typical tornado outbreak you might see even in far western Kansas. CAPE's of 3000 or more are rare anomalies around here. Also, around here we get what we call the "Denver Cyclone." It forms over or just east of the Denver metro area when the eastern plains come under southerly or, more typically, southeasterly flow. It is an orographically induced vortex and can last a good period of time. It often spins off what is called the DCVZ, or Denver Convergence Zone, along which supercells can rapidly erupt under favorable spring or summertime conditions. The storms that form along this convergence zone come under the influence of the converging winds at various heights along the zone, and as they grow and develop landspouts can and often do form. Storms that produce mesocyclonic tornadoes can also form along this boundary, though they are far less common
and the tornadoes are usually much weaker than tornadoes forming from a similar storm under similar conditions 150 miles further east in the Great Plains.
The storms here have a tendency to be high based, most likely because of the lower dewpoints and higher elevation, with the LCL's usually quite high out here, (hmm, wonder if that's why they call it the "High Plains" :lol
which for the most part precludes the formation of any significant tornadoes in eastern CO; that isn't to say we never have significant tornadoes around here, but they are much less frequent here than in western Kansas or Nebraska. Violent tornadoes are almost unheard of. The only one in recent memory was the F4 that plowed through Limon, a small town of about 3,500 souls 100 miles southeast of Denver, 15 years ago on June 6, 1990. I guess it's a blessing and a curse. I can't wait until I get my driver's license January, because that means next spring I can head for the Heartland and catch some real tornadoes (barring another seemingly tornado-less spring and summer like this one was :evil: ) instead of chasing Colorado's weak, oversized, connected-to-the-cloud-base vorticies with an identity crisis(Am I tornado or am I a dust devil?) Oh, I mean "landspouts"; sorry if that wasn't politically correct :roll:
This is what I have learned over the past 15 years growing up in "Landspout Alley."
I hope this explanation was helpful to you.
