Jump to content

Landspout

From Wikipedia, the free encyclopedia

Landspout
Image
Landspout in Colorado, 2021
Area of occurrenceEvery continent
SeasonAny
EffectWind damage

A landspout is a type of tornado not associated with a rotating mesocyclone. Atmospheric scientist Howard Bluestein coined the term in 1985 because these columns of air resemble weak Florida Keys waterspouts occurring over land. Unlike classic supercell tornadoes, landspouts form during the growth stage of a developing convective cloud as ground-level rotation is pulled upward, making them generally weaker and short-lived.

Characteristics

[edit]

Landspouts are a type of tornado that form during the growth stage of a cumulus congestus or occasionally a cumulonimbus cloud when an updraft stretches boundary-layer vorticity upward and tightens it into a focused vertical axis.[1] Landspouts can also occur due to interactions from outflow boundaries, as they can occasionally cause enhanced convergence and vorticity at the surface. These generally are smaller and weaker than supercell tornadoes and do not form from a mesocyclone or pre-existing rotation in the cloud. Landspouts can form in the flanking line of supercell thunderstorms, following the predominant formation area of landspouts in general within updraft zones without undercutting downdrafts. Because of their lower depth, smaller size, and weaker intensity, landspouts are rarely detected by Doppler weather radar.[1]

Landspouts share a strong resemblance and development process to that of waterspouts, usually taking the form of a translucent and highly laminar helical tube. Landspouts are technically considered tornadoes, as they are in contact with both the ground and a cumuliform cloud. Not all landspouts are visible, and many are first sighted as debris rotating at the surface before eventually condensing.

Orography can influence landspout (and, consequently, supercell) development. A notable example is the propensity for landspout occurrence in the Denver Convergence Vorticity Zone (DCVZ).[2][3]

Life cycle

[edit]
Image
Dying Colorado landspout, 2025

Landspouts originate as ground-level rotation that is pulled upward by a developing parent cloud's updraft. While most landspouts are relatively short-lived (typically just few minutes), rarely some can persist much longer and cause significant damage. They typically progress through distinct stages of formation, maturation, and dissipation. Decay occurs when a nearby downdraft or rain-cooled outflow undercuts the parent cloud's updraft, severing the surface vortex from its low-pressure source. Landspouts can occur individually or form in lines and clusters.[4]

Transition to mesocyclonic tornado

[edit]

Rarely, a landspout may transition into a mesocyclonic tornado if the attendant misocyclone merges into a stronger mesocyclone. A notable example occurred during the 1997 Central Texas tornado outbreak, where a landspout touched down along a surface boundary before merging with a supercell's mesocyclone and rapidly intensifying into a catastrophic F5 tornado.[5]

Damage

[edit]

Most landspouts are relatively weak, not surpassing the EF0 category.[6] However, on rare occasions, they have been observed to reach up to EF2 and EF3 intensity.[7][8]

Examples of such unusually strong landspouts include:

See also

[edit]

References

[edit]
  1. 1 2 Wakimoto, Roger M.; Wilson, James W. (1989). "Non-supercell Tornadoes". Monthly Weather Review. 117 (6): 1113–1140. Bibcode:1989MWRv..117.1113W. doi:10.1175/1520-0493(1989)117<1113:NST>2.0.CO;2.
  2. ↑ Szoke, Edward J. (8 November 2006). The Denver Cyclone and Tornadoes 25 Years later: The Continued Challenge of Predicting Non-supercell Tornadoes. 23rd Conference on Severe Local Storms. St. Louis, MO: American Meteorological Society.
  3. ↑ Szoke, E. J.; Augustine, J. A. (1990). A decade of tornado occurrence associated with a mesoscale flow feature: The Denver Cyclone. 16th Conference on Severe Local Storms. Kananaskis Provincial Park, Alberta, Canada: American Meteorological Society. pp. 554–559.
  4. ↑ Forbes, Gregory S.; Wakimoto, Roger M. (1983). "A Concentrated Outbreak of Tornadoes, Downbursts and Microbursts, and Implications Regarding Vortex Classification". Monthly Weather Review. 111 (1): 220–235. Bibcode:1983MWRv..111..220F. doi:10.1175/1520-0493(1983)111<0220:ACOOTD>2.0.CO;2.
  5. ↑ Adam L. Houston; Robert B. Wilhelmson (1 March 2007). "Observational Analysis of the 27 May 1997 Central Texas Tornadic Event. Part II: Tornadoes" (XML). Monthly Weather Review: 727–735. doi:10.1175/MWR3301.1. Retrieved 28 September 2026.
  6. ↑ "Tornado Facts". Tornadofacts.net. Retrieved 9 August 2024.
  7. ↑ "Storm Spotter Field Guide: Non-supercell Tornadoes". Retrieved 2 September 2025.
  8. 1 2 "Landspout Tornadoes continued..." (PDF). The Dryline — The Official Newsletter of the National Weather Service in Amarillo. José Garcia. Summer 2014. p. 3. Retrieved 2 September 2025.
  9. ↑ "Tornado Archive". Tornadoarchive.com. Retrieved 2 September 2025.
  10. ↑ Purdom, James F. W.; Weaver, John F. (October 1990). "A Satellite Perspective of the June 15, 1988 Tornado Outbreak in Denver, Colorado" (PDF). American Meteorological Society. Archived from the original (PDF) on 7 March 2022. Retrieved 2 September 2025.
  11. ↑ "European Severe Weather Database". European Severe Storms Laboratory. Retrieved 2 September 2025.
  12. ↑ "June 7th, 2021 Weld County tornado". Weather.gov. Retrieved 2 September 2025.
  13. ↑ "Storm Events Database June 7, 2021" (Report). National Centers for Environmental Information. National Centers for Environmental Information. Retrieved 2 September 2025.
  14. ↑ National Weather Service in Grand Junction, Colorado (2025). Utah Event Report: EF2 Tornado (Report). National Centers for Environmental Information. Retrieved 17 December 2025.
  15. ↑ "European Severe Weather Database". European Severe Storms Laboratory. Retrieved 21 February 2026.
[edit]
  • Wikimedia Commons logo Media related to Landspouts at Wikimedia Commons
  • Advanced Spotters' Field Guide
  • Online Tornado FAQ
Retrieved from "https://en.wikipedia.org/w/index.php?title=Landspout&oldid=1381175331"