User:Penitentes/Fire tornado (draft)

Fire tornado
Fire tornado
	Aerial view of an EF3-strength fire tornado generated by the 2018 Carr Fire in California
Area of occurrence	Observed in North America, Australia
Effect	Wind damage, burning, propagation/intensification of fires

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Fire tornadoes, also referred to as fire-generated tornadic vortices (FGTVs) or pyrotornadoes, are vortices generated by a fire that reach the scale and strength of a traditional tornado.

...

Fire tornadoes are one of many kinds of vortices that appear in fires, varying in size, but are generally a few dozen to a few hundred yards wide.

Few confirmed examples exist, all of them occurring in the 21st century. The mechanism that leads to their formation are not entirely understood, but research suggests they have roots in both fire and cloud processes, making them distinct from both fire whirls (common in wildfires) and traditional tornadoes, which typically form via the mesocyclone of a supercell thunderstorm.

Pyro-tornadogenesis was first scientifically identified following a destructive vortex that formed during a bushfire on the outskirts of Canberra, Australia, in 2003. The vortex was filmed by multiple bystanders at a distance but was not generally accepted as a genuine fire-generated tornado until 2012. Several other examples have been recognized since.

Definitions

The scientific literature contains multiple names for the phenomenon, including "pyrogenetic tornado", "fire-generated tornadic vortex (FGTV)",^[1] and "pyrotornado".^[2]

According to the American Meteorological Society's glossary of meteorology, a tornado is defined as "a rapidly rotating column of air extending vertically from the surface to the base of a cumuliform cloud."^[3]

The terms fire whirl and fire tornado have often been used interchangeably to describe a vortex of any size or duration occurring in a wildfire. Only in recent years have scientists begun to distinguish types of vortices from one another, in particular highlighting the rare cases of actual pyro-tornadogenesis (or tornado formation during/due to a wildfire).

One of the first formal attempts at creating a rigid nomenclature for vortices in fires was in a National Oceanic and Atmospheric Administration (NOAA) technical memorandum from 1978, where National Weather Service (NWS) meteorologist David W. Goens separated fire whirls into four general classes: fire devils (typically 3 to 33 feet in diameter with rotational velocities less than 22 mph), fire whirls (typically 33 to 100 feet, with rotational velocities of 22 to 67 mph), fire tornadoes (typically 100 to 1,000 feet in diameter with rotational velocities up to 90 MPH), and fire storms (1,000 to 10,000 feet in diameter with winds estimated in excess of 110 mph). Goens' classification did not enter general usage,^[4] but attempts have been made in more recent years to suggest a consistent classification scheme.^[2]

Formation

Fire whirls and fire tornadoes both necessarily begin with a fire, the combustion from which heats the atmosphere above it. As that hot air warms it rises, forming a strong updraft.^[5] Updrafts as strong as 130 miles per hour have been found in pyrocumulonimbus clouds, equaling the strength of those found in tornado-producing supercell thunderstorms.^[6] The rising hot air is replaced at its base by cooler air, which generates a horizontal inflow jet, or winds converging from all directions towards the fire and the base of the primary updraft.^[5]

The second ingredient is the presence of wind shear, or air is flowing in different directions adjacent to the inflow winds. The wind shear provides the initial source of rotation. This rotation inhibits the dilution and mixing of air, allowing the column of rising air to act in a chimney-like fashion, strengthening the updraft, inflow winds, and surface combustion.^[5]

These are the basic underlying processes behind the development of all fire-related whirlwinds. Where fire tornadoes diverge from smaller and briefer fire whirls is in their development of a connection to a pyrocumulonimbus cloud. A pyrocumulonimbus cloud is a fire-generated thunderstorm, formed when the water vapor contained in the rising updraft and associated smoke plume rises high enough into the atmosphere to condense into liquid cloud droplets, forming distinctive bright white clouds. The process of condensation releases heat back into the atmosphere (called latent heat release). This is the same process that fuels an ordinary thunderstorm.^[5] Wildfires have long been known to be capable of generating severe convective storms, which in addition to the strong updrafts can also produce lightning and hail, though typically not precipitation.^[7]

The precise manner of the link between fire tornadoes and pyro-convection is unclear. It is currently hypothesized by researchers that the latent heat release in rapid pyrocumulonimbus development reinvigorates the updraft, and the heat release and updraft stretches the column and concentrates its pre-existing rotation (or 'vorticity') in the lower atmosphere, causing it to accelerate in much the same way a figure skater does when they pull their arms in. The involvement of the pyrocumulonimbus cloud in the development of fire tornadoes is what distinguishes those vortices from smaller-scale fire vortices, which concentrate their rotation solely through fire-related processes.^[1]^[8]

possibly need to describe in more depth CRV, too:

A counter-rotating vortex pair is two counter-rotating(one clockwise, one counterclockwise) vortices rotating around one another. This phenomenon caused a death in the El Dorado Fire of 2020 in California.^[9] "Like water flowing around a boulder in a stream, he found, wind is forced to split around the plume of superheated air and ash rising off a wildfire. And just like water flowing around a boulder, “these two eddies develop,” said Lareau, “which we call counterrotating vortices [CRVs]. Between those CRVs there’s this kind of wake—air moving back toward the fire in opposition to what the wind would be doing if the fire wasn’t there.”" from Eos article

Embedded and shedding vortices

University of Nevada Reno scientist Neil P. Lareau and others published a research paper in 2022 that studied fire-generated tornadic vortices in the 2020 Loyalton, Creek, and Bear fires in California. The paper identified two distinct morphologies: some vortices remained embedded within the main fire, and some that detached from the main fire and traveled 'downstream' while remaining pendant from the leaning smoke plume.^[1]

Impacts and hazards

Fire tornadoes are associated with pyrocumulonimbus clouds and their attendant hazards, including cloud-to-ground lightning strikes, extreme darkness as the cloud nullifies solar radiation, ember showers, and winds.^[10]

In Australia, following the 2012 scientific confirmation of the 2003 tornado, the Australian Capital Territory Emergency Services Agency (ACT ESA) intended to raise the issue of fire tornado impacts with the Standards Australia Wind Loadings Committee and the Australian Buildings Code Board. Building codes there specified structural engineering requirements for cyclonic winds, but not for tornadic winds.^[11]

The Carr Fire tornado killed a firefighter, collapsed electrical power transmission towers, and caused other damage on the outskirts of a metropolitan area. [Scientific papers argue they pose a hazard?]

https://www.ncdc.noaa.gov/stormevents/eventdetails.jsp?id=774718

The Carr Fire tornado was estimated to have a peak gas temperature of 2,700 degrees F.

Detection and warning

Fire tornadoes can be detected in much the same manner as regular tornadoes, including the use of Doppler weather radar systems to detect rotation aloft. In the United States, where several fire tornadoes have occurred, some have been surveyed by National Weather Service meteorologists and given ratings on the Enhanced Fujita scale, as in a typical tornado damage survey—the first being the Carr Fire tornado.^[12]^[13]^[14]^[15]

The National Weather Service does not yet have a unified standard for warnings for fire tornadoes: as of 2020, the NWS had not issued specific policy guidance to its 122 forecast offices. Decisions are made on a case-by-case basis by the agency's constituent weather forecast offices (WFOs), with some offices concluding internally that they will not issue tornado warnings for fire tornadoes: one meteorologist with the National Weather Service office in Hanford argued that "We need to get the science down before we start building policy about when we alert the public about such things. We don’t want to overburden emergency services or the public with limited science."^[12]

During the Loyalton Fire, staff at the National Weather Service office in Reno identified rotation within the smoke plume and chose to issue a modified tornado warning for a possible "fire-induced tornado", the first of its kind. Staff there had the advantage of a favorable location for radar detection and prior conversations about what to do in a fire tornado scenario, based on the experience of an incident meteorologist who had previously been assigned to the Carr Fire.^[16]^[17] Several weeks later, during the Creek Fire, the NWS office in Hanford considered—but ultimately decided against—issuing a tornado warning. A warning coordination meteorologist there said the decision was made because they feared making people conflicted about whether to shelter from the tornado or evacuate from the wildfire.^[12]

Tornado warning issued by the National Weather Service in Reno, NV, for the Loyalton Fire

000
WFUS55 KREV 152135
TORREV
CAC035-152230-
/O.NEW.KREV.TO.W.0001.200815T2135Z-200815T2230Z/

BULLETIN - EAS ACTIVATION REQUESTED
Tornado Warning
National Weather Service Reno NV
235 PM PDT Sat Aug 15 2020

The National Weather Service in Reno has issued a

* Tornado Warning for...
  Southeastern Lassen County in northern California...

* Until 330 PM PDT.
* At 228 PM PDT, a pyrocumulonimbus from the Loyalton Wildfire is
  capable of producing a fire induced tornado and outflow winds in
  excess of 60 mph was located south of Chilcoot, and is nearly
  stationary.

  HAZARD...Tornado.

  SOURCE...Radar indicated rotation.

  IMPACT...Extreme fire behavior with strong outflow winds capable
           of downing trees and starting new fires. This is and
           extremely dangerous situation for fire fighters.

* This tornadic pyrocumulonimbus will remain over mainly rural areas
  of southeastern Lassen County in the vicinity of the fire.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

TAKE COVER NOW! Move to a basement or an interior room on the lowest
floor of a sturdy building. Avoid windows. If you are outdoors, in a
mobile home, or in a vehicle, move to the closest substantial shelter
and protect yourself from flying debris.

&&

LAT...LON 3975 12012 3972 12007 3970 12014 3971 12015
      3973 12015
TIME...MOT...LOC 2128Z 240DEG 0KT 3972 12013

TORNADO...RADAR INDICATED
HAIL...<.75IN

$$

WH

List of confirmed fire tornadoes

The following are confirmed examples of fire tornadoes.


Fire	Date	Location	Max wind speed/rating	Path length	Max width	Summary
McIntyres Hut Fire	1/18/2003	Canberra, Australian Capital Territory, Australia	EF2	12 mi (20 km)	490 yd (450 m)	The Canberra vortex was the first to be described as a genuine fire tornado. During the tornado, a fire tanker's trailer was lifted off the ground, and a police car was stripped of its beacons and other attachments and lofted into a storm drain. It also damaged the roofs of houses and snapped softwood pine trees several meters above the ground.^[18]
Carr Fire	7/26/2018	Redding, California, United States	EF3 >143 mph	3,300 ft (0.63 mi; 1.0 km)	333 yd (304 m)	The Carr Fire tornado collapsed steel power transmission towers, uprooted and stripped bark from large oak trees, damaged roofs, lofted vehicles and a metal shipping container, and scoured the ground. It caused four deaths. Three were killed when the roof of a home collapsed, and a firefighter was killed when his vehicle flipped multiple times. Six people were injured.^[13]^[19]^[20]
Loyalton Fire	8/15/2020	Loyalton, California, United States	EF1	0.43 mi (0.69 km)	137 yd (125 m)	The Loyalton Fire produced three anticyclonic tornadoes, which were observed and filmed by bystanders along California State Route 70 and U.S. Route 395. The first tornado snapped and uprooted multiple Jeffrey pine trees in Roberts Canyon..^[21]
			EF1	0.09 mi (0.14 km)	20 yd (18 m)	The second tornado snapped several quaking aspen trees in its short path along the northeast-facing slope of Roberts Canyon.^[22]
			EFU	3.16 mi (5.09 km)	156 yd (143 m)	The third tornado produced by the Loyalton Fire traveled more than three miles (4.8 km), but produced no damage that the National Weather Service could identify among burned sagebrush.^[23]
Creek Fire	9/5/2020	Mammoth Pool Reservoir, California, United States	EF2 115-125 mph	12.02 mi (19.34 km)	50 yd (46 m)	The Creek Fire produced two tornadoes. The first was rated EF2 by a National Weather Service incident meteorologist; it snapped multiple trees two feet (0.6 m) in diameter 20 to 30 feet (6.1 to 9.1 m) above the ground, debarking them and removing branches. The damage occurred just north of Mammoth Pool, inside Wagner Campground and near Chawanakee Joint Elementary School.^[12]^[14]
Creek Fire	9/5/2020	Bass Lake, California, United States	EF1 90-107 mph	1.12 mi (1.80 km)	25 yd (23 m)	The second tornado produced by the Creek Fire, rated EF1, was described by the surveying incident meteorologist as short-lived but strong. The tornado snapped live trees 15 inches (38 cm) in diameter and uprooted others, leaving their root balls completely exposed.^[12]^[15]^[24]
Bootleg Fire	7/18/2021	Fremont–Winema National Forest, Oregon, United States	EFU	N/A	N/A	The National Weather Service confirmed that the Bootleg Fire produced a tornado. The tornado caused extensive tree damage and scoured roads and soil. A professor of atmospheric science at the University of Nevada characterized the vortex's strength as "akin to an EF2-type tornado".^[25]
Downton Lake Fire	8/18/2023	Gun Lake, British Columbia, Canada	EF0			A wildfire-generated tornado developed near the north shore of Gun Lake (at its northeast end near Gold Bridge) at approximately 4:45 a.m. PDT (1145 UTC). The tornado was captured on video and later confirmed by researchers, who noted possible snapped and uprooted trees in the area.^[26]^[27]Cite error: The opening `<ref>` tag is malformed or has a bad name (see the help page).^[28]