Downbursts can be large, called a "macroburst" 2. Therefore, "macrobursts" and "microbursts" are severe conditions of downdrafts.
Cross section of a conceptual vortex ring model of a microburst Caracena, ; All downbursts are characterized by a circulation termed a "vortex ring", a vertically rotating circle of air.
Downdrafts can be dry or wet. Dry downbursts will not necessarily show a solid perturbation from the base of the cloud to the characteristic curl.
Instead, a dry downburst is generally only visible when the vertically descending winds hit the ground and pick up substantial quantities of dust. These types of downbursts are common in Arizona and will be particularly evident during the early portion of the monsoon season when there is still little precipitation associated with thunderstorms. Wet downbursts, on the other hand, have the characteristic precipitation curl tracing out the vortex-ring circulation that surrounds the concentrated downdraft within the rain shaft.
Most wet downbursts will describe a "foot shape" as the strong vertical winds carrying precipitation hit the ground and curl upwards. Gustnadoes are features that seem to combine some of the characteristics of dust devils and tornadoes. In essence, a gustnado is a tornado-like vortex that appears to develop on the ground and extend several hundred feet upward.
These vortices generally develop along the leading edge of an outflow boundary from a thunderstorm cell. Although generally of limited duration, the winds of gustnadoes can be strong enough to cause damage. Gustnadoes are often mis-identified as fires. For example, associated with the photograph below, team members identified a gustnado occurring along an outflow boundary near the town of Guadalupe.
Upon arrival in the Guadalupe area, no evidence of the feature was seen but follow-up discussion with the Guadalupe Fire Department found that the Fire Department had been called out in response to a report of "a downed airplane that caused a huge fire just south of town". They had been unable to find any fire or downed plane and were relieved when we informed them that the feature had been a gustnado.
Dust Devils. A dust devil is a vortex of dust-filled air created by extreme surface heating. Diameters range from 10 feet to greater than feet; their average height is between and feet but can extend to several thousand feet.
They display some characteristics similar to tornadoes: both cyclonic and anticyclonic dust devils have been observed and large dust devils have been observed with accompanying "suction vortices" smaller dust devils rotating around the main vortex. Luckily, severe tornadoes are fairly rare in Arizona. Although we have many of the weather features such as abundant moisture, superadiabatic heating, etc.
In particular, we often during the summer time fail to have a strong jet stream a narrow corridor of very strong winds generally found about 6 miles up in the atmosphere overhead.
A jet stream often acts as a super vacuum creating convergence at the surface as it aids in sucking up the air from the ground. However, tornadoes have occurred in Arizona and will occur in the future.
In particular, during severe thunderstorms particularly in the cold-front produced thunderstorms of the fall we will see what is often termed by the media cold air funnels. A cold air funnel is quite simply a funnel cloud, vortex of spinning air.
If a cold air funnel cloud extends down to the ground, it becomes a tornado. In other words, a cold air funnel is a potential tornado and must be treated as such. A funnel cloud should not be taken lightly as any funnel cloud has the potential to become a tornado. Tornadoes may not move at all Don't risk outrunning it! Of course, watch for flash flooding! A bathroom is generally considered a good safety area given the number of pipes in the walls of the building.
The average start date is July 7 and the average end date is September The monsoon is considered to have started when there are three consecutive days when the dew point averages 55 degrees or higher, according to the National Weather Service.
During the monsoon, humidity rises and temperatures typically drop into the 90s and low s after peaks above prior to the onset of monsoon. A storm during the monsoon can bring severe flooding and deadly flash floods.
Such a storm can dump an inch of rain in one Phoenix neighborhood and leave others dry. Follow Life's Little Mysteries on Twitter llmysteries. Plan outdoor activities to avoid being outside between mid afternoon and mid evening, especially in higher elevations where lightning is more common. If you are outdoors when lightning becomes a danger, find a low spot away from trees, fences and poles.
When indoors, do not touch any wires or plumbing inside a building. Telephone lines and metal pipes can conduct electricity. Unplug appliances not necessary for obtaining weather information. Avoid using corded telephones or any electrical appliance. Use phones ONLY in an emergency. Remember to bring pets indoors.
Lightning and thunder are very scary for pets, and they are likely to panic or even run away to try and escape the storm. If someone is struck by lightning, call immediately. Click here for additional lightning safety information. Weather plays a key role in the growth and vitality of wildfires across the southwest.
Persistent drought conditions and summertime heat waves significantly dry and prime forests for severe wildfires. Shrubs, grasses, and tress become the dry fuels needed to stoke a wildfire once it starts. A long duration of very low relative humidities and gusty winds can lead to rapid fire growth and dangerous conditions for firefighters and the general public in the path of a fast moving wildfire.
As the monsoon arrives an increased threat of lightning comes with it. Lightning, accompanied by little rainfall, start many wildfires each year. However, humans are the number one cause of wildfires due to carelessness or intentional actions. National Weather Service offices predict the weather conditions that may lead to the development and spread of wildfires.
When critical fire weather criteria are expected to be met, the NWS coordinates with all federal, state, county, city and local fire and wildland agencies to plan ahead for potential wildfires. Take action ahead of time by preparing your home against wildfires. Clear the brush at least 30 feet away from your home and time tree branches away from chimneys and electrical lines. Enclose roof eaves and undersides of decks with fire resistant materials. Develop a home evacuation place in case you need to leave in an emergency.
Have two exit routes from your neighborhood, and listen to instructions from public officials. Tornadoes do occur in Arizona.
Unfortunately, many of them here are not detectible by radar because they are either too small, hidden by interfering mountains, or develop from the ground up. While they do not last long, they can occur with little or no warning, and can do considerable damage. If you see a tornado, which stretches from the clouds all the way down to the surface, take the same precautions you would for a severe thunderstorm. Move inside a strong building away from windows. A small, central, interior room like a bathroom is best.
If caught outside or in a vehicle, lie flat in a nearby ditch or depression. Mobile homes, even if tied down, offer little protection from tornadoes, and should be abandoned. Please Contact Us. Please try another search. Multiple locations were found. Please select one of the following:. Location Help. News Headlines. Skywarn Storm Spotter training webinars! This Day in Weather History. Customize Your Weather. Privacy Policy.
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