Monsoon thunderstorms are convective in nature. By that, we mean that the thunderstorms are powered by intense surface heating. In addition, strong moisture influx into Arizona is also required. It originally was linked to the total amount of water in the atmosphere above the weather station a precipitable water amount of 1", a quantity thought to be necessary for convective thunderstorm activity.
Temperatures needed to produce Tucson's thunderstorms are somewhat lower. The Arizona monsoonal circulation does not produce thunderstorms every day during the months of July-September but rather occurs in a pattern that has "Bursts" and "Breaks".
According to climatologist Andrew Carleton:. In lower levels, during a "burst", there is strong surface heating and strong southerly or southeasterly transport of moisture into Arizona. This creates intense atmospheric destabilization and leads to strong widespread thunderstorm outbreaks.
Our own meteorologists suggest that a break usually occurs when the subtropical ridge re-develops over NW Mexico and drier air spreads into Arizona. The first phase is a series of spotter training sessions presented by National Weather Service personnel and members of the Office of Climatology at Arizona State University. Specific training is given in observing and evaluating visually unique or distinct atmospheric phenomena in the Southwest United States such as dust walls, dust devils, and eddies or vortices associated with down bursts Caracena et al.
Much of this training complements existing severe storm spotter programs such as the Arizona Skywarn Amateur Radio Network. The spotter training uses the materials and follows the type of instruction suggested by the National Weather Service Moller Storm cells in Arizona are generally short-lived.
There are three basic stages of thunderstorm development: the updraft cumulus stage, the mature stage and the dissipating stage. The lifecycle of a thunderstorm cell going through these stages is, on average, about minutes. The first stage of thunderstorm development is the updraft cumulus stage. In this stage, the primary activity within the cell is pronounced vertical uplift. Warm moist air is lifted adiabatically and condenses to form cumulus-type cloud formations.
As the updraft stage continues, the formation of towering cumulus begins. Little or no precipitation occurs during this stage. The second stage of thunderstorm development is the mature stage that is characterized by both updrafts and downdrafts. Downdrafts are associated with air that is pulled downward by precipitation. Normally downdrafts will be found near the leading edge of the thunderstorm cell. The air descending from the thunderstorm will often hit the ground and be forced out ahead of the cell creating a gust front.
The common desert term for such a phenomenon is haboob. Haboob: A lens-shaped dust wall generated from surface outflow see downburst from a mature thunderstorm cell. The name comes from the Arabic word habb , meaning "wind. Their average duration is less than three hours. The average maximum wind velocity is over 30 mph and dust may raise to heights exceeding feet. Localized pockets of intense downdrafts can create severe weather conditions called "downbursts".
A "downburst" is a strong downdraft that induces an outward burst of damaging winds on or near the surface. 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, ; We want to hear from you. AP — A Scottsdale school board president is accused of keeping a dossier on some parents, including photos and personal finances. Scottsdale Unified School District officials announced Friday that the district will hire an outside forensic investigator to see if any school resources were utilized in the creation of Google Drive folders on […] 16 hours ago.
Marshals Service shot and killed a man suspected of murder in another state near Sky Harbor Airport, the agency said Friday. Sweet James Best fall road trips to take on a motorcycle Autumn in Arizona brings the beauty of color-changing leaves and a relief from summer heat. Email Story. Now, the season officially begins on June 15 and ends on September 30 which happens to coincide with great Arizona Staycation rates and Chandler hotel deals for summer. Just for reference: Based on the dew point method, the monsoon would usually start, on average, around July 7 and conclude approximately two months later, soon after Labor Day.
Monsoon storms can produce several hazards, including dust, wind damage, and flooding. If you are driving and see a wall of wind approaching, get to a safe place as soon as possible. This can mean going directly home or to your hotel , if you have the time, or it can mean exiting the freeway, pulling into a parking lot, and waiting out the storm.
If you feel like conditions are too bad to continue driving, slowly pull off the side of the road as far right as you can, turn off your car, turn off your lights, and keep your foot off the brake pedal. Otherwise, drivers might come up behind you and, thinking you are still in motion, rear end your vehicle. Because the rest of the year is so dry, the ground in the Valley has a difficult time absorbing the intense monsoon rains.
Washes fill quickly, and entire streets may even flood. A few years ago, I was impassable for a brief period. What looks like only an inch or two can be much deeper. As little as 6 inches can sweep you off your feet and 24 inches can wash your car off the road. Even a high-clearance vehicle is at risk in just 24 inches.
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