Wind Damage >> Derechos, Tornadoes And Cyclones X

The rain produced by the newer storms reinforces the cold pool, strengthening the inflow of air from the back side of the developing storm complex and encouraging the downward transport of higher momentum air from aloft. These processes can enable the system Derechos, Tornadoes And Cyclones X to attain a nearly steady-state condition. 

At this point, the convective system typically exhibits a pronounced bow shape on radar (see figure below) and satellite, with an area of moderate to occasionally heavy rain located near the center of the cold pool, Derechos, Tornadoes And Cyclones X well behind the arc of intense rain immediately behind the gust front. 

As long as the thermodynamic and kinematic environments support the continued development of new thunderstorm cells in the downwind direction along the advancing gust front --- a process known as downwind or Derechos, Tornadoes And Cyclones X "forward" propagation --- the convective complex will persist, along with the potential for downbursts and microbursts. 

An animated, visible data satellite view of a derecho-producing convective system appears below. This particular event (May 31, 1994) occurred in a relatively dry environment over Utah and western Wyoming. Because of this, Derechos, Tornadoes And Cyclones X there was minimal supplementary cloud cover that tends to obscure the active storm towers of systems occurring in more moist regimes. 

As a result, the case well-illustrates the process of forward propagation along a convective system gust front. As the arc-shaped gust front advances from southwest to northeast across Utah, Derechos, Tornadoes And Cyclones X the rapidly-growing, new updrafts appear as sharply-outlined whitish clumps (cumulus and cumulonimbus clouds). 

These stand in marked contrast to the more fibrous debris clouds (cirrus "anvils") that are left behind as the gust front continues northeastward, Derechos, Tornadoes And Cyclones X undercutting the older updrafts and severing their link to warm, buoyant air. The derecho-producing convective system is therefore seen to be comprised of a series of discrete, downwind-developing, individual storms. 

For more on thunderstorm propagation and Derechos, Tornadoes And Cyclones X derechos, see Derechos and Flash Floods. TYPES OF DERECHOS Two main types of derechos may be distinguished. 

This classification largely is based on the overall organization and behavior of the associated derecho-producing convective system and reflects, Derechos, Tornadoes And Cyclones X in part, the dominant physical processes responsible for the thunderstorms that produce the damaging winds. 

Serial derechos. The type of derecho most often encountered during the spring and fall is called a serial derecho. These are produced by multiple bow echoes embedded in an extensive squall line (typically many hundreds of miles long) that sweeps across a very large area, Derechos, Tornadoes And Cyclones X both wide and long. 

This type of derecho typically is associated with a strong, migratory low pressure system. An example of a serial derecho with a very extensive squall line and embedded smaller scale bow echoes is the one that affected Florida, Cuba, and adjacent parts of the Gulf of Mexico, Derechos, Tornadoes And Cyclones X the Caribbean Sea, and the Atlantic Ocean during the early stages of the "Storm of the Century" on March 12-13, 1993. 

Progressive derechos The second type of derecho is called a progressive derecho. These are associated with a relatively short line of thunderstorms (typically from 40 miles to 250 miles in length) that may at times take the shape of a single bow echo, Derechos, Tornadoes And Cyclones X particularly in the early stages of development. 

In some cases, the width of a progressive derecho and its associated bow echo system remain relatively narrow even though they may travel for Derechos, Tornadoes And Cyclones X hundreds of miles. An example of this type is the "Boundary Waters-Canadian Derecho" that occurred on July 4-5, 1999. 

In other cases, the progressive derecho and associated bow echo system begin relatively small, with a narrow path, Derechos, Tornadoes And Cyclones X but over time grow to exceed 250 miles in width. The line of thunderstorms of a progressive derecho often begins as a single bow echo that evolves into a short squall line, typically with more than one embedded bowing segment. 

Such development occurred with the "I-94 Derecho" over the north central United States on July 19, 1983 (see Fig. 2 in that event's discussion page). Progressive derechos may travel for many hundreds of miles along a path that is relatively narrow compared to those Derechos, Tornadoes And Cyclones X of serial derechos. Often they are associated with an area of weak low pressure at the surface. 

Hybrid systems Occasionally, derechos having characteristics of both serial and progressive events are observed. These events are known as hybrid derechos. For example, Derechos, Tornadoes And Cyclones X the "Southern Great Lakes Derecho of May 30-31, 1998 was attendant to a strong, migrating low pressure system. 

However, the derecho path and the associated bow echo convective system had many characteristics of a progressive derecho. Low dewpoint derechos Most derecho-producing thunderstorm systems originate in and/or Derechos, Tornadoes And Cyclones X move through areas of very moist air. 

For example, nearly all of the cases included in Noteworthy Events occurred with surface dewpoint temperatures at or above 70° Fahrenheit. In contrast, Derechos, Tornadoes And Cyclones X bands of widespread wind-producing storms sometimes occur in environments of very limited moisture, for example, with dewpoints in the 40s or low 50s (°F). 

Such systems are known as low dewpoint derechos. Low dewpoint derechos most often occur between late fall and early spring in association with strong low pressure systems, and Derechos, Tornadoes And Cyclones X are a form of serial derecho. The May 31, 1994 Utah-Wyoming derecho shown in the animated satellite loop in Derecho Development is an example of a low dewpoint event. 

This system produced a 105 mph wind gust at Provo, Utah, where sixteen people were injured, and Derechos, Tornadoes And Cyclones X tore off part of the roof of the Saltair Pavilion on the Great Salt Lake. A wind gust of 140 mph was measured on Camel Back Mountain in nearby Dugway Proving Ground. The derecho occurred in an environment where average surface dewpoints were around 45 °F. 

More information about low dewpoint derechos is available in this study. Derechos are widespread, Derechos, Tornadoes And Cyclones X long-lived windstorms associated with a band of rapidly moving showers or thunderstorms. Coined by Dr. Gustavus Hinrichs in 1888, "derechos", a Spanish word which means "direct" or "straight ahead". 

Although a derecho's strength can produce destruction similar to tornadoes, the damage pattern produced by these events will occur along relatively straight lines. Thus the term, Derechos, Tornadoes And Cyclones X straight-line wind damage. Derechos are produced by a family of downbursts clusters. Downburst clusters have overall lengths of 50 to 60 miles (80 to 100 kilometers).

Asbestos Testing

Asbestos might still be located in many different structural materials and products, in spite of their age. Consequently, the only way to ultimately know is to have samples of the material in question analyzed. Check your local health office for reports on sampling and testing for more   read more..

OSHA Requirements For Crime Scene Cleanup

Fourth, the fact that nursing homes are subject to infection control requirements imposed by the Health Care Financing Administration (HCFA) of the U.S. Department of Health and Human Services under the Medicare and Crime Scene Cleanup OSHA Requirements For Crime Scene Cleanup Medicaid programs and to infection control requirements of states doe  read more..

Trash Clean Up From The Nashville Flood

Nashville flooding, FEMA Disaster No. DR 1909 TN (Source: FEMA) Some contractors, in order to increase their payments under their debris removal contract, will collect ineligible debris, such as debris not located on the right-of-way, and haul it to the collection site for payment. This can happen a  read more..

Hoarding And Housecleaning

There are clouds in the painting, of course. Almost any one of us would have included those clouds, thick with electricity and rainwater. And there is the wheat field, smudged out like an empty palm, orange beneath the storm-stricken sun. Surely, many of us would have insisted on the wheat as well.   read more..

Flood Damage House Hurricane Sandy

Many people have been displaced to shelters. Am I at risk of getting MRSA (Methicillinresistant Staphylococcus aureus)?Outside of healthcare settings such as a hospital, there is little risk of healthy people gettinginfected with MRSA. However, it is important to practice good hygiene. You can prote  read more..

Preventing Child Lead Exposure By Window Replaceme

Preventing Child Lead Exposure by Window Replacement Project Funder: National Institute of Environmental Health Sciences Project Partners: NYU School of Medicine, NYC Health Department, Oneida County Health Department, and local weatherization agencies Project Description: The National Institute of   read more..

Mildew

Bathroom Tip Places that are often or always damp can be hard to maintain completely free of mold. If there's some mold in the shower or elsewhere in the bathroom that seems to reappear, increasing ventilation (running a fan or opening a window) and cleaning more frequently will usually prevent mold  read more..

Tornado

Tornadoes Tornadoes are nature’s most violent storms. Spawned from powerful thunderstorms, Flood Damage Tornado tornadoes can cause fatalities and devastate a neighborhood in seconds. A tornado appears as a rotating, funnel-shaped cloud that extends from a thunderstorm to the ground with whirling winds that can re  read more..

What Is Needed To Be A Crime Scene Technician

Sometimes total electrical isolation is a good thing— and that's the idea behind a power-over-fiber (PoF) communications cable being developed by Sandia engineers. "It's common to isolate communications between systems or devices by using fiber optic cables, but if power is required, Crime Scene Cleanup What Is Needed To Be A Crime Scene Technician   read more..

Electrical Systems In Flood damaged Buildings

Question: Do electrical systems and equipment submerged through flooding have to be replaced? Answer: Floodwaters are not just water; the water may also be contaminated with chemicals, sewage, oil and other debris. When the floodwater is salt water, its corrosive effects are particularly damaging. A  read more..