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Rockhounder

Weather (WX) Q & A:

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It's a real photo, Mist, taken in Uruguay.  I have seen similar clouds roll through this area that look like the special effects in "Independence Day".

 

Around here, it is normally a cold front, with the colder, drier air pushing under the warm moist air, pushing it up and forming the cloud.  If you watch closely, it is not really a cloud moving, but new cloud forming and the warm air lifts.  Plus lots of churning at the boundry line.  Usually a very noticeable wind shift  and temperature drop at ground level just before the cloud comes over.  Thunderstorm to follow shortly.

 

You'll see them at the leading edges of "outflow boundaries" too, typically associated with the bigger "supercell" systems.

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Thats a nice arcus roll cloud. Often seen near the coast and associated with sea breezes and with gust fronts as Rocky said.

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Good Job OFG!

Thanks, Rocky.  It is awesome watching those move through here...especially when they are really low and look like  you can almost reach up and touch them

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The velocity of a european swallow. .....carrying a one pound coconut.

Are you implying that coconuts ....migrate?

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How fast does a dust storm travel?  

 

~ Here's what I found out, Holly...

 

The wall of dust, which originated between Phoenix and Tucson, rolled into the Valley just before 7:30 p.m. Tuesday, Ellis said. The mile-high dust storm moved between speeds of 50 and 60 mph and appeared to be nearly 100 miles wide, according to the Weather Service's radar. The dust began to settle by the time it reached Yuma later in the evening.

 

A typical dust storm in Arizona might reach 1,000 feet and travel between 30 and 40 mph, Ellis said.

 

 

Read more: http://www.azcentral.com/community/phoenix/articles/2011/07/06/20110706phoenix-dust-storm-weather-abrk.html#ixzz1SaTxyNoS

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~ OFG...   Do I stay IN my car during a Dust Storm?  Or do I get out and run for it?   :blink:

Best thing to do in a dust storm is to get butt naked, take pictures of yourself with the storm in the background and post them here before the dust storm hits.  That way we will all know what you look like when we are out searching for you.

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Best thing to do in a dust storm is to get butt naked, take pictures of yourself with the storm in the background and post them here before the dust storm hits.  That way we will all know what you look like when we are out searching for you.

~ Ok.... thanks!  :thumbsup: (not sure how that will help, but YOU'RE the expert.)

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~ Ok.... thanks!  :thumbsup: (not sure how that will help, but YOU'RE the expert.)

You see, it also gives us a reference point to begin the search and well as honing our "navigation by the crescent moon" skills...

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Best thing to do in a dust storm is to get butt naked, take pictures of yourself with the storm in the background and post them here before the dust storm hits.  That way we will all know what you look like when we are out searching for you.

  :thumbsup:

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~ Here's what I found out, Holly...

 

The wall of dust, which originated between Phoenix and Tucson, rolled into the Valley just before 7:30 p.m. Tuesday, Ellis said. The mile-high dust storm moved between speeds of 50 and 60 mph and appeared to be nearly 100 miles wide, according to the Weather Service's radar. The dust began to settle by the time it reached Yuma later in the evening.

 

A typical dust storm in Arizona might reach 1,000 feet and travel between 30 and 40 mph, Ellis said.

 

 

Read more: http://www.azcentral.com/community/phoenix/articles/2011/07/06/20110706phoenix-dust-storm-weather-abrk.html#ixzz1SaTxyNoS

 

Good job, Taken!  :yes: 

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Are you implying that coconuts ....migrate?

 

The swallow may fly south with the sun or the house martin or the plover may seek warmer climes in winter, yet these are not strangers to our land?

 

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I think they look awesome!  :woot:

 

I read a book a long, long time ago that had a chapter describing how it felt to be in a dust storm and how the Bedouins knew to tuck their clothing all around them and to hunker down so that the sand wouldn't strip the skin from their bodies.  It was pretty intense reading. 

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Since OFG & Adi called me out on a cloud identification error, I thought I'd post this from NSSL:

 

To tell the difference between wall clouds and shelf or roll clouds, remember a wall cloud 1) suggests inflow and an updraft, 2) maintains its position with respect to rain, and 3) slopes upward away from the precipitation area. In contrast, shelf clouds 1) suggest downdraft and outflow, 2) move away from rain, 3) slope downward away from the precipitation area.

 

 

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The shelf cloud is a low-level horizontal arcus-type accessory cloud that appears to be wedge-shaped as it approaches. It is usually attached to the thunderstorm base and forms along the gust front. The leading edge of the shelf is often smooth and at times layered or terraced. It is most often seen along the leading edge of an approaching line of thunderstorms, accompanied by gusty straight winds as it passes overhead and followed by precipitation. It is an extension of the main cloud, unlike the roll cloud. The underside is concave upward, turbulent, boiling, or wind-torn. Tornadoes rarely occur with the shelf cloud.

 

A Roll cloud is a relatively rare, low-level horizontal, tube-shaped accessory cloud completely detached from the cumulonimbus base, unlike the more common shelf cloud. When present, it is located along the gust front and most frequently observed on the leading edge of a line of thunderstorms, a cold front or line squalls. The roll cloud will appear to be slowly "rolling" about its horizontal axis. Roll clouds are not and do not produce tornadoes.

 

The wall cloud is defined as an isolated cloud lowering attached to the rain free base. The wall cloud is usually to the rear (generally south or southwest) of the visible precipitation area. Sometimes, though, the wall cloud may be to the east or southeast of the precipitation area. This is usually the case with high-precipitation supercells where the precipitation has wrapped around the western edge of the updraft. Wall clouds are usually about two miles in diameter and mark the area of strongest updraft in the storm.

As the storm intensifies, the updraft draws in low-level air from several miles around. Some low-level air is pulled into the updraft from the rain area. This rain-cooled air is very humid; the moisture in the rain cooled air quickly condenses (at a lower altitude than the rain-free base) to form the wall cloud.

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