Dust Storm Shapes. Thunderstorm Outflow METEOROLOGIST JEFF HABY.
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This gravity current in the atmosphere is the front of an outflow of cold air from a thunderstorm. It is about 1000 metres high and advancing at 25 metres per The front of this gravity current can be seen by suspended dust, but usually such fronts in the atmosphere are completely invisible, and their sudden wind changes present a serious hazard to aircraft. The most dangerous form of thunderstorm outflow is called a microburst . This is so small and appears so unexpectedly that it is difficult to give warning of its presence. The very large changes in wind that it can produce may only last for 2 to 4 minutes, but 18 aircraft accidents over the world have been solely attributed to microsbursts. A microburst is surrounded by a ring vortex, spreading along the ground. This sudden changes in wind may be lethal to aircraft approaching, or taking off, at comparatively low speeds Another gravity current of cold air is produced by the sea breeze, a result of the temperature difference between sea and land. As well as producing welcome cool air inland, a sea breeze front is capable of carrying pollution inland from Los Angeles, a distance of 40 miles
In the Sahara there are 2 types of the Haboob. In the south a strong and hot version occurs, creating a common sandstorm. In the north the Haboob is colder and causes less dust storms than in the South.
The Haboob also occurs in the southwest of the US. Especially in the dry states, suchs as Texas and Arizona. The photo above is from Lubbock, Texas. This haboob looks really scary, but fortunately it doesn't last long. However, it canT wreak havoc in those hours.
In July, 2002, this downburst caused a major dust storm near Columbus, N.M. ( Photographed by Len Zgonina)
The gust front, marking the leading edge of a Forward Flank Downdraft, or FFD outflow of an HP supercell is so strong that is picks up dust from the ground. Since the outflow air is cooler, it races along the ground ahead of the storm at 60 MPH-plus. This is sometimes called a "Haboob" in the SW United States. The view is to the west towards Meade, Kansas on May 27, 2001. The supercell core is to the far right. Note the "cold front slope" the cooler dusty air has contrasted against the "cleaner" air ahead of the storm.Chase Log
The Severe Weather map on the Wunderground site shows in blue, the high wind warnings for the drought stricken areas, raising the possibility of more dust storms in the United States, as well. The Green on the right shows the areas that were flooded all winter with the flooding following the Mississippi. The West Nile virus has reached this flooded area and in an ominous example of synchronicity the area was flooded all winter and spring, raising the possibility of the threat of West Nile Virus outbreaks as mosquitoe breeding season begins. Between drought, flooding, and the West Nile Virus, it looks bad year for farmers and for the MidWest of both Canada and the United States...
Greenwood Dust Storm
Kermit Sand Dunes