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Weather Processes
After understanding the climatology of past weather events, the next step is to understand the relevant processes that create the weather. MAG researchers are examining a variety of different phenomena to better understand how the atmosphere works.
COLD FRONTS
Many scientists consider the structure and dynamics of cold fronts to be well known. Research by MAG meteorologist David Schultz questions some of our commonly held beliefs about cold fronts. For example, some cold fronts are associated with a strong wind shift prior to the frontal passage, rather than accompanying the frontal passage. Schultz has reviewed the circumstances under which such prefrontal wind shifts can occur.
DERECHOS
Thunderstorm complexes sometimes produce widespread severe surface winds, called derechos. Derechos can be extremely hazardous to life and property and can be as destructive as hurricanes in the most extreme cases. Research led by Drs. Michael Coniglio and David Stensrud of NSSL has improved our knowledge of when they occur and the meteorological conditions that favor their development and maintenance (visit Dr. Michael Coniglio's derecho page for more information).
Additionally, NSSL's numerical modeling capability has been used to better understand how derechos, and strong thunderstorm complexes in general, persist for long periods of time. Our understanding of these types of thunderstorm systems was based largely on how the cold thunderstorm outflow winds interact with the winds in the lower atmosphere (3 to 5 kilometers above the ground). Based on the model simulations in this study, it was found that the motion of the systems combined with knowledge of how the winds change with height 5 to 10 kilometers above the ground also plays a significant role in their structure and longevity. Efforts to use these findings to better predict severe thunderstorm complexes are currently underway at the NOAA/Storm Prediction Center.
TORNADOES ASSOCIATED WITH HURRICANES
Nearly every landfalling hurricane produces at least one tornado. Which hurricanes are likely to produce a large number of tornadoes? This is the question that University of Oklahoma graduate student Stephanie Verbout and her advisors (several of whom work at NSSL and MAG) asked. They found that the presence of an upstream trough seemed to be significant in providing deep-layer shear to the environment of the hurricane. Not all such hurricanes with upstream troughs were tornado-outbreak producers. Storms landfalling along the eastern United States were not likely to produce tornadoes outbreaks because the right-front quadrant of the hurricane (the favored quadrant for tornadoes) was offshore.
MAMMATUS CLOUDS
Although mammatus clouds are some of the most photogenic clouds in the atmosphere, they are also some of the most poorly observed clouds. Only a handful of previously published quantitative observations of mammatus clouds exist.
