This assignment uses your laminated Skew-T diagram and nsharp. Select Ntl from the program menu and then select the nsharp icon. Load the observed sounding for Nashville TN (BNA) for November 11, 1000 UTC, 2002 (select the file /cirp/data/gem/sound/back_data/sound_11_02.gem).
Play around with nsharp until you are comfortable with all its bells and whistles.
Later in the evening, the following took place in Tennessee.
- November 10, 2002 8:30 PM CST
An intense tornado or family of tornadoes cut a swath across Cumberland and Morgan Counties in Tennessee. Four people died
near Crossville in Cumberland County as home were destroyed in several small communities. Mossy Grove, Morgan County, 40
miles west of Knoxville, was devastated. More than half of the two dozen homes were reduced to piles of rubble. At least 7 people
were killed there, and 28 were injured. Two others died near Petros.
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November 10, 2002 8:10 PM CST
A tornado destroyed two mobile home parks, 3 homes and a church north of Manchester, Coffey County, Tennessee. Two people
were killed and 19 were injured.
1. First, review the information on stability and CAPE available at COMET.
2. Using the text information (show text option) plot the surface temperature and dewpoint on your skew-T.
Compute the temperature of a parcel lifted from the surface to 500 mb adiabatically and compute the difference between the parcel's temperature and the environmental temperature at 500 mb. How does this compare to the nsharp value of the lifted index? Repeat using the virtual temperature rather than the actual temperature. Explain any differences. Which temperature should be used to assess stability?
3. Using nsharp, determine the lifting condensation level, the level of free convection, the equilibrium level and temperature of a parcel lifted from the surface to each of these levels.
4. Explain why the CAPE is relatively large in this instance.
5. Assume that the surface temperature increases by 3C. Assuming that nothing else changes, what is the temperature a parcel of air lifted from the surface would be when it reaches 500 mb? What is its lifted index? Compare your answers to those provided by nsharp. Explain any differences.
What is the parcel's equilibrium level and temperature?
6. Assume that as the temperature increases by 3C that the dewpoint also increases by 2C. Repeat the questions in #3.
7. How realistic would you expect it to be to increase the temperature or moisture content in this instance to explain the tornado outbreak? What other explanations might be given for the occurrence of the tornados?