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This module contains several objectives on how to use the IST, from starting and stopping the IST, to changing, adding, and deleting data points both on the skew-T and the hodograph.

Objective 1 - Open the IST

1. From the Upper Air pull-down menu load the following four skew-Ts from the US Central cascading menu: Rapid City, SD (KUNR), Minneapolis, MN (KMPX), Lincoln, IL (KILX), and Amarillo, TX (KAMA).

Note: Making a tear-away of the U.S. Central cascading menu, facilitates multiple selections.

2. From the Frames option menu in the Toolbar, set the frame count to two.

3. Step to the latest 12Z data.

4. Over the skew-T chart, but not directly over the plotted sounding, press Mouse Button 3 to open the pop-up menu. From the Interactive Skew-T cascading menu, select KAMA.

The AMA sounding remains and is overlaid with the IST AMA skew-T in a different color that corresponds to the IST Legend. The other skew-Ts are toggled off.

5. With Mouse Button 2, click on the IST Legend to make it editable. Two dialog boxes open and the raw data points for the AMA sounding and hodograph appear.

6. Move the dialog boxes so they do not interfere with your view of the data.

7. Keep this displayed for the next objective.

There are two ways to modify the temperature and dewpoint temperature profiles: interactively with the mouse pointer, or manually by entering data point values. These methods are described in Objectives 2-6.

Objective 2 - Edit the Skew-T Interactively

1. Move the mouse pointer to the 700 mb (or nearest to 700 mb) data point of the temperature profile. The mouse pointer changes from a left-pointing arrow to a right-pointing arrow.

2. Press Mouse Button 1 on the data point and drag the point to the 20 C temperature line and release. The point stays at this new position.

3. To test the premise that the IST assumes constant pressure, try dragging this new data point to the 600 mb level at 20 C. Notice that the point position is corrected back to 700 mb.

4. In the Skew-T Controls Dialog Box, select the PMAX Lifting Method and click the Lift Parcel Menu button to recalculate the thermodynamic parameters. Observe these values.

5. Click the Reset Skew-T menu button in the Skew-T Control Dialog Box. The original data points are restored.

Objective 3 - Add a Data Point to the Skew-T Manually

1. In the Add/Change Point portion of the Skew-T Control Dialog Box, enter the following values: P = 700, T = 20, and Td = -20.

2. Click the Add Point to Skew-T menu button in the Skew-T Control Dialog Box and observe the data points adjust to the new specified locations.

3. In the Skew-T Controls Dialog Box, select the PMAX Lifting Method and click the Lift Parcel menu button to recalculate the thermodynamic parameters. Observe these values.

4. Click the Reset Skew-T menu button in the Skew-T Control Dialog Box. The original data points are restored.

Objective 4 - Add/Remove a Data Point to/from the Skew -T Interactively

1. Move the mouse pointer to the temperature line where there is no data point. The mouse pointer turns into a four-way cross.

2. Click Mouse Button 2 and observe not only the new temperature data point, but the corresponding dewpoint data point that is automatically plotted at the same pressure level.

3. In the Skew-T Controls Dialog Box, select the PMAX Lifting Method and click the Lift Parcel menu button to recalculate the thermodynamic parameters. Observe these values.

4. To remove this same point, position the mouse pointer over the temperature data point added in Step 2 and click Mouse Button 2. The temperature and dewpoint data points are removed from the sounding.

5. Click the Reset Skew-T menu button in the Skew-T Controls Dialog Box. The original data points are restored.

Objective 5 - Edit the Hodograph Interactively

1. Press Mouse Button 3 over the hodograph (but not directly over data points) to open the pop-up menu. Open the Zoom cascading menu and select the 6.3X option.

2. Press Mouse Button 2 to pan the hodograph to the desired viewing position.

3. Move the mouse pointer over a data point on the hodograph. The mouse pointer changes from a left-pointing arrow to a right-pointing arrow.

4. Press Mouse Button 1 over the data point and drag to a new position.

5. In the Skew-T Controls Dialog Box, click the Lift Parcel menu button to calculate the new helicity, storm motion, and other related variables. Observe these new values in the Skew-T Parameters Dialog Box.

6. In the Skew-T Controls Dialog Box, click the Reset Hodo menu button.

Objective 6 - Add/Remove a Point to/from the Hodograph

Remember that you can only add a new data point to the hodograph manually.

1. In the Add/Change Point to Hodograph portion of the Skew-T Controls Dialog Box, type in the pressure, wind direction, and wind speed values in mb, degrees, and knots.

2. Click the Add Point to Hodograph menu button and observe the new data point.

3. In the Skew-T Controls Dialog Box, click the Lift Parcel menu button to calculate the new helicity, storm motion, and other related variables. Observe these new values in the Skew-T Parameters Dialog Box.

4. In the Skew-T Controls Dialog Box, click the Reset Hodo menu button.

Objective 7 - Close the Interactive Skew-T

1. Once you have edited the sounding, from the File pull-down menu of the Skew-T Controls Dialog Box, select the Save As option.

2. In the Save Skew-T Dialog Box, enter a unique file name and press the Save menu button. The unique file can be found using File -> Open.

3. If you want to continue to display the various skew-Ts, but close the IST, open the pop-up menu over the IST Legend and choose the Unload option.

4. Click the Clear button in the Tool Bar to remove the skew-Ts and to close the IST.

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