As opposed to the previous tasks, this task will require you to estimate the percent of time that a value (i.e. SWE) is expected to be equaled or exceeded using only the observed data.  This type of analysis is considered to be non-parametric (i.e. a fully-parameterized model will not be an outcome) and cannot be used to extrapolate beyond the range of data used in the analysis.  In this case, only observed data will be included in the analysis.  However, the results of hypothetical event simulations could be included within this type of analysis as a way to “extrapolate” beyond the range of observed data.

  • Click Analysis | New | Duration to create a new Duration analysis.
  • Name the analysis “LittleMeadows_Duration”.
  • Select the Linn-LittleMeadows-SWE data set within the Data Set drop down menu.
  • On the General tab:
    • Within the Time Modification Window panel, select both the Start Date and End Date Enter a Start Date of 01Oct1980 and an End Date of 30Sep2018.
    • Within the Duration Period panel, select User-Defined within the Duration period drop down menu and enter the following seasons:
      • 15Oct to 31Mar
      • 01Apr through 15Jul
  • Leave all other options unchanged. The General tab should appear similar to Figure 1.

Figure 1. LittleMeadows_Duration General Tab

  • Click the Compute button at the bottom of the Duration analysis editor. A window informing you that the computations are complete should appear.  Click OK to close this window.

Question 15:  What is the percent of time expected to equal or exceed 50 inches of SWE accumulation within the winter season?  What is the percent of time expected to equal or exceed 50 inches of SWE accumulation within the spring season?

Within the winter season, 50 inches of SWE is expected to be equaled or exceeded approximately 1% while this magnitude of SWE is expected to be equaled or exceeded approximately 2% in the spring


Question 16:  Is the percent of time expected to equal or exceed 10 inches of SWE accumulation within the winter season greater than, equal to, or less than the spring season?

10 inches of SWE accumulation is expected to be equaled or exceeded less often within the spring season than within the winter season.


  • Click OK to close the Duration analysis
  • Click the Save button to save the study.

Continue to Task 6. Perform a Cyclic Analysis of the 3-day Precipitation Time Series.

Download the final project files here: Parametric_Modeling.zip