Operational Weather Analysis ... An On-Line Book

"Operational Weather Analysis" Exercise

Boundary Challenge

Exercise Objective: The objective of this exercise is to identify surface boundaries on a series of surface charts.


In Chapter 6 a boundary was defined as a curvilinear-discontinuity characterized by cyclonic shear and convergence. Boundaries include features such as fronts, troughs and the edge of outflows from thunderstorm complexes. These boundaries typically separate two types of air, somewhat in the sense of "air mass" differences, but not strickly along the lines of the traditional "air mass" analysis concept. As the definition above indicates, boundaries are quasi-linear areas of convergence and cyclonic vorticity, both of which generally imply a zone of rising air.

Boundaries features include the following. Although not every feature is found with every boundary, the first two are found with all boundaries while the other features depend upon the type of boundary.

  • A cyclonic wind shift along the boundary:
  • Wind shifts that are sometimes abrupt (greater than 60 degrees), and sometimes subtle (less than 30 degrees);
  • A temperature gradient or change perpendicular to the boundary, e.g. front;
  • A moisture gradient or change across the boundary, e.g., dryline;
  • A weather change across the boundaray, e.g. fog on the coolside of a warm front; and
  • Cloud cover or precipitation along boundary.
  • Identifying a boundary on a surfac chart can sometimes be easy and at other times very challenging. This exercise provides examples that cover the spectrum of difficulty. Each exercise provides a surface sectional (main source: weather.rap.ucar.edu) plus one or more additional charts that might aid in identification of one or more boundaries on the surface chart. Your challenge in each exercise is to identify the boundaries on the surface chart.

    After completing your boundary identification, compare your analysis with the answer provided. This answer also describes why the boundaries were placed where they were placed. No effort has been made to explain the implication of these boundaries on the forecast. That would require numerous additonal charts for a thorough analysis of the situation.

    Suggestion: Save the surface chart image to your computer and then print it. This will allow you to thoroughly analyze surface data and more easily locate the boundaries.

    Exercise A (complexity level: 1)

    Exercise B (complexity level: 1-2)

    Exercise C (complexity level: 2)

    Exercise D (complexity level: 2)

    Exercise E (complexity level: 3)

    Exercise F (complexity level: 3)

    Exercise G (complexity level: 3-4)

    Exercise H (complexity level: 3-4)

    Exercise I (complexity level: 4)

    Exercise J (complexity level: 5)

    Return to the Operational Weather Analysis Exercise Page

    last updated on 5/20/2017