Iowa Public Television

Home  -  Educators  -  Challenges

  Educator Resources:

Web sites for educators
Elementary videos
Challenge Activities
   -by Subject
   -by Soft Skill
Odyssey Teacher's Guide
Teacher Created Units
School Improvements
Professional Development

Challenge Question Number 1 for Meteorologist #1078

Related Subject(s):
Computer Studies/Data Processing
Earth/Space Sciences
Language Arts
Related Soft Skill(s):
Acting Professionally
Collecting Information
Learning New Ideas
Locating Information
Organizing Information
Using Technology
Understanding Written Information

Describe a typical "challenge" encountered in your work:
One of the most difficult tasks facing a meteorologist during the winter season is forecasting snow amounts. We have to decide whether to issue appropriate Watches, Advisories or Warnings to heighten the public’s awareness of the impending weather situation. Issuance of these products also impacts the community and can affect school and work schedules as well as their associated financial considerations.

Clearly describe what you expect from the students:
You come in during the day shift and must compose tomorrow’s forecast for your location. It has been fairly warm the past few days with highs in the 50s, but a storm is coming which will bring in cooler air with some precipitation. You have access to three computer models and must decide which one to follow for your forecast tomorrow, even though each presents a different scenario. Model A predicts temperatures cold enough for snow with 0.53 inches of liquid precipitation. Model B moves the storm just 50 miles to the north, which would give your location warmer temperatures and rain, with a bit more liquid precipitation -- 0.58 inches. Model C is the same track and temperature forecast as Model A, but forecasts 0.35 inches of liquid precipitation.

Considering the following facts, compose tomorrow’s forecast for your location and issue the appropriate warning or advisory if needed. You can also issue a forecast without an Advisory or Warning, and then brief the afternoon shift that one may need to be issued at night for the next day.
- The ratio of snowfall to liquid precipitation in Iowa is usually around 13 to 1 (1 inch of liquid precipitation = 13 inches of snow)
- Criteria for a Heavy Snow Warning is 6 inches or more.
- Criteria for a Snow Advisory are 3 to 5 inches.

In order to give the teacher some guidance in evaluating the student's project(s); list some tips that may help to assess the student's work:
Although there are no right or wrong answers, the students need to address the following points, all of which need to be considered in forecasting. Even non-weather related issues must be assessed.
- Was the impact of their forecast taken into account? Issuance of a Heavy Snow Warning could close schools and businesses, activate road crews on overtime, and cause other financial or societal consequences. People take action on your forecast even before the precipitation starts. Make sure you forecast the most probable scenario and not necessarily the worst case solution, which can issue unnecessary actions and responses.
- Was snowmelt considered since it’s well above freezing the past few days? This would lower the forecast accumulations somewhat. The exact amount of melting is difficult to predict however since it depends on the amount of solar heating and ground temperature.
- Did the students realize that only a small amount of additional liquid precipitation could have a great impact on forecast snow amounts? Forecast precipitation only varied from 0.35 to 0.53 inches, which doesn’t seem like much, but altered snow amounts from 4.5 to almost 7 inches. This can be especially crucial when minimal amounts can quickly turn into a bigger event. 0.08 inches of liquid or around an inch of snow can become a problem with the addition of less than .2 inches. This changes the forecast to .27 inches of liquid precipitation or 3.5 inches of snow and a needed advisory.
- Large winter storms often encompass several hundred miles and even a slight change of course, in this case 50 miles, can have a dramatic impact on your forecast. Did the students realize that this shift in position from Model A to B, could change the forecast from Heavy Snow Warning to nothing more than a light to moderate rain?
- Did the students weigh the options of issuing a warning during the day, with lower confidence but greater lead-time, versus waiting until the nighttime hours with greater confidence but less lead-time? Remember that issuing after 10:00 PM does little good since this is after the evening news and most people have gone to sleep for the night. You may technically be giving people 8 hours of lead-time if it issued at midnight, but makes little difference if no one hears it.


Contact Us:
Copyright 2009, Iowa Public Television
The School to Careers project is supported by funds from a USDE Star Schools grant.
Enhanced Careers made possible through a generous grant provided by the Alfred P. Sloan Foundation

The views presented on this site do not necessarily reflect those of Iowa Public Television; nor does IPTV endorse the businesses represented. Our mission is to make students aware of a variety of careers with as much objective information as possible.