Department of Geological and Atmospheric Sciences

Meteorology 311 - Forecast Contest


Forecast Contest Log In page

Other forecasting links


A forecasting contest will be part of the required coursework for MTEOR 311 this semester. The contest will begin Tuesday, Sept. 20 The contest will involve forecasting the daily Maximum and Minimum Temperature, and categorical amount of Precipitation and Snowfall for Des Moines, IA and a Floater City chosen by the instructor to represent an area where weather conditions are a challenge to forecast.


Forecasts will be made every TUESDAY for the period starting at 06 Z that night and lasting for the next 24 hours. Thus, for Des Moines during standard time, the 24 hour period for which the forecast is made will correspond to midnight-midnight, or the calendar day of Wednesday. The floater city will be roughly similar, although local time may vary by one or two hours.

The floater city will be chosen by roughly 11 am on Tuesday, and posted on the front window of the map room, and will appear on the forecasting web page.


Forecasts will be scored as follows:

  • 1 point is lost for each degree of error on the maximum and minimum temperature forecasts.
  • 4 points is lost for each category of error on precipitation and snowfall forecasts

For precipitation, the following categories apply:

  • 0 = 0.00 - Trace
  • 1 = Trace - .05 inch
  • 2 = .06 - .25 inch
  • 3 = .26 - .50 inch
  • 4 = .51 - 1.00 inch
  • 5 = greater than 1.00 inch

For snowfall, the following categories apply:

  • 0 = 0 - Trace
  • 1 = Trace - 2 inches
  • 2 = 2 - 4 inches
  • 3 = 4 - 8 inches
  • 4 = 8 inches or more

Some categories overlap, especially with snow. With snow, some reports are only given to the nearest inch, and the overlap method is more fair.


As an example of scoring, if I forecast MAX=35, MIN=22, Precip = 2, SNOW =2, and what verified is a MAX of 37, Min of 20, with a trace of precip and trace of snow, I would lose 2 points on the MAX, 2 points on the MIN, 4 points for being one category incorrect on precipitation (trace would be counted as category 1 to minimize error), and 4 more points on snowfall (for the same reason).


Students should enter their forecast by accessing the web site at prior to 7 pm on Tuesday. You can use any machine that has a web browser. You also can get to the site through a link from the ISU Weather Data page ( On the forecast site, you will first have to select the link to Portfolio. The first time you do this (sometime before Sept. 8) you will need to then select "create an account" and give yourself a login and password. It might be easiest to use your ISU Net-id and password so you can remember it better . You may also have to enter a course password, in which case you can use "mt311". Normally, you just need to log in to portfolio, and select the Forecast link at the top of the page. Enter your forecast parameters and click to submit them.

If there are computer problems, or you are unable to get to a computer, you may write your entries on a piece of paper and give it to me, or slip it under my door (Room 3101) before 7 pm. Scoring will be somewhat similar to golf -- the lower the score, the better. Results will be posted on the Internet and in the map room to encourage healthy competition. Grading will be based on participation, but good performance or good improvement over the semester will be considered in final grading for borderline grades.

Weather News

Daily Weather Story

Click the image to see the most recent NWS weather story for central Iowa.

Low on Ice

How does the current sea ice extent compare to the past?

5-Day QPF

Where is it going to rain or snow in the next week? See the five day QPF from HPC.

Drought Monitor

How this outlook impacts the current drought situation? See the latest drought monitor.

Fall 2022