This is a preliminary set of rules for Spring 2012 until okayed by the TAs and Professor Hakim.

Introduction

Forecasting is optional and for extra credit.  Students who submit a minimum of 18 forecasts will have extra credit points added to their final as outlined at the bottom of this page. There are 23 weekdays during the period of the forecast competition during which you may submit a forecast. This is Monday through Friday ONLY, including Memorial Day, May 28. Maximum possible extra credit is 10 points added to the final.

You will be entering your forecast for maximum and minimum temperature and precipitation at Seattle-Tacoma Airport.  Observations are taken over a grassy runway, with an elevation of 452 feet above mean sea level.

The time period you are forecasting for is a 24 hour period beginning at local midnight of the day following that on which you make your forecast (as long as the forecast is made prior to the 10PM deadline).  For example, a forecast entered at 8:30 PM (local) on April 24, will be verified against observations made between midnight and 11:59 PM April 25. The maximum temperatures often occurs an hour or two before sunset and the minimum temperature often occurs near dawn.  Remember, however, that fronts and changing weather can result in the maximum and minimum temperatures occurring at any time during the day.  It is possible, for instance, for the maximum temperature to occur at night and for the minimum to be reached at mid-day due to the passage of warm and cold fronts.  This type of occurrence is infrequent in the Pacific Northwest but occurs more often than one might expect in other parts of the nation.

A few days before you begin forecasting (when instructed), you need to sign up for the competition.  When you do this, you will provide your student identification number, a pseudonym (nickname) and a password.  This will allow you to enter forecasts anonymously and prevent other people from entering forecasts for you.  It also allows everyone to check each other's progress without revealing true identities.

In addition to the forecasts of your fellow students, forecasts from the National Weather Service (NWS),  forecasts based on computer models,  the class consensus (average), persistence (today's weather used as tomorrow's forecast) and climatological values will also be entered.  These should provide a benchmark for how you are doing.

The forecasts from computer models are labelled as MOS.  This stands for Model Output Statistics, but you don't need to worry about what that means.  GFS-MOS is based on a global model that runs around 7 PM PDT each night.  We are entering values from the forecast generated the evening before  the day you forecast, so the forecast is usually about 36 hours old for the minimum and 48 hours old for the  maximum temperature.   On average the GFS-MOS should be the worst model forecast. The forecasts from the NWS are from the mid-afternoon update usually issued around 4 pm local time.

Rules

1. Forecasts are for the 24 hour period beginning at midnight and must be entered before 10 PM.  If you enter a forecast after 10 PM, it will be submitted as your forecast for the following forecast day.  The clock on the entry form is used to determine the forecast day.  It updates every minute.
2. The first forecast will be for Tuesday, May 1st and can be made anytime before 10 PM on Monday, April 30th.
3. The last forecast is for Thursday, May 31st (i.e. entered before 10PM on Wednesday, May 30th).
4. You are forecasting maximum and minimum temperature and precipitation for Seattle-Tacoma airport (Station ID is KSEA).
5. Temperature is forecast in degrees Fahrenheit.
6. Precipitation is forecast as None, Trace or Measurable.  "None" means that no rain falls during the forecast period.  "Trace" means that rain fell but there was not enough to measure.  "Measurable" means that measurable precipitation (over 0.01 inches) fell.
7. The rules for snowfall are the same as those for rain; the precipitation is considered as measurable if over 0.01 inches of liquid water equivalent (melted snow) fall.  As a general approximation 1" water equivalent equals 10" snow.
8. You may replace your forecast as many times as you like until the 10 PM cutoff.  Only the last forecast you enter before the deadline will  actually be scored.
9. You may forecast for any days you choose and you may enter more than the required number of forecasts.
10. On days you do not forecast, you will automatically receive the GFS-MOS forecast plus 20 error points.
11. Pseudonyms and passwords should be easy to remember and consist of mixed alphabetic and numeric characters only. Please do not use inappropriate pseudonyms.
12. You are responsible for remembering your own pseudonym and password.  Forgotten passwords will result in a 50 point penalty which will be added to your precipitation score.  If you forget your password, contact your TA and he will remove your password from the file to allow you to enter a new one.

Scoring

The objective is to have the lowest overall score.  Your score will only count toward extra credit if you have entered at least 18 forecasts by the end of the contest.  This means you can skip no more than 5 days of the 23 contest days.

In the beginning, all forecaster's scores appear on a red background.  Once forecasters have entered the required minimum number of forecasts to obtain extra credit on the final (18), their scores appear on a green background.

Submissions are scored as follows:

1. Temperature: 5 points per degree error: (Actual Temperature - Forecast Temperature) X 5, up to a maximum of 100 points per forecast. 
2. Precipitation:
1. Measurable rain when no rain forecast: 20 points
2. No rain when measurable rain forecast: 20 points
3. Trace when no rain or measurable rain forecast: 10 points

Bluesky scores as follows:

    10 points for maximum temperature: (56 - 54) X 5 = 10
    55 points for minimum temperature: (34 - 45) X 5 = 55
    10 points for precipitation.
 

How much extra credit will you receive?

Extra credit will be awarded as the highest of: