Prediction Scheme Project

The aim of this project was to make practical use of our Daily Analysis of Rainfall and Temperature (DART) Study to create plausible, climate-based daily weather predictions. The project had no intended application apart from personal interest, and was only instigated because of boredom during the strict COVID-19 restrictions in 2020.

The result of the week-long investigation and development is a statistical prediction scheme that produces daily predictions of temperature and rain that are based solely on past weather data. The predictions are generated in web-ready form for the full or partial calendar year ahead.

The scheme has desired outcomes that will evaluate its potential application and guide any further development. Commencing June 2020 and continuing indefinitely, the experimental predictions will be verified against the observations to assess the performance of the scheme.

Daily Analysis of Rainfall & Temperature (DART) Study

This study is the foundation of the statistical prediction scheme. For every day of the year this study describes: (1) the past rainfall and frequency, and (2) the past temperature means and extremes. The study is ongoing, just as the volume of daily weather data collected by this PWS is constantly expanding.

Rainfall & Frequency

January | February | March | April | May | June | July | August | September | October | November | December

Temperature Means & Extremes

January | February | March | April | May | June | July | August | September | October | November | December

Desired Outcomes

The future of the scheme, including any further development, depends on how it performs in the context of these ambitious outcomes.

Predictions

Temperature predictions are expressed in whole degrees and represent the mean maximum and minimum temperatures in the DART Study on the given date.

The maximum temperature prediction applies to the 24 hours beginning at 9.00 am on the given date, which conforms to our standard observing practice.

The minimum temperature prediction applies to the 24 hours ending at 9.00 am on the given date, which conforms to our standard observing practice.

Rain predictions are given as a chance and possible rainfall. The prediction applies to the 24 hours ending at 9.00 am on the given date, which conforms to our standard observing practice.

Chance is expressed as a percentage. It compares the number of times that daily rainfall of 0.1 mm or more occurs in the DART Study on the given date, with the total number of daily rainfall observations in the DART Study on the given date.

Possible rainfall is expressed as a range. It normally represents the most common range of rainfall in the DART Study on the given date. In the event that two or more ranges tie for the rank of most common, the higher rainfall range shall be represented. The rainfall ranges are: 0-1 mm (in practical terms 0.1 - 0.9 mm), 1-10 mm (1.0 - 9.9 mm), 10-25 mm (10.0 - 24.9 mm) and 25+ mm (≥ 25.0 mm). These ranges are based on the definitions of our four climate variables under the heading of days of rain.

Warning » These predictions are strictly experimental. They are based solely on the statistical analysis of past weather data and are devoid of any meteorological rationale.

2020

Verification

Verification is an automated four stage process using the scheme's inbuilt verification algorithms. Stage one deals with temperature, the remaining stages deal with rain.

Stage one rounds the predicted and observed maximum and minimum temperatures to the nearest whole degree, and then calculates the difference by subtracting the predicted value from the observed value.

Stage two classifies each rain prediction as either correct or incorrect.

Stage three selects the correct predictions of rain and then further classifies each case according to whether the predicted rainfall range: (1) matches the observed, (2) overestimates the observed, or (3) underestimates the observed.

Stage four selects the occasions when rain was predicted and did not eventuate. The predictions are based on chance and it is therefore reasonable to expect that not all will eventuate, particularly if the chance is low. The verification estimates the number of cases that could reasonably be expected to be dry, and recommends an adjustment to the assessment in stage two.

2020