How forecasts are made and why they are uncertain
Grade 9 Science Worksheet
Circle the best answer.
A forecast gives a 40% chance of rain Saturday and 50% Sunday (model data, independent days). What is the chance of no rain on either day, by Bo's math?
- 50%
- 30%
- 90%
- 10%
A city has 10 forecast spots, each with a 40% chance of rain (model data). About how many spots would you expect to get rain, by Esme's math?
Use the picture in question 1.
- About 4
- About 0.4
- Each of the 10
- About 40
On 50 days with a 20% chance forecast (model data), rain fell on 10. What does that suggest, by Jun's math?
Use the picture in question 1.
- The forecasts were wrong, since it rained
- The forecasts matched: rain fell on 20% of those days
- It rained on 50% of the days
- A 20% chance means rain on 20 days
Read this first
Forecast accuracy (NOAA)
Forecast length About how often right 5 days 90% 7 days 80% 10 days or more about 50% Using the table, how much accuracy is lost going from a 5-day to a 10-day forecast, by Kira's math?
- Zero; accuracy holds
- About 50 percentage points
- About 40 percentage points
- About 10 percentage points
NOAA: models are generally accurate out about four days; after that, run-to-run differences grow. What should a day-8 forecast do, by Milo's reading?
- State the day-8 weather as certain
- Show lower confidence, or a range
- Skip new observations
- Use last year's weather instead
Why does a finer grid show more detail, by Pia's reading (NOAA)?
- Finer grids need less computing
- More grid points cover the same area, so smaller features show
- Fewer points make sharper forecasts
- Grids set the climate normals
NOAA: smaller time steps make models more accurate. What is the trade-off, by Ren's reading?
Use the picture in question 6.
- They skip the starting data
- They need more computations
- They forecast climate instead
- They need less computing
NOAA: the Dallas/Fort Worth normal rainfall is 36.14 inches; one record year got 62.61 inches. How far above normal was that, by Tala's math?
- About 26.47 inches
- About 36.14 inches
- About 98.75 inches
- About 1.73 inches
Why does one record-wet year barely move a 30-year normal, by Zee's reading (NOAA)?
Use the picture in question 8.
- Normals reset each year
- Climate is each day's weather
- The normal averages 30 years, so one year is a small part
- Normals ignore rainfall
A 30-year average is 36.14 inches a year, and one year comes in 26.47 inches above it. About how much does that one year raise the 30-year average, by Ari's math?
Use the picture in question 8.
- About 0.88 inch
- About 0.088 inch
- About 8.8 inches
- About 26.47 inches