How forecasts are made and why they are uncertain

Grade 9 Science Worksheet - Challenge Me

Circle the best answer.

1. 1.

   A forecast card reading 40% beside a 60% chance of none. A classmate says a 70% chance of rain that ended dry proves the forecast wrong. Which reply fits NWS, by Esme's reading?

   • Correct; 70% means it must rain
   • Correct; it means rain falls for 70% of the whole day
   • No; 70% leaves a 30% chance of no rain at that spot
   • No; it means rain over 70% of the area
2. 2.

   Each of three days has a 20% chance of rain (model data, independent days). What is the chance of at least one rainy day, by Luz's math?

   • About 48.8%
   • About 51.2%
   • About 60%
   • About 0.8%
4. 3.

   NOAA: the Global Forecast System runs 4 times a day, and each run takes 2 hours. How many hours of computing a day is that, by Milo's math?

   • 2 hours
   • 6 hours
   • 8 hours
   • 48 hours
5. 4.

   Using NOAA's grid rule, a 3 × 3 grid becomes 12 × 12 for the same area. How many times the points must be computed, by Noah's math?

   Use the picture in question 3.

   • 16 times
   • 4 times
   • 8 times
   • 144 times
6. 5.

   Four evidence cards, labeled A to D. Which evidence best shows a forecast system is reliable, by Pia's reading?

   • It rained once when 90% was forecast
   • Over many days, rain falls on about the share of days forecast
   • The model runs on many computers
   • Its 10-day forecasts sound confident when read aloud on television

7. Read this first

   Forecast accuracy (NOAA)

   Forecast length	About how often right
   5 days	90%
   7 days	80%
   10 days or more	about 50%

8. 6.

   Model data: two models agree for days 1 to 4 and split apart after day 5. What does that suggest, by Ren's reading (NOAA)?

   • Confidence drops beyond day 4, so give ranges
   • A new 30-year normal began on day 5
   • Both models are already wrong from the very first day
   • Forecasts improve after day 5
9. 7.

   A town's July normal high is 31 °C, and today's forecast high is 38 °C (model data). Which statement fits, by Tala's reading?

   • Today is forecast 7 °C above normal, and one hot day is weather
   • The July climate is now 38 °C
   • Today is 7 °C below normal
   • The normal must be wrong
10. 8.

    A forecast card reading 40% beside a 60% chance of none. Which summary of chance-of-rain forecasts fits NWS, by Zee's reading?

    • The share of the day that it rains
    • The share of the area that gets rain
    • A promise that rain will fall
    • The chance a spot gets at least 0.01 inch; the rest is the chance of none

11. Forecast accuracy (NOAA)

    Forecast length	About how often right
    5 days	90%
    7 days	80%
    10 days or more	about 50%

12. 9.

    Which summary of forecast limits fits NOAA, by Ari's reading?

    • About 50% right at 5 days and 90% at 10
    • Right each time out to 30 days
    • Equally right at each range
    • About 90% right at 5 days, 80% at 7, and about half at 10 or more
13. 10.

    Which summary of how weather models work fits NOAA, by Bo's reading?

    • Use fewer grid points for more detail
    • Guess at random, then keep the top guess
    • Average the past 30 years and then call that average tomorrow's weather
    • Start from observations, solve the equations in time steps, repeat