Forecast of the Day • A National Weather Forecasting Contest
Wednesday March 25, 2020
Assignment: Predict the 24 hr precipitation amount (inches) for Hatteras, NC (KHSE)
As a low pressure system moves through the area, widespread rain is expected for Tuesday into Wednesday in most of Virginia and North Carolina. Let's predict Wednesday's 24-hr precipitation amount for Hatteras, North Carolina and see how much they get. Our contest day runs from 0600 UTC (2 am EDT Wednesday morning) to the next 0600 UTC (2 am EDT Thursday morning).
Question: Why do you think that the model forecasts for precipitation amount vary so much in this case, from almost nothing (0.06 inches) to nearly 1 inch? Do you think that, in general, forecasting precipitation amounts is easier or more difficult than forecasting temperatures?
What Happened?
Yes, predicting precipitation amounts is generally more difficult than predicting temperatures. Even in pretty ordinary low pressure systems, there are often bands of heavier precipitation that are difficult for the models and forecasters to detect and predict. And predicting the exact position and timing of convective storms is even harder. The total precipitation for Hatteras turned out to be somewhere in the middle of most of the model forecasts. And remember that we're predicting the amount in inches, and most storms produce only hundredths of an inch in one day. One or two full inches of precip is quite a lot.
| Forecaster | Precip24, inches (error) | Comment | Day Score |
|---|---|---|---|
| OBSERVED | 0.49 | Precip24 FINAL. | |
| 1. T-Dawg15 | 0.5 (0.01) | 2.3 | |
| NAM-MOS-00-DAY01 | 0.54 (0.05) | 2.3 | |
| 2. Josh15 | 0.42 (-0.07) | I think that the forecast model varies for precipitation because different areas humidity and amount of water there at a certain time affect the amount which makes it harder to predict rather then with temperature. | 2.3 |
| GFS-MOS-12-DAY02 | 0.42 (-0.07) | 2.3 | |
| 3. Eavenly15 | 0.6 (0.11) | drizzle...? | 2.3 |
| 4. Keith15 | 0.67 (0.18) | 2.3 | |
| 5. Grace15 | 0.3 (-0.19) | Yes it is definitely harder to estimate the precipitation amount than temps. Rainbow fall amount can very because of air pressure, low or high pressure systems, temperature, amount of water evaporated and condensed into rain, etc. | 2.3 |
| 6. Gus15 | 0.7 (0.21) | 2.3 | |
| 6. Alex15 | 0.7 (0.21) | 2.3 | |
| NAM-MOS-00-DAY00 | 0.78 (0.29) | 2.3 | |
| GFS-MOS-18-DAY01 | 0.78 (0.29) | 2.3 | |
| GFS-MOS-12-DAY01 | 0.78 (0.29) | 2.3 | |
| CLIMATE | 0.2 (-0.29) | NCDC Climate Normals, 1981-2010 | 2.3 |
| GFS-MOS-00-DAY01 | 0.78 (0.29) | 2.3 | |
| GFS-MOS-06-DAY02 | 0.78 (0.29) | 2.3 | |
| NAM-MOS-12-DAY01 | 0.9 (0.41) | 2.3 | |
| GFS-MOS-06-DAY01 | 0.9 (0.41) | 2.3 | |
| GFS-MOS-18-DAY02 | 0.9 (0.41) | 2.3 | |
| NAM-MOS-12-DAY02 | 0.06 (-0.43) | 2.3 | |
| PERSISTENCE | 0.02 (-0.47) | 2.3 | |
| 8. Sara15 | 1 (0.51) | 2.3 | |
| 8. ashleigh15 | 1 (0.51) | 2.3 | |
| 8. Abbygale15 | 1 (0.51) | 2.3 | |
| GFS-MOS-00-DAY00 | 1.08 (0.59) | 2.3 | |
| 11. Lizzie15 | 1.2 (0.71) | 2.3 | |
| 12. Leah15 | 1.5 (1.01) | 2.2 | |
| 12. Joscelyn15 | 1.5 (1.01) | Answer: I think the precipitation varies so much because it's for 2 states. I think predicting precipitation is harder than predicting temperature. | 2.2 |
| 14. Mikayleigh15 | 2 (1.51) | 2.2 | |
| 14. EmilyV15 | 2 (1.51) | 2.2 | |
| 14. Miles15 | 2 (1.51) | 2.2 | |
| 17. Dorothy15 | 2.24 (1.75) | 2.1 | |
| 18. Anna15 | 2.6 (2.11) | 2.1 | |
| 19. Autumn15 | 3 (2.51) | 2.1 | |
| 20. Elizabeth15 | 3.15 (2.66) | 2.1 | |
| 21. Shyann15 | 6 (5.51) | 1.8 | |
| 22. Shelby15 | 7 (6.51) | 1.7 | |
| 22. Jasper15 | 7 (6.51) | more difficult then forecasting temps | 1.7 |
| 24. Hailey15 | 26 (25.51) | 0 | |
| 24. EmilyS15 | 60 (59.51) | 0 |