- 1
Check the model and run
The title shows the model name and the run time in UTC (for example, GFS 12Z). Newer runs use fresher observations.
- 2
Find the forecast hour
The forecast hour (F024, F048...) is how far into the future the map is. Use the slider to step through time.
- 3
Read the color scale
The legend at the bottom explains what each color means. Units change by parameter, so always check it.
- 4
Compare runs
Don't trust a single run. Look at the previous runs and other models to see whether the forecast is consistent.
UTC (Z) to U.S. time zones
Model runs use UTC, also called "Z" or Zulu time. Times shown as Standard / Daylight Saving.
| UTC | Eastern | Central | Mountain | Pacific |
|---|---|---|---|---|
| 00Z | 7 PM / 8 PM | 6 PM / 7 PM | 5 PM / 6 PM | 4 PM / 5 PM |
| 06Z | 1 AM / 2 AM | 12 AM / 1 AM | 11 PM / 12 AM | 10 PM / 11 PM |
| 12Z | 7 AM / 8 AM | 6 AM / 7 AM | 5 AM / 6 AM | 4 AM / 5 AM |
| 18Z | 1 PM / 2 PM | 12 PM / 1 PM | 11 AM / 12 PM | 10 AM / 11 AM |
Example: 12Z = 6 AM Central Standard Time (7 AM during Daylight Saving).