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Pictures from around western Colorado and eastern Utah
What is "Z" Time?

Since weather observations and forecasts are provided around the globe, it is important to understand when each piece of data is valid for. To overcome the problem of numerous time zones, it was internationally agreed upon that weather time stamps would be based on the Prime Meridian, or Greenwich Mean Time (GMT).

Other names for GMT include Universal Time Coordinated (UTC) or "Z" Time.
In the Mountain Time Zone:

Z = MST + 7 hours
Z = MDT + 6 hours
MST = Z - 7 hours
MDT = Z - 6 hours

examples: 11 am MST = 1800Z (6:00 pm GMT)
1800 MDT (6:00 pm) = 0000Z (Midnight the next day GMT)

Map of World Time Zones