Why does the NWS Use Zulu Time on Everything?

[Drew.Gardonia]

Ran a quick search on here, found nothing, so I will ask.

Why does the NWS always have to use ZULU time for EVERYTHING (every radar image, every weather statement, satellite scan). We're here in the U.S., the weather occurs here in the US, yet we base everything off the Greenwich Mean Time which is based in England.

Seems odd in my opinion, why not just say what time it really is where we are at?

Does anyone have a logical explanation for this?

 

[Patrick Marsh]

Because the United States is a member of the World Meteorological Organization, which by treaty has agreed upon using the UTC time zone. This ensures data is collected and distributed in a manner that consistent between countries.

As a member of the WMO, the US is obligated under treaties to share meteorological data for free with other WMO governments.


Edit: I should point out that I meant to say, "This ensures data is collected and distributed with times that are consistent between counties." However, my above statement is true, as well, because data is supposed to be shared in a common format (grib2 is the current official format, I believe)

 

[Drew.Gardonia]

thank you Patrick for that explanation, I figured there had to be some "official" reason, but I just wasn't sure what it would be.

 

[Bob Hall]

Operationally it also simplifies things and makes correlating disparate systems/data much easier. The company I work for uses prevailing local time for servers. It is a pain when something goes wrong and you have to start looking at time stamps and sorting out which system is in which data center.

 

[J Tyler]

It IS a pain, having to get in the habit of subtracting 5 hours (or whatever) from whatever time is given. However, I do understand why it is done. Weather is a global event, so you can look at what every station in the world is reporting at 18Z, no matter what time zone they may be in.

 

[rdale]

It's not a big deal after you've been following weather for a while. Vets don't have to compute in their mind what time 18Z is, you just know it.

 

[Jason Foster]

It's not a big deal after you've been following weather for a while. Vets don't have to compute in their mind what time 18Z is, you just know it.

Kinda the same with hams. They tend to be Zulu (UTC, GMT, etc) users as well, especially if you play on HF.

 

[Donovan Gruner]

I set my computer clock on my chase comp to "z" time. After having it like that for a few years, it's natural to me at this point. Not that it's really that hard to figure out, but that was just a little helper for me.

 

[John Wetter]

I always think of it as you use UTC time because then it doesn't matter where you are... You just know what time it is. Otherwise, whose 2pm are we talking about?

 

[Daniel van Os]

It also creates a continuous timescale, regardless of which state you're in and regardless of daylight saving time.

Daniel

 

[Keith Hosman]

I have a watch that has dual timekeeping capabilities, the digital is always on Zulu (UTC) and the analog is local. We (local EMA and Public Safety) log things on a 24 hour clock like the military does, so my analog reads 12/24 hr. I also have a wall clock in both my office and in my shack at the house that keeps both Zulu and Local time as well. Like Jason said for those who operate amateur radio especially HF and do any contesting are already familiar with Zulu time.

I find it easier to relate to Zulu time, it is a constant, no time zones to deal with right now it is 15:13 Zulu time, and no matter where you are on the planet it is 15:13.

 

[Todd Renshaw]

UTC is useful for astronomy too. An astronomical event can be seen in many countries and many time zones at the same exact moment. (Imagine if you had to send a notice that an asteroid was due to pass in front of a certain star. Would you really want to express that for all the different time zones across half the planet?)

Think of Zulu/UTC as the "global" time.

 

[Ben Holcomb]

It can get really confusing with Daylight Savings time. If an area/country does not do DST, they will be in different timezones depending on the time of the year, but always the same UTC offset. It's easy enough to learn 24-hour UTC, just takes some practice. I leave my HAM radio GPS set to UTC so that I have a UTC display and keep the clock in the car radio set to localtime. You can also setup multiple clocks with Windows 7.

I have all of my webservers running as UTC now. It's too much of a pain to figure out where they are when comparing logs.

 

[David Wolfson]

Well, we could keep time the same way most servers actually do internally -- POSIX time. Ah, the joy! If you want an instant headache read this: http://en.wikipedia.org/wiki/Unix_time

 

[Drew.Gardonia]

if you're in central time how do you figure the UTC? is UTC minus 5 hours? or UTC minus 6 hours?