Sunday morning marks the start of Eastern Standard Time. The sun will set at 4:40 PM on Sunday. I know that's a depressing thing for a lot of people who suffer from varying degrees of Seasonal Affective Disorder. Sure, it's brighter earlier in the day, but the early darkness can really be a downer for some.

The first day of E.S.T. signals the start of a long, dark winter for some, but for me it comes with a sigh of relief - for one reason: the computer models.

The forecasting computer models that we use are all initialized (started) at certain times of day - usually either two or four times a day. These times are 00Z,06Z,12Z,18Z. If you're thinking "what's with the z?", it stands for Zulu. Zulu time is also used for military and aviation purposes.  It is also known as Greenwich Mean Time and Univeral Time.

As we learned in middle school geography, the Prime Meridian runs through Greenwich, England. GMT, Zulu, or Universal time are all based on the current time in Greenwich, England.

The computer models initialize off of current data, some of which is collected by weather balloon launches throughout the world. All of the launches are conducted simultaneously - at 00z and 12z. Depending on where you are in the world, that can mean any hour of the day - local time. For us, during Daylight Saving Time, 00Z=8pm and 12Z=8am. When we switch to Eastern Standard Time (this weekend) those hours shift to 7pm and 7am. This one hour difference means that I get a look at critical computer forecast models earlier.

It allows me an extra hour to receive and decipher the new information, which is critical given the time of year - winter. When that big snow/rain storm is bearing down on us, I'd hate to have to wait until just before, or during, the 11pm newscast to get the latest computer projections. Thanks to the end of Eastern Daylight Time, I don't have to wait for it. I get it all before the 11PM news starts, which, in theory, should help me give a more accurate forecast.

-Fred