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4 Answers

Weather Forecast Time Periods

Asked by: 3447 views ,
General Aviation

I'm confused about how to interpret time periods for weather forecasts. For example, when a forecast says it's a 12 hour forecast does that mean the forecast was made 12 hours prior to the valid time or that the forecast is for a period of time for 12 hours following the valid time? 

In the explanation below, what is meant by the "forecast interval"?

Low altitude Significant Weather charts are issued four times daily and are valid at fixed times: 0000, 0600, 1200, and 1800 UTC. Each 4 panel chart is divided on the left and right into 12 and 24 hour forecast intervals (based on the current ETA model available).

Thanks

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4 Answers



  1. Brian on Oct 24, 2011

    ” For example, when a forecast says it’s a 12 hour forecast does that mean the forecast was made 12 hours prior to the valid time or that the forecast is for a period of time for 12 hours following the valid time? ”
     
    No. It is released at 0000, 0600, etc; as you’re quoted text indicates. Depending on when you view the chart, the most recent 6 hour interval (getting to this word momentarily) will be the time that forecast was made. 
     
    “what is meant by the “forecast interval”?”
     
    Interval just means a space/section of time. In this case a, 12 hour and 24 hour intervals. If it helps, you may ignore the that word in your quoted definition without losing the overall context. I.E. — “Each 4 panel chart is divided on the left and right into 12 and 24 hour forecasts.”

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  2. james r pierrot on Aug 25, 2013

    Interpret this valid time 1200utc20120611

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  3. james r pierrot on Aug 25, 2013

    I have been given a question to interpret a valid time, I do not know this format.

    1200utc20120611?

    I get the 1200Zulu but not the rest

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  4. Mark Kolber on Aug 26, 2013

    1200utc20120611

    Does that help?

    BTW, what chart are they referring to? I’m not aware of any of the “official” charts that current use that format.

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