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Sky Clear and Rain?

Posted by on June 25, 2008 1 Comments Category : Flight Instructor Blog Tags : ,

Funny story for you with humor that only a pilot may understand. I was checking the ASOS at my home airport on the way in tonight and I heard something interesting on the radio:

Automated weather, time 2156 zulu, winds 290 at 9, visibility 10, sky clear, light rain, temperature 22, dewpoint 16, altimeter 30.22

Sky Clear and Rain? I’m confused. I’m not sure where the rain came from? I sure didn’t see any. Now here is the really funny coincidence, as I was listening to the radio on the way home, Creedence Clearwater Revival came on singing, “Have you ever seen the rain?” Now if you aren’t familiar with the lyrics, let me quote the chorus for you:

I want to know, have you ever seen the rain?
I want to know, have you ever seen the rain?
Comin down on a sunny day?

No, CCR, I haven’t seen the rain come down on a sunny day, but it sure wasn’t for the lack of trying.

Now, to turn this into an educational experience, I’m going to add a quick lesson. How do you seriously know when an ASOS might be reporting inaccurate or corrupted data? You can look for a “$” sign at the end of the METAR report. Here’s an example:

260256Z AUTO 19007KT 8SM FEW080 22/19 A3002 RMK AO2 56010 T02220194 LTG DSNT NW-NE SLP158 $

You know from the $ sign at the end of the report that maintenance is needed on the weather station system making this report. That is the station’s way of saying, “I’m in need of some attention.” You don’t know what is broke but you know that something may be inaccurate. I would recommend trying to find another surface observation in the area and compare it to the other to make sure they are reporting somewhat similar weather.

Fly Safe.

1 Comment

  1. Chris on Jun 30, 2009

    Automated stations only report clouds below 12,000 feet. (Their METARs include CLR instead of SKC to indicate this.) With clouds at, say, 14,000 feet, a correct report of “…sky clear below one two thousand, light rain…” is certainly possible.

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