trivial pursuit: international terminal forecast (TAF)

[nick name]

Canceling a flight because of weather can lead to some unusual
pursuits. While getting a weather briefing, I came across the
following snippet which is part of the Fallon (NAS) TAF:

KNFL 2312/2409 VRB06KT 4800 BR VCSH SCT009 SCT060 OVC080 650809 651703
QNH3003INS

Now I must confess that I had a decoded version. Still I was a bit
surprised that "4800" refers to visibility in meters (I knew this but
forgot it). What was even more surprising was the decoding of "650809
651703". I could see no correlation whatsoever. After a brief but
fruitless web search for an explanation (this is *not* a NWS encoding)
I decided to look at "official" FAA guides. This led me to a dead end
with the latest version of AC-0045F, the FAA weather bible.

So, my main question is: where is the FAA sanctioned decoding
algorithm? Or do military/international forecasts not count as a part
of weather briefings? I *was* able to find a document that explained
the above code. It is anything but simple. For those that like a
challenge, decode the above 2 numbers. Answers will appear in next
week's column.

[Scott Skylane]

nick name wrote:
> Canceling a flight because of weather can lead to some unusual
> pursuits. While getting a weather briefing, I came across the
> following snippet which is part of the Fallon (NAS) TAF:
>
> KNFL 2312/2409 VRB06KT 4800 BR VCSH SCT009 SCT060 OVC080 650809 651703
> QNH3003INS
>
> Now I must confess that I had a decoded version. Still I was a bit
> surprised that "4800" refers to visibility in meters (I knew this but
> forgot it). What was even more surprising was the decoding of "650809
> 651703". I could see no correlation whatsoever. After a brief but
> fruitless web search for an explanation (this is *not* a NWS encoding)
> I decided to look at "official" FAA guides. This led me to a dead end
> with the latest version of AC-0045F, the FAA weather bible.
>
> So, my main question is: where is the FAA sanctioned decoding
> algorithm? Or do military/international forecasts not count as a part
> of weather briefings? I *was* able to find a document that explained
> the above code. It is anything but simple. For those that like a
> challenge, decode the above 2 numbers. Answers will appear in next
> week's column.

Shorthand for civil twilight, or thereabouts?

Happy Flying!
Scott Skylane

[nick name]

On Jan 23, 4:08*pm, Scott Skylane > wrote:
> nick name wrote:
> > Canceling a flight because of weather can lead to some unusual
> > pursuits. While getting a weather briefing, I came across the
> > following snippet which is part of the Fallon (NAS) TAF:
>
> > KNFL 2312/2409 VRB06KT 4800 BR VCSH SCT009 SCT060 OVC080 650809 651703
> > QNH3003INS
>
> > Now I must confess that I had a decoded version. Still I was a bit
> > surprised that "4800" refers to visibility in meters (I knew this but
> > forgot it). What was even more surprising was the decoding of "650809
> > 651703". I could see no correlation whatsoever. After a brief but
> > fruitless web search for an explanation (this is *not* a NWS encoding)
> > I decided to look at "official" FAA guides. This led me to a dead end
> > with the latest version of AC-0045F, the FAA weather bible.
>
> > So, my main question is: where is the FAA sanctioned decoding
> > algorithm? Or do military/international forecasts not count as a part
> > of weather briefings? I *was* able to find a document that explained
> > the above code. It is anything but simple. For those that like a
> > challenge, decode the above 2 numbers. Answers will appear in next
> > week's column.
>
> Shorthand for civil twilight, or thereabouts?
>
> Happy Flying!
> Scott Skylane

Hint: 650809 651703
is decoded as:
Icing: Moderate icing in cloud expected at 17000 feet (5181m) AGL
extending to 20000 feet (6096m) AGL
Icing: Moderate icing in cloud expected at 8000 feet (2438m) AGL
extending to 17000 feet (5181m) AGL