Weather Codes and Snow Cover

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Paul C
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Weather Codes and Snow Cover

Post by Paul C » Fri Mar 04, 2016 9:57 pm

I am currently in debate with the Met office over the correct codes for snow, mainly "State of Ground Codes"

I have found the list provided to be vague at best. Its ok if fresh fall of dry snow falls over 1cm, but how do you record what I call a "dusting". Why are there references to "one half of the ground" I can see if you have a fall of snow it can be anything but full cover, unless its melted in a unshaded spot, but that would bring into question your station area, we cant have screen in the shade of a tree etc or building.

Below list are two images - please let me know what State of ground code" you would put and depth of snow.

Thanks
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Carl M
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Re: Weather Codes and Snow Cover

Post by Carl M » Sat Mar 05, 2016 10:04 am

Good question looking at the WOW code its either C10, 11 or 12 for snow on the ground, but not measurable or 0 in the depth.
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Paul C
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Re: Weather Codes and Snow Cover

Post by Paul C » Sun Mar 06, 2016 10:31 am

I am not clear what they are saying at the moment, apart from use code 5 - which I assume means 5 for snowfall. They are clearly very interested in fall of 1cm or higher ( are we all ) as this impacts on travel. I have emailed the same pictures and are waiting for a reply.

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Paul C
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Re: Weather Codes and Snow Cover

Post by Paul C » Mon Mar 07, 2016 8:56 pm

Reply from Met Office

"With the examples you attached they would have been entered as a trace on the old 3208 forms. However as you pointed out there is not an option for this on WOW. I’ll raise this as an issue and see how it goes."

The debate goes on

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Paul C
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Re: Weather Codes and Snow Cover

Post by Paul C » Fri May 27, 2016 8:53 pm

Further from Met office QC department

Snowfall from 0.1cm to 0.4cm is Trace - TR is recordable

0.5cm and upwards is 1cm

Guessing 1.0cm to 1,4cm is 1cm

1.5cm to 2cm is 2cm

They are very keen to have accurate up to date snowfall records.

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Re: Weather Codes and Snow Cover

Post by Andy Woodcock » Fri Sep 02, 2016 3:03 am

Just come across this thread.

I would say that neither of the photos would count as a day with snow lying it's just too thin.

Also I would only assess snow that's on a natural ground surface (grass, soil etc) rather than an artificial surface like wood which has different thermal properties to grass. I don't count snow lying on concrete or the car for the same reason.

It is a real minefield this one as so often in Cumbria we have just a trace of snow lying at 9am from a fleeting overnight shower, when I lived in the Midlands it was always 'all or nothing' which was easier!

To standardise, I have a football pitch at the back of my house and if that is half or more than half covered with snow then it's a day with snow lying, but if it's more green than white than that doesn't count.

Also, I only measure snow to the nearest 1 cm as to be any more accurate is difficult due to the uneven effect of the grass it's lying on!

As winter approaches maybe we could all post some borderline situation snow photos and get a consensus, although I am hoping next winter will be so snowy we will all be recording snow depth by the foot not by the centimetre! Lol

Andy

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