[Misc] The Award-winning official "More Snow Tomorrow?" Thread [2024-25 Season]

[Woodchip]

I was out walking last night (in the Beckenham / Sydenham area) and it was bitterly cold. When the wind blew, my face felt like it was being sliced with tiny knives. I was surprised that there's no hint of frost though, and no icy windscreens. Is this usual?

Because of the low humidity the dew point is low (meaning that it needs to be colder before dew forms). Frozen dew is what makes windscreens and pavements/roads white.

That's the way I understand it anyway.

Sent by the power of squirrel poo

 

[Papa Lazarou]

I was out walking last night (in the Beckenham / Sydenham area) and it was bitterly cold. When the wind blew, my face felt like it was being sliced with tiny knives. I was surprised that there's no hint of frost though, and no icy windscreens. Is this usual?

The lack of actual frost is because the air is very dry. This has the effect of lowering the dew point of the air (the temp at which moisture condenses out). So, at the moment we have an airmass over us with dew points temps of -8C to -9C, so unless the air gets to that temp there will be very little actual frost.

 

[Papa Lazarou]

Because of the low humidity the dew point is low (meaning that it needs to be colder before dew forms). Frozen dew is what makes windscreens and pavements/roads white.

That's the way I understand it anyway.

Sent by the power of squirrel poo

There is a difference between frozen dew and frost, but the process by which they are formed is the same

 

[Notters]

This is due to low dew points, basically the air is VERY dry and so there is no moisture in the air to create frost.

Also the wind will make it sublimate/evaporate faster than it can condense/settle.

 

[mlg57]

Yes it's pretty much the same up here in Newport Pagnell, we have -4, frozen bird baths and a light frost on the front of our cars (very easy to scrape) but none on the side and back windows, and no frost on the grass or pavements whatsoever.

 

[Papa Lazarou]

I suspect the Met Office will finally issue warnings for the possible snow Sat night at luchtime today....

They will appear here:

Met Office: London South East England: severe weather warnings

I'd go for Yellow warnings for all of Sussex - we shall see. The details could paint a potentially very snowy picture.

 

[Estonian Seagull]

It was -24 degrees walking to work this morning. Your nasal hairs freeze as soon as you get outside and then thaw out once you get into the warm office building. Nice....

 

[Woodchip]

There is a difference between frozen dew and frost, but the process by which they are formed is the same

Close enough for laymen. lol

Sent by the power of squirrel poo

 

[leigull]

What affect does the humidity or dew point have on the possibility of it snowing, if any?

 

[Papa Lazarou]

Significant Snow This Weekend - Latest Weather News - Netweather.tv Hope the link works

 

[Papa Lazarou]

What affect does the humidity or dew point have on the possibility of it snowing, if any?

Dry air contains less moisture, so it takes more to create instability/clouds/snow. You rarely get snow from within a dry / cold airmass, as it tends to be stable. (which is where the illusion that "It's too cold to snow" comes from).

What happens, and will hopefully this weekend is that a much moister airmass bumps into the cold air, and as you usually get a warm front first, which tends to lean forwards from the ground, you get moist air aloft with the cold drier air below.... which gives snow or sometimes freezing rain.

 

[Fungus]

It was -24 degrees walking to work this morning. Your nasal hairs freeze as soon as you get outside and then thaw out once you get into the warm office building. Nice....

If you blow your nose, do all the hairs snap off?

 

[Kalimantan Gull]

Sounds like you'll be lucky in sussex. What about us in devon, will the warm front win out down here or can we get snow?

 

[Spanish Seagull]

Just been sent home from work here in Barcelona.....We have all of 1/2 inch of wet snow

 

[fleet]

I am planning to fly in Sat am watch the match and fly out of LHR Sunday morning back to America. I have to get back for Monday. SO the big question, will the snow mean I can't get back? If so I have to stay here and miss the match which would be very sad indeed.

 

[leigull]

Dry air contains less moisture, so it takes more to create instability/clouds/snow. You rarely get snow from within a dry / cold airmass, as it tends to be stable. (which is where the illusion that "It's too cold to snow" comes from).

What happens, and will hopefully this weekend is that a much moister airmass bumps into the cold air, and as you usually get a warm front first, which tends to lean forwards from the ground, you get moist air aloft with the cold drier air below.... which gives snow or sometimes freezing rain.

Thank you Papa L

 

[Papa Lazarou]

I am planning to fly in Sat am watch the match and fly out of LHR Sunday morning back to America. I have to get back for Monday. SO the big question, will the snow mean I can't get back? If so I have to stay here and miss the match which would be very sad indeed.

Gatwick is ground zero for possible disruption Sat night into Sunday - far enough East, but not too far, far enough north (away from coast) and at about 200ft ASL. I'd be very worried if I were you.

 

[Papa Lazarou]

Sounds like you'll be lucky in sussex. What about us in devon, will the warm front win out down here or can we get snow?

Too far west for anything lasting - sorry

 

[fleet]

Gatwick is ground zero for possible disruption Sat night into Sunday - far enough East, but not too far, far enough north (away from coast) and at about 200ft ASL. I'd be very worried if I were you.

What about LHR? I would be staying in Brighton Saturday night so need a clear M23 and M25 at 7.30 am Sunday to get to LHR at 8.30 and off at 10.30?

 

[Napper]

What about Shoreham ?