The problem is we're in a polar maritime air mass. More often than not Pm air means that dew points are either just about cold enough, or just slightly too mild for snow, hence the marginality we've seen. Furthermore, those dew points also mean that during the day snow will often melt fairly quickly. It's actually not because of the sun like a lot of people think.
To get proper long lasting snow that lies for days, you need a proper Arctic air mass or a cold continental air mass in place. Those air masses have much lower dew points. That's why during December 2010, snow lay on the ground for days, even though it was extremely sunny.
Originally Posted by: Bolty
Yes, that is the issue (polar maritime air mass!) - The ground was not cold enough before and it never got that cold.
Unlike in December 2010 for instance when the snow fell and stayed for several weeks in many parts and almost a month over the moors.
This cold snap/ especially yesterday was a bit of a deja vu of what happened in the south NYD - - again - the SW had more of a North westerly wind than an Arctic blast of northerly wind - which only resulted in temporary coverings of wet snow over Moors whilst rain/hail with soft hail/ice pellets fell at lower levels and as you rightly said it never got that cold either - It was only the wind that made it feel cold - not even a frost - in fact now as I type it's still 1.5c above freezing. Also when we did have showers last night, the temperature rose by 0.5 of a degree to above +2c to give rain/sleet or soft hail. It's only a 2 day event for many and the south west never really got cold. Today's high was 7c - Which is average.
I saw some webcam's in Aviemore - doesn't look like a lot of snow fell there either - Can't tell the depth but perhaps 5cm or 2 inches"?
Now we have milder weather coming on Saturday night pushing in from the NW bringing rain instead of a wintry breakdown of snow first is frustratingly annoying. I saw photos and the cold in eastern and south eastern Europe and the amount of snow Italy and Greece had - which puts out slushy deposit of wet snow and +1c to shame.
I use to remember some classic wintry breakdowns to milder weather with precipitation starting off as snow back in 90's and early 00's but with this utterly crap cold snap we have had - it never really got that cold enough anyway to start off with.
What was very interesting - John Hammond compared this cold snap with January 1987 when daytime temperatures never rose above -6c in many parts and we were talking over a foot of snow with blizzards.
What's even more sad and embarrassing was that Heathrow had to cancel over 80 flights because there was sleet.
Ok, it's better to be safe than sorry, I get that! But come on!? The rain turned to sleet at Heathrow and the temperature fell to +2c? I mean really? in mid-winter!?
Yet we had the news reporters there as if there's no tomorrow.
Apart from the storm surge for N. AND Eastern coast - this cold spell was too over hyped. - I can go on for ever but I think I have contributed to this winter rant thread enough for now.
We can only hope that this SSW will deliver a proper block to bring us a deeper and more prolonged spell of colder weather (more than a couple days) where it snows and lasts all day and temperatures actually fall below freezing for once.![](/twocommunity/Images/Emoticons/msp_thumbup.gif)
Edited by user
14 January 2017 00:08:12
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Reason: Not specified
Home Location - Kellands Lane, Okehampton, Devon (200m ASL)
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Sean Moon
Magical Moon
www.magical-moon.com