shuggee

Aye it's turned to snow here in Holyrood too

Rain washing away the snow here... Brilliant

Heavy snow all morning - 2cms in the western suburbs earlier at 12noon.

I love it - no warnings, no mention on the BBC - and what happens! 2cms of lying snow on the western outskirts of Edinburgh and traffic chaos! Even in the city centre/Leith patchy snow is left 3 hours since the last heavy shower...

Clear skies, lying snow, little wind - those are the major factors. Heat radiates away and Mr frosty frost comes out to play! The 850s are irrelevant in these circumstances bingobob Here's all the relevant charts:

Yeah they do. I'll go have a look

Unfortunately (but as you might expect) there's no definitive answer to using either of those measures for temps at surface. The significance of dam values is that the rule of thumb for wintry ppn is anything sub 528dam. But of course there are exceptions in certain set-ups. And remember the true dam value is only shown on the HGT 500-1000 charts - not the 500Hpa charts which many people get muddled up with. As for the 850s - remember they are the air temps 1.5kms up. Again, a rough rule of thumb is to add 10ºC to get surface temps at sea level, but this is even less reliable than the dam thickness rule above!

It will be a pleasure to remind the team :lol: Sub zero dew points creeping in from the east as I type

Hey! I don't live in Leith. Holyrood don't you know And yes it is bloody annoying - I mean you can drive for 5 hours from London to Carlisle - how many English regions does that journey take you through? But five hours north from Edinburgh and you're only just over the Black Isle - and that's classed as one 'forecast area'. It is ridic.

Yes, it's not until the early hours that the cold kicks-in from the east and any ppn turns to snow Cookie

Mike it's not the 528 dam line on the 500Hpas that indicates the possibility of snow - that is the wrong chart. You need to look at the 500-1000 HGT charts for the correct dam line that's fits your understanding

BBC News 24 forecasts are showing no snow showers whatsoever across Scotland Thurs or Friday <_<

To be honest gg I've not sat down and looked through the charts enough to come to a conclusion. I'll probably take time out come tomorrow evening to have a proper look and will post a summary in here then. But that will be after my weekly game of badminton

Really badly lol - unless the conditions are perfect. City centre/Leith needs uppers (the temps on the 850hpa charts) to be lower than -7 to be certain of snow in my experience. In the set up shown for Thurs/Friday the wind needs to be coming from the north east, too much of an easterly direction and it brings the warmth off the sea. Ideally we would want it to have gone over Fife first. Obviously out of town and up a bit, e.g. Dalkeith, Penicuik, Bathgate etc. do very well indeed.

Great advice Andrew!

In a frontal situation ppn charts become reasonably reliable say 18-24 hours out. For showers - it's always a guess. You can be in the middle of the area progged 3 hours before to get showers and they all bypass you - hence their notoriety. Think more in terms of general trends and themes rather than thinking "in 1hr 47mins we are forecast to get 2.1mm of rain" - because that is unforecastable.

All changed for youse

Please use this thread to have a good old chat about the prospects for something wintry in north west England

Please use this thread if you want to discuss the prospects for something wintry in the south west of England Beat me to it Gn :)

Please use this thread to have a good old chat about the prospects for something wintry in southern central England

Please use this thread to have a discussion about the prospects for something wintry in the north east of England

Please use this thread to discuss the prospects for something wintry across the English Midlands

Please use this thread to have a good old chat about the prospects for something wintry in Wales

Please use this thread to have a good old chat about the prospects for something wintry in East Anglia and south east England

Please use this thread to have a good old chat about the prospects for something wintry in Ireland