850pha Temperature

[A Winter's Tale]

Winter 2010/2011:

Last -5c: April 12th

Last -10c: January 29th

First -10c: November 27th

First -5c: October 20th

Winter 2009/2010:

Last -5c: May 13th

Last -10c: April 19th

First -10c: December 18th

First -5c: ?

Christmas Day:

2010: -5c

2009: -5c

2008: 0c

2007: 0c

....

[Isolated Frost]

You could have credited me, mate haha.

[A Winter's Tale]

You could have credited me, mate haha.

Sorry about that.

[Isolated Frost]

Sorry about that.

Just joking mate! Interesting to see when that -5C line hits us. If it were to be October you would need some decent Northern blocking, ridging to the west and lp systems steering to the east, and usually n blocking is greenland high in October/November.

That's how we can tap into early cold. Northern England, Scotland and in particular the Shetlands managed snow on the 20th or 21st. Aberdeen recorded early morning snow aswell.

Southern England managed early snow due to this setup, Atlantic blocked, lp to north east, troughs in continental europe - brilliant snowy setup for October.

[Radiating Dendrite]

Just joking mate! Interesting to see when that -5C line hits us. If it were to be October you would need some decent Northern blocking, ridging to the west and lp systems steering to the east, and usually n blocking is greenland high in October/November.

That's how we can tap into early cold. Northern England, Scotland and in particular the Shetlands managed snow on the 20th or 21st. Aberdeen recorded early morning snow aswell.

Southern England managed early snow due to this setup, Atlantic blocked, lp to north east, troughs in continental europe - brilliant snowy setup for October.

With a blocked Atlantic now being forecast for October then we could see some early wintriness if the blocking is favourable. I would not be surprised to see snow showers knocking on the door of N. Scotland and maybe some sleet further south.

[Isolated Frost]

With a blocked Atlantic now being forecast for October then we could see some early wintriness if the blocking is favourable. I would not be surprised to see snow showers knocking on the door of N. Scotland and maybe some sleet further south.

But we haven't actually saw any blocked atlantic synoptics, just long-range forecasts. Even during the proposed settled spell with HP to the SE, the jet stream remains in N Atlantic vacancy with lows moving SSE/SE to NNW/NW, skirting north of Scotland. We need lowering pressure in Scandinavia, higher pressure in the Atlantic and Greenland/Iceland, aswell as lower pressure on the continent. Quite unlikely right now. Any settled weather will bring warm uppers, and little snow risk, so cool weather is unlikely for now, especially as HP moves further east into the continent while we get a warm, humid southerly flow instead of a clearer flow with HP in the N Sea/N France.

Ideally, the HP moves towards Russia - the Azores high effectively sinks and extratropical cyclones from the jet move towards Scandi and stall under cooler Arctic air around there - and with that, strengthening heights over Greenland, ridging towards the mid-Atlantic, and the Arctic air gets pumped down towards us.

Though, that will take a while probably, and I can't see many signals for that, at least in early-mid October. Best hope now is that pressure rises from the Azores again, and something moves north or north-west - low pressure continues north of Scotland, and with higher pressure in Greenland, pulling in a pM flow and some wintry showers in the North and West really.

I start to look for cold usually around halloween, GMT switch, bonfire night area - that's when lowland areas can realistically get snow. After the hp moves away in late September/early October - I'll start watching for mountain/hill snow in the UK.

[damianslaw]

But we haven't actually saw any blocked atlantic synoptics, just long-range forecasts. Even during the proposed settled spell with HP to the SE, the jet stream remains in N Atlantic vacancy with lows moving SSE/SE to NNW/NW, skirting north of Scotland. We need lowering pressure in Scandinavia, higher pressure in the Atlantic and Greenland/Iceland, aswell as lower pressure on the continent. Quite unlikely right now. Any settled weather will bring warm uppers, and little snow risk, so cool weather is unlikely for now, especially as HP moves further east into the continent while we get a warm, humid southerly flow instead of a clearer flow with HP in the N Sea/N France.

Ideally, the HP moves towards Russia - the Azores high effectively sinks and extratropical cyclones from the jet move towards Scandi and stall under cooler Arctic air around there - and with that, strengthening heights over Greenland, ridging towards the mid-Atlantic, and the Arctic air gets pumped down towards us.

Though, that will take a while probably, and I can't see many signals for that, at least in early-mid October. Best hope now is that pressure rises from the Azores again, and something moves north or north-west - low pressure continues north of Scotland, and with higher pressure in Greenland, pulling in a pM flow and some wintry showers in the North and West really.

I start to look for cold usually around halloween, GMT switch, bonfire night area - that's when lowland areas can realistically get snow. After the hp moves away in late September/early October - I'll start watching for mountain/hill snow in the UK.

Yes late sept/early oct isn't a time to be expecting any significant cold weather - it is often quite a mild period and high pressure set ups at this time of year are often of the warm variety - thanks to still relatively warm seas and a warm continent. You really need a cold high with arctic air embedded within it to deliver anything remotely cold at this time of year.

Alot will depend on the strength of the atlantic in the coming weeks - a weak inactive atlantic could allow more favourable northern blocking in time, so whilst the imminent pattern change to high pressure won't bring any cold weather, in time through october we could see something much more colder.

[Isolated Frost]

Yes late sept/early oct isn't a time to be expecting any significant cold weather - it is often quite a mild period and high pressure set ups at this time of year are often of the warm variety - thanks to still relatively warm seas and a warm continent. You really need a cold high with arctic air embedded within it to deliver anything remotely cold at this time of year.

Alot will depend on the strength of the atlantic in the coming weeks - a weak inactive atlantic could allow more favourable northern blocking in time, so whilst the imminent pattern change to high pressure won't bring any cold weather, in time through october we could see something much more colder.

Yep agreed - hopefully Greenland can link up with the Azores region, but Greenland is not currently playing ball, could be a lot more different come this time next month.