Penellype's Weather Channel 2

[Chippy Minton]

Definitely been winter here, most snow we've had for years, chilly but not proper cold (-3C minimum I guess). A beast from the east would not be welcome as we hope to start getting out more.

[Penellype]

The cold winter continues, with some rain and snow for parts of the southern half of the country over the weekend. Remaining cold until Monday night into Tuesday, when a band of rain and snow moves in from the west warming things up for most areas. The snow should turn to rain south of Scotland as the warmer air arrives.

A couple of milder days are very likely to be followed by a cold spell starting next weekend, and what happens next appears up for grabs. Some of the models have a few days of cold followed by milder weather, others have a very cold "beast from the east" type setup with a strong easterly wind blowing snow in from the north sea. The models are really struggling with this, with massive swings between runs at times. Therefore take any newspaper stories about the upcoming cold with the usual helping of salt, as nothing is at all certain beyond about a week.

[Penellype]

After a brief short interlude of tolerably pleasant weather today and tomorrow, things are about to turn nasty again. A band of rain looks like getting stuck over the middle of the country on Tuesday and Wednesday with quite a few places seeing upto 48hrs of relentless rain with a serious risk of flooding. It will turn quite mild while it rains. On Thursday a vicious little low winds itself up across the country to add gale force winds to the mix and the rain is likely to turn to snow in the north as the low moves away to the east (some model runs have this further south). It then looks likely to turn colder again for the weekend.

There are warnings in force already for rain and flooding for Tuesday, Wednesday and Thursday, with an amber warning for the likely worst hit area, mainly in Lancashire and West Yorkshire.

[Nicos]

Wow! Very interesting Pen. Much appreciated

[Penellype]

The SSW is currently occurring and the temperatures over the pole have rapidly warmed:



Image from Meteociel.fr.

The north pole is in the centre of the image, where the warmest temperatures are. The polar vortex (blue) has been split in half. The models show the polar vortex reforming somewhat over the next week or so but remaining displaced from the pole, before possibly weakening again as another warming may occur.

With regard to cold weather resulting from this, there are plenty of ifs and buts. It is always hard to pin the cause of a weather event down to a specific thing. There appears to be a relationship between a SSW and northern blocking (high pressure over the pole), which can, if it is in the right position, lead to very cold weather here. The important point is that the position of the blocking matters enormously. The winds flow clockwise around a high pressure system which means that any high to our west pulls down a northerly wind, and high to our north pulls in an easterly - both of these are cold. There is therefore a good chance, if high pressure is over the pole, that it will pull in cold winds. However, if the blocking is to our east, or more towards Canada, it can either pull in a southerly wind or have little effect at all, and even if it is to our north, if the Azores high is ridging over Spain any effects from the blocking may be small.

In addition it can take weeks for the warming to start affecting the troposphere (where weather takes place), and sometimes this seems not to happen at all. There are also complications this year in that the stratosphere has in general been disconnected from the troposphere with a strong polar vortex, usually an indication of low over the pole, and yet large amounts of northern blocking, so there is no guarantee that it will reconnect, and the northern blocking is already giving us some cold weather. This is somewhat unusual, and the effect of a SSW on the current pattern might be different from its affects on the more normal pre-SSW pattern of high to the south and low to the north. We will simply have to wait and see.

Currently we can expect the weather to remain cold and in general drier than usual (but not completely dry) for the remainder of this week as the wind is generally easterly or northerly. Towards the end of the week the models are favouring high pressure from the west collapsing over us, which would remain cold at first, but if the high moves further south this could allow in milder westerly winds. This is not a certainty and where it goes from there is anyone's guess, particularly with the uncertainties from the SSW thrown into the mix.

[Chippy Minton]

Seen in the Daily Moan....

Grahame Madge of the Met Office said: 'Many weather agencies are united in the view that this Sudden Stratospheric Warming (SSW) will take place next week. When that happens - around 30km up in the stratosphere - our traditional wind pattern can be reversed.

The 'sudden stratospheric warming' (SSW) event happens when the temperature in the stratosphere soars by 50C (122F). This 'reverses' Britain's wind pattern, from the warmer west out in the Atlantic to the east – and Siberia.

It can take two weeks for the effects of a SSW to be felt. This was the case in February 2018 with the infamous Beast from the East, which saw much of the UK gripped by travel chaos and school closures amid heavy snow.

What is less clear is the long-term outlook for the impact of this event. Two out of three SSW events result in very cold episodes but one in three has little impact at all.

They helpfully provided a graph, possibly attached if I used the technology correctly.

So, assuming the SSW occurs we've a 66% chance of a bit of parky weather. Any of this showing up in your models Pen?

[Plot70]

I managed to get the second half of a bed dug and the weeds piled loosely in the hope that the frost will "freezer burn" the roots.
I did not get the manure on because the snow was accumulating too quickly for me to be able to see what I was doing.
The birds were just weathering the storm in the trees.
You can see the last of the greens that I saved from a pigeon attack waiting for me to take them home.

[Nicos]

Thanks Pen!...I’m crossing my fingers for snow

[Penellype]

Quick update - I haven't much time at the moment.

As predicted it has got a lot colder, and this is set to continue for at least a week. It is likely to get even colder after the weekend as the wind swings round to the east. After that the models are much less certain, with some runs bringing in even colder air, setting up a severe cold spell which could last potentially into February. Other runs turn milder, but once we have set up a cold spell like this, milder usually involves quite a bit of snow at first.

Regardless of whether or not it turns milder, there is low pressure about and snow is likely to feature from time to time. At present the upper air temperatures are not particularly cold and much of the precipitation is borderline rain/snow and hard to predict with confidence. If the colder runs are right and the upper air gets colder next week and any precipitation is going to be to be snow.

[Chippy Minton]

Unexpectedly heavy snowfall hereabouts, was expecting a light dusting, woke up to about an inch. Everything covered. Sprouts might taste a bit sweeter though after this cold snap.

[sandspider]

Thanks folks, we were lucky. A river downstream burst its banks and the water receded before it got through our doors! Close one. Hope the rain tomorrow isn't as bad.

[Penellype]

Quite a few warnings appearing relating to ice, wind and rain through to Sunday. The boxing day storm has been named Bella and there is an amber warning of wind for parts of the south west.

https://www.metoffice.gov.uk/weather...ate=2020-12-24

[Penellype]

Just legged it back from the allotment as heavy snow set in. I always forget that York is on the east coast when it comes to snow showers.

[burnie]

One of our local hills roads has the snow gates closed, not that I can use it due to covid restrictions at the moment as it goes over into Aberdeenshire.

[Penellype]

Lapping at the house

I hope all is ok Sandspider - very worrying for you. There has been a huge amount of rain in places. Thankfully a couple of drier days now, but another deluge on boxing day I'm afraid.