Penellype's Weather Channel

[veggiechicken]

Hope Ophelia is not as bad as she sounds. Stay safe everyone, especially our Irish friends across the water.

[Penellype]

Met office have extended their amber warning of wind from Northern Ireland into the west of Wales, Isle of Man and south west Scotland. https://www.metoffice.gov.uk/public/weather/warnings

You may have noticed an orange-red hue to the sky, making it look rather eerie out there. This is due to Saharan dust being sucked up from Africa on the eastern side of Ophelia along with the unusually warm air. You may find deposits of fine sand on your car.

[veggiechicken]

The Sahara dust has already coated my car

[Penellype]

Well, the forecasts a week or so ago that predicted a strong low pressure system slap over the top of us this weekend were pretty much spot on. The timing is slightly different, but this is the chart for Saturday from the latest GFS run:



The strongest of the winds will be to the southern side of the low with a Met Office yellow warning for the west of England and Wales and most of the southern half of England. https://www.metoffice.gov.uk/public/...ate=2017-10-21. Southern Ireland is also in the firing line again.

Currently this storm has not been named as there is no amber warning - it may become storm Brian if the warning level is raised. At the moment it is in its infancy in the atlantic, but over the next 24 hours it will get caught in the jet stream and undergo "explosive cyclogenisis" to create a deep low, which will weaken slightly as it tracks towards and over the British Isles. Expect a wet and very windy weekend.

On the above chart there is another low lurking to the south of Greenland, and current thoughts are that this is going to behave completely differently. This is expected to suck warm air up from the south again so that by the middle of next week we are again in a warm air stream:



This wouldn't necessarily be dry as we are still fairly near the influence of the low pressure, particularly in northern and western areas. It is also important to note that at this time of year warm upper air temperatures under high pressure do not necessarily translate to warm surface temperatures as there can be complications such as fog.

This chart looks to me to be reasonably straightforward in that there is a ridge forming in the atlantic, building towards high pressure over Greenland, with a trough to the east of it. I would expect this to result in the UK turning cooler, with a northerly wind, but the models are having none of that. By Sunday 29th we have a very odd chart where the low has sunk to the Azores and the high has toppled over to join the one to the east of us, with a low developing over Greenland:



While this looks probably dry, I haven't a clue whether it would be a warm and sunny high or a damp, cold and cloudy one so I'll leave that to the experts.

Not surprisingly, given the strange chart above, there is huge uncertainty in the forecast beyond the next 4 or 5 days as can be seen from the ensemble chart for York:



Today's rain and the weekend storm are clear to see at the bottom, along with a fall in upper air temperature as the low passes east. The rise with the southerly wind in the middle of next week is supported by many but not all of the members, and the chaotic temperature lines and rainfall spikes after that show that the idea of a fairly prolonged period of high pressure may be a fantasy. We will see.

Update: The storm has now been officially named Brian by the Irish Met Office Met Eireann

[Penellype]

I was wondering when the winter scaremongering would start, and here we go...
WINTER WEATHER UK: Britain faces SNOWMAGEDDON as La Niña to bring Big Freeze | Weather | News | Express.co.uk

Before you start panicking, just have a look at the Express's record in forecasting winter:
https://www.netweather.tv/weather-fo...er-mega-freeze

I notice the Express appear to have ditched the perennially unsuccessful Nathan Rao in favour of Lara Deauville, who is new to me. However the scaremongering headlines are the same.

IT IS FAR TOO SOON TO MAKE ANY SENSIBLE PREDICTIONS ABOUT WINTER.

[Thelma Sanders]

I suppose if they forecast a bad winter freeze every year, sooner or later they will be right

Does make me LOL though

[Penellype]

The thing is there is always just enough of a grain of truth in what they say to make you think that they COULD be right.

Yes, we appear to be heading into a La Nina.
Yes we are heading towards solar minimum, although as I understand it the link to a cold winter is more to the phase where you start to come out of solar minimum - give it another 2-3 years for that one.
Yes we are having a more active hurricane season (thought to possibly be linked to northern blocking = possible colder winter later)
Yes the QBO is in its easterly phase now, which supposedly weakens the westerlies = more likelihood of colder winter (the westerlies look pretty strong to me at the moment though...)
Not sure about the PDO - I thought that was heading into a warm phase, but I could be wrong.

There are many, many other factors. For what its worth, the models are tending to go for another mildish winter, with some colder signals at times, but it is far, far too early to take them seriously.

[1Bee]

Frankly, I'd love to have a few spells of hard frosts and snow... winter somehow seems so messy and mucky when it's just muddy and dull all the way through.

[Penellype]

In the interests of balance, yesterday's CFS 6 month forecast (NOT TO BE TAKEN SERIOUSLY BEYOND NOVEMBER and even November with a pinch of salt) is going for relentlessly warm, wet and windy weather for much of the winter, with the cold arriving in April. For details see the October CFS 6 month look ahead video at GavsWeatherVids - UK Weather Forecasts And Latest News.

I should perhaps point out that the CFS is a climate model (that's what the C stands for) and as such tends to factor in climate change and err on the warm side.

[Greenleaves]

It will be what it will be....I trust Penellype over all these so called forecasters

[Penellype]

Potentially chilly night tonight with a possible touch of ground frost in Scotland and parts of northern England where skies clear. Be aware if you live in a vulnerable area.

[Penellype]

Early heads up for what MIGHT be a rather chilly spell around the beginning of November. The models have become increasingly consistent in showing high pressure to the west dragging the wind in from the north at around this time.

GFS:



ECMWF:



IF this is correct, and it is a big IF at 10 days away, then it would be cold enough for snow:



The ensemble chart for York shows the drop in temperature well:



Many of the lines drop below the -5 isotherm which is one of the requirements for snow. Timing differs between individual ensemble members, but if you pick out the actual lines there are very few that don't show this cold snap.

This would be proper winter cold with frost at night - not particularly unusual for November. How long it would last depends on the position of the high, and in this the 2 models are quite different. The GFS has high pressure building over Greenland, which could prolong the cold. The ECMWF has low pressure over Greenland, in which case the normal course of events would be for the high to collapse over us and break the northerly flow. Everything could look very different in a few days time, but it will be interesting to see how this develops.

In the shorter term, after a chilly night last night the next few days and nights should be warmer, particularly the further south and east you go. The west will be wetter than the east, with most places away from the south east seeing some rain especially on Wednesday. After that it looks likely to become cooler and drier under higher pressure for a few days towards the weekend.

[1Bee]

*pleasesnowpleasesnowpleasesnow *

(Apologies to those who hate it, or who are inconvenienced by it... )

[Lumpy]

^^^^^^^^^^^^^^^^ posted by anonymouse

[Lumpy]

Penellype, could you explain the pics I put on the 'What makes you happy' thread as I have never seen a rainbow opposite a red sky like that.