Penellype's Weather Channel 2

[Penellype]

Well, my long term forecast for a cool and wet summer was somewhat inaccurate to say the least! Long term forecasting is just guesswork really.

Next week looks l like producing a heatwave for several days, with some of the model runs again producing temperatures upto 40C by 16th, one of the runs this morning has 40C for 4 consecutive days, although hopefully that one won't verify. Some of the runs go much cooler (near average) at around the same time so there is a lot of uncertainty. What does seem more certain is that there is virtually no rain in the forecast, except for north west Scotland, for the next week at least.

In the longer term there are hints that the 2nd half of August could be more unsettled, although whether this will reach the south east is debatable. The pressure pattern certainly seems to be rather stuck at the moment and if it does break down it could only be temporary, like the slightly wetter interlude that we have just had, at least in the north. As far as autumn is concerned, I really don't know.

Most of the autumn/winter forecasts that I have seen (not many) seem to imply that high pressure will move north and give us a colder winter. I'm not sure about that - most of the main drivers (solar cycle, QBO in particular) are more favourable for a milder winter, but it is very, very early days. It is rare for a cold winter to follow a hot summer, and this is quite definitely a hot summer.

[Nicos]

Thanks Pen.

[sandspider]

Looks like we're in for some rain and a bit colder next week, but possibly nicer the week after...

[Penellype]

Definitely a change in the weather with some much needed rain. Longer term a lot of uncertainty particularly around the track of hurricane Danielle, which may or may not come this way as a deep low pressure system. Other hurricanes/storms are brewing in the tropics and this always adds to the uncertainty as the storms are too small for the models to predict accurately.

[Penellype]

After a period of much needed wetter weather, high pressure looks likely to take over again soon. This will be a completely different setup to the high we had before, with some quite cold nights possible and a risk of ground frost in some areas. Fog is also a possibility as the high builds over the country.

Keep an eye on the forecast temperatures for your area as it could soon be time to get out the fleece to cover vulnerable crops.

[sandspider]

First frost here this morning...

[Penellype]

Yes, after months of above average temperatures the weather pattern appears to be changing. The high pressure that has brought warm and dry conditions is still there over Europe and keeps attempting to come back, but another ridge is becoming increasingly established in the atlantic, and as this builds towards Greenland it pulls the wind into the north. We currently have a battle between these 2 ridges, with low pressure in between, hence the more unsettled weather and swings from warm to cold and back again.

The outlook at present looks cool and unsettled for the next week or so, followed by massive uncertainties depending on which ridge wins. The picture is complicated by the possibility of ex-hurricanes influencing the setup (at the moment everything has gone fairly quiet in that department). It could literally be anything from an Indian summer to cold and wet.

[Chippy Minton]

Do we have a name for this weather pattern? It's not an Indian Summer (bit late and it's wet, not at all like summer), but it is remarkably mild. Here in the NW it's 16C today (October average being 14C), night time temperatures not really dropping below double figures but it feels autumnal, wind, rain, etc. The tumbling tomatoes are still flowering and setting outside, the courgettes are happy enough, the only things that have given up for winter are the melon and the cucumbers.

Very odd.

[Penellype]

Do we have a name for this weather pattern? It's not an Indian Summer (bit late and it's wet, not at all like summer), but it is remarkably mild. Here in the NW it's 16C today (October average being 14C), night time temperatures not really dropping below double figures but it feels autumnal, wind, rain, etc. The tumbling tomatoes are still flowering and setting outside, the courgettes are happy enough, the only things that have given up for winter are the melon and the cucumbers.

Very odd.

I'm not sure what the weather pattern is called, but basically its blocking high pressure to the east and low pressure to the west, resulting in a sustained southerly or south westerly flow coming up from Africa or the Azores (it varies slightly from day to day). The low pressure is trapped to the west of an "omega block" which is a bulge of high pressure with a low either side. This is the situation at midnight tonight:



The black line is the jet stream, with colder air to the north and warmer to the south of it. We are in the warmer part, but the low pressure to our west is fairly close by meaning that western areas in particular are unsettled.

Nothing is going to change very fast - this is the picture by mid day on Sunday:



As you can see, everything looks very similar. It is not until we get into November, outside the "reliable" timeframe, that the models start to allow the low to break through and change the pattern. We can in fact expect it to get warmer over the next few days, with notably mild nights for the time of year too.

[sandspider]

Finally got cold here, frost.

P, what's December and winter generally looking like? If you have the time and your crystal ball is working!

[Penellype]

P, what's December and winter generally looking like? If you have the time and your crystal ball is working!

December is currently looking cold. There is very good agreement between the models for large amounts of "northern blocking" which occurs when high pressure settles in the arctic. This can lead to cold here in 2 ways - if the blocking is over Scandinavia and stretching across to Greenland the wind direction is easterly. If the high pressure is far enough north the wind can originate in Siberia and becomes very cold indeed, leading to a "beast from the east". The 2nd way we can get cold is if the high settles over Greenland, which then brings the wind in from the north. This can become very persistent if the high extends south into the Atlantic, blocking off the progress of low pressure systems from the west.

The current situation is that for some considerable time we have had high pressure to our east and low to the west, which has given us a very warm autumn, becoming wetter as the high has gradually moved east. The high is now starting to drift north towards Scandinavia, so that by the end of this week the wind will have started to turn easterly. This is not a beast from the east, contrary to the scaremongering from the usual newspaper suspects, which only need a sniff of the word "cold" to start predicting snowmageddon. Initially at least there will be a southerly tilt to the wind, so although it is cold because it is coming across the continent, it won't be very cold.

The models are divided about what happens next, although all options are cold. There is a significant possibility that the high will stretch towards Greenland while remaining lodged across Scandinavia, resulting in a persistent easterly over several weeks. There is also the possibility of "retrogression" where the centre of the high moves west, lodging across Greenland. Some of the recent model runs have shown very high pressure over Greenland, extending down into the Atlantic. If this happens we could be "locked in" to a long cold spell. However, there are other possibilities - the high could move to the Canadian side of Greenland, which would allow the warmer lows to move in underneath it, so it is not a done deal by any means. The critical factor in this scenario is how much blocking there is in the Atlantic.

So, my prediction for December is that it will become increasingly cold but rather dry over the next couple of weeks, followed either by a gradual warm up (which could involve snow) or a continuation of a similar theme, with winds either from the north or east. Further ahead, the models are undecided about January, with some continuing the cold theme while others revert to milder, wetter and windier conditions. The general consensus at present seems to be for a milder February. This pattern would in general tie in with the La Nina situation, which tends to favour cold in the early winter, followed by milder later on.

Clearly a cold December is not great news in the current energy crisis, and worryingly a lack of wind appears on the cards too, which is about the worst case scenario from the point of view of electricity supply. If you have a smart meter and are able to join your energy supplier's program to save energy at peak times (Octopus call theirs Saving Sessions, other suppliers may have different names), you may just be able to help keep the lights on!

[sandspider]

Thank you for the thoughts, as ever! Generally better than the weather forecasts

[Bren In Pots]

Thanks for your forecast Pen.

[Penellype]

The freezing weather is finally coming to an end during tomorrow, when a band of rain with possible snow to start with moves east across the country. The ground is frozen and extremely cold, and the rain is likely to freeze on impact. There are several Met Office warnings for snow, ice and freezing rain covering most of the country including an amber one for parts of the north. Please be careful if you are going out because surfaces that look wet may be a sheet of ice and impossible to stand up on. Similarly apparently wet roads may be lethal skating rinks.

Warnings at https://www.metoffice.gov.uk/weather...ce/uk-warnings

[Nicos]

Thanks for that Pen - I imagine a lot of people will be out and about tomorrow….keep safe peeps!