Penellype's Weather Channel 2

[Penellype]

I threw it down overnight here. I woke up thinking there was a sudden gale, then realised the noise was rain, not wind.

Yes, that would be the cold front passing through - colder air behind is setting in now. The rest of October is looking as though it could be really quite cold for the time of year as high pressure is taking hold to the north and west. This means that the wind direction will generally be either northerly or easterly, and this sort of pattern tends to take some shifting. However we do have hurricane Delta in the Gulf of Mexico at the moment and ex-hurricanes do sometimes change weather patterns, so we shall see.

[Penellype]

Any more updates Pen?

The frost we were forecast never happened - was there a bit of a shift in the fronts?

Looks like we are in for a few dry days so hopefully I'll manage to get the grass cut soon....

Sorry, I've been struggling to keep up with stuff recently due to an increase in activity at work.

Frost at this time of year is usually dependent on clear skies, although the air mass we have been in has been rather cool for the time of year. Patchy cloud is hard to forecast and it can make quite a big difference to the temperature, which is probably why you missed the frosts.

The weather is about to change - it has (supposedly) been dry, although we have had some rain or drizzle every day for the past week including today, as often happens here when the wind is from the east. Tomorrow a low pressure system will start to move in from the west, changing the wind direction to south or south westerly, which is warmer. It will, however also bring rain, and the remainder of October looks likely to be unsettled and changeable with wind and rain at times. Western Scotland looks likely to be extremely wet and there is a yellow warning of rain there for Monday into Tuesday.

The models are consistently seeing a hurricane forming near the east coast of America next week. This could potentially change our weather and the occasional model run has had it causing high pressure to build over us into November. However the majority of runs seem to keep us unsettled, with lows arriving regularly from the west for the foreseeable future.

[Penellype]

The storms we have just had have contained the remains of 2 hurricanes - Epsilon and Zeta. Whether Zeta is responsible or not, the weather is thankfully about to become drier and less windy for the remainder of the week. It looks like higher pressure will then dominate for a while, but as often happens the models are not sure where the high is heading, with various options open. In general if the high heads south or east we are likely to return to milder, wetter conditions, if it heads north or west we will be colder.

Whatever happens the high pressure this week is likely to contain clear skies, at least at first, leading to potentially frosty nights.

[sandspider]

One fairly hard frost here on Tuesday night. Certainly feels a fair bit colder.

[Chippy Minton]

Tropical Storm "Iota", it's a record year. Wonder what happens when they run out of the Greek alphabet It really has been a strange year weatherwise, although seems like normal service is resuming here, back to "unsettled"

[Penellype]

Tropical Storm "Iota", it's a record year. Wonder what happens when they run out of the Greek alphabet It really has been a strange year weatherwise, although seems like normal service is resuming here, back to "unsettled"

I was wondering the same thing, although there are plenty of Greek names left.

After what has been meant to be a dry week (which has been somewhat wet and often foggy here), things are becoming much more unsettled. The high pressure to the east, which has been bringing the drier, sometimes foggy weather is slipping east, allowing several low pressure systems that are lurking to the west to move in. This is sucking warm air up from the south, and temperatures will be unusually mild for the time of year in the next few days. There will be frequent rain though, with possible flooding in places as the ground is already saturated. So often wet, windy and mild for the next week or so.

There are possible signs of a change towards the end of next week. As the high recedes into Europe this allows room for the lows to move further east rather than to the north east, allowing the wind to swing round to the north as the lows move through. Some of the model runs have high pressure ridging north in the atlantic and depending on positioning this could result in it becoming cold enough for snow in the north (or possibly even further south) in a week to 10 days time. There could also be frost as ridges of high pressure between the lows collapse over us. At present this varies from run to run and between the models, but it is worth being aware of the possibility of sharp frosts and potential snow by next weekend.

It may all come to nothing - there are tropical storms and hurricanes around and these can change everything, depending on where they go.

[Penellype]

Models have backed off the idea of snow and a cold weekend, reducing the cold snap to just a chilly day on Thursday with snow confined to Scotland at most. A cold night with frost is still likely on Thursday night.

[sandspider]

Any chance of an update when you get a moment, P? Likely to be a cold winter?

Forecast getting generally colder here, maybe a frost tonight.

[Penellype]

Any chance of an update when you get a moment, P? Likely to be a cold winter?

Forecast getting generally colder here, maybe a frost tonight.

Cold with possible frost (depending on cloud) and fog for the next couple of days, then likely to warm up again for a few days. After that there is a general consensus that it could get colder as high pressure may form over Scandinavia or in the atlantic (depending on which model and run you look at). Both scenarios are cold, the first pulling in an easterly wind, the second a northerly or north westerly. There is a lot of uncertainty though so it may not happen like that at all.

For later in the winter it is too soon to tell, but my feeling has always been that we are unlikely to see a repeat of last winter's exceptionally mild and westerly conditions. It may all depend on how strong the La Nina gets (currently moderate) - a very strong La Nina favours a milder winter, whereas a weak to moderate one favours cold apparently. But there are plenty of other drivers too so it really depends on which one(s) are most important.

I think will will see at least some cold periods this winter, either with frosty high pressure or lows trapped by "blocking" highs bringing some snow, but when and how long for is impossible to say. There are already indications of these patterns attempting to form at times, although so far they have been pushed away as a result of a strong polar vortex (caused by cold temperatures high in the atmosphere over the north pole). This is forecast to weaken as we go into December, but forecasts can be wrong.

[sandspider]

Thanks P, appreciate the effort. Certainly very cold today.

[Penellype]

I probably should really modify the "warm up for a few days" to it should be less cold, as the likely temperatures will probably still be in single figures.

[Nicos]

Thanks Pen.
4 weeks to Xmas !!!
Any chance of letting us know nearer the time please if there"™s a chance of a white Xmas?

[Penellype]

I can try, but it will probably depend very much on where you are. I think the chances of snow in December are quite high. The weather patterns at the moment are unusual, with high pressure starting to build to the north, although the models are not yet in full agreement as to the full extent of this, but in general the forecasts are on the cold side. Things can change a lot in a month, but the current run of the extended GFS has this for snow depth for York:



There are a LOT of caveats here. There are 31 ensemble members and not all of them are showing snow. This is only one run of the model and this shows snow depth, not falling snow. Snow depth predictions often assume that every flake of snow will stick, whereas in reality some (possibly all) will melt. In addition, it is far too soon to take any of the timings anywhere near literally. However, the model does imply that there is a fair chance of snow falling some time around Christmas, and this does seem to be a recurring theme in the longer range models at the moment. (A similar plot for last year would probably have shown no snow at all even this far ahead, as the atmospheric setup was completely different).

This run is for York, which would be in the firing line for snow if it was in the form of snow showers blowing in off the North Sea. There are other ways of getting snow which put different areas at risk, so it is worth repeating that unless we have a widespread snow event that covers the whole country (unusual), whether or not you get a white Christmas may depend very much on where you live.

As always, any forecast for more than about 5 days in the future must be taken with an appropriate dose of salt and everything could look very, very different in 4 weeks time.

[Nicos]

Brill explanation - thanks!

[Penellype]

Yellow warnings of snow and ice for parts of Scotland now until Friday.

There is still the possibility of some snow for parts of England and Wales from tomorrow and over the weekend. Snow is incredibly hard to forecast and the conditions are very marginal, but the most likely areas are the western side of the country and high ground. It is possible that eastern areas could see snow too, depending on how heavy the precipitation is - heavier = more likely to turn to snow due to evaporative cooling.

Regardless of whether or not it snows it is about to get colder and the cold could last for some time, depending on where the high pressure goes. The models are not in agreement over this yet, but some runs are very cold, and if it hasn't happened already, you can expect armageddon -type headlines in the press. A cold and potentially wintery December looks likely, at least for the first couple of weeks, but this is not (yet) a repeat of December 2010, the coldest for 100 years or 100 days of snow (to quote common headlines!).