UKC

It's only a forecast - but still.....

http://www.ecmwf.int/products/forecasts/d/charts/medium/deterministic/msl_u...

In reply to CurlyStevo:

A pity Wetterzentrale doesn't agree

In reply to Andy Nisbet:
"A pity Wetterzentrale doesn't agree"

http://www.wetterzentrale.de/pics/avnpanel1.html

Interesting site, I'll keep my eye on that. I guess the high pressure air mass was a lot warmer than I anticipated and the NE winds will not be as cold as they normally would be at this time of year. Still typically if a high pressure area gets established to the NW of scotland it does signal cold weather. Guess we'll see what happens nearer the time. I think we'll see frosts to sea level if the weather pattern does get established even it isn't mega cold

In reply to Andy Nisbet:
I'll be happy if its just less windy and rainy

In reply to CurlyStevo:

The colours on http://www.wetterzentrale.de/pics/avnpanel1.html are 500mbar height contours which are not that well correlated with surface temperature. Better to look at the 850mbar temps http://www.wetterzentrale.de/pics/avnpanel2.html which currently show a very mild spell Fri/Sat and then a return to colder temps in the middle of next week, but nothing exceptional (not as cold as ECMWF).

Even more useful is the ensemble forecast http://www.wetterzentrale.de/pics/MT8_Aberdeen_ens.png You can see there's a lot of spread by next Tuesday, an indication there is not much certainty in the forecast.

In reply to Mark Bull:

You also need to take into account that the altitude of the 850mbar pressure surface is higher when sea level pressure is high, so will naturally be colder anyway. It's also difficult to infer the presence or absence of an inversion from the charts.

In reply to Mark Bull:
ta

In reply to Mark Bull: love that ensemble!

In reply to franksnb:

as a lay person its pretty hard to tell what it means beyond what mark said. I guess if you keep your eye on it and note what happens you'll get a feeling for it.

In reply to CurlyStevo:

I'll try to explain a bit: an ensemble forecast is a set of model runs all with slightly different initial conditions: the idea is to understand the possible spread and uncertainty. The thin coloured lines on the chart are the individual forecasts, the white is the average of them and the red is the 30-year observed average. If the individual lines are all close to the white one, then there is some confidence in the forecast: once they diverge there is less.

There is also a sea-level pressure ensemble here: http://www.wetterzentrale.de/pics/MT2_Aberdeen_ens.png (the lower chart: the upper one is sea-level temperature, but this isn't very helpful as for some reason the diurnal variation doesn't show up properly, maybe because at the model's resolution, it thinks Aberdeen is actually in the North Sea!)

In reply to CurlyStevo: Will Kinder be in?

In reply to Mark Bull:
Ta, I Still don't know what the scale on the left means and how much divergence means the forecast is pretty uncertain (or conversely certain)

In reply to CurlyStevo:

The scale is temperature in Celsius at the 850 mbar pressure surface. At neutral pressure (1013 mbar) this surface is at about 1460 metres, but in very high pressure (say 1040 mbar) it goes up to 1670 metres and in very low pressure (say 960 mbar ) down to 1010 metres. You could roughly extrapolate down to a temperature at 900 metres, say, but for freezing levels out to 6 days you are better off looking at, for example, http://www.mountain-forecast.com/peaks/Ben-Nevis/forecasts/1344 which is, as far as I know, derived directly from the GFS model output.

As a rough guide, if most of the ensemble members are within +/- 2 deg C from the average, that is a strong signal, so reasonable confidence, within +/- 5 deg C is some signal, but low confidence, +/- 10 deg C is no signal (zero confidence).

In reply to Mark Bull: Could you start a website somewhere doing this sort of explanation on daily basis? It would beat MWIS, Met Office. Thanks.

In reply to CurlyStevo:
UK Weather Forecast
Looking ahead to the next 10 days, and things will be turning much cooler!

Initially we have high pressure in charge for long periods, so plenty of settled weather to come with some chilly days and frosty nights. The only blips in this trend will be later Wednesday and in to Thursday, and later Saturday in to Sunday when some weak frontal systems will move in bringing some rain, though the rain becoming increasingly patchy the further South it heads. We will also see some scattered showers, wintry over higher ground, across Northern and Western Scotland along with Northern Ireland at times.

In to next week our area of high pressure moves to the West of the UK, introducing a colder Northerly airflow. This is likely to lead to a drop in daytime temperatures, a continuation of some overnight frosts, and the likelihood of some wintry showers over higher ground, perhaps even to lower levels across Scotland for a time.

This is something we are keeping a close eye on, with more details about this to come later today.

In reply to wykealpha:
fingers crossed

In reply to CurlyStevo:

Britain is braced for a polar plunge next week, according to today's article written by the Consumer Affairs editor of the Daily Express. It's based on a forecast by Jonathan Powell of Vantage Weather Services.

http://www.express.co.uk/news/uk/442698/Britain-braced-for-Polar-plunge-as-...

It's only the second time this month the Express has run a prediction of sensational cold temperatures.

Bit of further reading ....
http://www.newstatesman.com/blogs/media/2012/08/dont-trust-daily-expresss-w...
http://www.theguardian.com/environment/georgemonbiot/2012/jun/15/daily-expr...
http://notalotofpeopleknowthat.wordpress.com/2013/10/22/daily-express-forec...

In reply to Pay attention:


'Polar plunge' eh? Not just a 'Big freeze'?

And let me guess: sometime next Summer we'll be in for a 'Sahara sizzler'.

Nice to see the journos making an effort ...

In reply to Pay attention: Vantage and Exacta appear to be solely funded by the Express

In reply to Rob Parsons:

Looking ahead to the next 10 days and we are going to see a drop in temperatures.

Through this weekend temperatures will remain around average, with some patchy rain to come at times on Saturday and Sunday for Scotland and Northern Ireland after a mostly dry but cloudy day for England and Wales, before the patchy rain spreads Southwards on Sunday.

On Monday we will see some spells of rain pushing from West to East, clearing to leave scattered showers. The showers will turn increasingly wintry across Scotland, Northern Ireland and the far North of England as the day goes on.

Then in to Tuesday and Wednesday we will see some scattered wintry showers across the country, most likely over higher ground in the South but we could see some snowfall to lower levels in the North, particularly across Scotland where we could see some small accumulation of snow during the overnight period too. For some sheltered Eastern areas though, especially inland it will remain drier with some crisp sunshine.

Thereafter there is some uncertainty, but temperatures look likely to remain low with some overnight frosts and fog, and the risk of some further wintry showers in the North.

So turning colder for all, some snow around next week in the North but at this stage nothing too significant is expected.

In reply to wykealpha:

From MWIS

"In the long term, the majority of forecast models suggest cold conditions until the end of the month, with only occasional
warmer periods"

In reply to CurlyStevo: Im busy dusting off the rust and sharpening from my tools. WInter is about to start for all those that manage to remove themselves from the sofa!!! Well fingers crossed anyway