Heads up for some chilly nights next week

[Containergardener]

Thanks for warning Pen. I put my thermometer on deck to see what it said last night, was down to 7.1 but GH was down to 6.3. I'd have through be opposite. Not too bad and everyone's happy out there still.
Temps next week I've seen 28s for here believe it when I see it but could do with some ripening tomatoes.

[Penellype]

Do you work with weather Penellype?
BBC and weather channel don't seem to have picked up on it yet. Not like they ever do! I tend to check the weather often online, and their predictions constantly change. So reading charts like that can be very helpful, thanks for sharing!

I don't work with weather (apart from the effect it has on my gardening etc), but I am fascinated by it - all aspects from the complex computer modelling to standing in the garden looking at the clouds. If the forecasting aspect interests you I can recommend gavsweathervids.com where I have learned a good deal about what goes into forecasts. He does daily videos which are not just standard forecasts and include all sorts of fascinating details such as the influence of sunspots and sea surface temperatures on the overall weather patterns, long range forecasts and the types of data that go into them, and of course the daily computer predictions. Its worth a look and will show you why things are never as clear cut as they seem from the ordinary forecasts.

[Penellype]

Predictably the latest run of the GFS has backed off the heat a little. The following charts from http://www.wetterzentrale.de/de/show...&zip=&bw=False show what I mean.

Yesterday evening's chart (for York), the mid day run of the GFS, was:



The weather forecasts use the "Operational" run which is the highest resolution and most recent program. This is the thick green line on the graph. As you can see, around 17th August this is much higher than the white line, the average of all 20 runs (which start with subtly different initial conditions to allow for experimental error in measurements).

The midnight run, which is the latest available is:



You can see that the green line has dropped considerably and is now much more in line with the other runs and the average.

Don't misunderstand me, this is still a heatwave. The temperature values up the side of the graph are the upper air temperatures. Forecasters talk about "isotherms", which are lines on the map connecting points of equal temperature. You can see from the first chart that on 17th that the green line has crossed the 20C isotherm at 850mb. You can add roughly 10-15C to this temperature at ground level depending on the moisture content of the air, hence last night's forecast for 32C here. The midnight run has dropped the green line to the 15C isotherm, which is more like 25-30C down here. Still very warm.

[Ryez]

That's brilliant! Quite fascinating that you mentioned sunspots. This is heavily under investigation. They do seem to increase the sun's brightness, and that must, logically, have some effect on the weather i.e. warming up the oceans, but it is so hard to isolate the effects and measure them due to all the local weather conditions and cycles that take part on earth. I came across weather modelling on the second year of my physics degree, as it is classed as a chaotic system, first studied by Lorenz, the inventor of the butterfly effect and chaos theory. Are you sure you are not a physicist?

[Penellype]

That's brilliant! Quite fascinating that you mentioned sunspots. This is heavily under investigation. They do seem to increase the sun's brightness, and that must, logically, have some effect on the weather i.e. warming up the oceans, but it is so hard to isolate the effects and measure them due to all the local weather conditions and cycles that take part on earth. I came across weather modelling on the second year of my physics degree, as it is classed as a chaotic system, first studied by Lorenz, the inventor of the butterfly effect and chaos theory. Are you sure you are not a physicist?

Back in the days when I was at Uni (longer ago than I care to remember) I did chemistry and went on to do an MSc in quantum theory, which is sort of physics. I didn't really understand a word of it though!

Sunspots go in an 11 year cycle, with quite definite maxima and minima. We are currently heading towards a minimum from a notably low maximum in the current cycle. There appears to be some correlation between solar minimum and cold winters in the UK - the last solar minimum occurred around 2009-2010. Low solar maxima are correlated with cooler periods in general - the "little ice age" when people could walk on the Thames in winter was during a prolonged period of very low solar activity. There are plenty of other factors involved however - nothing is ever easy in weather forecasting, particularly in the longer range department!

[vixylix]

I'm off next week... there better be some warm weather

[Ryez]

Though so!! The use of technical terminology gave it away! There is a website for space weather, I check it for fun when solar activity is high, just cause I am interested in solar flares. Now I am rather curious for correlations of weather and sunspots! And that's indeed the magic word. In the first year we used images from NASA to measure the ozone hole, and yes you can clearly see it has become larger, but correlating it with the actual reason for why that happened is much more difficult as there are so many factors involved.

SpaceWeather.com -- News and information about meteor showers, solar flares, auroras, and near-Earth asteroids

It gives sunspot number and other info.

[Penellype]

Yes, I've seen the spaceweather website, and tried on numerous occasions to see the northern lights when alerts have been issued, but so far I've not managed to see it.

You might find this interesting - weather related videos on solar activity Solar Cycles 24 and 25

[BUFFS]

Remember that if it is sunny the temperature will rocket very quickly in a greenhouse.

so they tell me, I will let you know if it ever happens round here..

[Ryez]

That's interesting stuff, thanks Penellype, it's great that we get the weather from a Pro!

[Penellype]

As often happens the models are backing off the heatwave as the time gets nearer. Tonight's run of the GFS shows a much less exciting 850 hPa temperature of around 12.5C here, which will still be pleasantly warm but nothing out of the ordinary. Any real heat looks very likely to be confined to the south.

This often happens with forecasts in the 5-10 day range - the models can get very excited about something and forecast quite extreme heat, cold, rain, wind etc, but as the time approaches they often moderate it and sometimes change it completely. This time all of the models were going for extreme heat, not just the GFS, but the end result has been just the same.

[Thelma Sanders]

I bear the long forecasts in mind, but don't think of them as set until it's just a few days ahead, otherwise I get all disappointed when we don't get what was forecast.
I've been waiting all week for some showers that never really arrived, all we got was a 10 minute 'spit' that didn't even wet the path *grump*