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There was already a guide written by me about UK thunderstorm set-ups, but it was done some 7 years ago now and I've felt for a while that it needed a re-vamp and updating to make a more comprehensive guide to the processes that produce the various types of thunderstorms we see in the UK. So here it is ... the Netweather guide to thunderstorms in the British Isles .... 15 pages long: Thunderstorms in the British Isles.pdf

If some are wondering why I have started an autumn thread now, I point out that the summer 2013 thread was started on the 4th of April, when we were still freezing and spring hadn't even started. Autumn tends to be a forgotten season, people tend to look at prospects of the following winter instead. You can get some lovely warm later summer weather well into October. I do like October sunny warm weather. What are the prospects for Autumn 2013? Dry? Wet? Stormy? Cold?

First signs of Autumn #1 - flowers fading on Elders, tiny berries forming. Time to dust off the demijohns!

Ed Hawkins posted a small comment on this CR. http://www.climate-lab-book.ac.uk/2013/wmo-report/

I'm not sure whether someone has already posted a link to this new WMO report about recent global temperatures in relation to those of the preceding decades: http://www.wmo.int/pages/mediacentre/press_releases/pr_976_en.html

BBC weather for the week ahead

Well... There's no USAF support this year for any Airshows, which is a bit of a swizz, but the last few years there's Been an A10 tank buster, ospreys, and a stealth bomber at riat, not to mention the Migs, .... Would love to see a Sr71 for sure, and if you are savvy with the NOTAMs scheduled U2s are quite frequent over Gloucestershire....... The trick is to get there the day (days) before and see everything arrive most of the static stuff flies in from somewhere..... I'm excited. I even got the tent out and camped in the garden last night to check everything was still in one piece after last years bog. Yay!

KNOCKER I have found a really good tutorial on the stratosphere and Jetstream for you. It is probably targeted 1st/2nd yr uni http://www.ccpo.odu.edu/~lizsmith/SEES/ozone/class/Chap_6/index.htm I would like to sit down and read myself.. ..One day.LOL I have taken one of the professors diagrams and highlighted the position of atmospheric layers and also the position of major Jetstream/s on the pic' below This is a vertical profile that illustrates the change in temperature at different altitudes and at different latitudes of first of the global atmospheric layers Notice the top of the tropopause is highest at the equator and lowest at the poles ( a thermocline or temperature gradient) the temperature gradients from equator to pole This temperature difference between poles and equator is different at different altitudes I have marked in a thermocline in brown. Changes in solar contribution amongst other things alters the temperature gradient profile. This can affect Jetstream strength and position and weather in the troposphere picture from http://www.ccpo.odu.edu/~lizsmith/SEES/ozone/class/Chap_6/6_Js/6-02.jpg and modified and linked to my pics https://picasaweb.google.com/104698633266954768357/STRATOSPHERE#5897831796751546930 Hope that assists.. CLICK the thumbnail below to invoke an enlarged picture

Well, that's kind of what I was saying. Effectively, it is *Incredibly* difficult to do this. Not least because, unlike our little logistics map computer model above, the Navier Stokes equations (actually approximations therein) that make up most dynamical cores are known to be non-linear, very sensitive to initial conditions, and exceptionally difficult to solve anyway. On top of the notion that our models are approximations, so, indeed, are our measurements; we can see that our logistic map exhibits chaos (I don't like the term, but it suffices, here) when we alter our initial conditions by as little 1 in 10,000,000,000. What are the sensitivities inside the models? Are they published? Can we measure sufficient points around the globe at sufficient accuracy? So, in that respect, whilst you may have seen my posts as arguing *for* the models, I am suggesting somewhat the opposite: they are known to have exceptional difficulties. Whether the climate scientists have solved them sufficiently for them to have skill is something that is, in my view, a basis for scepticism of claims made *because* of model output. We must remember that they are tested by simulation (does the model replicate past atmospheric states?) which is not the same as forecasting (does the model predict the future state of the atmosphere?) We are at the stage where we might be able to say "we can simulate past climate using the following attribution of climate variables" I certainly don't think extrapolation such attributions into the future is sufficient, suffice to say that there are at least problems with degrees of freedom (most climate variables are known not to be independent (ice cover for instance depends somewhat on how much sun there is)) and there is also, perhaps, a case of incorrect attribution, which can be an artefact of principal component analysis (ie you use PCA to figure out what does what for a small part of past climate, use that to simulate all of past climate, and if the skill is sufficient extrapolate forward - given only about a third of the past instrumentally recorded climate actually has a measurable CO2 signal, it raises warnings about whether this attribution is sound, or a (in)convenient coincidence) They're all very difficult questions, and I am certain that I don't have the answers although I am looking ...

26th January 2003

Well it looks like the GOM disturbance aka Inv 94L is nothing more than a basic storm and rain event as the surface trough axis has pushed ahead NW of the convective mass with a southerly windflow sending it all for a "welcome" downpour for TX & Lou with minor attempts at forming Low centres and circulation failing to transpire fully on a few occasions thus far. 95L however is looking quite a visible feature 900 miles SW of cape verde with brief images of possible banding visible on its SE periphery but its not just a fast transit & closeby prominent SAL that are most likely to hold it back but ever increasing proximity to the low level strong Easterly trade winds that make any circulation more difficult the more it gains in latitude, "IF" this keeps further south, not moving much further North on its 8-15° Lat path until it leaves the Atlantic, then it may have a better chance at TD and more once it slows down after the less antiles? NHC are keen on this in hindsight and currently have it on "Orange" 30% so a watch is on but the Mid-July activity for developments East of the Caribbean are most definitely on target and 95l is merely the beginning. What`s equally intriguing is the timing of these waves and relative nearby TUTT & ULL`s and such in wether they lay victim to diminishing any chances of enhancing thunderstorms by "shredding" them or the opposite by aiding waves if their further away by clearing out upper diverging air well ahead of any tropical wave?

I can't express how happy I am to see summery weather in summer. Went to the beach yesterday (and even went into the sea - yes it was cold ) and went cycling today. Perfect summer weather for summer activities, long may it continue please!

Are you not going to give Autumn a complex if you just ignore it ? Poor little fella, I'm going to get I love Autumn tee shirts Contrasting in need no way I can see Michael getting into that skirt/dress. October 1985 was one that stands out for me (warm)

For instance (as a corrolary to my last post) consider the equation commonly referred to as the logistic map , xt = Rxt-1(1-xt-1) This is a remarkably simple dynamical equation. Essentially, what we do is we say that x has a relation to a previous time period. So we choose a value of R (in this case we'll choose 4) and we'll plug in what x was the previous time period into the x we're currently interested in. Clearly, we're going to need as starting point for t=0; I'll use 0.2. Here's what the chart looks like: Pretty unremarkable apart from the observation that the pattern appears to be complete unpredictable (no reoccuring cycles etc etc). Now, let's say we have a way of measure units to one 10 billionth of a unit ie 0.0000000001. That's a pretty small change, I'm sure you'd agree. Here's the chart with a starting condition of 0.2000000001 along with 0.2, Now, if you're still awake, that's pretty amazing. It follows the pattern for, say, the first third, but then goes and does it's own thing a little later on. Maybe a fluke, so let's add the next one 10 billionth of a unit. Here's the chart for the three of them, Same thing: the third attempt is nothing like the first or second. Here's what it looks like for, So what can we say about this? Well we *know* that these series' are produced in a deterministic way, after all we know the equation that produces them. The only thing that has changed is the starting condition which we have perturbed (adjusted) by exceptionally small amounts which leads us, to effectively be unable to predict the final outcome no matter how accurate the initial conditions happen to be. Of course, a wild outlier as in incoming parameter will lead to a wild outcome, too. It is just like being between a rock and hard place. It is therefore an obvious conclusion, in the case of the logistic map, that higher quality data does not necessarily lead to more accurate predictions. Weather and climate models certainly behave in this manner [ii] Take this morning's GEFS 850hPa ensemble output, This should now look familiar with the classic signature of initial conditions vastly affecting the outcome. This is all obvious with the weather. When the runs bifurcate, we know that confidence in a forecast rapidly drops away; but what happens with climate predictions? Well, they publish ranges, too, based on ensemble runs, and statistical analysis of those runs. https://en.wikipedia.org/wiki/Logistic_map [ii] http://judithcurry.com/2011/02/10/spatio-temporal-chaos/

Yep, with a few adults. They young ones are a dull brownish grey. It's fun watching the adults feeding them meal worms in the garden lately.

They look like young starlings to me.

Latest anomaly for Dec and for Jan

Not autumn strictly but here is a plethora of charts I've saved from the CFS over the last 2 months depicting the same -NAO pattern

Yes!

Amazing photo of wind turbines causing lines of low level cloud in North Sea http://www.climatewatch.noaa.gov/image/2011/wind-turbines-churn-the-air-over-the-north-sea

I think it doesn't matter it's a little bit cooler. Lot of the sea ice is thin. It will melt anyway during the summer. But I can be wrong

Graham's hierarchy of disagreement

Cool photo. The beauty of spring is hard to destroy – even when it is caught in the grips of ice. This daffodil was completely entombed in ice after water dripped on it from a conservatory roof. http://www.shropshirestar.com/news/2013/03/27/icy-grip-on-spring-daffodil/