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Hiya

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    Scotland - Weather Chat

    in Regional

    Posted · Edited by Hiya

    I travelled far and wide yesterday.  Moved about 3cm off the car in Kingussie and went off to Aviemore where there was only a dusting.  Went to Carrbridge where there was about 3cm and temp was about 0C.  Off down the A9 at 3pm there was about 10 cm in the Dalwhinnie/Drumochter area, -1C frozen slush on the road and some idiotic driving.  Beautiful sunset, drifting snow off the tops catching the golden light, hundreds of deer and grouse at the side of the road and a golden eagle soaring overhead, magical.

     

    Only an icy dusting at Bruar and nothing by Pitlochry.  Very heavy wet snow and sleet coming over Sheriffmuir with the temperature hovering about 1/2C.  Just the wrong side of marginal for what might have been a really good snow event in low lying areas.

     

    4C and raining at the house in Glasgow, 7C today with the snow line on the Campsies slowly rising.

     

    post-2658-0-05740900-1418050848_thumb.jp

    • Like 12

    Scotland - Weather Chat

    in Regional

    Posted

    Are you up there Hiya? Thats were my folks live so shall ring them in a min - I bet they really want me ringing early on a sunday to ask them to check the weather. 

     

    2C here and some cloud cover and light breeze

    Yes just up for the weekend, been chucking it down all morning. Off to carrbridge for a walk.

    • Like 1

    Scepticism Of Man Made Climate Change

    in Climate Change

    Posted

    Is the climate getting more extreme?

     

    As is often asserted by a vast army of commentators, a warmer climate means more extreme weather. The corollary is quite clear: in a warming climate we should expect seriously cold spells, as well as scorching heatwaves as our planet struggles to keep up with pace of change. On the face of it, this is a reasonable thing to think and to expect. More heat, more moisture, more peculiar weather patterns.

     

    Observations also seem to corroberate this idea. We've seen arguably the hottest year for Australia, and some lethal cold in America. These weather events certainly seem to confirm it. Also, we see that more and more heat-records are broken year in and year out. A consequence of this is that such fluctuations, since the quantity of them is apparently increasing, must be determinable from the climate record - the mean of any series is not stable enough to absorb outliers, for instance.

     

    Let's have look shall we?

     

    Here's HadCrut4,

     

    Posted Imagehadcrut4.png

     

    Clearly, we've been warming; so, essentially, we can test the assertion that a warmer world means more extreme climate. One way of doing this is to see if the climate record fluctuates a lot, and by how much. Essentially, you measure the distance the temperature record appears away from the trend line. However, HadCrut4 is not as simple as that. This series contains trends within trends. We can see this is we simply detrend using a normal linear trend,

     

    Posted Imagehadcrut4_linear_trend.pngPosted Imagehadcrut4_detrended.png

     

    So, what to do? Well, we need to create a line to fit the HadCrut4 series in a much tighter way. There are zillions of methods of doing this, some complicated, some quite easy. I will use the easily available polynomial regression. Unfortunately, because of the trends within trends we have to use quite a high order to capture the qualities of the series. Here's the polynomial regression of order nine,

     

    Posted Imagehadcrut4_poly.png

     

    This, it seems to me captures the qualitative nature of the series; it captures it's ups and it's downs quite nicely. Quantitatively it is also a better fit - as it should be - as shown clearly by the r2 scores on both the linear trend and the polynomial trend. Now, of course, we have a model of the temperature series we can subtract that polynomial from the actual data series to gives a series where there are no trends, nor trends within trends - effectively, the random noise of climate fluctuation. Here it is,

     

    Posted Imagehadcrut4_poly_detrend.png

     

    I've added a linear trend to the result to check whether we really have removed any trace of trend. Whilst there are numbers - not zeroes - this is an artefact of floating point computation which often never reports zero but reports very small values either side of it. It is also, perhaps, the product of Guassian Elimination which is the algorithm used to compute the regression which is known to be sometimes numerically unstable particularly with floating point arithmetic. Anyway these numbers are sufficiently small that they might as well be zero, and rounding to, say, 10 decimal places effectively makes them zero. I could have done that, but you chaps might as well know the problems with semi-numerical computational analysis.

     

    Interestingly the r2 value is also (more or less) zero - indicating that there is no correlation between a linear trend and the resulting series. This is what we want: we have effectively removed the trend, and the trends within trends leaving effectively noise - the fluctuation of the climate.

     

    Now we can have a good close look at it. First things first, let's draw a graph. Here it is,

     

    Posted Imagehadcrut4_30yr_stdev.png

     

    The standard deviation is a measure of how much a series disperses from the average; which is ideal for us who want to test the assertion.

     

    Well, it seems to me, that the hypothesis that the climate will fluctuate more wildly given a warming climate is completely falsifiable, and, here, it is falsified. It simply isn't borne out by simple observation. Indeed, the complete opposite is true. Empirical evidence only shows that a warming climate makes the climate more stable.

     

    That's not to say other observations about the weather are incorrect, but it puts them in their place. Quantities of record heat temperatures, and a lack of quantity of record cold climate are purely because the trend of the climate is up. This is a mathematical consequence of an upward trend - of course you expect an increasing frequency of warmer records if the climate warms(!!) - and certainly not evidence of the major physical changes of warmer climate - and the subsequent nightmare, going to hell, we're all going to burn catastrophists take on things.

     

    This analysis shows that warming up the world makes things more stable - at least in the short time frames of the temperature record.

     

    I love a bit of DIY science.  Good job.

    Scotland - Regional Discussion - 23/12/13 >>>

    in Regional

    Posted

    I think the key was the word 'slack' - if we'd had even a modicum of surface cold ahead of the front it could easily have been a very snowy setup. As it is we were reliant on latent cooling from heavy precipitation to drag the freezing level down and that's a pretty difficult ask, especially since the front appears to have been a bit weaker than initially modelled and also because it's the middle of the day after a not all that cold night.

     

    Exactly the reasons why it wasn't going to snow to low levels. 

    Scotland - Regional Discussion - 23/12/13 >>>

    in Regional

    Posted

    Hmm, it's going to be in the top 10 certainly but not sure it's quite record breaking - Phillip Eden currently has the anomaly at around +2.1 to the 25th for Scotland (+1.6C for North, +2.3C for West and +2.5C for East), the 81-10 mean is 2.8C for the whole month which means we're probably running around the 5C mark to the 25th. The next few days aren't going to see anything massively mild to push that upwards so I reckon we'll be stuck somewhere between 5.1C and 4.7C for the month as a whole. Anything above 4.9C would put us at 5th highest in the rankings but I think we're probably safe from ending up in the top 4, which are:

    1988: 5.8C

    1971: 5.7C

    1934: 5.6C

    1924: 5.6C

    The next ones down are '31 and '21 (both 4.9C), '74 and '42 (4.8C) and then '56 and '53 (4.7C). The lack of very mild Decembers since 1988 has been very noticeable given almost all other months have seen either record or near record highs in the 100 year series since then - 2006 at 4.4C was the mildest since then and we're almost bound to come in higher than that, so this will be the mildest December in 25 years and will bring to end the longest run of consecutive sub 4.5C Decembers in the last 100 years.

    http://www.metoffice.gov.uk/climate/uk/datasets/Tmean/ranked/Scotland.txt

    Seems odd to say when talking about mild months in the context of AGW/the general increase in Scottish and UK temperatures in the last 100-200 years but we were overdue a mild DecemberPosted Image

    Extremes are a good way of evaluating a long range forecast. Further the deviation from the average the better since there is less chance of the forecaster being "accidentally" correct. Your forecast for December is quite impressive, certainly better than the offering from netweather, but there is an inconsistency between predicted weather and average temperature which would have moved it into the outstanding category.
    • Like 3

    Scotland - Regional Discussion 16/12/2013 >

    in Regional

    Posted

    you could be right for many in scotland but looks severe for N/E Scotland

     

    Posted Image

     

    A bit of IMBY in my statement yes, around Peterhead it does look quite bad.

     

    Gusts over 80 mph I would put down as serious.  We'll see if the Tay bridge gets closed, which is supposed to be at 80 mph but a couple of times when there has been a lot of hype about a storm they close it as a precaution. 

     

    I'm bored of wind and rain now, can we get some snow please?

    • Like 3

    Scotland - Regional Discussion 16/12/2013 >

    in Regional

    Posted

    I am not really up on chart reading Hiya but i think you said in a post yesterday? that there wasn't really a tight enough gradient and this would  allow pressure to spread instead of being squeezed?

     

     

    Yes pretty much.  I stand to be corrected, but to me apart from the very low pressure the weather won't be anything of note.

    • Like 1
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