PhilipEden

The sequence of monthly CETs so far this year confirm what we all know anyway, and that is what a late spring it is. Another technique is to use aggregate degree-days on a 6°C base (i.e. add up each daily mean temperature [mean of max and min is near enough] and then subtract 6) because plants don't grow much at all if the temperature is below 6. Round these parts 50 deg-days usually produces the first daffodil, 100 deg-days plum blossom, 200 deg-days laburnum: Year 50dd 100dd 200dd 1983 26Feb 17Apr 14May 1984 11Apr 24Apr 22May 1985 02Apr 17Apr 19May 1986 24Apr 06May 25May 1987 27Mar 17Apr 01May 1988 15Feb 02Apr 04May 1989 28Jan 09Mar 02May 1990 04Feb 05Mar 02Apr 1991 11Mar 29Mar 12May 1992 27Feb 20Mar 28Apr 1993 17Feb 22Mar 27Apr 1994 08Mar 31Mar 03May 1995 12Mar 31Mar 25Apr 1996 11Apr 23Apr 27May 1997 08Mar 23Mar 29Apr 1998 10Feb 23Feb 07Apr 1999 04Feb 18Mar 12Apr 2000 27Feb 21Mar 03May 2001 16Mar 10Apr 13May 2002 02Feb 05Mar 13Apr 2003 09Feb 23Mar 21Apr 2004 04Feb 20Mar 25Apr 2005 11Feb 23Mar 25Apr 2006 26Mar also 1969 09Apr 27Apr 14May 1962 11Apr 04May 22May That shows just how late the spring of 1996 was, thanks to consistent cold from March to May. How welcome that early-June heatwave was, even to those of us who don't enjoy high temperatures. Philip

Even apparently legitimate statistics can still be used to spin a story: http://www.climate-uk.com/temp3.htm You could equally correctly, though even more misleadingly, say that "parts of Britain had their warmest winter this century", because at Stornoway and Kirkwall it was the warmest since 1997-8 and at Lerwick since 1991-92. Philip

Lots of points to refer to ... I'll probably miss one or two, but hey ... One curiosity that will interest Kevin especially, is that (based on the Manley figures, doesn't quite work with Hadley) this is, unless I've missed one, the first time since 1969-70 that every month from Nov to Mar has come in below 6°C. Another curiosity that has been talked about before, and which may now be acquiring an extraordinary symmetry, is the absence of transition periods in autumn and now spring, so that for many of us there were few if any maxes below 10°C before mid-Nov, very few maxes over 10°C between mid-Nov and last week, and the likelihood of few if any maxes below 10°C after Mar 23. Re standard periods, I've always favoured the latest 30-year period for individual sites for all the reasons that it was established in the first place. But recognising that we are in a period of marked climate change I also, where I have space, talk about the ranking of a particular month/year/whatever over the last 100 years. So this March, for instance, was 1.4 degC below the 1971-2000 mean, and it was 29th coldest in the last 100 years. (It's similar to having a rolling-100 year average, but for the purposes of communicating with Joe Public it avoids having two different differences, which is liable to confuse). Re calendar months sometimes giving a false impression ... yes, well, that happens all the time. I remember on 14 May 1996 Bill Giles making the crass comment that, if the second half of the month was as cold as the first half, then it would be the coldest May on record. The next day (the 15th) he said we were on course for the driest May on record, then it started raining and hardly stopped for the rest of the month. An awful lot of months are made up of contrasting periods. Remember how the sunshine last month was approaching 300% of the average after the first week? It finished on 94%. Re having CETs for 30 or 31-day periods other than calendar months ... this is, naturally, of most interest at the extremes. Thus we have achieved a 30-day CET above 20°C between 22 June and 21 July 1976, and between 23 July and 22 August 1995, while the CET for 26 Dec 1962 and 25 Jan 1963 was close to -3°C. I've gone into these before, though I'm not sure where (!!) ... by the way, are factual threads archived on net-weather? FWIW, there is a running 30-day CET on the "How is March Shaping Up?" page on the website and it is interesting to note that the lowest 30-day figure during winter 2005-06 was 3.2°C, compared with 3.1°C for the lowest such period during winter 2004-05. Philip

FWIW, the NTLRF* comes out at +0.3, in other words 8.4°C. Philip (*NTLRF = Not The Long-Range Forecast)

Low 999 just east of Newfoundland with marked trough extending across Atlantic, Br.Isles to Denmark. High 1018 Madeira and High 1030 northern Greenland. Cyclonic/southerly gradient across the UK. Anomalies: -13mbar between Azores and Newfie, +13mbar east Greenland, -7mbar Romania. Strong easterly anomalous flow over northern and central parts of the UK but cyclonic/variable southern regions. Manley CET is 5.01, Hadley likely to be 4.96. Philip

Exactly right ... and refining one's efforts over twenty years or more leads one to become, setting false modesty aside, something of an expert. I don't like "official" ... we live in a world where "official" is widely used to attach a false or spurious credibility to an idea, a person, etc. Although GM was my M.Sc supervisor, and I subsequently exchanged letters with him a couple of times, I cannot say that I ever had a proper climatological conversation with him, much to my regret. However, I believe he would have appreciated my attempt to draw back from the three-site index used by the MO and to continue his own series using his own method. Let's just call them the Manley CET and the Hadley CET. That's clear enough. Philip CORRECTION: not my supervisor, my external examiner Philip

It's simply a normalisation adjustment. If the 1971-2000 mean of the three stations they use to calculate the Hadley CET for, say, April is 7.97, and the 1971-2000 mean of the CET is 8.11, then the adjustment for that month is +0.14. The figure will vary (smoothly, one hopes) from one month to the next. Until two years ago, when they used Ringway and Squires Gate they also applied a slowly growing urbanisation adjustment which had by then reached something like -0.25 + or - 0.05 throughout the year, but of the stations they now use one is entirely rural and the other two minimally urbanised, so the urbanisation factor is now exceedingly small. I think they explain the detailed procedure in a paper which can be accessed on their site (sorry, don't have the URL handy). If the max of Lancashire and Oxford this afternoon comes out at 13°C, then the Manley CET for March will be exactly 5.00°C (if 14°C then 5.02°C) and the Hadley CET probably 4.85 + or - 0.05 (but don't hold me to that latter figure as I haven't QC-ed all the obs yet). At a local level, it will be variously the coldest March since 2001, 1996 or 1987 ... when I have time I'll try to produce a 'cheimochronic' map for the month. Philip

Sshh, don't tell anyone, but on BBC shifts I can access the relevant station data. I've also more-or-less sussed out their fudge factor, whoops, sorry, I mean "bias adjustment". Philip

Given the wraith-like quality of their figures over the last 2 or 3 years you are clearly being extremely generous to them! My attempt to emulate the Hadley figure for February produced 3.8°C on March 1. This month's Hadley figure is likely to be approx 0.1 to 0.2 degC below the Manley one. Philip

Oddly enough, there's some stuff about it in "Weatherwise", a book wot I rote 12 years or so ago. A lot of the subjects Paul Simons writes about have turned up in that book. I must have climbed into a time machine, travelled to the future, read all of Paul's columns, and travelled back to put them in the book. Funny I can't remember. But it's the only possible explanation ....... Philip

Well, after 3 days, it is the entirely unexpected months of December 1973 and January 1974, both of which warmed up rapidly thereafter. There appear to have been several instances in the 60s and early 70s. But nothing since then unless I missed it. Philip

I'd say that, if we are ranking the unusual aspects of this winter, the absence of strong winds has been at least on a par with the lack of rain. Here in Luton I have had just 9 days with gusts >30mph since the beginning of November. There were 9 such days last October alone, and I don't remember that as a particularly windswept month. There were 30 in Dec/Jan/Feb last winter, and 42 in winter 2001-02. Philip

Well, yes, you're right up to a point. The only thing I would add is that the tropical airmasses have still been flooding western and northern parts of the British Isles, but on practically every occasion we've had high pressure somewhere near southern Britain, so that down here the tropical air sat above the subsidence inversion while stagnant cooler air remained beneath the inversion. Hence the large number of of 10+ days at places like Kinloss, Lossiemouth, Edinburgh, Aberdeen. As for London ... 12 days at Heathrow, 14 at LWC and Gravesend, but only 7 days at Hampstead 140m above MSL and 2 days at Kenley (175m). And SF's tutor ... he gave it away by mentioning CG, although CGS would have even more helpful ! ... Dr Smith of Oxford and Lost-in-Space. Philip Ah ... you've already done that bit! P

This is something I've notice in this district (Luton) as well, Kevin. I've just asked my spreadsheet to tot up the figures since Dec 1 for the whole of the UK and Ireland - isn't Excel wonderful? - and it shows some interesting variations. As you'd expect, the far southwest comes out way ahead of anywhere else with 43 at Valentia and 42 at Scilly, but then the northwest comes into play as well ... Belmullet 29, Machrihanish 24, Culdrose 23, Barra 23, Milford Haven 22, Plymouth 21, Chivenor 21, Stornoway 19, Tiree 19, St Mawgan 19, Camborne 19, Stornoway 19 ... and surprisingly Altnaharra 19 and Lossiemouth 18. The lowest are the hilly areas, again as you'd expect ... even the modestly upland sites of Eskdalemuir, Fylingdales (NYorks), Thorncliffe (Staffs), Lake Vyrnwy and Sennybridge (both Powys) all register zero days of 10°C or more, and there've been only 2 such days at Dunkeswell (Blackdown Hills), Kenley (North Downs), Little Rissington (Cotswolds), High Wycombe (Chilterns), Waddington (Lincoln Edge) and the relatively low-level Wattisham (Suffolk) and Andrewsfield (Essex). Philip

Actually, to be serious for a moment, hoar frost along with dew and fog drip, is a form of precipitation. Historically, therefore, it has never been excluded in monthly rainfall totals. In the old days of manuscript observations the figure would be entered in brackets and followed with a subscript x for frost, w for dew, and fe for wet fog ... eg (0.2)x (except I can't do a subscript). In the exceptionally dry February of 1891 there were several stations which recorded 2mm or less during the month, entirely consisting of aggregates of frost and dew. Philip

I had to do a double take, because I thought for half a second you had got the century wrong ... not as dramatic a contrast, but exactly 100 years and 1 month later we had one that I can remember: September 1965 148.7mm October 1965 32.2mm November 1965 119.4mm And the opposite in 1940, which I certainly don't remember: June 1940 20.9mm July 1940 112.5mm Aug 1940 15.0mm Philip Eden If Eden's First Law is any good, it will undoubtedly not happen, because I wrote a centre-page feature for the Daily Telegraph's millennium edition at the back-end of 1999 predicting, tongue firmly in cheek, a hugely cold winter in 2007-08 plus-or-minus one year, and repeated it in Book of the Weather. Philip Eden

I remember spotting this one after June 1970, and gleefully predicted another hot one in 1980. I couldn't believe my luck when the first week or so of June 1980 turned out to be very warm, if a bit humid and thundery, but the weather then broke and the rest of the month was cold and wet. This is when I formulated Eden's First Law of Weather Cycles: as soon as a weather cycle is spotted, it will fail. It followed on from a shoal of letters and short articles in "Weather" magazine in the late-60s and early-70s predicting a very cold winter in 73-74, 74-75 or 75-76 based on a long-running approx 11-year (i.e. sunspot) cycle of cold winters (1963, 1951, 1940, 1929, 1917, 1907, 1895). All three, of course, were ridiculously mild. The Law was proven a few years ago when another extraordinary 11-year sequence failed spectacularly: November rainfall as a percentage of the 1971-2000 mean: 1802 59% 1813 66% 1824 134% 1835 103% 1846 59% 1857 56% 1868 61% 1879 37% 1890 116% 1901 66% 1912 76% 1923 91% 1934 63% 1945 17% 1956 33% 1967 78% 1978 48% 1989 61% and 2000 was, of course, rather different at 181% Philip Eden

Can I caution against reading too much into the MO's sunshine series? Since the gradual replacement of Campbell-Stokes recorders with Kipp & Zonen radiation sensors began at the turn of the century, sunshine figures have been all over the place. The MO tell me they apply a blanket +10% correction to KZ figures to produce what they claim to be a seamless link, but anyone who has spent more than five minutes examining records from the two different types of sensor will know that there is nothing seamless about it. On a daily basis, the comparison of CS to KZ varies between -15% and +100%. On a monthly basis that reduces to -5% to +40%. Having tabulated and analysed these figures for four years, my provisional conclusion is that it is simply not possible usefully or accurately to merge the two sets of records. Philip Eden