snowking

I will be finalising my summer thoughts during this weekend but just to say, very little has changed from my thoughts posted here: http://forum.netweather.tv/topic/72635-the-seasonal-forecast-thread/?p=2670262 As previously discussed, one of the better periods of the summer looked to be Late May/First Half of June....I look at the moment to be about 5-7 days out on this, but certainly as we head into June the prospect of a more pleasant spell looks increasingly likely. The next likely extended settled spell then looks most likely around the middle of July. Also, as previously stated, there is an expectation based around rolling the current analogue years forward into the Autumn (and assuming that ENSO and QBO behave as expected) that October may end up being the best month of the year - thats one that I will have to keep an eye on as the months roll by. The predominant pattern for the summer is still expected to be the mean Sceuro type trough pattern, with temperatures below average and rainfall around average. Thus far May has backed these thoughts up for me, and indeed if we take a look at a couple of examples from this month so far: And compare it to the expected 500mb anomalies projected from the two best match analogue years for May: And the overall QBO derived analogue years: We see a pretty strong resemblance to the month so far - the predominant flow from a Northerly quadrant, with the positive and negative 500mb anomalies placed in similar fashion. This, in turn, lead to an unusually high rainfall anomaly projection for the near continent: And so it is even more interesting to read this from Nick Sussex: Obviously the enhanced May rainfall anomaly didn't quite stretch down that far based upon the analogue years, but an indication nonetheless that the continent has been seeing this enhanced rainfall signal. SK

RE: Risk of snow tomorrow Looks to be the potential for up to 10cms above 200m in Scotland, with the risk of a few cms across the highest ground elsewhere (Pennines in particular) Other high ground likely to see snow falling - Wales, NE England, perhaps Chilterns, Cotswolds and Downs too, though accumulation unlikely in these areas other than temporary deposits To lower ground the chance of a wintry mix within the showers with supportive dew point profiles, but the atmosphere generally from around 900mb downwards is less supportive - you will be relying on downdrafts if you wish to see anything wintry here. The next risk then comes as this rather active occlusion: Heads in from the North-East. Mostly rain, but sleet/snow likely across the higher parts of the Pennines, perhaps the North York moors too - perhaps a few flakes to lower levels overnight during any heavier bursts. SK

Stronger hints beginning to develop in the GFS now for a more settled spell towards the end of this month: It will be some days yet before we can get a decent comparison from the ECM EPS suite, but the timing fits in perfectly with expectation at present. The MJO just beginning to show hints of an eventual phase 1 progression (both the GFS and GEM moving towards this area): The 500mb anomaly projection for phase 1 in May ties in nicely with a potential Azores HP influencing the UK: If we roll this forward into June: So my thoughts for later in the month and into the start of June remain the same - settled weather taking over, and it could end up being one of the best periods of the summer SK

Not too much support for tonights 12z ECM det. from the ensemble means out to day 10 i'm afraid to say: Fairly strong signal (and almost universal support) for low pressure to be anchored just to the North-West of the UK - always the chance in such a setup of transient ridges from the south, but its a largely unsettled picture up to day 10 at present. I would be looking towards the day 12-15 period at the moment for signs of something more settled, and whilst we can possibly conclude that the 11-15 day mean height anomalies are merely portraying a weakening overall signal, there is a notable reduction in the projection of the mean trough that dominates proceedings for the UK through the earlier period. Below is days 6-10 vs days 11-15 from the GFS 12z: My summer research had always suggested that the best chance of an extended settled period was around the final days of May and into early June. Still a lot of time to run on this one at present but for now the predominant signal is unsettled and cool for most. Perhaps just the very first few signs of change on the horizon though for later this month. SK

Sorry i've been pretty busy recently so have been away from this thread for a while Just to clear up CC - my thoughts from the preliminary research were for below average temperatures but rainfall around average - which will prove a bit of a shock to the system given the deluges of last summer! So certainly better than 2012 (which isn't particularly difficult to achieve) but given a projected mean 500mb anomaly pattern suggestive of toughing primarily just to the East of the UK, still not fantastic. The only real straw to clutch is that the composites created do suggest high pressure never too far away from the South-West of the UK (similar to the last few weeks really) which may give southern areas in particular some periods of respite. One more tidbit - analysing the similar analogue years (QBO and ENSO based primarily) the best chance of a prolonged settled spell is around the final week of May and the first two weeks of June, so thats certainly one to watch out for to see what sort of shape my current forecast is in. Kind Regards SK

It must be said there has been a big swing back towards slightly below average from the 0z ensembles across the North, these for Glasgow: Red is the 0z, in comparison to the previous 3. This now leaves it more in line with the GFS ensembles temperature wise, and it must be said the GFS has been there now for quite a few runs: (ECM in red, GFS in black) You suspect that the tide is perhaps turning against the duration of any warm up proving significant, particularly across the northern half of the UK. This noticeable too with the centre of our positive 500mb height anomalies being nudged a bit further south over the last 24 hours. If we take a look at day 10: ECMWF 12z yesterday: 0z Today: Though it should be noted that for as long as we have the disparity between the ECM and GFS 500mb outlooks, we cannot be hugely confident of the outlook beyond day 5, with the GFS resembling something closer to the suggested summer baseline pattern with a Sceuro type trough the main player for the UK at day 10: The 11-15 day mean then establishes this prognosis further: This, again, has been a pretty consistent suggestion from recent GFS outputs now. A lot of uncertainty heading in to the medium-term then still, but our warm up seems currently to be getting shorter and less geographically spread SK

Well I am happy to report that the downward trend from the ECM has now reversed from 0z yesterday: Red is last nights 0z, blue is yesterdays 12z, and green was yesterdays 0z. But then typically as the ECM starts a climb upwards, the GFS has been on a downward trend over the past 24 hours (black is yesterdays 12z): But I would say theres enough agreement for at least something slightly above average in todays outputs with some fine, milder weather for around 5-6 days which will be very much welcome should it transpire Now we want to see this repeated over the next couple of days SK

Awaiting the 12z ensembles but it should be noted the general trend from the ECM over the past 48 hours has been to reduce the mean from slightly above average to below average (Red is the 0z from today, then Blue, Green, Black): At the same time the 0z in particular showed an uptick in mean precipitation projection: I'll have to report tomorrow what the subsequent 12z and 0z runs following on from this suggest, but nothing above average currently looks on the horizon to me, and we may be made to wait until the second half of May before we see such an occurrence SK

Just to give you all an idea of why I don't presently buy into a long, settled spell for May. Heres a few of the composites from my initial summer forecast research for May (showing 500mb anomaly): First of all, based around the strongest QBO index value years: Then with strong ENSO matches added: And finally, with the two strongest composite years in terms of QBO and ENSO at the same time: It will be interesting to see how long any sort of positive euro height anomaly can be maintained, because the expectation from me is that the Sceuro type trough is likely to become dominant. In fact, the best chance of the summer for a long settled dry spell for me looks likely to be very late May or early June. Only one run, but the subtle changes from the GFS ensembles in the 1-15 day time range is noticeable vs previous outputs Yesterdays 12z: Todays 0z: You need more than one run to create a trend obviously though, so some tense viewing of future ensemble outputs will ensue I suspect! SK

It will certainly prove an interesting test for the various NWP MJO outputs. ECM currently the only one hugely keen on phase 2: Meanwhile GFS, GEM and UKMO tend to stick with a weak phase 1 projection: And just to offer some balance....the JMA goes off on its own merry way: But it does throw up another outcome to look at - the ECMWF projection keeps us in phase 2 for around 5 days, before pushing into phase 3 territory, and phase 3 has us back to something less settled looking: MayPhase3500mb.gif So it could prove an early season chance for us to see which model to look at in the coming months for MJO projection - the ECM projection of phase 2 would do very nicely! Sk

I think we need to hang fire for a while yet in terms of the outlook beyond day 10. The 6-10 day 500mb anomaly means paint the picture pretty well: I guess we can call that a displaced Sceuro trough - whatever you want to call it, its likely to result in a mostly unsettled phase of weather for the UK. Some hope from the North American models perhaps of something more settled in the 11-15 day range: But in all honesty, its not an especially strong anomaly signal just yet, so we will have to wait a few more days yet to see where we stand on this. The most recent EC32 update suggested a continuation of the slight below average temperatures - heres the TMax projections for Birmingham: And here's the last 5 ensemble mean Tmax values for Glasgow: As you can see from that, nothing spectacularly warm projected, with values around 12-13c from the May the 4th (be with you) onwards. So, in the shorter term, our baseline summer pattern with that Sceuro type trough dominating proceedings for the UK (though the chance of course of a temporary ridge of high pressure once again towards next weekend). Beyond that the American currently pointing towards some sort of Euro pressure build, though this should be taken with a pinch of salt for a few days yet until we see a stronger anomaly signal develop, or indeed see the ECM start to become interested - GFS/ECM combo is pretty useful at such range, where as disparity breeds uncertainty SK

Ensemble means today show pretty good continuity to day 10, with a Sceuro type trough setup, though HP never too far away to the SW, so some hope for those further S and W that we may see influence from this from time to time (Ensemble mean height projections for days 6-10 added for comparison to overall summer 'baseline' prediction) Interestingly, this sort of setup corresponds pretty well to the overall H500 mean anomaly projection for this summer based around similar QBO/ENSO index years: If we focus this in a little more, and take a look at May based upon the two strongest composite years (1978 and 1962), we see a similar result: So, we should be looking at those ensemble means as the likely baseline conditions for the period through May-August. Summer 2013 will likely be nowhere near the record levels of rainfall experienced through summer 2012 (generally expected to be around average overall), but the cooler than average temperature theme is likely to persist SK

Unfortunately for those of us looking for a bit of warm, settled weather, the Sceuro type trough setup is the overwhelming signal for the summer as a whole from as early as May, and as such, the closer we move towards the new month, the more likely we are IMO to see something more akin to the ECM offering as opposed to the GFS (not to mention that 9 times of out of 10 you would trust the ECM more than the GFS in the extended range)A fairly pleasant weekend to come but it looks increasingly cool and unsettled towards the end of the month SK

I have highlighted the key part of Matt's wording there If we take a look at the GFS 11-15 day outlooks over the past few runs: With high pressure just to the SW and NE of the UK, always the chance of something drier from time to time with temporary ridges building (as per this coming weekend), however I suggested back at the start of this month that unfortunately, given the signal for a rather cyclogenesis dominated start to May from my preliminary summer forecast work, and the fact that synoptic setups at present seem to be becoming rather locked in for long periods (likely to bear fruit at present, especially given the lack of MJO forcing at present), the second half of April in general was likely to be rather unsettled. Interestingly, though, whilst the idea is of a low pressure dominated pattern, the rainfall levels overall didn't look anything particularly concerning (especially against the backdrop of Summer 2012), and to a certain extent, the last couple of EC32 runs tend to suggest this: With just a gradual increase in rainfall as we head towards May. For interest purposes, my early research suggests the best chance of any extended settled weather is during the latter part of May and into the first half of June SK

Thanks for that BFTV, that will be a huge help! And thanks for clearing up the method of calculation. The reason I found it slightly suspect is that it would be far easier to adjust anomaly data than actual data, but this explanation helps to allay my concerns. The explanation came from the Met Office website here: http://www.metoffice.gov.uk/research/monitoring/climate/surface-temperature I am investigating any potential links between global mean average and Central England temperatures and the following: - Atmospheric C02 concentration - Maximum (smoothed) sunspot count per cycle - Solar cycle duration The only other problem I have encountered so far is that the C02 data I have found here: Globally averaged marine surface monthly mean data Only goes back to 1980, which makes comparisons rather limited with a much smaller sample size, however some interesting findings so far on the solar side of things, with the correlation between CET and max sunspot count giving a higher correlation than solar cycle duration, which is in contract to the paper by David Archibold based around projections of solar cycle 24 and 25, where they used the De Bilt dataset and found stronger correlation with solar cycle duration (though I suspect I may have calculated slightly differently in that I have taken the average CET through each of the solar cycles). Thanks again SK

I'm wondering if anyone is able to help I have been carrying out some research as part of an article i'm about to write based around AGW vs Solar Influence. Thus far I have been using the CET, but I am now looking to produce graphs based around global temperatures. However, I have been unable to find any dataset that offers the actual global average temperature (either on a monthly or annual basis) as opposed to the temperature anomaly. I must also say at this stage that the reasoning given for the lack of this actual temperature data amongst any of the HAD, CRU or NOAA sets seems rather suspect to me, for example: Anomalies are used because: They are relatively constant over large areas, even if the actual temperature at different locations is quite different. In other words, the anomalies can tell us something about the temperature over a much larger area than the temperature that is actually measured. They help to avoid biases by making the data record less sensitive to missing data. For example, imagine a situation where observations from an observing station in the Arctic were missing in one month. If actual temperatures were being averaged together, the global average temperature would seem warmer in that month because temperatures in a cold region of the globe were missing. This does not occur when averaging anomalies, although the lack of knowledge of the temperature anomaly in that region would still reduce the accuracy of the global average. Perhaps I am just oversimplifying things here, but surely in order to work out the anomaly vs the long term mean, you first have to calculate the actual average, before then calculating the difference between the long term mean and the actual average value to give you the anomaly? In which case, it seems a mystery to me as to why the actual temperature values are not published. Anyway, any help on this would be greatly appreciated. Ideally if the temperature sets were provided in some sort of tabular/spreadsheet form that would be great, but even if only provided in a text format I can always manually copy/paste the data across. Many Thanks, SK

Awaiting the ECM ensemble means later, but in terms of the height anomalies, a decent picture being painted for southern areas through next week with the likelihood of high pressure dominating: Really quite solid agreement on this pattern inter-model and inter-run. The 11-15 anomalies offer something of interest to me in terms of the May-August projections based around matched QBO/ENSO index values thus far: Notice the negative height anomalies developing around Scandinavia - a mean Sceuro high is a common theme across both the ENSO and QBO derived composites through many of the summer months, with HP based just to the South-West. I wonder whether this may be the first signs of such a baseline pattern setting up. Such a scenario would offer mostly near average rainfall but a significant negative departure from the 1981-2010 temperature series. Before we worry about any of that though some nice settled and pleasantly warm weather to come for our friends in the South, those of you in the North, however, may have to suffer more in the way of cloud and patchy rain into next week. SK

Typical that as I am up in Birmingham it's snowing like mad back home! Have fun folks SK

Hi John Just to clear up, my final comment was based primarily upon early research into the summer. So far from the analogue years I have amassed, based largely upon closely matched ENSO and QBO index values (to include not only their current/projected states, but also the 12-18 months in build up to the current indexes and how closely matched these may have been to previous periods), there is quite a strong signal for the first half of May, and second half of June to be rather low pressure dominated. The bit in the middle remains a mystery for now, but there is a weak ridging signal from the South-West based upon a mean composite for June, shown here: When compared to May: But given that the present rainfall anomaly is suggested to be slightly below average for May using those composite years, the suggestion for me would be at some stage we would likely see a drier period during May. Given that the overall signal is for a mean Sceuro trough (interestingly a pretty consistent signal throughout the summer period), but at the same time the hints towards June of potential ridging from the South-West, something has to give in terms of the precipitation signal. Up until now, I had been undecided as to whether this may mean that the first half of May would be driest, or the second half. However, given the current model projections (even though ECMWF looks on its own, I have very rarely even in this winter, never mind previous years, seen the ECM ensemble mean to be proven wrong vs the GFS), and GFS's recent ensemble tendency to correct southward with the overall pattern in recent months, together with the ECM 32 day precipitation projection from recent runs: I am now more sure of an unsettled pattern becoming locked in through the second half of this month. Given recent tendency for patterns to be rather slow moving (stretching back many months now) at present, this seems the most logical route forward. I hope that helps to explain my thinking somewhat Kind Regards SK

Some huge differences between the model suites today, but a lot of straw clutching taking place from those wishing for an extension of the cold and snow chances. Its a bit of a case of ECM vs the world in regards to the actual pattern for the UK, however in terms of the overall temperature trend, it is very much upwards. I've seen a few comments about the ECM ensembles 'delaying the warm up'. Up until the middle of last week this was true, however, since then we have seen a consistent prognosis from the ECM EPS for an upward jump in both Tmax and Tmin values, along with a signal for increased precipitation amounts. Below is a selection of tmax ECM EPS runs all the way from todays 0z back through to Wednesday: Really very little difference there and a continued noted increase in temperatures from around April 8th. The difference comes from the likely patterns. The GFS/GEM combo offering something very settled and, dare I say it, 'spring-like', though perhaps more unsettled for the far north Where as the ECM mean is far more progressive with a breakdown in the day 6-10 period, and Atlantic low pressure systems barreling into the UK - in other words, support for the ECM det.: If people would like it put into really basic terms though, the dead giveaway of an impending temperature jump is this: Pretty solid agreement on a return to a positive NAO signature, though worth noting here that, once again, the GFS operational is out on its own in the extended range (getting rather tiresome now), perhaps indicating that something more akin to the GFS Ensemble Mean is in order: On the face of it, thats not a million miles away from the ECM at day 10, just a little further north with the pattern. So then, as a hopecast I would be going for something more akin to the GFS....however back into reality, I think it looks more and more likely that we will have to endure a return to unsettled and wet conditions unfortunately, with temperatures probably just below the seasonal norm, though feeling far warmer than of late. Perhaps the ECMWF is being a little too progressive, and in reality I think we may be waiting until next week before we see anything change significantly. Unfortunately I fear that once this pattern sets in, we may be waiting until the second half of May before we get another chance of any extended dry and warm conditions. SK

I think that's the big wildcard at play here We have seen plenty of signs that the solar cycles will become longer, lower in sunspot numbers, and promote an overall cooler outlook than over the past 20 years or so in NW Europe, but this is by no means confirmed just yet (cycle 24 is far lower than those that went before it, indeed the lowest maximum since the 1930's and the end of cycle 23/start of cycle 24 provided I think it was the lowest minimum since the 1870's from what I remember). However, for now let's assume that this proves to be the case, and that cycle 25 proves an even quieter cycle. We are then entering a solar driven cooling trend against the background of a global temperature higher than that experienced during the Dalton and Maunder minimums. So I think anyone expecting those sorts of conditions should put the brakes on things for now. But certainly from the research I have carried out into this for a commercial client with a vested interest, I would be very surprised if winters for the next 20-30 years, on average, are not much colder than those of the last 20 years - providing, at times, comparisons to winters in the period from 1940 to 1987 SK

Potentially Though the way I would look at it is that the ECMWF is slowly coming into line with the majority model consensus, which was always for this system to remain largely to the south of the UK. Still a few days to go yet though! SK

ECM ensemble mean further south with the potential disturbance for Southern areas on Wednesday/Thursday: And consequently the ensembles less keen (12z Green vs 0z Red) on much in the way of precipitation into Heathrow: Temperature wise no real swing from the 0z suite: And so its as you were really as of this morning, though of note is that the ECM det. is on the warmer side of the ensembles between 192 and 240 SK

And that leaves them firmly in line with the 0z ECM ensembles (as posted earlier) temperature wise at least, with a marked increase in scatter but an overall mean trend upwards from around the 8th April (with similar increase in precipitation too). Still a lot of cold weather to get through until then though, and the risk of snowfall for southern areas towards the middle of the week (midnight on the 4th was the peak of the precipitation on the 0z ECM EPS) Ill take a check again later once the 12z ensembles are out SK

One to watch out for next week If we see snow falling in the region, that will be 7 consecutive months with snow falling (the first snowfalls reported back in October). That is bound to have happened in the past, but I most certainly wasn't around to experience it Extraordinary. Welcome to the postmodern winter... SK EDIT: Heavy snow shower here in the last half an hour too!