Singularity

You may as well ask us to name 'The Best Thing Ever'... it's all relative

Pretty peed off at today's outcome to be honest, but you can't win it all. Steady rain, not all that heavy, just a nuisance. Having said that, there may be a silver lining to come down here soon - there's some clearer skies coming up from The Channel which could allow temps to jump up into the 20's, even a chance that GFS could end up remarkably close to the mark with the maximum temps should the skies behave themselves with nothing blowing up on the coast to fill in the gaps... jinxing it I know! Now then, where's the evening threat for the SE at the moment? A lack of lightning activity over NE France suggests that it hasn't initiated yet, but there's still some 8 hours or so in which that can happen. Curiously enough, the 06z Euro4 has brought some of the evening action further west than any previous run. Things kick off rapidly between Brighton and Dover... could they get slammed with the most intense precipitation twice in the same day?! Looking ahead to tomorrow for a moment, the shift east in the low has resulted in a similar shift east of the slow moving frontal boundary on the Euro4 output for example. That model has also explored the possibility of an area of enhanced instability just ahead of the boundary, affecting areas Dorset/W. Hants northward during the morning hours. The 00z even suggested a notable wave in the boundary developing close to the S. Coast which really boosted the rain to troublesome levels. The 06z has backed off with more of a 'sporadic thunderstorms' theme. One big spanner in the works as far as forecasting is concerned is GFS, which insists that the boundary will traverse only Cornwall and Dorset before fizzling out. That's a huge difference for less than 24 hours ahead, I am struggling to retain my sanity forecasting two such highly volatile days in succession!

I must admit, I shouldn't complain about missing out this time around (so far at least), as I was afternoon in the midst of a somewhat supercellular storm in mid-July with lightning every 2 seconds or so, albeit mostly inter-cloud.

Many thanks Vorticity! Rooting around, the Trappes sounding you mention suggests some dry air aloft, though not full-on anticyclonic subsidence (given the origin, not surprising I suppose!). There's also quite a capping inversion at around 950m: ...hence it would take a fair bit of heating to initiate surface based storms this afternoon/evening. As it is, dynamic uplift may do the trick instead for the SE as has been suggested (again, by Vorticity with his very detailed analysis). Here in the western reaches of the New Forest, it's finally raining good and proper, but though the rain drops are large, they're not falling at much of a rate. to think what could have been... actually, just look at Brighton eastward for that!

The ridge of high pressure is really putting up a good fight... if this was winter we'd be shivering under cold but infuriatingly dry air, waiting for the precipitation to push north... only for the warmer air to result in rain As the low has developed during the first 9 hours of today, we have seen plenty of precipitation making a break for the UK, but they have been moving outside of the main moisture plume, and from the looks of things encountering some issues with either having been surface-based (despite the time of day... low probability) or subsidence from higher in the atmosphere, associated with the ridge of high pressure. Air descending in this way tends to be very dry indeed, snuffing out convection very quickly. I can't be sure without observed soundings of the atmosphere though (GFS-based ones don't really show much sign of it but the forecasts are proving inaccurate anyway) - anyone know where I can find some for Southern UK? Thanks in advance It does appear from current radar imagery that the moisture plume is at last being drawn up toward the far SE, with some torrential rain and plenty of electrification. Yes, I am envious...! The overall motion is to the NW, however there is also expansion of the moisture field to the north, hence the SE coming into the line of fire. Some embedded activity has made it to the Isle of Wight, which is not far from here. Listening out of the windows when I can.

The storms in The Channel seem to keep running ahead of the moisture plume, decaying, and then triggering new storms within the plume as their outflow interacts with the broad scale winds. The plume's arrival seems a little behind schedule now, and it's become hard to figure out which 'wave' of storms - if any (!) - is going to be the first to reach land without fizzling out. It's pretty random and relatively localised where storms are developing electrical activity. Currently it's all west of the IOW. So any such activity across the UK is likely to be a bonus this morning at least, the rain being the main focus as many have been saying over the past 24 hours. IF there are breaks in the cloud early-mid afternoon, temps could soar into the mid-20's in places (GFS has an optimistic 27*C just NW of Southampton), likely triggering some classic homegrown activity with a higher risk of lightning (particularly CG). Complicating matters may be further imports from The Channel... it could get very messy. Then comes the possible second wave of elevated storms, which exists on some models but not others - while the NMM 18z held onto this feature and tracked it across CS England from the SE, Euro4 suddenly ditched it on its 18z run... awaiting the 00z with interest). Has to be said, Meteociel's version of NMM is looking wide of the mark for 7am: ...but on this site, it often seems to be missing the assimilation of existing precipitation data into the first few hours of the run, which means it has to start from scratch... a waste of potential IMO. The MeteoCenter website runs the model with the assimilation, which yields a more convincing result, albeit over 3-hour intervals rather than 1-hour. You'll have to browse to the charts via http://www.meteocenter.eu/WRF-forecast/EU/Europe.html#model as they can't be linked to directly. The 2100 Thu and 0000 Fri output is particularly menacing for The Solent region as it suggests more than 60mm falling in the space of 3-4 hours.

Who's up for climbing Mt. El Nino then? Wicked maps there Recretos, I look forward to the 3D stratosphere measurements again this winter - I was lurking in the shadows here when you dished those out last winter, much to everyone's amazement Just read a blog comment over on 'wunderground' by 'StormTrackerScott' which is an interesting read: "This 3rd Kelvin is no joke. Continuing to build and also hints on the TAO of the strongest WWB so far this year showing up west of the Date Line. We should also notice that 2015 is doing something that 1997 couldn't do and that is shove 30C SST's into Nino 3.4 sub surface. Giving credence to all these model projections showing 2.5C to 2.8C ENSO." Complimenting this is the following image: ...however it's the "hints on the TAO of the strongest WWB so far this year" that really get me thinking. We've already had some exceptional WWBs so far this year, something even stronger this month would be astounding. In case you're wondering - I too am pondering as to what the 'TAO' is...?

Interesting how Euro4 keeps on piling those storms in from The Channel right through Thursday, while WRF has the elevated convection clearing quite sharply north to be followed by a drier interlude before a scattering of surface based storms across S. England in the afternoon. The BBC forecasts this morning have resembled Euro4 quite closely, giving the impression that it will be thundering for much of the day across many parts of S. England in particular. It's been a long time since I can last remember that happening... in fact longer than I can recall to any effect! Closest I can come up with is when storms rattled in throughout an entire night while I was paying a visit to Portsmouth one weekend. The streets were full of drunken youths throwing cans into the air... as if they expected to attract lightning for some crazy reason. I still expect the high-res models to be overdoing the totals as usually happens, but given the very high available moisture for this event, I'm not sure that the actual values will be as close to half the projected values as I have seen in past events this year (namely the two in July). I'm actually amazed to have now seen 3 Euro4 runs on the trot delivering between 60 and 110 mm across CS England. Takes me back just over 8 years...

What a grim day it's been, maximum temps 3 or 4*C short of expectations due to the cloud persisting instead of breaking up nicely. Very light winds though so not all bad. There's been a wicked, increasingly blood-red sky these past 15 minutes. Perhaps a harbinger of improved prospects tomorrow? You know, "red sky at night...". Or do I have it the wrong way around?

As the jet stream close to the UK weakens early next week and an area of low pressure finds itself up against a strong high over Scandinavia, there's a wide range of possible paths for that low to follow. The NOAA anomaly this morning reflected a path that was too close to the UK for comfort, the evening ones have adjusted to a path further west with high pressure having more of a say in things. It could just as easily carry on trending that way as it could about-face tomorrow morning. I wouldn't expect massive shifts though, given that they cover 4 days at a time (hence their tendency to be more consistent than the individual model runs). At this end of the UK, events Thu-Fri are demanding a lot of attention, the prospects beyond that taking a back seat for the time being.

Features of particular interest late Wed- middle of Fri: Firstly, some intense elevated thunderstorms later on Wednesday night, taking advantage of decent mid level CAPE. They are packing a bit more of a punch on this NMM run compared to the past few. Storm helicity with those looks troubling - some rotation seems possible, but this does tend to be limited when it's elevated storms you're talking about (at least I hope that's the case... this predicted helicity covers the atmosphere up to 3km ASL and is even higher for the 0-1km range in isolation, at nearly 600). Following this is a window for surface heating and some surface based thunderstorms, but the models show little agreement on this aspect and for the most part don't seem all that keen on it this evening. Then, overnight into Friday: Something monstrous from NE France? I wouldn't normally take this too seriously at this range, but GFS also has an intense feature moving up from the SE. Something to keep a close eye on! This then merges with a frontal boundary as it becomes very active yet slow moving across central parts of the UK. This feature's position has shifted east a bit when compared with the previous few model runs. A similar trend is seen with GFS. The net totals by noon Friday are striking and bear remarkable similarity to the GFS output for the same period: ...though, as usual with NMM, the totals are that bit more extreme. 150mm in the vicinity of Reading... ouch. Thankfully, this model is well known for overdoing the rain rates in these situations, the actual values often not far off half of those predicted!

Taking ECM as an example, this morning's model output suggests that the high pressure over Scandinavia may be shifting south by about a week from now, some 3 or 4 days after it arrived there: Given that this should encourage another intense plume of heat to build across NW Europe, I think it will be worth keeping an eye on how the Atlantic behaves at that time, and of course what manner of low pressure develops to our S or SW, as the models seem quite keen on that as well. GFS drives an area of low pressure past the NW of the UK just as the plume is starting to build, the effect being to divert the hotter air to our SE while feeding down cooler air from the northwest. A ridge from the west then traps the heat across Spain, Portugal and S. France until a low dives SE from Iceland, interacts with LP over NW Europe and 'lifts' the heat out to the east of the UK while we experience a soggy run of days. I would post the corresponding charts but let's face it, the finer, hotter outcome of the ECM run is more pleasing to observe for many of us: ...which is largely down to the jet stream tracking further south in the Atlantic, with the Azores High greatly suppressed as opposed to flexing its muscles. So which is more likely to verify? Well, given the affect of events in the Pacific mentioned by M. Ventrice (cheers for the heads up Knocker), it's pretty much an open goal as to who scores the winner to be honest. A consideration of other model output finds GEM not a long way from where ECM ventured, while UKMO at T+144 seems to be a blend of ECM and GFS. So we have ECM as the most optimistic operational output, and GFS as the most pessimistic (of the 'major' models). Looking at the GFS ensembles, the spread of outcomes suggests to me that some runs are near to ECM's output: A glance at the 20 ensembles in thumbnail form via http://www.netweather.tv/index.cgi?action=ensviewer;sess= for T+192 hours reveals 10 or 11 perturbations that could do the trick in terms of building some heat from the south rather than blasting it away to our east. Some reasons to be hopeful, then, after a fairly benign run of days Sat-Tue. Admittedly it might tend to be pretty decent for the far southeast during that time, but yet again the NW are looking for ways to shove to one side a stream or rather cool N. Atlantic air. To be honest, I can't imagine living through such summers as this one has been up there!

Hi there GW Having read your post, I think I get the gist of it - floes of multi-year ice, which became full of holes in the bad melt seasons but which have since filled with first-year ice? I'm not as familiar with the subject-specific terminology so forgive me if I'm wide of the mark

By the power of the emoticon I was trying to suggest that it could be bust... depending on whether the anomalies persist, as you say I figured the presentation considered the gradual climb over the past 20 years to be from from the moisture feedback (punctured by the occasional stalls that you mention). I'm aware, though, that the ability of the atmosphere to hold moisture doesn't increase linearly with increased temperature... the rate is far greater. So perhaps a more pronounced spike ought to have occurred if the above theory is anywhere close to the mark. In light of all this, the notion that El Nino is simply amplifying the detrimental synoptics, resulting in a larger bite out of the apple, so to speak, is an inviting one. an assessment of recent synoptics in comparison to the 'norm' would be of great interest - if I ever get the time, I'll give it a shot

The MJO is currently hanging around at relatively low amplitude in phase 6... the placement is very good for warmth to occur this time of year (based on the composites at http://www.americanwx.com/raleighwx/MJO/MJO.html), and although the amplitude is low, we are seeing suggestions in the model output of high pressure to our E/NE which does tie in nicely with the phase 6 composite for amplitudes greater than 1.0: Incidentally phase 7 in July has a similar appearance, as does phase 8 in June. Shifting by 1 phase each month... coincidence? Anyway, it will be interesting to see how soon the MJO leaves its current state, as it's spent the past 24 hours drifting in the opposite direction to what the models predicted would be the case. If it lingers for much longer, we could perhaps see high pressure to our E/NE proving increasingly stubborn in the model output. Shorter term, we already have a lot of uncertainty to contend with thanks to the anticipated low pressure over NW Europe. For example, while GFS has the system pushing in late Wednesday and crossing England on Friday, UKMO delays the arrival by at least one day and then moves it to our SE on Saturday, managing to do little more than introduce some instability to the atmosphere overhead. This by and large looks to be a consequence of low pressure near Iceland being held back further west by UKMO, the difference notable as early as Thursday. Having said that, GFS' 00z operational run had the low in a similar place to UKMO's 12z, yet the European low still pushed north(east) sooner. Perhaps it simply reflects differences in the model physics. In such situations, we often see GFS and GEM in one camp and ECM and UKMO in the other. The GEM 12z operational is similar to GFS so that's half of the equation in place... let's see what ECM comes up with later this evening. Considering the GEFS ensembles with respect to the GFS and UKMO operational runs, the spread of outcomes (see below - showing the range of 500mb heights across the ensemble suite) regarding the European low is not particularly large on Friday, just about encompassing the UKMO operational along with the GFS. By Saturday it has become much, much larger... unusually so for less than a week ahead. Clearly the advance of the Atlantic trough is a long way from sorted out: By the way, if I could do with explaining anything in my posts further, please don't hesitate to ask - I'm still getting used to sharing my analysis in this way

Not 100% on this but I attended some seminar speeches last year which spoke of Antarctic sea ice increasing over the past couple of decades due to the fact that a warmer climate simply means added moisture yet still well below freezing across the continent... there was then this idea that one day a critical temperature threshold would be reached, at which point the effect of added frozen precipitation is overwhelmed by increased SSTs, so preventing the extra ice extent expansion from taking place. So perhaps it's something along those lines. Or there may be some intense storms involved. Or it could be something else entirely - I'm not in a position to draw conclusions on this to a scientific standard. Edit: hang on, just located a map of SST anomalies. If anything they're a nudge below the LTA along much of the Arctic sea ice edge. Bang goes the theory...?

The 18z GFS operational takes the deported heat as far north as Svalbard (much diluted by then of course): This is largely down to the Atlantic trough jumping back south again when compared with the 12z. Seems that its behaviour is anyone's guess at the moment.

I've been keeping a nervous eye on the Central Pacific cyclone activity, as it raises the odds of a 'polar explorer' taking place, compared with when you have the usual relatively low activity (when viewed against W. Pacific activity). I feel like we could do with some tech for detecting 'rotten ice' as Gray-Wolf likes to call it. Sounds like ice which is full of weaknesses and holes?

Thanks, that explains one of mine... - - - - - - - Anyway, looking at the ECM 12z operational for Thursday 13th, it has an exceptionally deep and intense storm system just southwest of Iceland (see image below), which being so extreme does give cause to question the extent to which the trough is able to nudge the Scandi High to the east over the following few days. A weaker trough is likely to make at least a little less progress - in the spirit of the GFS 12z operational output. Despite their differences, both of those two models have substantially shifted the balance of power from the Atlantic trough near/over Iceland to the Scandi High, when compared to their output 12 or 24 hours ago. It seems that the broad-scale signals for mid-August are changing in important ways. The venture of the MJO into phase 6 may be having some effect (http://www.cpc.ncep.noaa.gov/products/precip/CWlink/MJO/CLIVAR/ALL_emean_phase_full.gif) but I actually (rightly or otherwise...) see an adjustment upward in the expected atmospheric angular momentum as a more significant player: ...as I have heard it said that this encourages troughs near the UK to trend further west with time, though the means by which that takes place is something I've yet to get my head around (but posts by the likes of Tamara have assisted greatly over the past year or so).

I'd go so far as to say that this year has often behaved strangely, one way or another. I suppose it can in theory be a second-year El Nino depending on how you look at the SSTs, though it's only really this year that upwelling/reduced downwelling has really manifested in the W. Pacific to bring things in line with the typical El Nino pattern. In fact - assuming I'm recalling this accurately - the delay in that behavior was enough to keep the atmosphere in a more La Nina type arrangement during much of the first half of this year. - - - - - - - Looking at the 12z GFS today, it appears that as early as Monday, a significant adjustment has occured over NW Europe regarding the position of the shallow low that goes on to become a significant player in our weather later in the week. Here's the 06z version of events followed by the 12z, for comparison: A glance at the UKMO 12z op run reveals a similar adjustment as of T+96, yet the focal point for development still turns out to be about as far east as it was come T+120 (dubious in my humble opinion!). It will be interesting to see which way ECM goes tonight - I'd surprised if the low wasn't initially further west, but will the main development still occur to our SE then E or will it be something more to our S? With that LP developing notably further west than seen in the previous few operational GFS runs, there are interesting results by Thursday: As much as I feel UKMO is a bit dubious in how it evolves, it still fits in better with recent model consistency than this GFS outcome, so arguably it's more sensible to expect something closer to UKMO at this stage. At least that still involves what could be a very warm easterly next Thursday. I would post images but the last time I did that they had to be from another site and my post disappeared... The most positive interpretation I can think of is that we've now had two GFS runs in a row which have avoided the 'stalled frontal boundary' situation for England, instead allowing for very warm conditions for at least Wed-Fri and possibly Tue-Sat if the 12z GFS turns out to be close to the actual outcome. Looking further ahead, that GFS 12z produces a strong Scandi High as the Atlantic trough doesn't extend SE and 'scoop out' the low pressure over Central/Eastern Europe. A very interesting outcome and one of my favourite runs of recent days

Ah yes... temporarily forgot about the need to stay on topic! Forgive me, it's my first day Plenty of other threads for other topics I see I am hoping that ECM and GFS are too keen to develop low pressure to our SE and lift it north. At the very least it could help if it stays trapped under the western flank of the high pressure over Scandinavia, though admittedly a sustained feed of heat and moisture could cause problems where it clashes with cooler air to the northwest.

I real headache this one, as there's ample moisture but the extent to which the frontal system can engage with that is highly uncertain - check out the precipitable water values (mm) from WRF-NMM: Yet precipitation amounts are actually very low or nil: ...which is more or less what the BBC forecast this evening was in support of. GFS is not that far away this evening so perhaps the picture is finally becoming clearer - unlike for next week when it looks like the proximity and precise dynamics of a shallow low to the SE will make all the difference. The GFS 12z was unfortunate for large parts of England, and ECM is worryingly similar, though who's to say whether the rain would be so persistent as GFS has come up with. Warm and showery is a possibility I think. For some of the kindest output tonight, we can look to UKMO - as has often been the case in recent days: I sure do like how images work in here

Good questions and points knocker, I'll do what I can to answer/explain them; First quote, I was referring to the way 500mb heights are influenced by temperature as well as surface pressure. This is due to the fact that pressure falls more slowly with height in warmer air relative to cooler (as it's less dense). I must admit that the idea of this leading to stronger, more expansive areas of high pressure being possible is pretty much paraphrased from various comments I've read online over the past few years (I remember it being linked with the Russian heatwave in 2010 I think it was), but it seems logical enough to me. The link with warmer, drier summers as a result of global warming is then a case of supposing that, if the amount of heat in the atmosphere in a 'neutral' ENSO year was to become as high as in an 'El Nino' year at this point in time, then unusually strong and expansive ridges of high pressure over Europe would become more common. If anyone on this site (and I'm sure there are plenty with enough expertise) knows of stats/theory/facts that take this proposed link apart, please don't hesitate to correct me! Finally, I realise I didn't clarify that I was referring to the 'heat from the east' for that date in particular, not the run as a whole. Up the learning curve I go

The MJO seems to have been doing the tropical weather equivalent of 'faffing about' lately, and the models have been all over the place with respect to what it gets up to next. I notice today has seen it move into phase 6, in a way that only UKMO (currently AWOL from the plots, ironically enough) has managed to foresee (I've been tracking the MJO outlooks daily for the past two weeks): Increased convective support in the W. Pacific could give rise to another burst of frantic cyclone activity with associated WWBs possible. It's now a question of whether the models are right about a sudden switch to decaying mode and later emergence in the W. Hemisphere/Africa. It would be far more interesting if we got something like UKMO was predicting - a strong phase 6 event. Then we could have some fun figuring out why the rest of the models were hopeless

Afternoon everyone, I've spent a little time lurking behind the curtains of this forum, and my science-obsessed mind has been drawn to mentions of teleconnections and analogue year composites which have recently become a subject of fascination on my part. Indeed we see a nice example above, representing a classic 'enhanced Euro Ridge' response to a strong El Nino configuration in the latter stages of the summer season. I suspect this relates (at least partially) to increased atmospheric warmth piling up into a greater 'bulge' in the troposphere (I prefer to describe it that way to avoid detailing complicated dynamics!). In this way we get a glimpse of the rationale behind warmer, drier UK summers as a result of global warming... though it's unlikely to be that straight forward I'm afraid. ECM seems to want to add more amplification to the pattern than suggested by the composite, digging low pressure southeast from the mid-Atlantic rather than firing it northeast. At a glance (been busy this morning as usual), GFS seems more in line with the composite out to 7-8 days ahead, though the Polar/Arctic pattern does still allow for more of a Scandi High with lower heights S. of the UK than would otherwise be expected: A case of 'heat from the east' on that run, touching 30*C in CS England