Glacier Point

Chuck's method places this May's projection in third place of the all time winter -NAOs, not far behind that year that shall not be named.... One thing the method does not address however is the impact of the AO on the NAO, and, as we know from bitter experience, we need both the NAO and AO in tandem to sustain the desired synoptics. I would view next winter as being a possible re-run of 2005/6 at this stage - certainly the overall context with the solar flux, NAO signals, likley La Nina and easterly QBO pretty much auguer well for cold outbreaks.

Just as in May, the underlying variables remain the same: No polar height anomalies in the upper atmosphere; Indeterminate ENSO state; SSTA driven pattern likely to prevail. For May I suggested the anomaly range to be +1 to +2, shame I plumped for the higher end but with the SSTAs around the UK of a similar value, this is where we should once agin be looking. As we progress through the month, there should be a building of a substantial high pressure centred close to or just west of the UK which is likely to lead to warm days and cool nights. Reanalysis of the last three years under similar conditions puts up some warmth in the west and cool in the east. With some warmth projected for next week, we're likely to start on an above average footing and this will tip us towards the upper end of the range but not as far as the GFS would currently have us believe... 15.3 C for me please

Thanks all for your comments. Just one or two updates before the forecast 'goes live' tomorrow. The polar cross sectional temperature anomalies show on balance the slight suggestion of a cold anomaly across the upper atmosphere which, if this persists, will marginally favour warmer conditions to develop earlier in the season with the upper zonal winds stirred up once more. That could shunt the projected high a little further east to sit slap bang over the UK. AS things currently stand, there is no impact showing on the crucial polar height anomalies around 30 hPa so the general outlook remains as stated. http://www.cpc.noaa.gov/products/precip/CW...hgt.ao.cdas.gif The upper zonal winds across the equator are showing quite reasonable -ve anomalies so May's QBO is likely to be into the moderate strength category. This shouldn't have too much direct impact but it will serve to strengthen the subtropical ridges.

Summer 2007 This will be my fourth seasonal forecast and I won't try to pretend that any of the three previous ones have been close to the mark. What I have learnt through error is that long range forecasts for the UK and western Europe are essentially influenced by a surprisingly small number of variables with each one vying for dominance. In order of importance, I would consider the following as being key to a winter or summer outlook: 1) the polar pressure anomaly, more particularly at the 30 hPa to 100 hPa level which is essentially a representation of the Arctic Oscillation (AO) and temperature of the polar stratosphere; 2) the climatic trend for warming; 3) the relative state of El Nino Southern Oscillation (ENSO); 4) Atlantic Sea Surface Temperature Anomalies (SSTAs). This summer poses a particular dilemma as the most influential factor (polar pressure anomaly) is likely to be a non player whilst there are considerable uncertainties about the timing and strength of any La Nina. Looking at the most recent polar temperature anomalies from surface to stratosphere, we see that there is no overall trend emerging for either warm or cold and, as a result, we see no particular height anomalies - especially at the critical 100 hPa - 30 hPa level where most of the influence for upper level zonal winds and broad weather patterns takes place. Note how unusual this is in terms of the winter and spring which were marked by big anomalies (mostly -ve height anomalies across the polar region driving the AO rampantly +ve. Now with the final subsidence of the polar vortex and shift to an easterly phase Quasi Bienniel Oscillation (QBO) in April the weather patterns have returned to something a little more like a little rather than a lot above average. All the indications are for this situation to continue. There are no warming or cooling events showing up in the upper atmosphere whilst the QBO can have an impact on polar pressure anomalies but does not according to seasonal correlations for the June July August period. Key assumption (1): The upper level polar temperature and pressure anomalies will be minimal allowing other factors to influence the summer pattern. Speaking of the QBO, note the correlation of the -ve or easterly phase QBO with (blue) height anomalies across from Bermuda to the Azores and Iberia - (remember this is a linear correlation map so a blue colour infers a reverse correlation). April's QBO showed a switch to the easterly phase with an index of -5.18. Current upper equatorial zonal wind anomalies depict a building of the easterlies indicative of a strengthening -ve QBO but recent westerly winds in the western pacific have hindered this making a summer with a weakly -ve QBO the call. http://www.cdc.noaa.gov/Correlation/qbo.da... The climatic trend for warming is really self evident. Over the last decade, the string of above average months is mightily impressive and statistically overwhelming. This doesn't preclude average or below, neither does it imply warming to an anomaly in excess of +2 as other factors such as the polar stratosphere have enhanced any warming dramatically (note how the excessive warming trend of March and April suddenly disappeared during May when the polar anomalies shifted). Bottom line is that the -warming trend is likely to add +0.25 to +0.5 to seasonal averages on a highly probable frequency - as well as shifting pressure patterns northwards. Key assumption (2): The climatic trend for warming will more than likely favour an above average summer in terms of temperature but not of the magnitude +2 or +3 on its own. Moving on to La Nina. Most of the models have picked up on the large body of below average sub-surface waters across large parts of the equatorial Pacific, particularly off the coast of Peru and within the ENSO region 3.4 (often regarded as the key to determining the strength of ENSO events). Currently the Pacific SSTAs show neutral ENSO conditions with the hint of cold water anomalies at the surface beginning to gain strength based upon latest weekly SSTA analysis: http://www.cdc.noaa.gov/map/images/sst/sst.anom.gif With the developing easterly trade wind regime associated with the -ve QBO, these cold water anomalies at depth should be dragged to the surface or up-welled favouring a developing La Nina although the situation in the western Pacific remains unclear with westerly winds tending to suppress any cold water development at the surface. The excellent IRI site summarises the position neatly regarding La Nina and some of the uncertainties about timing and strength of La Nina. http://iri.columbia.edu/climate/ENSO/currentinfo/update.html http://iri.columbia.edu/climate/ENSO/currentinfo/SST_table.html Taking a view on La Nina is important as can impact quite considerably on our weather patterns although not as much as an El Nino event. The impact of the ocean-atmospheric coupling of a La Nina is not easy to identify in western Europe. This reanalysis for linear correlation for June-July-August for the Multivariant ENSO Index (MEI) shows no real impact of either ENSO state: Many strong La Nina summers have, however, tended to feature mid Atlantic ridges and low pressure centred over western Europe during July and August. Currently we are in ENSO neural conditions. http://www.cdc.noaa.gov/people/klaus.wolter/MEI/ The majority of models suggest a steady decline in the Multivariant ENSO measure (MEI) indicating a slow but steady decline towards a weak to moderate La Nina event by the late summer or autumn. This seems very probable given the state of the easterly trade winds and sub-surface cold water anomalies. However, the overall change in SSTAs during May compared to April was highly marginal and the difference between mid April and mid May's SSTA across the tropical Pacific tells the story nicely. April ENSO: May ENSO: Difference:- Considering the MEI for April was 0.088, this makes May's MEI also around this mark. The Southern Oscillation Index (another measure of ENSO) is also falling making La Nina less certain. An MEI of around 0 for May would make any of those models predicting a La Nina (MEI <0.5) for the Summer far from being on track. Key assumption (3): ENSO neutral conditions will affect the early part of the summer with a decline towards weak La Nina by August - I.e. no major climatic impact from this factor. This leaves the Atlantic SSTA as the main driver for the summer over the UK and western Europe. In order to identify how the pressure patterns will be affected by the SSTAs, we need to establish the most likely base period and lag effect. There is much divergence on just how long it takes for a surface anomaly to influence the atmosphere (for the mid latitudes). Some research suggests one month, others more subtly over a longer period (seasonal SSTA lag). It makes sense to identify a trend if any and taking the period March - May gives an indication of both the shorter term and longer seasonal trend. If the trend and the more recent pattern are similar, then more confidence can be given. Looking at the SSTA for the Atlantic during the period March - May we see the following: - cold water anomalies up and down the western Atlantic; - warm water anomalies in the central and eastern Atlantic; - warm water anomalies the Davis Straits; - developing warm water anomalies around the UK. Taking the first three sets of anomalies, we can see 14 broad matches since 1952 which might help to predict how the summer pressure patterns might look if influenced by the SSTA alone. Removing years where there was an El Nino or strong La Nina which might distort the atmospheric response, we have a reasonable sample of 8 years. This is the composite reanalysis of all those years compared to the March-May 2007 output: Historic: Current: The reanalysis for May to date (when the polar anomalies faded) using these analogues provided a reasonably good explanation of the experienced pattern: Analogues: May 2007 pressure pattern: Tellingly, this hints at the climatic changes over the last decade or so which suggests the high pressure belts to have migrated northwards making lower pressure further north over Greenland much more likely. Rolling forward, the JJA outlook for 500 hPa pressure anomaly pattern based on the analogues looks like this - and I think we will not deviate too far from this type of pattern given one or two allowances for climatic trend: Notably, there is a considerable inter-month variance with June and Augusts witnessing a similar pattern with July the month most likely to see a more unsettled picture. June: July: August: Analogues should however be only used as a guide. We also need to look at the current SSTA and the influence of the climatic tend. For example, taking the last three most recent analogues (and an early warming trend) suggests July and August to look like this… July: (upper low shifted west) August: For what it's worth, frame this pressure anomaly pattern for August as the blueprint for the overall Summer. In terms of interpreting the likely impact of the current SSTA, my first point of call for predicting summer patterns from SSTAs are cold (or neutral) water anomalies in the sub-tropical or tropical Atlantic. Time and time again we have seen these generate displaced high pressures to the north and east of the anomaly centre. This year we see two such anomalies - around Bermuda which has shown up in the March-May SSTA pattern and a more recent development in the area off the west African coast. Sandwiched in between the two is a warm water anomaly around the Azores. Taken together the three should influence a substantial and complex if not rather flat sub-tropical high pressure belt with a +ve long wave height anomaly east of Bermuda extending across the Atlantic to the Azores and Iberia. Handily, this also conforms with the seasonal correlation for the QBO in the sub-tropical Atlantic. For the UK and western Europe, the analogues suggest high pressure to be in control during June and August, and with the warm SSTAs, I think a repetitive high pressure block will be located over or close to the UK - perhaps just to the west during June. With a strong Azores High, this will necessitate some sort of upper level weakness around Biscay and mid Atlantic trough. The analogues imply July to see something of a pattern change with low pressure in the near Atlantic. However, the current SSTAs also suggest high pressure to be in control but shifted east a little which could help draw some very warm air northwards. The climatic trend also backs this shift of the July upper low westwards. Key assumption: The impact of Atlantic SSTAs will be for a strong sub-tropical high pressure belt with +ve anomalies east of Bermuda and between the Azores and Iberia, with a secondary ridge over NW Europe. In terms of the summer forecast, the absence of any lead from polar pressure anomalies, no La Nina within the early and middle part of the season, and the SSTA there is a high probability of an above average summer. With the QBO entering a -ve phase, there will be periods of high latitude blocking which may serve to allow the ridge to partially break down but this should be a persistent feature so long as La Nina remains weak and the polar stratosphere does not warm. A cooling stratosphere will open the flood gates for even greater warmth however. The predicted temperature departure is between +0.75and +1.5 C for southern England which is perhaps surprisingly low given the forecast pressure anomaly patterns. Remember though the distorting factor of the polar stratospheric anomalies - which are not present and the likely pattern for June which is unlikely to deliver a record month given the pressure anomaly pattern. Rainfall is predicted at below average for the entire UK throughout the period although July is the most likely month for a return to more average rainfall totals. So a summer more along one of the vintage traditional lines given the influence of the Azores High but with the added factor of warm SSTAs around the UK and the climatic trend to shift pressure patterns around 5degrees north, something very pleasant in store I think.

Just thinking the same thing myself Ben. It's been quite some time since we've seen the North Atlantic Basin this cold. La Nina also looks a bit iffy at surface level although -ve sub-surface anomalies still exist but whether they get the right conditions to be drawn to the surface is the key question. IRI update paints an excellent picture for those interested... http://iri.columbia.edu/climate/ENSO/curre.../technical.html 1995 continues to look like the best match for the current SSTA pattern. Now how did that one go ?......... GP

Good luck with the forecast Ian, most of which I would concur with - particulalry this being an SSTA-driven Summer pattern. One of the main issues will be the relative strength and positioning of the sub-tropical high pressure systems. The baroclinic responses are complicated by the cold-warm couplets at play in the Atlantic right now. I'll release my Summer forecast in the next week or so (so I can see where La Nina and polar anomalies are going) - but my thoughts so far would be of a complex high pressure arrangement in the Atlantic. Composite reanalysis suggests a strong Bermuda High slightly displaced east and north. This will infer a high degree of phasing with the jetstream and ridge development in the central Atlantic which could extend to the eastern Atlantic IF there is a high degree of momentum. We are now in an easterly phase QBO and this might inhibit high level zonal winds however. We also see a large pool of warm anomalies directly over the Azores - in contrast to many of the last few years so my incling is for the Azores High to be strong and slightly displaced east towards Iberia - not the UK. However, there will likely be a low pressure response in the central northern Atlantic and, allied to the SSTAs of the last few months, will favour high pressure development directly over the UK. I Would agree with your assessment (or inference) of some less settled phases of weather - particulalry in the north - more akin to an average type summer but with an overall CET out-turn above average. There is also a possibility that we might get a re-run of 1995 based on the SSTA right now. Once agian, best of luck, let's hope it pans out this way. GP

I would tend to agree on a slightly -ve NAO projection based on both the current May plot and the March-May current plot as the UKMET also base their statistical analysis on this time frame. This could of course mean nothing if the polar stratosphere cools once more and the NAO signal gets swamped by a +ve AO. An easterly Quasi Bienniel Oscillation should however help in this respect by negating to some extent any cooling events that might occur.

Double regrets... 1) Missing the midnight deadline. 2) Not changing my April punt 3 days in to a high 10. Time to make ammends.. The temperature and height anomalies over the polar region show signs of a decline of the polar vortex, and, with no hint of cold or warming trend in the stratosphere, I think we will not see any forcing of the pattern from this quarter (somewhat an unusual conclusion over the last few months). The SSTA for ENSO Region 3.4 show a small -ve anomaly but the modelling is split on how far they will drop over the month: http://weather.unisys.com/surface/sst_anom.html http://iri.columbia.edu/climate/ENSO/curre.../SST_table.html Right now those models predicting a 0 to -0.5 MEI index value look about right and May ought to tell us whether we go down the La Nina route or not during the Summer. Bottom line, probably a La Nina but not right now and ENSO neutral conditions for May. This leaves the Atlantic SSTAs as the main driver, allied to natural intra-month variations. With the eastern Alantic showing +ve values and the western Atlantic -ve anomalies, we should see a mean trough-ridge scenario but with some less settled periods typical to May - in other words, an Azores High, Icelandic low type scenario characteristic of a +ve NAO. The SSTA in the Atlantic show values +1 to +2 in the SW approaches and this is where we should be looking. With both ECM and GFS hinting at the Azores High taking a dive or flattening a little for a spell of less settled weather, there is some case for a slight downward correction but overall above average between +1.2C and+2.2C. I'll side with 1.7C above giving a CET of 13.0C. Thanks.

I've yet to do a full analysis, but intitial indications for La Nina alone would be a fine and warm June followed by a rapid decay to very unsettled monsoonal type conditions for July and August. We must however balance this with the climatic trend and state of the polar Stratosphere which are equally if not not more important, particulalry to western Europe. Which brings me onto the Winter.. Very briefly: Climatic trend; propensity for a cold polar Stratosphere arising from the westerly phase QBO and solar minima; Stratosphering cooling just at the right time during November to super-charge the polar westerlies resulting in record +AO during December-January; El Nino signal in the Atlantic for low pressure was as expected, but displaced much further north due to the above factors resulting in strong SW'ly draw with SSTAs well above average in this sector - note there was precious little sub-tropical flow. The NAO was notably less +ve throughout the Winter and this supports the view discussed a few months ago that by far and away the most important climatic index for the UK is the AO. Any signal from the oceanic state of the NAO (which I still believe was for a neutral-negative value) was swamped by the state of the AO. You could argue that 1995 does indeed mirror this type of pattern very well so a conclusion that we might be working towards a similar start to the Summer has some merit to it. It all depends if and how strong the La Nina event becomes. GP

1995 has some interesting parallels in terms of the teleconnections this year... Both years fell at low points of the solar flux. Both years followed rampantly +ve AO winters - both record breakers in this respect. Both years featured upper level weaknesses around the Azores-Canaries-Iberia during the Spring (which continued into the Summer). Both years featured a decaying Spring El Nino. However, the SSTAs are not similar and this year I think we are looking at a strengthening La Nina which will differ from the ENSO neutral conditions experienced in 1995. So, as a very broad analysis from these comparisons, I'd suggest a similar Summer but with an increasing influence of La Nina as we progress, particularly mid July onwards. GP

We may well do so SB, especially with the ECM outputs taken at face value. I was considering a tactical shift to a value above 10C, but never change your mind, especially with the potential for a mid month cool down. That said, I'd look to buy a position at the top end of the guess range.

Well now here's a thing. SSTAs to our SW have started to drop off and continue to do so. I fancy this trend to continue over the next month which means I would place the upper bar at +1.5 (9.6C). Change in SSTAs over the last month: The decline of El Nino continues apace, so much so that La Nina looks iminent but for what it's worth the composites favour low pressure in the Atlantic and a strong SW'ly flow which almsot certainly deliver the 9.3 - 9.6 range. However, the switching of the equatorial upper zonal winds and cold pooling associated with a solar minima tend to indicate much more blocking to our NW and a greater -ve height anomaly over Scandinavia delivering something of a NE'ly anomaly to the 850 hPa wind flow pattern: Meantime, the upper Troposphere and Straotosphere continue to look cold although there is a hint that this cold and -ve height anomalies are beginning to fall back a little and the latest trend for polar height anomalies is for blocking over NE Canada which will prevent rampant warmth from taking hold. Putting all these together, and taking account of the lastest ECM outputs, I favour an above average return but not excessively so. Therefore..... 9.0C GP

Following on from the first assessment of Atlantic SSTAs, there have been some significant changes in the anomalies since the start of the month. This reanalysis illustrates the change in anomalies since March 1st: Although the region around the Azores remains above average, there has been a significant cooling here with a general easing of the big +ve anomalies of the winter across the N. Atlantic, most probably related to the expansion of the polar cell in the last few weeks. If this trend were to continue, we would start to replicate the conditions of last Summer with a potential displaced high pressure cell. However, we should also bear in mind that we may have a developing strong La Nina in place which argues for big troughing over western Europe and a stationary mid-Atlantic ridge which would tend to be cooler than recent Summers. GP

Not sure there SB, the models were playing catchup with the drop in the SSTAs during late Feb onwards and have still not fully registered the current situation. There is also some statistical basis for calling strong to moderate Nina when they form during the Spring. This could well develop as the key factor this summer. GP

As our thoughts turn towards the Summer, we start to see some trends in N. Atlantic SSTA which, in isolation, suggest this year may be different to last year in terms of pressure anomaly pattern. March - May SSTA 2006: March so far 2007: Differences observed to note: 1) There was a degree of weakness in +ve SSTA around the Azores during 2006 which, in my book, was a key factor in inducing that repeated high pressure pattern. This year, there as a trend at least towards a strong +ve anomaly between the Azores and Canaries - perhaps likely to support a high pressure cell ridgeing into Iberia. 2) The cold pooling off the eastern US was much further south last year. At this latitude this was ideal for positive height anomalies to develop and support ridgeing NE towards Europe. This year the pool is much further north which could underpin a stronger and flatter jet - especially with a greater snowfield over NE Canada. Plenty of time for things to develop and I must stress that SSTAs are not the only game in town - we need only look at the impact of surface pressure over the Pole this winter - but I think the initial hints are for a moist, tropical maritime type pattern with numerous Spanish plumes. GP

Renalysis of declining El Ninos and transition of the equatorial zonal winds during this period puts up some quite similar indications for upper mean pressure anomalies but with subtle differences which could mark the difference between well above and just slightly above average. The QBO is in transition from westerly to easterly phase. Reanalysis of z500 hPa and surface T suggests something of NE'ly component to the obligatory SW'ly resulting in a risk of below average conditions.... The MEI decay suggests a similar overall pattern, but with much more of an Atlantic component..... Blending the two produces the following z500 hPa, T surface and 850 hPa vector anomalies: The Atlantic continues to look warm, typically +1.75 C around the central region and lots of cold air still spilling off NE Canada invigorating the jet and an surface pressure / temperature profile consistent with an E Nino winter.... With the polar vortex showing signs of decay and warming at upper levels, we could well be looking at a -ve NAO / AO regime from mid month onwards. The ECM extended however puts the first 10 days as well above average. My thoughts are of a gradual cooling off from mid month onwards as we witness transient -AO / -NAO phases, but overall above average +1.C making my CET Punt for March 7.3 with night time minima being the main driver once again. Now let's see if we can have some better luck at Cheltenham than these dire winter CET predictions. GP

Q: Which climatic index was also at ridiculously high (record breaking) values during this time ? A: http://www.cpc.ncep.noaa.gov/products/prec...ndex_ensm.shtml We are building towards the winter conclusions and I think the state of polar field will figure highly in our discussions. It is not the only factor, but we should remember that this is largely influenced by Stratospheric conditions, which have similarly broken records for extent of cold conditions.

Excellent progression from both ECM and GFS12z (inspite of huge potential for model error as the jet phases twice over North America) to suggest that a -ve NAO pattern is not far off now. First up.... I've been waiting to use this one, and to paraphrase Monty Python, that westerly QBO is dead (well almost): 30 hPa zonal wind anomalies have declined to 0 values over the last few days to suggest that the switch to an easterly QBO. This matters, not least if we look at the reanalysis for weak westerly QBO and correlation for Feb March QBO: Weak westerly QBO Feb/March linear correlation to easterly QBO Remember the second image is for a linear correlation not anomaly values so a -ve (easterly) QBO is the opposite or inverse to what the correlation shows. This verifies quite nicely with the last few days' pattern across the NH - note the match on the Atlantic pattern with low a low pressure solution to our west and height rises extending from Greenland to Norway: Next up...the AO continues to show a -ve tendency with +ve height and temperature anomalies prevelent with the prospect of a sustained Stratospheric warming starting to feed downwards: http://www.cpc.noaa.gov/products/precip/CW...index_mrf.shtml http://www.cpc.noaa.gov/products/precip/CW...hgt.ao.cdas.gif Then we have the North Atlantic showing a tripole suggestive of -ve NAO conditions (cold anomalies to the north - warm central north Atlantic - cold to the south: http://weather.unisys.com/surface/sst_anom.html Then the GFS and ECM are starting to pick out the development of a classic Feb weak El Nino / -ve NAO / -AO pattern, not least through tonight's t168-240 resulting in a possible re-run of the last 48 hours: http://www.meteo.psu.edu/~gadomski/ECMWF_12z/hgtcomp.html http://www.ecmwf.int/products/forecasts/d/...0912!!/ http://www.ecmwf.int/products/forecasts/d/...0912!!/ http://www.wetterzentrale.de/pics/Rtavn2281.html Give it another day or so, and I will start to get very hawkish about this one... GP

Huge uncertainty continuing in the short term in any number of areas making longer range outputs of limited value. One thing looks a good bet - Atlantic lows - but the key aspect would appear to be how far into Germany and beyond these depressions manage to undercut the Scandinavia block. If we continue to see undercutting, this will set up the kind of evolution shown by the GFS 06Z which provides some backing to last night's ECM at the t240 range for height rises from Scandinavia towards southern Greenland: http://www.wetterzentrale.de/pics/Rtavn2281.html GP

Light snow now here just outside Pershore, Worcs. No temperature values because my thermometer / hygrometer has bust !!

I think we are in a period of standing still until the models come to grips with the changes in the NE Pacific. With the GFS chucking out all sorts of solutions, the ECM provides the only meaningful tool in the longer range outlook analysis. This is picking out the redevelopment of a trough in the NE Pacific and consequent ridge into the western US (+PNA) quite in contrast to the GFS which is at times hell bent on developing a -ve PNA pattern: http://www.cpc.noaa.gov/products/precip/CW...a/pna.sprd2.gif The other aspect of the ECM which, frustratingly is always at t240, is the prospect of a ridge developing from the NE Atlantic towards Iceland and Southern Greenland: This is logical given that a low pressure scenario for the central Atlantic looks the most probable aspect of the modelling right now - and indeed what we know about weak El Nino. With two convergences of the jet prorammed over the t168-240 period, we must have little confidence in any solution over the Atlantic but I would certainly buy into a low pressure out to the west pattern - but crucially with an increasing trend towards a -ve NAO (remember that one?). This interests me most because I am keen to test my theory that I put forward in my winter (busted) forecast of a -ve NAO winter given the relaxation of the QBO and diminshing influence of the earlier stratospheric cooling. To achieve this, we must shift the Scandinavia block temporarily to allow the jet to undercut enough to allow the polar vortex over NE Canada to displace enough south once more. I note also some discussion on the AO on the other thread and this is one I definately agree on - trend down, maximum neutral if that. Add this to possible movement with the NAO and the last third of Feb promises much. GP

Looks like the SW Midlands has lead a very charmed life for the last 2 hrs - and no sign of it abating just yet. 12cms already now min. depth. here just outside of Pershore.

06z leaves margin for error in terms of just how big a snow event we could be looking at... On the face of it, 850 hPa values look a little too high for midlands south: http://85.214.49.20/wz/pics/Rmgfs482.gif http://85.214.49.20/wz/pics/Rmgfs483.gif http://85.214.49.20/wz/pics/Rmgfs542.gif http://85.214.49.20/wz/pics/Rmgfs543.gif But surface values likely to be underestimated given the blanket now falling and sharp frost tonight and likely Friday: http://85.214.49.20/wz/pics/Rmgfs484.gif 850 winds projected from the south but surface winds strong easterly which could draw in cold air from the near continent: http://85.214.49.20/wz/pics/Rmgfs485.gif The placement of the 528 DAM line is pretty consistent with most recent UKMO Fax so at the moment it looks like a snow to rain scenario for the midlands but this will be very susceptible to tiny shifts and timing ahead of the front - especially that tongue of cold air to the east. Fax updates should be quite informative, as they always are. GP

Indeed Darren, a classic... http://www.wetterzentrale.de/pics/Rtavn001.html Heights not as big as could be expected over Greenland but we have the legacy of a solar minima and westerly QBO sustaining some big pools of cold air around - I reckon we could be looking at a repeat in 10-14 days. 7cms so far and still going strong - I think we may end up with 12cms by the end of play.

Oh, remember them - especially the 1980s one when the 'blizzard' ground to a halt and headed south leaving us to wake up 'green'. Hopefully tomorrow will remind us of those days when we woke as kids to a strange light outside...... Brutal dew points now being recorded and to reiterate Steve's point, massive drops in temperature now showing up which must augur well. All we need now is for the ppn to be a bit heavier than anticipated - and there's potential there with the developing system, instability and high RH values.