Thanks stormchaser, my forecast was based on many of the parameters you mention including the metoffice seasonal models. What you say is of course true, and everything could completely crumble and my 'extremely dry spell' from now until August could never even materalise. And if it does materialise what is there to judge whether this forecast was simply right by chance. 

I'm looking for warmth this Spring, but I would not say no to a blizzard of epic proportions either, an Easter shocker? 

Cheers as always Gavin 

I hope you don't mind if I quickly sum up my own, slightly different angle on things:

The JMA ensemble mean clearly has more members placing low pressure right by the UK rather than to the south and NW with a ridge in between. Looking at the ECM 00z ensemble mean, the low anomaly on day 10 is more focused to the NW with a ridge close to our east. The GEFS 12z mean is very similar for the same timeframe.

They all show a fair risk of seeing some Atlantic influence, but ECM and GFS leave room for ridges from the SW to move across the UK and continue on eastward - this is being reflected in recent operational runs.

I think that the orientation of low and high pressure anomalies on the ensemble means, even the JMA, could allow us to be on the warmer side of the jet at times, feeling the effects of either tropical maritime or continental air. CFS looks a bit bonkers, and for some reason the chart you have differs greatly from this:

http://www.cpc.ncep.noaa.gov/products/people/wwang/cfsv2fcst/imagesInd3/glbz700MonInd1.gif

...which shows a tendency for Atlantic westerlies, often rather unsettled but not too chilly out of the rain, with transient settled spells possible as ridges move through from the SW between low pressure systems.

The overall trend across the models does seem to be towards the mean trough locating somewhere south of Greenland or Iceland, with high pressure not far to the east of the UK. This signals near average temperatures and changeable conditions.

Finally, a comment on the May outlook - this time the chart you show is similar to my usual source:

http://www.cpc.ncep.noaa.gov/products/people/wwang/cfsv2fcst/imagesInd3/glbz700MonInd2.gif

...but to me it shows a setup that could place the UK on the warm side of the jet stream, with a good chance of seeing imports of warm air drawn up from the Mediterranean. Low pressure areas would likely track across the UK at times, so we'd see some rather cool spells too - but overall I'm seeing a slightly warmer than average month there.

With it being so quiet I thought I would add my Spring forecast which I issued on my weather forecasting page on 6th March.

Apologies if some of it is a touch dumbed-down for an audience of expectionally knowledgeable folk - but it was written for the general public and I am not going to re-write it - also please note it is for Reading and the surrounding area specifically.

It is based on pattern-matching, long-range models and just generally what I feel is going to happen.

-----------------------

Welcome to my Spring 2014 forecast.

I must start with a caveat that all forecasts for more than 5 days in advance are subject to a great amount of uncertainty and can only be used as a guide. Some parts of this forecast will come true, others will not.

For some time I have been confident of a dry March and I am pleased to say this is the predominant pattern expected. Temperatures will climb to above-average for a while and there will be reasonable amounts of sunshine. Rather Spring-like.

In the second half of March, I expect more average temperatures and a week of unsettled weather from roughly 15th March.

For the end of the month, I have low confidence, I suspect there may be high pressure over Scandinavia bringing chilly easterly winds, dry but below-average temperatures and lots of cloud. I wouldn’t rule out some wintriness.

Overall temperatures slightly above average, sunshine amounts average and rainfall below average.


April has no strong signal for any weather pattern.

The beginning of the month is most likely to be slightly cooler-than-average in the same way that March finished. I also expect a couple of brief cold northerlies which could bring some surprise wintriness.

The remainder of the time will see fairly average April weather of sunshine and showers – some days fine, other days more showery.

Overall temperatures, sunshine and rainfall all to be average.


For May I expect high pressure either to our east or our north-east which at this time of the year brings a more positive effect in terms of the warmth of the air being dragged in from the continent – as opposed to the end of March when a continental airflow brings colder temperatures.

It should reach the hot category at times especially in the first half of the month (25’C or higher) though probably never for more than 2-3 days in a row.

There will be heavy showers at times too bringing average rainfall during the month as a whole.

Less warm towards the end of the month when I expect it to be cloudier but drier.

Overall temperature to be above-average, rainfall average and sunshine slightly above average.


The most likely scenario for summer is for cooler than average temperatures with high pressure over the Atlantic giving more northerly-influenced weather. In terms of rainfall average rainfall is most likely.

But do bear in mind that it wasn’t until April last year when a hot July became possible – and May when I then forecasted it. Summer is a long way ahead – good summers often cluster together like bad summers, or cold winters.

------------------

Roll on thunderstorm season :-)

The Met Office ensemble mean LRF maps updated five days ago. They are nicely covered in Gavin's videos these days, so I'm basically providing another angle on things for those who are interested 

http://www.metoffice.gov.uk/images/prob_ensemble/20140301/2cat_20140301_z500_months24_global_deter_public.png

Starting with the good old 500hPa (or 500mb) height anomalies, the pattern is a striking one; it shows with remarkable clarity a jet stream tracking well south fo normal, with a marked negative anomaly across much of NW Europe and the Mediterranean, and a large area of positive anomalies extending from Iceland, through Scandinavia and well on into Russia.

The most notable implication for surface conditions is a predominantly unsettled regime across Europe that poses some risk of seeing another very large flooding event similar to last year 

You can see it clearly in the pressure anomalies:

http://www.metoffice.gov.uk/images/prob_ensemble/20140301/2cat_20140301_mslp_months24_global_deter_public.png

...which also show an interesting setup across the UK; the north, particularly the NW, is favoured for seeing some decent periods of dry and settled weather, with temperatures and cloud amounts depending on whether there is a continental or Atlantic feed - unfortunately there looks to be a risk of seeing a fetch across the North Sea occuring quite often, which can generate a fair bit of mist, murk, haar and low cloud.

Any clearer interludes could generate very nice conditions, however, particularly as we progress towards the latter stages of spring. This seems to be reflected in the 2m temperature anomalies, which are a tad above average for the north:

http://www.metoffice.gov.uk/images/prob_ensemble/20140301/2cat_20140301_temp2m_months24_global_deter_public.png

Across the south, the temperature anomaly reverses - but it is very weak, essentially showing a season averaging out close to the LTA, which is also true for the north. The continent shows a marked divide between a slightly colder than average west and a warmer than average east. Most of Asia looks a bit toasty, and Scandinavia looks to go into the frying pan, which seems to happen at some point every year these days.

With all that continental troughing going on, the south is clearly at risk of seeing periods of showers, more persistent rain or whole low pressure systems moving across at times, but with their origin tending to be from a latitude south of the UK, temperatures would probably tend to hold up overnight, combatting the supressed daytime maxima.
That said, I don't think this entirely explains the near average overall temperatures - I reckon we'd see some imports of warm air at times, wrapping around the continental troughs.

http://www.metoffice.gov.uk/images/prob_ensemble/20140301/2cat_20140301_prec_months24_global_deter_public.png

This precipitation map suggests that the UK will escape the worst of the rain, in fact it could be drier than average for many parts, though the signal is, as usual, weak. Convective input is probably being underestimated for the south, though.

Across Europe, I am surprised that the positive rainfall anomalies are not stronger, but they are certainly extensive!

The effects of El Nino are very marked here - clearly it is being predicted by the model.

Not going to bother making a spring/summer hopecast this year after my horrendous winter forecast lol

Even the annual March snowfall failed to appear this year dreadful!

Most winter forecasts were way off the mark, I only recall one or two of the many going for a wet/very wet winter if I recall correctly.

Over the weekend, I had a look at similar years to 2013 for Nov-Dec, then from those looked at which ones were similar for the following Jan-Feb.

The resulting closest match years were 1994, 2007 and 2011, and of those the only particularly good match was 1994.

Looking at all three combined, March looks like this:

March 1994, 2007, 2011

... which bears considerable similarity to the patterns of late, although the change occuring this week will act in the opposite direction so the anomalies may not end up being as pronounced.

April then looks like this:

April 1994, 2007, 2011

...which indicates a very dry month under persistent high pressure. Not surprising when you think about the fact that 2007 and 2011 are two of the warmest, driest Aprils on record!

The current NWP output and long range models, however, show almost the opposite to the above pattern.

With this in mind, I took out 2007 and 2011 to leave only the closest matching year, 1994. In March, the pattern looks similar to that for 1994, 2007 and 2011 combined, but then for April:

April 1994

...the pattern is drastically different, and much closer to what the current model output is suggesting for next month.

Looking further ahead to May, using that one remaining good analogue:

May 1994

Not a pretty sight, although the UK looks like it could be on the warmer side of things at times. Potentially very wet though!

http://www.cpc.ncep.noaa.gov/products/people/wwang/cfsv2fcst/imagesInd3/glbz700MonInd2.gif

This CFS prediction isn't actually that far away from the above.

Dare I look at summer 1994? Worth a gander...

June 1994

...how about that, June saw a very nice pattern for the south, close to a Euro High - but not so good for the north with a westerly flow from the Atlantic dominating.

July 1994

Blimey, that's a toasty pattern for July! Shame this can't be taken at all seriously!

http://www.cpc.ncep.noaa.gov/products/people/wwang/cfsv2fcst/imagesInd3/glbz700MonInd4.gif

CFS is close, even so... but that can't be taken at all seriously either 

August 1994

A marked change for August to an unsettled regime... which is showing up on many long range model projections as well.

This is all purely out of interest, the same technique didn't do too badly for last summer, but that time I had a few more very good matches to work with. I wouldn't count on a summer like 1994, although there does seem to be a general signal among the long range models for something broadly similar... but details are what matter.

What annual March snowfall? Just like winter March has turned into a pathetic joke in recent years. This is the 4th March out of 6 with no lying snow here whereas between 2000 and 2008 only March 2003 failed to record lying snow.

After 2010 it looked as though this was going to be the first snowy decade since the 1960s but since January 2011 it has been worse than the 90s. This is the first year ever recorded with no lying snow between January and March here. 19th November the sole day with lying snow in the past year and 13th March 2013 the last day with snow lying throughout the day.

Cmon 2013 wasn't bad at all, sure this winter and 2011 were awful; but I think its a fair price for 2010. 

Browsing around, looking at model outputs and analogues and the like, I get the impression that the setup coming our way this weekend could be seen quite often in the coming months.

The evidence is rather weak at the moment though, with most LRF output lacking any particularly strong signals regarding the placement of troughing, other than that it will likely be at a lower latitude than normal.

The way I see it, a mean trough position somewhere south of Greenland is within reach, and that would make for an interesting run of months, with unsettled and at times cool periods - as some trough energy finds its way across the UK from the mid-Atlantic 'breeding ground' - interchanging with often very warm (hot later on) and more settled ones.

Obviously all I can really do is cross my fingers and hope! Meanwhile there will be those who cringe at the idea and will be hoping for something very different... 

I've been out and about today on the Surrey-Sussex border. Definitely oak before ash - so only a splash of rain forecast. Probably as reliable as many another LRF.

[It is suggested that oak responds to mild temperatures and ash to high light levels, so the mild but wet winter would indeed favour the oak. Then you have to hope that the synoptic pattern for spring is influenced by that of winter.]

I'm expecting a summer of high latitude blocking with a trough just to our west for June and July with August seeing drier conditions with temps around average to above the further East and SE you are.

My own 'suspicions' for the summer are quite close to that; blocking being quite frequent to the E and NE, with troughing in the Atlantic drifting back and forth in terms of mean location, such that sometimes it is out to our west and the UK is on the hot side with continental air, but other times, the trough is more or less over the UK and bringing considerable spells of rain and showers... but with temperatures holding up enough overnight to produce a mean somewhat above the LTA overall for June and July at least.

I'm less sure about August - either the blocking becomes stronger and more influential, or it collapses and a major pattern change unfolds 

I hope people don't mind if I do another review of my LRF

2014

January

Milder than average especially at first and very unsettled, a chance of cold snowy periods later.

CET above normal

February

Potentially coldest month of the winter, some snow showers likely in S and E. Unlikely to be overly cold or prolonged though.

CET below normal

March

Settled, dry, rather chilly. Some late frosts and even wintry showers. Sunshine prevalent

CET below normal

April

Showery. Slightly below average temperatures. Some settled spells

CET slightly below average

May

 Extremely dry and sunny. Chilly winds at first, although very warm weather possible later. Perhaps an early heatwave.

CET around average

June

Very dry theme continuing. Some rather cool sea breezes making temps chilly at times. Somewhat below average temperatures.

CET slightly below average

July

Another dry month especially in the east. However it will be warmer than june with a few thundery outbreaks possible

CET above average

August

The dry run ends with august. Changeable, sometimes very wet or showery but still often mild.

CET slightly above average

September

Dry, rather warm and perhaps thundery. 'Indian summer'.

CET much above average

October

Probably a little drier than average

CET around average

November

Drier than average theme perhaps continuing. Average temps, becoming chilly.

CET slightly below average

December

Changable. Mix of short cold wintry spells and warmer mild spells.

CET around average.

I have already covered January and February. I messed up the temperature aspect of March, however the rainfall projection was reasonable, the metoffice reported 85% average rainfall and 127% sunshine. There was a notably late and widespread frost on the 24th across most of the UK apart from the SW, however this notwithstanding it wasn't a particularly frosty month. So my first three months have been decidedly mixed, lets see how April ends up. 

Picking up from this in the CET thread, what are the chances of a warm May this year... let's see what CFS and the Met Office ensembles show:

http://www.cpc.ncep.noaa.gov/products/people/wwang/cfsv2fcst/imagesInd3/glbz700MonInd1.gif

Interesting... a positive anomaly centred just NE of the UK, extending through Scandinavia but also up to Svalbard. Then a weak negative anomaly extending from Canada to just south of Greenland.

That all sounds rather a lot like the synoptics we had to end March and begin April this year. Areas of low pressure to the SW could bring some particularly warm conditions with the chance of plumes. On the other side of the coin, areas of low pressure more towards our east could drag in some relatively chilly air from the NE on occasions.

On balance, though, I'd say it favours a warmer than average month, but potentially wetter than average across the SW in particular while it could be much drier than average to the north, especially so across the NW.

http://www.metoffice.gov.uk/images/prob_ensemble/20140301/2cat_20140301_z500_months24_global_deter_public.png

http://www.metoffice.gov.uk/images/prob_ensemble/20140301/2cat_20140301_mslp_months24_global_deter_public.png

The Met Office ensemble mean hasn't updated as early this month as in March, which is annoying... yet when you look at it, the similarity of the Apr/May/Jun mean to the CFS mean for May is striking, which given the different period lengths involved is actually quite uncanny!

The surface pressure anomalies reveal one of the main reasons why I reckon warmer than average is favoured; any low pressure systems to our east look likely to reach quite far south as well, and this means that a cyclonic flow of warm air may tend to dilute any cold air from the NE, resulting in near average conditions, or there could be a SE flow setup bringing very warm conditions for all we know...

The corresponding 2m anomaly map is up to 0.5*C below the LTA for England and Wales, and up to 0.5*C above for Scotland. This isn't in line with my interpretations for May across the former two, but it does cover a 3 month period, and the output goes on to show a cooler 500mb height/surface pressure setup relative to the LTA developing into the summer, so I suspect the negative anomalies may be largely in June.

The Met Office ensemble mean outlook has finally updated 

First, I'll look at months 2-4, which is the only range I pay all that much attention too really:

http://www.metoffice.gov.uk/images/prob_ensemble/20140401/2cat_20140401_z500_months24_global_deter_public.png

Starting with the 500hPa anomalies, the signal is for above average heights across ALL of the mid-high latitudes... covering most regions at the latitude of the English Channel upward!

Perhaps a sequence of strong height anomalies progressing around the hemisphere? The weak signal for low heights from the Azores to Spain hints at a jet tracking a long, long way south of normal, further even than in the summers of 2007 and 2012.

http://www.metoffice.gov.uk/images/prob_ensemble/20140401/2cat_20140401_mslp_months24_global_deter_public.png

Switching to the projected surface pressure anomalies, and this notion is greatly reinforced; given that low pressure areas tend to situate just above the line of the jet, the jet stream position could be estimated to be about one third of the way northward through the negative anomalies stretching across the Atlantic.

As for the positive anomalies, they stretch across Greenland, which brings 2007 and 2012 to mind... however, they also extend across Ireland, Scotland and the far northern reaches of England, and continue a little way to the NE of the UK, and there is no negative pressure anomaly across any part of the UK. This is markedly different to 2007 and 2012, and combined with the position of the negative anomalies, the signal is for low pressure areas to track to the south of the UK while ridges build over the top.

Having the southerly tracking jet that steams right through Central Europe as well naturally promotes high pressure ridging through Greenland, the northern half of the UK and on into Scandinavia - it is a pattern that was observed during the particularly cold spells of winter 08/09, 09/10 and December 2010.

I have long wondered if we would ever see that sort of pattern turn up in summer, with the jet cutting right through Europe rather than buckling north to pass close to the UK and bring the storms our way, as happened in 2007 and 2012.

So what are the implications for surface temperature and precipitation?

Well, both of those are tricky to pin down, and the reason is continenental airmasses wrapping around low pressure systems and interacting with the ridges of high pressure to the north of them. We have already seen in recent times how the UK can recieve unusually warm conditions from the SE if the trough is far south/southwest enough, but also how it only takes a disturbance on the periphery of the trough to bring slow moving areas of precipitation and supressed daytime maxima, though temperatures tend to remain above average overall, and with the air rather humid it can feel very muggy.

The ensemble mean suggests that low pressure areas will most often locate in a position similar to what brought an unseasonably warm finish to March this year... but there is much room for variation around that, so I imagine the UK could see some notable hot, sunny spells of weather, interspersed with humid, showery, probably quite often thundery ones. Colder air has the potential to feed in from the N/NE at times, moderating the overall temperature anomaly.

This theory is well reflected in the outputs for temperature and precipitation, which are a little above average and very close to average, respectively.

http://www.metoffice.gov.uk/images/prob_ensemble/20140401/2cat_20140401_temp2m_months24_global_deter_public.png

Perhaps the Azores will be left very much in want of their namesake high...? Meanwhile it could be really quite wet across Italy are surrounding areas, as above average temperatures combine with an unsettled regime.

As far as the weather here goes, I would be happy if this verified, as it would be a summer quite unlike anything I have good recollection of, and IMBY probably by far the most thundery since 2006, maybe longer.

If only we could have more than a sliver of confidence in long range model output!

Despite this, I'm getting a good feeling from the fact that CFS has been showing uncannily similar ideas at times over the past month of output, I mean just look at this current one for July:

http://www.cpc.ncep.noaa.gov/products/people/wwang/cfsv2fcst/imagesInd3/glbz700MonInd3.gif

http://www.cpc.ncep.noaa.gov/products/people/wwang/cfsv2fcst/imagesInd3/glbz700MonInd1.gif

The CFS multi-run mean for May has a pattern which has been cropping up in a lot of recent GFS runs from around day 9 or 10 onwards.

ECM and the rest are also hinting at such a setup evolving, and I really hope it does, as it looks like a good one for plumes and thundery breakdowns 

Obviously there are many who don't feel the same way, but you had your fun in 2010, 2011 or 2012 depending on what combination you seek 

http://www.cpc.ncep.noaa.gov/products/people/wwang/cfsv2fcst/imagesInd3/glbz700MonInd2.gif

This for June is very interesting. It's been evolving steadily in this direction for many weeks now, and the indication is for high pressure to be increasingly influential from the east as May gives way to June.

Let's not beat around the bush here - what CFS is currently showing is something with the potential to be one of the hottest Junes on record 

Worth keeping an eye on, for sure!

...but putting a sensible hat on, this is far from output to be relied upon, and we could do with seeing the Met Office ensemble means trend in that way as well... which we won't know about for another few weeks 

Having said that, at least the April update was not far away, and it's not too hard to see the extensive mid-latitude positive height anomalies that were signalled for becoming a more marked anomaly confined more to the near-east of or right over the UK, while the negative anomalies focus more towards the Azores.

A sneak peak at July gives this from CFS:

http://www.cpc.ncep.noaa.gov/products/people/wwang/cfsv2fcst/imagesInd3/glbz700MonInd3.gif

More changeable, but the positive height anomaly to the east remains and is of notable strength for such range... yes, it does appear that CFS is seeing a seriously toasty June/July combination. With August seeing a more unsettled westerly setup signalled, it does bring 2006 to mind a bit, and 2003 is in there too I suppose.

So to summarise, the current LRF model outlook from CFS is the hottest, but also most thundery, that I have seen in the past half-decade (which is the entire time I've been paying it much attention). The Met Office mean outlook from last month was not as markedly in that direction, but didn't strike out against it either, also showing the potential for some notable plume conditions at times... just not as much as CFS.

Fingers crossed, hot/thunder lovers!