Model Output Discussions 12z 03/05/2016

[Frosty.]

The Ecm 12z is looking good with the uk bathed in warm air,  the warmth reaching northern Britain from sunday onwards and for southern UK in particular, a very warm and increasingly humid weekend and early next week with plenty of sunshine and scattered thunderstorms for quite a few days but then high pressure brings mainly dry and very pleasant conditions towards the end of the run. Apart from some mist and fog occasionally lapping onto eastern coastal parts of the uk for a time it's a very nice spell at last this spring!

[Frosty.]

Ecm 12z charts. 

[Summer Sun]

Some thunder storms possible Tues to Thurs next week but remaining very warm through-out away from the east coast then settling down from Fri

[damianslaw]

Models showing a fairly blocked scenario for the foreseeable and unusually with such a southerly tracking jet we are set to fair well with the UK bathed in continental warm air with a predominant feed of air from between southeast and northeast - as far removed from the default normal westerly pattern as you can get, but if any time of year can produce such synoptics its now, traditionally when the atlantic is firmly at its weakest - so perhaps not that unusual.

Low 20 maxes look the norm for many from Sunday onwards - even into parts of Scotland, a tall order to achieve in high summer in some years..

Interesting how we are seeing similiar pattern to May 98 which produced a notable lengthy warm spell early- mid month on the back of the last strong El Nino which also produced a chilly April. May 08 produced similiar fayre... just an observation. Wouldn't be surprised to see a quick flip back to something much more unsettled mid month - as occured in both those months, though not necessarily significantly cooler.

Spring 16 is certainly delivering very different synoptics to those endured in late autumn 2015 and much of winter 2015/2016 when the atlantic prevented any blocking features or colder northerly or continental airstreams. 

Its been a while since we have had a decent lengthy warm dry spell in May (upwards of a week), 2008 the last time, though 2012 came close and we've had short lived such spells in 2009 and 2010, the last 3 Mays have been particularly dissapointing though.

[knocker]

The 6-10 anomalies are all on the same page continuing the theme of slipping the trough away to the south east and HP setting up over the UK, Thus continuing a dry spell of weather (apart maybe for the south early next week) and temps pretty good and above average. The chances are that the HP will be fairly transitory and will weaken as we get towards the 20th as more zonal pattern emerges although the temps still holding up pretty well. A certain amount of uncertainty regarding this so just a watching brief.

[Cloud 10]

UKMO with a very pronounced Atlantic ridge at day 6 which is maybe overdone,especially when compared to the ECM at the same timeframe.

 

UKMO..ECM..

 

Meanwhile the GWO continues in its high AAM state,and never seems to come any closer to its forecasted plunge into low AAM territory.

 

[knocker]

The GFS this morning has an interesting take on the upcoming evolution at the end of next week but starting at the beginning.

Certainly very warm for the next few days with low pressure to the south of the UK  bringing a southerly and then easterly flow to the proceedings. This could produce some thundery activity over some parts of the UK over the weekend but best left to the dedicated thread. But the same low pressure nudging a tad north will introduce rain and thundery outbreaks on Monday and Tuesday in the south which will edge a little north before dissipating.

This brings us towards the end of the week and the low pressure has moved east as expected but it would appear ( I use the word advisedly) to be linking with an upper trough orientated SE from the Arctic. Thus we have low pressure over Scandinavia which introduces a northerly component to the flow over the UK and a marked drop in temps to below average. It then proceeds to keep low pressure very adjacent to the UK.

Now I suspect that this scenario is very dependent on the position of the upper trough developing in the Arctic and becoming orientated to the east so what does the latest EC32 means update have to say on this.

On Friday the process of moving the LP to the south east is underway as the HP to the NE simultaneously swings SW over the UK which has been the theme for a while. At the same time it develops the Arctic trough and brings it south to connect with the other trough but just to the east of Scandinavia, This would suggest that surface developments would favour HP being more influential over the UK with the low pressure further east although it possible could just touch on the UK during the transition.

But it has to be said the EC32 very rapidly gets rid if the ridge over the UK and by the 18th there is a trough to the west with the upper flow in the westerly quadrant. During this period the temps have remained above average moving towards average later.

At the moment I'm treating the GFS output with much suspicion but hey, what do I know.

EDIT

A quick look at the GEFS anomaly and you can see where the ops is coming from but as it quickly establishes the ridge I increasingly doubt the ops interpretation.

 

Edited May 6, 2016 by knocker

[knocker]

The ecm is a little different to the GFS. It also has the low pressure moving east and introduces a NE/N flow. Meanwhile the HP slides SW and by the end of the run we have low pressure away to the east and HP building in the Atlantic and nudging into the UK. All of this does drop the temps to nearer average or just below..

At the end of the day there are some similarities between the GFS and ecm. Much depends on the position of the upper trough to the east.

Edited May 6, 2016 by knocker

[johnholmes]

Looking at the anomaly charts I use and NOAA last evening seemed to be keeping things more or less as they are. This morning ECMWF-GFS shows things differently. The question is-which is more likely to be correct? Is EC-GFS leading a change, it has done this a few times in the past months, or is NOAA nearer.

Until the next run from each we are left sitting on the fence.

links below

EC-GFS

http://mp1.met.psu.edu/~fxg1/ECMWF_0z/hgtcomp.html

NOAA

http://www.cpc.noaa.gov/products/predictions/610day/500mb.php

[Gibby]

HERE IS MY LATEST ANALYSIS USING DATA SUPPLIED BY THE NWP OUTPUT COVERING 5 OF THE WORLDS MOST POWERFUL WEATHER COMPUTERS ISSUED AT 09:00 ON FRIDAY MAY 6TH 2016

THE CURRENT GENERAL SITUATION Pressure is falling across England and Wales as an area of Low pressure near Spain and Portugal becomes more influential over the coming days. The resultant ESE flow will carry an activating warm front NW across the UK tonight introducing air with high humidity values to many parts of the UK over the weekend.

http://www.wetterzentrale.de/pics/Rtavn001.gif

CURRENT SNOW FORECAST AND/OR FREEZING LEVEL OVER THE UK The UK continues to see the freezing level across the UK range from just above 5000ft over NW Scotland to near 10000ft over SE England. The level then settles to around 8000ft UK wide by and over the weekend.

http://www.snow-forecast.com/maps/dynamic/uk

http://www.natice.noaa.gov/pub/ims/ims_gif/DATA/cursnow.gif

MODELS-2 WEEK HEADLINE Rather warm with thundery showers in the South. Perhaps rather cooler later.

THE GFS JET STREAM FORECAST  The Jet Stream's main core is situated well South of the UK near Southern Spain and North Africa in association with a large depression down there. This remains for some time before the Low pressure area edges East and opens the door to a finger of the flow to move South over the UK as Low pressure develops East of the UK in a week or so. Then towards the end of the period the flow reverts back South of the UK in association with UK based Low pressure.

http://www.netweather.tv/index.cgi?action=jetstream

GFS OPERATIONAL The GFS Operational Run today shows Low pressure developing over Spain and Portugal where it remains for some time before drifting ENE later next week. For the UK winds will be from the SE before backing more ENE next week with plenty of warm and humid air across the UK with the risk of thundery showers at times across the South inparticular early next week. Then as winds back Northerly late next week it looks like cooler and more showery air will track South across all areas with the showers mostly across the East. Towards the end of the run pressure becomes slack across the UK with still a lot of High pressure northern blocking evident further Low pressure and rain and showers seem probable in temperatures close to normal at the end of the period.

http://www.wetterzentrale.de/pics/Rtavn1441.gif

http://www.wetterzentrale.de/pics/Rtavn3841.gif

NEW GFS PARALLEL RUN The New GFS Parallel Run is very supportive of the theme shown in he Operational over Week 1 but makes rather less of the unsettled weather of Week 2 with more in the way of weak but High pressure close to the UK in Week 2 with fewer showers as a result and spells of sunshine in very average May temperatures as a result.

http://www.meteociel.fr/modeles/gfse_cartes.php?&ech=144&mode=0&runpara=1

http://www.meteociel.fr/modeles/gfse_cartes.php?&ech=384&mode=0&runpara=1

GFS CONTROL RUN As above the first week is well agreed upon within the GFS Camp this morning with Week 2 showing the more varied weather options. This Control Run shows that Week 2 has pressure rising from the West with a strong ridge across the UK by the end of the period with fine and largely settled conditions likely for the UK by then.

http://www.meteociel.fr/modeles/gefs_cartes.php?code=0&ech=144&mode=0&carte=0

http://www.meteociel.fr/modeles/gefs_cartes.php?code=0&ech=384&mode=0&carte=0

GFS ENSEMBLE DAY 14 DATA The clustering today continues to be unclear in the latter stages of the forecast period this morning with the majority slightluy in favour of a weak Northerly across the UK in two weeks but with plenty of other options in the mix too.

http://www.weatheronline.co.uk/cgi-bin/expertcharts?LANG=en&MENU=0000000000&CONT=euro&MODELL=gefs&MODELLTYP=2&BASE=-&VAR=cpre&HH=372&ZOOM=0&ARCHIV=0&RES=0&WMO=&PERIOD=

UKMO The UKMO model this morning shows a warm SE flow across the UK in three days time with the risk of thundery showers in the South. Then as we move through next week it looks like the risk intensifies and spreads North somewhat as the Low pressure to the SW over Spain advances NE through France backing winds off towards the East and later NE with cooler conditions likely to make there way across the UK later next week if the indicated movement process continues as shown.

http://www.wetterzentrale.de/pics/Rukm1441.gif

THE FAX CHARTS The Fax Charts show quite a complex scenario revolving around the movement of Low pressure over Spain and it's effects on the UK. Sunday looks the best day of the next 5 as the innitial push of thundery weather moves away to the NW behind a warm front introducing humid SE winds. Then early next week complex troughing looks like becoming straddled close to or over Southern Britain with thundery rain or showers more widespread and the best of the weather in the NW.

http://www.weathercharts.org/ukmomslp.htm#t120

GEM GEM this morning shows very slow changes over the next 10 days with the same thundery low pressure area over Spain taking a whole week to begin to lose any threat to the South and SE of Britain with an eventual rise of pressure from the Northwest  ensuring settled weather returns by Day 10 with the best conditions throughout looking likely to the NW with even by Day 10 something of a potentially showery NE flow close to the SE.

http://www.wetterzentrale.de/pics/Rgem2401.gif

NAVGEM NAVGEM today follows the theme shown elsewhere of the eventual movement away from the South of the UK of the thundery Low pressure moving NE from Spain next week while filling slowly. The run ends with High pressure in close proximity in very slack winds with benign and pleasant conditions for many areas by next weekend.

http://www.wetterzentrale.de/pics/Rnvg1681.gif

ECM ECM today is more clear cut in it's movement away from the UK of the Low pressure area over Spain, taking it across Europe next week and removing the risk of thundery rain and showers from the South by soon after midweek and lowering temperatures to more average values as winds back towards the North by next weekend. The run ends with High pressure in close proximity to the West and NW of the UK with the best weather there while there remain a cooler NE flow blowing from the North Sea over England and Wales with perhaps an odd afternoon shower over the SE.

http://www.wetterzentrale.de/pics/Recm2401.gif

ECM 10 DAY MEAN (12z) With so much uncertainty longer term this chart is not as reliable as usual in giving clues as to where we will lie in 10 days time. However, my best guess that there is an even distribution of members showing Low pressure to be both to the East and West of the UK with a slack pressure gradient likely over us with the risk of a few showers but a lot of dry weather too.

http://www.wetterzentrale.de/pics/Reem2401.gif

NOTABLE TRENDS & CHANGES FROM PREVIOUS RUNS The theme remains for a warm and humid period of weather across the UK before a gradual reduction in both temperatures and showers look likely later though all with low confidence.

31 DAY HISTORICAL VERIFICATION STATS FOR GFS, UKMO & ECM The verification Statistics of GFS, UKMO and ECM show at 24 hours ECM ahead at 99.6 pts with UKMO at 99.4 pts and GFS at 99.2 pts.  At 3 days ECM is leading with 97.1 pts to UKMO's 96.3 pts while GFS lags behind at 95.5 pts. At 5 days ECM leads with 88.5 pts to UKMO at 86.7pts and GFS at 83.0 pts. Then at 8 Days ECM has the leading spot from GFS with 61.3 pts to 51.3 pts. Finally at Day 10 ECM has the lead from GFS with a score of 45.8 pts to 37.1 pts.

http://www.emc.ncep.noaa.gov/gmb/STATS_vsdb/allmodel/daily/cor/cor_day1_PMSL_MSL_G2NHX.png

http://www.emc.ncep.noaa.gov/gmb/STATS_vsdb/allmodel/daily/cor/cor_day3_PMSL_MSL_G2NHX.png

http://www.emc.ncep.noaa.gov/gmb/STATS_vsdb/allmodel/daily/cor/cor_day5_PMSL_MSL_G2NHX.png

http://www.emc.ncep.noaa.gov/gmb/STATS_vsdb/allmodel/daily/cor/cor_day8_PMSL_MSL_G2NHX.png

http://www.emc.ncep.noaa.gov/gmb/STATS_vsdb/allmodel/daily/cor/cor_day10_PMSL_MSL_G2NHX.png

MY THOUGHTS  Whenever pressure patterns across the UK are the reverse of the normal, i.e. the reverse of Low pressure to the North and High to the South the models always struggle with the longer term projections and the methods that they try to reset the pattern are always difficult to interpret accurately and as a result they throw up a lot of differences between the models. That is what we have currently with Low pressure becoming deep and anchored down near Spain and Portugal sending spores of energy North over France towards the South and West of the UK in the coming 4-5 days with thundery rain in places early and late in this period. In between there will be a lot of warm and humid weather with sunny spells. Then as the Low is forecast to move East or ENE across Europe next week the winds over the UK look like backing NE or North and this will lower temperatures to average with time. What is less certain is how much influence that European Low will maintain influence across the SE portion of the UK by late next week and how much will High pressure build across the UK in it's wake--all questions uneasy to answer within this morning's output. What is more certain is that North sea coasts are going to have a torrid time soon as while many of us enjoy warm temperatures sea haar looks like giving some very cool temperatures for several days on end over the next week in those areas and any removal of the present pattern would be very welcome news for them. However, having said all that there is nothing particularly nasty shown within the output this morning and it maybe that conditions become fairly benign in the second week with no overall pressure area, low or high having overall control of our weather across the UK. So let's sit back and enjoy this early season warmth and coupled with the chance at least of some warm thundery rain in the South the growing season should gather momentum over the next few weeks. No report from me tomorrow as I will be in Salisbury Wiltshire for the day but back on Sunday morning.

Next Update Sunday May 8th 2016 from 09:00

[Singularity]

That Svalbard low is really getting on my nerves now! If it stays independent of the trough moving through Europe, we see a ridge to our N/NE with a warm flow off the continent tending to continue - as the NOAA anomaly plot last evening suggested - but if the two lows join forces, we find ourselves under a northerly flow, the potency depending on how far east the combined trough is. This would also be disastrous for the Arctic sea ice - though I'm not sure the alternative path is all that much better, to be honest.

Hopefully, even if we get the combining lows scenario, the trough will turn out to be further east, as we often see in the winter season - teasing us with biting northerlies which end up visiting the likes of Italy or Greece.

Good job we have this weekend's early taste of summer nice and secured - and of course anyone who's off work next week may do quite well depending on what happens with the potential convergence line from the south Tue-Wed. I expect the GFS 00z is too fast with the establishment of a cool northerly flow. Well, hopefully!

Edit: that UKMO 00z run has the Svalbard low moving toward Eurasia several days sooner than ECM. Looks like a slack northerly setting up so not terrible but it's alarming to see things moving along that quickly as it makes the GFS 00z seem less wild 

Edited May 6, 2016 by Singularity

[Gordon Webb]

55 minutes ago, Gibby said:

HERE IS MY LATEST ANALYSIS USING DATA SUPPLIED BY THE NWP OUTPUT COVERING 5 OF THE WORLDS MOST POWERFUL WEATHER COMPUTERS ISSUED AT 09:00 ON FRIDAY MAY 6TH 2016

THE CURRENT GENERAL SITUATION Pressure is falling across England and Wales as an area of Low pressure near Spain and Portugal becomes more influential over the coming days. The resultant ESE flow will carry an activating warm front NW across the UK tonight introducing air with high humidity values to many parts of the UK over the weekend.

http://www.wetterzentrale.de/pics/Rtavn001.gif

CURRENT SNOW FORECAST AND/OR FREEZING LEVEL OVER THE UK The UK continues to see the freezing level across the UK range from just above 5000ft over NW Scotland to near 10000ft over SE England. The level then settles to around 8000ft UK wide by and over the weekend.

http://www.snow-forecast.com/maps/dynamic/uk

http://www.natice.noaa.gov/pub/ims/ims_gif/DATA/cursnow.gif

MODELS-2 WEEK HEADLINE Rather warm with thundery showers in the South. Perhaps rather cooler later.

THE GFS JET STREAM FORECAST  The Jet Stream's main core is situated well South of the UK near Southern Spain and North Africa in association with a large depression down there. This remains for some time before the Low pressure area edges East and opens the door to a finger of the flow to move South over the UK as Low pressure develops East of the UK in a week or so. Then towards the end of the period the flow reverts back South of the UK in association with UK based Low pressure.

http://www.netweather.tv/index.cgi?action=jetstream

GFS OPERATIONAL The GFS Operational Run today shows Low pressure developing over Spain and Portugal where it remains for some time before drifting ENE later next week. For the UK winds will be from the SE before backing more ENE next week with plenty of warm and humid air across the UK with the risk of thundery showers at times across the South inparticular early next week. Then as winds back Northerly late next week it looks like cooler and more showery air will track South across all areas with the showers mostly across the East. Towards the end of the run pressure becomes slack across the UK with still a lot of High pressure northern blocking evident further Low pressure and rain and showers seem probable in temperatures close to normal at the end of the period.

http://www.wetterzentrale.de/pics/Rtavn1441.gif

http://www.wetterzentrale.de/pics/Rtavn3841.gif

NEW GFS PARALLEL RUN The New GFS Parallel Run is very supportive of the theme shown in he Operational over Week 1 but makes rather less of the unsettled weather of Week 2 with more in the way of weak but High pressure close to the UK in Week 2 with fewer showers as a result and spells of sunshine in very average May temperatures as a result.

http://www.meteociel.fr/modeles/gfse_cartes.php?&ech=144&mode=0&runpara=1

http://www.meteociel.fr/modeles/gfse_cartes.php?&ech=384&mode=0&runpara=1

GFS CONTROL RUN As above the first week is well agreed upon within the GFS Camp this morning with Week 2 showing the more varied weather options. This Control Run shows that Week 2 has pressure rising from the West with a strong ridge across the UK by the end of the period with fine and largely settled conditions likely for the UK by then.

http://www.meteociel.fr/modeles/gefs_cartes.php?code=0&ech=144&mode=0&carte=0

http://www.meteociel.fr/modeles/gefs_cartes.php?code=0&ech=384&mode=0&carte=0

GFS ENSEMBLE DAY 14 DATA The clustering today continues to be unclear in the latter stages of the forecast period this morning with the majority slightluy in favour of a weak Northerly across the UK in two weeks but with plenty of other options in the mix too.

http://www.weatheronline.co.uk/cgi-bin/expertcharts?LANG=en&MENU=0000000000&CONT=euro&MODELL=gefs&MODELLTYP=2&BASE=-&VAR=cpre&HH=372&ZOOM=0&ARCHIV=0&RES=0&WMO=&PERIOD=

UKMO The UKMO model this morning shows a warm SE flow across the UK in three days time with the risk of thundery showers in the South. Then as we move through next week it looks like the risk intensifies and spreads North somewhat as the Low pressure to the SW over Spain advances NE through France backing winds off towards the East and later NE with cooler conditions likely to make there way across the UK later next week if the indicated movement process continues as shown.

http://www.wetterzentrale.de/pics/Rukm1441.gif

THE FAX CHARTS The Fax Charts show quite a complex scenario revolving around the movement of Low pressure over Spain and it's effects on the UK. Sunday looks the best day of the next 5 as the innitial push of thundery weather moves away to the NW behind a warm front introducing humid SE winds. Then early next week complex troughing looks like becoming straddled close to or over Southern Britain with thundery rain or showers more widespread and the best of the weather in the NW.

http://www.weathercharts.org/ukmomslp.htm#t120

GEM GEM this morning shows very slow changes over the next 10 days with the same thundery low pressure area over Spain taking a whole week to begin to lose any threat to the South and SE of Britain with an eventual rise of pressure from the Northwest  ensuring settled weather returns by Day 10 with the best conditions throughout looking likely to the NW with even by Day 10 something of a potentially showery NE flow close to the SE.

http://www.wetterzentrale.de/pics/Rgem2401.gif

NAVGEM NAVGEM today follows the theme shown elsewhere of the eventual movement away from the South of the UK of the thundery Low pressure moving NE from Spain next week while filling slowly. The run ends with High pressure in close proximity in very slack winds with benign and pleasant conditions for many areas by next weekend.

http://www.wetterzentrale.de/pics/Rnvg1681.gif

ECM ECM today is more clear cut in it's movement away from the UK of the Low pressure area over Spain, taking it across Europe next week and removing the risk of thundery rain and showers from the South by soon after midweek and lowering temperatures to more average values as winds back towards the North by next weekend. The run ends with High pressure in close proximity to the West and NW of the UK with the best weather there while there remain a cooler NE flow blowing from the North Sea over England and Wales with perhaps an odd afternoon shower over the SE.

http://www.wetterzentrale.de/pics/Recm2401.gif

ECM 10 DAY MEAN (12z) With so much uncertainty longer term this chart is not as reliable as usual in giving clues as to where we will lie in 10 days time. However, my best guess that there is an even distribution of members showing Low pressure to be both to the East and West of the UK with a slack pressure gradient likely over us with the risk of a few showers but a lot of dry weather too.

http://www.wetterzentrale.de/pics/Reem2401.gif

NOTABLE TRENDS & CHANGES FROM PREVIOUS RUNS The theme remains for a warm and humid period of weather across the UK before a gradual reduction in both temperatures and showers look likely later though all with low confidence.

31 DAY HISTORICAL VERIFICATION STATS FOR GFS, UKMO & ECM The verification Statistics of GFS, UKMO and ECM show at 24 hours ECM ahead at 99.6 pts with UKMO at 99.4 pts and GFS at 99.2 pts.  At 3 days ECM is leading with 97.1 pts to UKMO's 96.3 pts while GFS lags behind at 95.5 pts. At 5 days ECM leads with 88.5 pts to UKMO at 86.7pts and GFS at 83.0 pts. Then at 8 Days ECM has the leading spot from GFS with 61.3 pts to 51.3 pts. Finally at Day 10 ECM has the lead from GFS with a score of 45.8 pts to 37.1 pts.

http://www.emc.ncep.noaa.gov/gmb/STATS_vsdb/allmodel/daily/cor/cor_day1_PMSL_MSL_G2NHX.png

http://www.emc.ncep.noaa.gov/gmb/STATS_vsdb/allmodel/daily/cor/cor_day3_PMSL_MSL_G2NHX.png

http://www.emc.ncep.noaa.gov/gmb/STATS_vsdb/allmodel/daily/cor/cor_day5_PMSL_MSL_G2NHX.png

http://www.emc.ncep.noaa.gov/gmb/STATS_vsdb/allmodel/daily/cor/cor_day8_PMSL_MSL_G2NHX.png

http://www.emc.ncep.noaa.gov/gmb/STATS_vsdb/allmodel/daily/cor/cor_day10_PMSL_MSL_G2NHX.png

MY THOUGHTS  Whenever pressure patterns across the UK are the reverse of the normal, i.e. the reverse of Low pressure to the North and High to the South the models always struggle with the longer term projections and the methods that they try to reset the pattern are always difficult to interpret accurately and as a result they throw up a lot of differences between the models. That is what we have currently with Low pressure becoming deep and anchored down near Spain and Portugal sending spores of energy North over France towards the South and West of the UK in the coming 4-5 days with thundery rain in places early and late in this period. In between there will be a lot of warm and humid weather with sunny spells. Then as the Low is forecast to move East or ENE across Europe next week the winds over the UK look like backing NE or North and this will lower temperatures to average with time. What is less certain is how much influence that European Low will maintain influence across the SE portion of the UK by late next week and how much will High pressure build across the UK in it's wake--all questions uneasy to answer within this morning's output. What is more certain is that North sea coasts are going to have a torrid time soon as while many of us enjoy warm temperatures sea haar looks like giving some very cool temperatures for several days on end over the next week in those areas and any removal of the present pattern would be very welcome news for them. However, having said all that there is nothing particularly nasty shown within the output this morning and it maybe that conditions become fairly benign in the second week with no overall pressure area, low or high having overall control of our weather across the UK. So let's sit back and enjoy this early season warmth and coupled with the chance at least of some warm thundery rain in the South the growing season should gather momentum over the next few weeks. No report from me tomorrow as I will be in Salisbury Wiltshire for the day but back on Sunday morning.

Next Update Sunday May 8th 2016 from 09:00

this is what this thread should be about unbiased and not favoring one type of weather over another

looks like the warm weather is coming as forecast even though the threat of rain / showers seem more limited to the south at least for the moment which is just as well as got outdoor plans this weekend be back next week

best wishes to all

[Frosty.]

What a beauty of a weekend according to the Gfs 6z with temps across England and Wales reaching the low 20's celsius on Saturday, perhaps 24c 75f in and around London and then Sunday looks even warmer, I think the gfs is under estimating the max temps and somewhere in the s / se could reach 27c 81f on sunday. Most areas look fine with long sunny periods but isolated thunderstorms will develop with intense rainfall but many areas should stay fine. Into next week it stays warm with some sunshine and still a risk of thundery rain / showers further south. It's been a crap spring but this spell of warmth will raise hopes for the upcoming summer!

[knocker]

1 hour ago, Gordon Webb said:

this is what this thread should be about unbiased and not favoring one type of weather over another

looks like the warm weather is coming as forecast even though the threat of rain / showers seem more limited to the south at least for the moment which is just as well as got outdoor plans this weekend be back next week

best wishes to all

Are you suggesting the rest of us are biased?

Anyway looking at the ecm anomalies this morning is not bad news. It has the trough far enough east to allow ridging just to the west of the UK although this is fairly short lived before zonality sets in. The upshot of this although there is a period of N/NWs they are mainly  from an anticyclonic circulation and thus don't impact severely on the temps.

This is more in line with the EC32 although it does make a bit more of the trough.

Edited May 6, 2016 by knocker

[knocker]

You can see where the GFS is coming from. Strong ridging western Russia and zoom.

 

[knocker]

Vive la difference.

[damianslaw]

Quite pronounced significant developments from the models today, notably GFS, all show a highly amplified meridional flow and the upcoming warm southeast airstream being possibly replaced in a weeks time by a much cooler northerly flow. All agree on the trough sat to our SE moving eastwards with a ridge developing to our west, but crucially there are signals especially from GFS for an upper trough NW of Iceland joining forces and digging south allowing for a much cooler flow from the north.

I suspect what may happen is a cooler interlude next week but the ridge to the west being more dominant with the trough further eastwards and less pronounced, before we see unfortunately a more unsettled flow from a west/NW direction, so make the most of the next few days.

[Polar Maritime]

Certainly a stark difference to next weekend with a cold Northerly over the UK, Which could lead to some pretty hard overnight frosts in places.

 

 

[Polar Maritime]

Ok a few off topic posts hidden, Onwards and upwards with discussion on what the models are 'showing' please. Ta

Edited May 7, 2016 by Polar Maritime

[Captain Shortwave]

1 hour ago, Polar Maritime said:

Certainly a stark difference to next weekend with a cold Northerly over the UK, Which could lead to some pretty hard overnight frosts in places.

 

 

A funny old spring isn't it, from winter to summer to possibly winter again in a fortnight.

The ECM is slower with the evolution towards a northerly scenario with most of the working week being warm and mixed.

      

Still the ens do show a significant cooldown by the end of the coming week, potentially a drop of 10 degrees in 24 hours from the warmth we are currently seeing.

Still there are a good few days of warm or very warm weather to come with the risk of some heavy downpours.

[Gordon Webb]

1 hour ago, Polar Maritime said:

Certainly a stark difference to next weekend with a cold Northerly over the UK, Which could lead to some pretty hard overnight frosts in places.

 

 

well that would be a shock to the system if that came off especially after this weekend

[Summer Sun]

The GFS ens shows quite a drop late next week

A low chance of snow on the Inverness ens

As things stand may the most of the warmth springs to mind by next weekend some places could be struggling to reach the mid teens

[Frosty.]

26 minutes ago, Polar Maritime said:

Onwards and upwards with discussion on what the models are 'showing' please. Ta

Indeed pm, and the models are showing a very warm weekend and early next week with temps between 24-26c across England and Wales tomorrow with warm air finally reaching Scotland..enjoy it folks!

[Tamara]

Irrespective of weather preferences, its a classic highly amplified Spring pattern with cold northerlies alternating with warm southerlies.

Many people point to this being a feature of Spring's following a strong El Nino winter. Its partly due to the fact that traditionally both sides of the ENSO coin, Nino or Nina, feature a waning process at this time of year - and it is the ying-yang effects of the atmospheric circulation as a result of these processes that give rise to sudden flips in weather patterns, at the same time as thermal differential gradients between the poles and mid-latitudes realign themselves in the transition between winter and summer

The last update discussed the possible longevity of the unseasonal cold spell lining up to commence from the last week of April. The considerations in terms of this were attached to the duration and extent of an attempted dip in atmospheric angular momentum (AAM) tied to the preliminary winds of change blowing across the Pacific Ocean that are set to very gradually, and uncertainly, tug the global atmospheric circulation towards a deceleration in globally averaged wind flow as indicative of the end of El Nino - and ever increasing chances of La Nina influence thereafter on global weather patterns through the second half of the year

In simple terms this adds up to reduced upstream jet velocity, and as a consequence, growing sequences of retrogressive global upper air patterns seasonally across the hemisphere. But, in between these increasing frequency retrogressive phases over time, systematically weakening rebounds of the atmospheric circulation to current default Nino signature continue still likely to occur in the shorter term, which, for late Spring and early Summer in our parish, hold the hopes for settled and warm conditions.

Disclaimer: Relating here to a transitional weak/neutral ENSO signal, so comparisons  and associated attempts at working assumptions made with the evolving rapidly strengthening Nino to exceptional levels 12 months back, and the unsettled UK summer that followed, are not valid. We should remember that a hot Nino type summer did actually occur in 2015 - it was simply too far east of the UK due to the strength of the Pacific westerlies coming from upstream interacting with cold Atlantic SST's

With the summer-time polar easterly regime now established, each dip in AAM suggests a westward pull upstream (and then working downstream) of the upper air patterns and encourages pressure rises to our north, backing westwards as the pattern retrogresses. Each bounce back in AAM again thereafter adjusts the upper air pattern back eastwards, at this time of year helping to shift the jet stream northwards and consequently assisting warm air advection from the south. The results, evolving with time, according to natural seasonal wavelength changes.

In describing this tug o' war process on the atmospheric circulation, we get an illustration of how the weather pattern flips, that were referred to at the start of the post, come about.

So we can think of the mid April to early May sequence as one of those initial retrogressions of the pattern which, as far as our Atlantic sector is concerned, saw our trough into Scandinavia develop at the same time as downwelling polar easterlies ( legacy of the stratospheric vortex final warming)) augmented further the blocking arrangement to our NW and Greenland. The retrogression of the whole pattern then shifted the Scandinavian trough back westwards, but, as this was happening, a bounce back in AAM saw a shift northwards of the jet stream,  the pattern shunted back eastwards again, with the emergence of mid latitude ridging taking up residency and re-amplifying this time to our east, to pave the way to this weeks highly welcomed sharp recovery in temperature and much more seasonally settled and  warm weather

Phase 8/0 of the Global Wind Oscillation, as predicted in the last post, denoted the bottom-out limit to the last dip in angular momentum. Its register on the upper air pattern was reflected by the late April cold spell from the arctic. The return of the Global Wind Oscillation, also as suggested in the last post, to Phases 5/6/7 depicts the relative recovery in angular momentum and the volte face to a warm seasonal late Spring pattern and warm air advection from the south. If anything this flip has happened sooner than seemed possible just before the arctic spell - so that gives us a feel that for the time being at least, irrespective of the changes in the Pacific Ocean - the atmosphere is still fully receptive to defaulting to a weakening Nino state

In this respect, the GEFS forecasts look strikingly familiar to the last updated post. We are back to exactly where we were about three weeks back in terms of the atmospheric state - with the models teeing up yet another retrogression of the pattern in the D5-7 period as the Global Wind Oscillation looks set for another return through Phase 8/0 (NB don't take the current GEFS forecast too literally).

These phases represent the transitional ENSO zone between Nino and Nina, and are a symptom of the continuation of the pre-cursor process of the last vestiges of warmth disappearing from the western Nino zones in the Pacific and the colder sub surface waters already evident surfacing off the coast of Peru - and being edged westwards by the stirrings of easterly trade winds which will increasingly be propagated north and eastwards from the Indian Ocean as more and more time progresses.

With this prognosis in mind, I've little doubt that the GEFS forecasts will continue to predict their over-bias orbit for Nina-like Phases 1/2 right to the time it actually happens - which looks probable eventually based on the direction of travel of the ocean/atmosphere relationship. Its a case of how long they may stay de-coupled as the transition continues. It is the uncertainties of this relationship in the coming weeks and couple of months that will determine what type of high summer we will get. In such a tricky transition as we have in terms of speed, timing and evolution of change, its difficult to know and provide confident answers to this. Seasonal models underpin this uncertainty. But then (fortunately) I don't attempt seasonal forecasts, and instead enjoy watching the process evolve down to 2 to 4 week period ahead instead.

With that time period in mind looking ahead for the rest of the month, the last post suggested we should look out for further programmed rises of heights to our NW during May as part of the retrogressive sequences discussed. So we should not be too surprised by a rinse and repeat of the April > May general pattern in the coming few weeks to take us into the beginning of June.

The computer models are coming together to suggest exactly that happening. There are simply differences at this stage in terms of placement of the Euro trough to the east which determines any attempted cold(er) air advection - following the humid warmth of the coming week.

The latest ECM Dutch ensembles this morning give a clear signal of the extent of the current continental warmth, and the distinct drop in temperature that may occur to our east by next weekend as the next programmed retrogression occurs

 

Also, the suggested marked change in dew-points in these ensembles shows clearly the contrasts of the characters of the humid air-mass from the south set to dominate through this week, and the arctic origins of the air-mass predicted to follow yet again from the north

 

Here in the UK, we might yet be hopeful to miss the coldest uppers - with the trough sufficiently far enough east of us. Unless it retrogresses yet again as it did in late April.

Frost looks like it might yet have another belated word, with more chilly nights to come.

With the bigger picture discussion in mind from above, its reasonable enough at this stage to expect another settling down of the pattern from the south west to follow any cooler/colder incursion sometime during the last week or so of the month, with another potential warm up - more particularly in the south. The extended 10 to 15 day ensembles already are already supporting the bigger picture hypothesis, hinting at something of a subsequent slow recovery of temperature in the Netherlands - so, being further west, we might reasonably expect to see that faster in the UK. Albeit likely courtesy of a switch to westerly atlantic based influence to follow the northerly which might leave NW parts most susceptible to any weather fronts

Enough though already. Before any of that happens, the best thing to do right now is take Frosty's advice and enjoy the lovely warm summer-like conditions we have this weekend that are set to last throughout the week - between some thundery rain edging northwards from the slowly eastwards migrating trough over mainland Europe to affect the south, more especially at first

[wishingforsnow]

Tamara's analysis and the current model output is also supported by the current Met Office extended outlook which, whilst vague does illustrate a picture of a cooler, slightly below average shorter period of weather to follow this warm spell encouragingly ending with the return of more settled weather and the temperatures creeping up again as we enter June. So very much a rinse and repeat throughout May. It reminds me of May 2014 which had a warm/hot spell early in the month with a thundery breakdown, followed by a period of cooler and more unsettled weather but becoming settled and warmer again by June.