Model Output Discussion - Spring 5th March Onwards 6z--->

[Polar Maritime]

Yes Frosty, The GFS has stuck with the more unsettled cooler end to April with some kind of Northerly flow for a good few days now. The devil will be in the detail..

[Frosty.]

Yes Frosty, The GFS has stuck with the more unsettled cooler end to April with some kind of Northerly flow for a good few days now. The devil will be in the detail..

Yes PM, the Gfs has been showing this type of arctic incursion shown on the 6z at times recently, as you say, the devil will be in the detail.

[johnholmes]

It will be a first class call for a pattern change if it is correct as the anomaly charts, NOAA only out that far, do not show anything like that, link below

http://www.cpc.noaa.gov/products/predictions/814day/500mb.php

nor is there any clue of this in the MJO GFS output, although after the winter I rarely take much notice of this for ideas on 500mb patterns.

http://www.cpc.ncep.noaa.gov/products/precip/CWlink/MJO/foroper.shtml

 

nor is the latest ECMWF very keen on that idea; it does show orange colours in the far NW indicative of 'real' surface high pressure but the trough SE of this is not shown as swinging east to allow the deep cold in the far north to sweep south. An interesting idea to watch though, very cold northerlies are not that unusual (v cold for April that is) at this time of the year.

http://www.wetterzentrale.de/topkarten/fsecmeur.html

Edited April 16, 2015 by johnholmes

[Captain Shortwave]

Not particularly convinced that we will see anything that cold in the final week of April. The high looks likely to set up over Canada which would probably be too far west for cold air to make an influence. I suspect we will see a deep trough develop in the Atlantic which will allow low pressure to push north east towards the UK and allow a more unsettled regime to take hold. But the detail about this look very uncertain, whilst a cold solution cannot be ruled out, at the same time it isn't inconceivable that the cold plunge into the Atlantic could allow a warm or very warm southerly to develop during the later part of next week. The ECM op for example gets temperatures into the twenties in London again by next weekend.

The phrase more runs needed comes to mind with a lot of scatter, a lot of warm members and some rather chilly ones.

 

Again the unsettled theme can be seem by the rainfall totals from around the 24th onwards

 

So the next 8 days look dry at least for now.

Edited April 16, 2015 by Captain shortwave

[Frosty.]

The GEFS 6z mean indicates a warmer, sunnier spell next week with high pressure centred on top of the UK but then, as with the 6z op, retrogression occurs and arctic air pushes south into the far north of the UK, thereafter, the UK becomes cooler and generally unsettled.

[Summer Sun]

A very unsettled end to the month again from GFS with potentially a deep low as well turning things very windy for a time

 

 

After a very dry April it would be turning wetter maybe even some snow for the high ground in northern England and Scotland

Edited April 16, 2015 by Summer Sun

[Milhouse]

The ECM has the high slowly slipping southwards during next week so we would swap a light northeasterly for a breezy southwesterly. Eastern England, which will see the coolest conditions during the first half of the week would warm up and winds change direction. Meanwhile more unsettled conditions pushing into western areas to end the week.

 

[Frosty.]

The Ecm 12z shows a warm up next week with plenty of sunny weather with high pressure dominant, I would think low to mid 60's F by the middle of next week but then towards the end of next week it gradually becomes unsettled from the west/northwest and cold by T+240 with showers turning wintry across the northwest, 522/528 dam thicknesses with snow on hills and night frosts, post day 10 would turn even colder.

Edited April 16, 2015 by Frosty.

[ANYWEATHER]

Settled with cold winds for the south for a while ,then settled for all , before the unsettled weather takes hold .

[damianslaw]

Most notable aspect of today's models, is the projection for significant height rises to the NW as we move through next week, sinking the jet southwards and ushering in much more unsettled and generally chilly conditions for the time of year.

 

I've said before many a time we are entering the time of year when northerlies reach their yearly maxim and cool N/NE airstreams can be very persistant despite what should be a rapidly warming period..

[Cloud 10]

Most notable aspect of today's models, is the projection for significant height rises to the NW as we move through next week, sinking the jet southwards and ushering in much more unsettled and generally chilly conditions for the time of year.

 

I've said before many a time we are entering the time of year when northerlies reach their yearly maxim and cool N/NE airstreams can be very persistant despite what should be a rapidly warming period..

 

There has been a strong final warming of the stratosphere this year with a large spike in temperatures over the pole,which i feel is at least partly responsible for the  sort of Northern hemisphere charts we are starting to see for the last week in April with Northern blocking becoming apparent and polar air being forced to lower latitudes.

 

 

The models will no doubt struggle with this change,and it will be interesting to see what happens when the dust settles in a few weeks time as thoughts turn to summer prospects....

[johnholmes]

post day 10 would turn even colder

frosty, how on earth do you know. It is far from a done deal?

http://www.wetterzentrale.de/topkarten/fsecmeur.html

shows it at 240h. I am baffled how that chart, taking into account also the 00z version, can turn into what you describe.

Nor is there much to support for your suggestion from the 8-14 NOAA output, see below

http://www.cpc.noaa.gov/products/predictions/814day/500mb.php

Mind you, you are not the only one, especially in winter, to try to 6th guess what any model MIGHT show!

Of course you may be right in the end but at the moment there is little meteorologically that I can see that supports your assertion.

Edited April 16, 2015 by johnholmes

[Captain Shortwave]

The ECM and ens not really going for anything particularly cool, though it does turn unsettled in week 2.

In fact the ECM looks quite warm for a time next week. Backed up by the ensembles too.

 

Looking closely, it looks like Sunday and Monday will provide the cloudiest conditions with a chilly north easterly wind. By Tuesday the flow should be slowly cut off allowing sunny and warm conditions to become more prevalent. Beyond the end of next week, things look likely to turn unsettled, but how it will pan out is still up for grabs.

Edited April 16, 2015 by Captain shortwave

[knocker]

Briefly, the latest EC32 update.

 

Day ten anomaly has the LP NNW of northern Norway with a trough into NE Europe and another trough SE west of the Uk. A weak ridge western Europe but the whole discourse vis the surface is low pressure areas NE Canada/NW of the UK and NE Europe. This brings a SW flow over the UK with perhaps temps slightly above average.

 

By the 3rd May still looking at LP to the NW of the UK but the winds have veered a tad and dragged the cooler air in so temps below average.

 

By the 10th of May LP is centred south of Greenland with the UK under the influence of ridging from the Azores HP so temps around average

 

By the 18th not really any clear signals but no apparent HP domination and around average temps.

 

Summary.

 

The unsettled period seems to be indicated between the 25th April-5th May with winds initially from the SW, veering NW, with temps below average a jot and thereafter some improvement.

Edited April 17, 2015 by knocker

[Frosty.]

post day 10 would turn even colder

frosty, how on earth do you know. It is far from a done deal?.

I never said it was a done deal, I just commented that the Ecm 12z T+240 chart last night showed sub -5 T850 hPa 528/522 dam thicknesses sweeping into the northwest of the UK bringing wintry showers and if that run had continued, it would have brought in even colder air from the northwest...I'm really disappointed how you have been so critical of what I thought was a fair and balanced post..cheers

[johnholmes]

I never said it was a done deal, I just commented that the Ecm 12z T+240 chart last night showed sub -5 T850 hPa 528/522 dam thicknesses sweeping into the northwest of the UK bringing wintry showers and if that run had continued, it would have brought in even colder air from the northwest...I'm really disappointed how you have been so critical of what I thought was a fair and balanced post..cheers

 

All I did was post the meteorology behind my view, cannot see why you are so upset really frosty, but I apologise if you feel I was unfair.

 

And to try and show I am basing my comments on what I see, below is the ECMWF 00Z output, doing just what you alluded to last evening, a cold outbreak from the north. So this model has shown two versions of what may happen. We all wait to see 9-10 days down the line what the actual chart shows. 

http://www.wetterzentrale.de/topkarten/fsecmeur.html

 

Like I commented last night, the 3 main anomaly charts do not suggest this is a likely outcome and it is very unusual for any synoptic model to be right and they wrong in the 10 day time scale. It has happened mind you although very rarely, so an interesting spell of model watching coming up as we count down to D+9/10 from today.

Edited April 17, 2015 by johnholmes

[Gibby]

HERE IS MY LATEST ANALYSIS USING DATA SUPPLIED BY THE NWP OUTPUT COVERING 5 OF THE WORLDS MOST POWERFUL WEATHER COMPUTERS ISSUED AT 08:00 ON FRIDAY APRIL 16TH 2015.

 

THE CURRENT GENERAL SITUATION High pressure will continue to build over Northern Britain with a strengthening Easterly flow over the South.

 

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

 

MODELS-2 WEEK HEADLINE A lot of dry, settled and occasionally warm weather across the UK. A little rain is likely at times especially later in week 2 with temperatures returning nearer to average.

 

THE GFS JET STREAM ENSEMBLE FORECAST A period of generally weak Jet flow activity remains forecast with the flow steered well North of the UK due to High pressure near the North of the UK itself. Later in the run the trend for the flow to strengthen a bit and move South across the UK looks feasible as pressure falls.

 

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

 

GFS OPERATIONAL The GFS Operational this morning shows High pressure across or near to the North of the UK over the next week or so with fine and dry weather with sunny spells and although the positioning of this could mean somewhat cooler temperatures at times with something of a North or NE drift. Later on this run indicates a fall of pressure from the North or NW with gradually more unsettled conditions developing for all. 

 

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

 

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

 

THE GFS CONTROL The GFS Control Run is very similar to the operational in theme with a week of fine anticyclonic weather to come giving way to quite deeply unsettled conditions through Week 2 with strong winds and rain at times for all in temperatures none to warm at times.

 

THE GFS CLUSTERS The GFS clusters are still unclear where we will be synoptically two weeks from now but the majority swing the pendulum in favour of Low pressure becoming more influential across the UK with rain at times and strong winds with only a small percentage suggesting meaningful High pressure across the UK by then.

 

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 UKMO shows High pressure across the UK towards the middle of next week but showing signs of receding away to the NW later in the week. However, for now fine and dry weather under reasonable temperatures by day seem likely for much if not all of the next working week.

 

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

 

THE FAX CHARTS The Fax Charts show High pressure in total domination over the 120 hour period with any troughs weak and dismissive in light winds from a Northerly source for much of the time, though a stronger Easterly in the South this weekend.

 

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

 

GEM GEM today shows High pressure too across the UK next week with fine and settled weather for all. It too drifts High pressure off to the NW late in the run with pressure falling across the UK and cold air to the North indicating stronger cyclogenesis by the end of 10 days across the South of the UK.

 

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

 

NAVGEM NAVGEM also shows High pressure giving way later next week with Low pressure just to the West of the UK delivering a change to unsettled and breezy weather with rain at times by next weekend.

 

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

 

ECM ECM today completes the theme shown by others that cold and unsettled weather caused by receding High pressure and cold air to the North engaging with falling pressure could give rise to an unseasonal cold Northerly with wintry showers and frost at night to end the period.

 

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

 

ECM 10 DAY MEAN(12z) The ECM 10 Day Mean Chart  from last night is much more cyclonic than recently with strong support that Low pressure will be back in control across the UK with rain at times under a West or NW flow

 

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

 

NOTABLE TREND CHANGES FROM PREVIOUS RUNS The trends this morning have shifted markedly towards a much more unsettled spell developing from later next week.

 

31 DAY HISTORICAL VERIFICATION STATS FOR GFS, UKM & ECM The current verification statistics for the past 31 days shows ECM leading the way at 3 days with 97.6 pts followed by UKM at 97.0 pts and GFS at 96.3. At 5 days ECM  continues to lead the field at 90.1 pts over UKMO at 89.1 pts and GFS at 86.9. At 8 days ECM remains the leader with 66.5 pts over GFS's 61.1 pts. Then at Day 10 ECM retains superiority at 46.7 pts over GFS at 43.9. 

 

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.prig

 

 

MY THOUGHTS Changes are afoot in the weather this morning but not in the short term. All models support at least a week more of High pressure dominated conditions revolving around High pressure centred over Northern Britain. With the High in that position the weather could be warmer at times but after the cool East wind anticipated for the South now until Sunday it shouldn't feel too bad in the sunny spells that should prevail aplenty. What has changed today is the increased support for more unsettled conditions to develop from the North or NW later as our High recedes and allows the cold air bottled up to the North of the UK to move South and engage with the warmer air of latitudes to the South and there looks a strong chance this morning that will spin up a fairly potent depression somewhere within our vicinity late next week or weekend with rain and wind becoming more of talking features than they have for some time. While support for this theory is stronger today we are still a week or so away and that's plenty of time for our High pressure to be more resilient and stubborn to the above theme. So let's enjoy the week or so to come of dry and fine weather with some warm sunshine as it does look this morning that it may become rather colder and more windy and unsettled to end the month.

 

Next update from 08:00 Saturday April 18th 2015

[Summer Sun]

Differences again this morning between GFS and ECM by day 9 and 10

 

GFS shows a ridge of high pressure building up from the south with milder temperatures for just about all

 

 

Whilst ECM is much more unsettled with winds eventually coming down from the north turning this a lot cooler than we'd expect by this time of the year

 

 

As ever more runs needed

[Captain Shortwave]

Looks like the tropospheric vortex is reaching it's endgame scenario with rapid attacks of warm air building various areas of high pressure over the pole. The main one seems to be building over Canada, at this stage I remain rather sceptical about a northerly blast as I would feel the blocking is too far west to allow that kind of scenario to establish. The ECM only gets there via a developing Atlantic ridge as opposed to a blocking pattern.

At this point I think the output will vary widely at the 5-10 day range, even more so than usual, though the GFS ens seem keen on the northerly idea.

[knocker]

This mornings D10 anomalies have HP N. Canada/Greenland, low adjacent N.England, LP off of N. Norway with a trough south (albeit with different orientations) and a ridge mid Atlantic.

 

This is conducive to LP to the N/NE of the UK with NW airflow. At the moment the tentative prognosis is for this situation to be around for three days or so before the meridional flow gives away to a more westerly zonality.

Charts courtesy weatherbell

 

 

[Frosty.]

All I did was post the meteorology behind my view, cannot see why you are so upset really frosty, but I apologise if you feel I was unfair.

 

.

It's me who should apologise John, sorry I over reacted, it's guys like you that I'm trying to learn from and make my input better, no hard feelings I hope.

[johnholmes]

It's me who should apologise John, sorry I over reacted, it's guys like you that I'm trying to learn from and make my input better, no hard feelings I hope.

 

none at all frosty

who knows which version will be correct come D9+

[stodge]

http://www.cpc.ncep.noaa.gov/products/precip/CWlink/pna/nao.sprd2.gif

 

Spectacular collapse in the NAO into next week suggesting a real pattern change after several months of relative stability.

 

http://modeles.meteociel.fr/modeles/gfs/runs/2015041712/gfsnh-0-144.png?12

 

And there's your evidence with a classic NAO negative pattern but will this become a west-based negative pattern

 

http://modeles.meteociel.fr/modeles/gfs/runs/2015041712/gfsnh-0-384.png?12

 

Well, not really. The jet trends south so nothing very summer or even spring-like after the current spell as we go into the last third of April.

 

http://modeles.meteociel.fr/modeles/gem/runs/2015041712/gem-0-156.png?12

 

GEM shows the southerly jet and hints at west-based NAO development perhaps a shade more than GFS

 

http://modeles.meteociel.fr/modeles/gem/runs/2015041712/gemnh-0-192.png?12

 

Yet the new Greenland/Canada block looks oriented to keep the cold air spilling South and South-West into the Atlantic.

 

Very interesting and different synoptics from what we've had for some time.

[Polar Maritime]

Yes this evenings GFS really ramps up the cooler more unsettled end to the Month. With a Northerly flow around the 25th followed by deep systems spinning in from the N/W.

 

ECMWF Also shows a Northerly flow for this period.

 

Edited April 17, 2015 by Polar Maritime

[Summer Sun]

Yes this evenings GFS really ramps up the cooler more unsettled end to the Month. With a Northerly flow around the 25th followed by deep systems spinning in from the N/W.

 

ECMWF Also shows a Northerly flow for this period.

 

 

12z ECM for that date above has south westerly winds

 

 

A breakdown of the high towards next weekend and into the following week looks a good bet but what it will bring isn't yet ECM has gone from a northerly to south westerly in 12 hours. More runs needed as ever