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

[ANYWEATHER]

Hi folks, the slippery slope is about to happen , but the good news it wont happen for another five days at least....The ecm and gfs show a major breakdown in our weather cold wet and windy weather looks likely from thereon . After all, you cant expect  sparkling sunshine to last forever in the Beautiful British  countryside.  

Edited April 18, 2015 by ANYWEATHER

[Frosty.]

Both Ecm runs today show a colder shot beyond T+168 and the Gfs 12z is similar. We know it's going to become more unsettled from the end of next week, the met office have mentioned that today, the question now is will we have a polar/arctic maritime outbreak during the following week?

[Polar Maritime]

Tonight's GFS is rather bullish with the Northerly, Then N/Ely, Before High Pressure pushes back into the New Month.

 

[knocker]

Last night's anomalies have the breakdown by T144

 

The GEFS has the blocking HP Greenland, small LP mid Atlantic but the main low  NW of N. Norway with associated trough running south over the UK. Surface analysis low to the NE and central Atlantic briefly giving a cool NE before giving way the the Azores ridge. The situation is quite fluid.

 

The ECM is similar but a slightly different orientation of the trough, more SSW. and more importantly in later frames has the Azores ridging further west so retaining the trough influence over the UK. This has yet to be resolved.

 

This morning's ops run going for roughly this analysis but at a slightly later time frame.

Charts courtesy weatherbell

Edited April 19, 2015 by knocker

[Frosty.]

Ecm for the third consecutive run is showing a colder shot for the last week of April with a chance of wintry showers on hills and night frosts.

[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 SUNDAY APRIL 19TH 2015.

 

THE CURRENT GENERAL SITUATION High pressure will lie across Northern Britain with a weak trough moving West later today across Central Britain.

 

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

 

MODELS-2 WEEK HEADLINE A lot of dry, settled and occasionally warm weather across the UK at first before becoming much more unsettled with rain and showers at times later.

 

THE GFS JET STREAM ENSEMBLE FORECAST The main Northern arm of the Jet Stream remains well North of the UK over the coming week before the two arms North and South of Britain move closer togenther across the UK later under a much more mobile undulating pattern through week 2.

 

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

 

GFS OPERATIONAL The GFS Operational this morning shows High pressure in control of the UK weather for the next 4-5 days as it's centre remains over the North of the UK bringing much fine and dry weather with the chill wind in the South decreasing. Pressure falls late in the week and a much more changeable, windy and often cool pattern develops thereafter with rain at times and temperatures on the cool side of average. things are shown to dry up a little from the SW late in the run. 

 

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

 

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

 

THE GFS CONTROL The GFS Control Run also shows a slow transition to more unsettled weather after the working week and though day to day differences are prominent synoptically between this run and the operational the message is the same. So after another 5 days or so of dry weather much more unsettled and changeable weather with strong and cool winds and rain at times look the order of the Week 2 period for all areas.

 

THE GFS CLUSTERS The GFS clusters continue to indicate a strong chance of an Atlantic mobile flow in two weeks time with High pressure well away to the SW with varying degrees of Low pressure affecting the UK under predominently Westerly winds. Only 10% of the group show High pressure beung maintained over the UK at the two week point.

 

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 gradually dissolving away to leave a much more unsettled look to the weather across Britain by next weekend with Low pressure gradually taking control from the West

 

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

 

THE FAX CHARTS The Fax Charts continue to show High pressure in control over the UK all the way out to 120hrs weakening somewhat later but not quick enough for much in the way of rainfall to affect any parts of the UK within the 120hr time span.

 

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

 

GEM GEM today shows High pressure too across the UK this week with fine and settled weather for all. It then shows a steady transition to cloudy and windier weather with falling pressure and rain at times under Westerly winds towards the start of the second week, this affecting all areas but not to a great degree across the South as High pressure clings on to the South..

 

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

 

NAVGEM NAVGEM also shows Low pressure deepening as it moves NE from a position to the SW of the British Isles to a point North of Scotland with troughs swinging East and SW or West winds strengthening towards next weekend with some rain for all by then.

 

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

 

ECM ECM today shows a similar pattern to the West as cloud, wind and rain replace the dry weather of the coming working week. As low pressure develops it eventually is shown to lie East of the Uk to bring all areas cold and windy and showery conditions with the threat of wintry showers over Northern hills in particular..

 

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

 

ECM 10 DAY MEAN(12z) The ECM 10 Day Mean Chart  from last night shows cyclonic conditions with Low pressure up to the north or NE of Britain with fresh and cold winds bringing rain and showers to all at times.

 

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

 

NOTABLE TREND CHANGES FROM PREVIOUS RUNS The trends this morning remain focused towards a much more unsettled spell developing from later next week with Low pressure much more influential for all.

 

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 97.5 pts followed by UKM at 97.0 pts and GFS at 96.2. At 5 days ECM  continues to lead the field at 89.5 pts over UKMO at 88.8 pts and GFS at 86.6. At 8 days ECM remains the leader with 64.0 pts over GFS's 59.0 pts. Then at Day 10 ECM retains superiority at 45.5 pts over GFS at 42.6. 

 

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 There seems firm agreement now from all models that a change is on the way to all areas of the UK by next weekend as High pressure across northern Britain for much of this week is planned to decline and become replace by Low pressure and stronger winds. We still have another 4-5 days after today of reasonable and sometimes very pleasant weather to come if you an keep out of a chill wind across the South and variable often large amounts of cloud near the East coast at times. Some warm sunshine will affect all parts at times through the week. Then it looks like Friday or Saturday could be a transition day towards cloudier weather with rain filtering in from the West, developing further as Low pressure develops over or to the North of the UK with stronger winds as a result. It then looks like this change could last some time with the threat that cold North or NW winds could deliver some unseasonably cold air down over Britain ala ECM and bring wintry showers to some parts. Whatever the outcome things will feel very different to what we have become accustomed to of late with sunshine amounts much lower and rainfall amounts rescuing an almost bone dry April for some parts. The period of change is just coming into the reliable timeframe so expect models to start firming up on the details that the unsettled spell will bring the UK over the coming days and continue to enjoy the fine and dry working week to come before any change takes place.

 

Next update from 08:00 Monday April 20th 2015

[Frosty.]

Before the transition to unsettled weather, the Gfs 0z shows increasingly pleasant conditions in the days ahead with more in the way of sunshine and lighter winds with temperatures rising comfortably into the 60's F, Friday is the day of change as rain spreads from the southwest.

[Summer Sun]

Before the transition to unsettled weather, the Gfs 0z shows increasingly pleasant conditions in the days ahead with more in the way of sunshine and lighter winds with temperatures rising comfortably into the 60's F, Friday is the day of change as rain spreads from the southwest.

 

Yep Friday is the day of change as the precip accu charts show

 

Up-to Friday hardly any rain, just some drizzly muck of the north sea now and then

 

 

Then its all change from Friday though Scotland and some eastern parts don't see much rain to start

 

 

Fast forward 48 hours and again some parts get very little rain with 4mm the most for some though wetter in the south west and northern England

 

 

By the 27th and 29th rainfall amounts increase for all areas in England and Wales though parts of Scotland and NI struggle to get more than 10mm

 

[Summer Sun]

Things could get quite stormy for a time during the final few days of April if GFS is correct

 

The low begins to move in next Sunday from the south west with its center at 985mb

 

 

By the Monday its over the UK now at 975mb

 

 

By the early hours of the 28th the center is over the north sea still at 975mb with tight isobars still near by the wind gusts would be strong probably touching gale force for some

 

 

During the 28th pressure starts to rise from the south as the low pulls away so winds will gradually ease during the day

 

 

By day 10 we have high pressure just to the south and low pressure to the north so west to north westerly winds

 

[Lincs Observation]

Just seen this video from the BBC on the "Blob", very interesting in the sense that the effects could give us quite a different summer than the last few years. I believe this may be starting to have an effect on a stubborn Jet Stream, It does seem more mobile and as long as it does not take up residence across southern Europe like the past few summers we could be onto a winner.

 

http://www.bbc.co.uk/weather/features/32355644

[knocker]

There is a thread already open on this LO if it's of interest

 

https://forum.netweather.tv/topic/82894-warm-blob-in-pacific-ocean-linked-to-weird-weather-across-the-us/#entry3189067

Edited April 19, 2015 by knocker

[Frosty.]

The Gfs 6z shows a spell of pleasant weather for most of the week ahead with long sunny periods and light winds under high pressure but then a change to generally unsettled conditions arrives and a brief cold blast into the far north with wintry showers / snow on hills followed by a very wet and windy spell with severe gales in places, however, later in low res the weather slowly improves with some fine and pleasantly warm spells.

Edited April 19, 2015 by Frosty.

[Polar Maritime]

A very cool/cold stormy outlook. With Gales, Even severe gales in places at times. Heavy rain with sleet/snow falling on Northern hills as systems rattle in of the North Atlantic from the N/W. With -10 850's touching the far N/W on the 26th it will feel more like Winter at times, With a biting wind chill. Quite a shock to the system for some, After a very dry and warm start to Spring. 

 

 

Edited April 19, 2015 by Polar Maritime

[Frosty.]

The GEFS 6z mean is strongly supporting a colder and very unsettled outlook.

Edited April 19, 2015 by Frosty.

[Frosty.]

The Gfs 12z shows a return to winter for Scotland next weekend with a risk of snow showers, the cold blast then sweeps south to the rest of the UK on the 27/28th with a risk of wintry showers even in the south, what a huge shock to the system this would be for southern England with the recent 25c temps, this would be quite something and certainly not boring..lol

[Frosty.]

Midweek (29th April) is even colder with snow in the south, even the southeast, quite amazing. Beyond that, although temperatures start to recover, it stays very unsettled into early may. This is an exceptional gfs run, anything like this occurring will give us plenty to talk about and hopefully increase the numbers in the forum.

[knocker]

The GEFS anomaly at 12z has the breakdown at T120 with the trough NNW of the UK and then swinging it like a pendulum To orientate it SSE by T240 and also to develop the Azores ridge in the eastern Atlantic.

 

The upshot of this is surface wise is a transition from cool NW/NE airflow to rather benign NW under the influence of the Azores high.

Charts weatherbell

Edited April 19, 2015 by knocker

[Winter Cold]

Midweek (29th April) is even colder with snow in the south, even the southeast, quite amazing. Beyond that, although temperatures start to recover, it stays very unsettled into early may. This is an exceptional gfs run, anything like this occurring will give us plenty to talk about and hopefully increase the numbers in the forum.

 

Yes Frosty, was a fun run to look at. I wish it would happen just for the weather stories, but highly unlikely of course:

 

   

 

 

Having said that the GEFS are quite strongly in favour of at least a week of sub zero 850s and below average temperatures, with even the mean hitting -5 for a few days in my patch of the woods for example. Interesting times ahead hopefully

 

[stodge]

The upcoming pattern change has been well signalled by the NAO for some time and the fall back to neutrality has now begun:

 

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

 

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

 

Certain to go negative and very sharply so in the next week to ten days with the index going as low as -2 before a recovery of sorts (a few members keep it strongly negative) back to neutrality at the very best by the turn of the month.

 

http://modeles.meteociel.fr/modeles/gfs/runs/2015041912/gfsnh-0-150.png?12

 

And there's the kind of chart this produces - note the heights to the NW of Greenland and the LP near the Azores powering the negative pressure anomaly.

[knocker]

The upcoming pattern change has been well signalled by the NAO for some time and the fall back to neutrality has now begun:

 

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

 

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

 

Certain to go negative and very sharply so in the next week to ten days with the index going as low as -2 before a recovery of sorts (a few members keep it strongly negative) back to neutrality at the very best by the turn of the month.

 

http://modeles.meteociel.fr/modeles/gfs/runs/2015041912/gfsnh-0-150.png?12

 

And there's the kind of chart this produces - note the heights to the NW of Greenland and the LP near the Azores powering the negative pressure anomaly.

 

Or you could argue the pressure distribution produces the NAO. Cart and horse?

[Frosty.]

Yes Frosty, was a fun run to look at. I wish it would happen just for the weather stories, but highly unlikely of course:

 

   

 

 

Having said that the GEFS are quite strongly in favour of at least a week of sub zero 850s and below average temperatures, with even the mean hitting -5 for a few days in my patch of the woods for example. Interesting times ahead hopefully

 

gefs194.jpg

I wish it would happen too Chris, and looking at the GEFS 12z mean, it certainly looks like becoming colder and very unsettled with a polar maritime and even the chance of an Arctic maritime flow, so it looks like very interesting model watching with a pattern change on the way.

[johnholmes]

The last sets of anomaly charts support lower than usual temperatures and fairly unsettled as well although the 8-15 does, as it usually does, tend to modify this a little.

Details of how cold, how unsettled will come as the T+00 gets closer from the synoptic models.

links to anomalies

 

http://www.cpc.noaa.gov/products/predictions/814day/814day.03.gif

 

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

[knocker]

There is a difference between the GEFs and ECM anomalies with the evolution from T120 to T240. At the moment the ECM is not going for any pronounced ridging in the eastern Atlantic. This tends to allow the trough to remain in situ over the UK with a NW flow and a more general zonality. How this pans out is rather crucial to how long the cooler unsettled spell sticks around.

[knocker]

This morning's GFS can be summed up pretty quickly, grotty. From t102 onwards to t240 a succession of lows bringing periods of wet and quite chilly weather to most parts. The only light may be be the emergence of the Azores ridge in the early ext. period as hinted at in last night's anomaly but at this stage breath shouldn't be held.

Edited April 20, 2015 by knocker

[Polar Maritime]

The unsettled cool/cold theme continues this morning from around the 24th.