Model Output Discussion - Heading Away From Easter

[Thundery wintry showers]

I am expecting an "inverse NW-SE split" between tomorrow and Saturday with a chilly north-easterly bringing a lot of cloud over south-eastern Britain (more so than we've seen over the last few days) but the north and west may hold onto brighter conditions. That said, the current satellite images show more of a north-south split with clear blue skies over East Anglia and the SE, and cloudier skies to the east of high ground from Lincolnshire northwards, which illustrates how difficult it can be to pin down cloud amounts in this setup.

The unsettled weather on the ECMWF still has the jet stream a fair way to the south of its usual position with low pressure systems more or less on top of northern Britain. If the jet was reasonably slack, we could get a mainly bright and showery spell out of this (as per 6th-15th April 2008 for example) but the low pressure systems come crashing in at regular intervals and this would probably translate to slow-moving fronts over large areas of the country, and a lot of cloud and rain. I won't be surprised if the ECMWF turns out to be near the mark either- I remember that it handled a similar synoptic situation rather well during mid to late April last year.

The high pressure spell on the GFS is still showing up at T+240 onwards- the most important detail in my opinion is that the GFS shows a changeable regime coming in between T+144 and T+192 (the back end of the high resolution part of the run).

As Chinomaniac suggested yesterday the jet is on its way northwards and the quicker the progression, the shorter the potential cloudy and rainy spell will be, but it will probably be a relatively slow process.

[Paul]

Have moved a number of posts into the model banter thread as they weren't really discussing the output

[Summer Sun]

The stand off between the main 3 models continues this morning

All at t120 2 x 00z and 1 x 06z

GFS

ECM

UKMO

GFS is the best as it brings continues to stay dry, settled and it will be warmer by day with double figures widely

A pattern change is clearly on the way next week its just a case now of whether it will be dry, settled and warmer as per GFS or wetter and windy as per ECM

GFS is standing firm currently sending that low north and keeping high pressure over the UK

[Captain Shortwave]

After the "Grey" Easterly, the breakdown seems slower and potentially with a warmer outcome as a strong ridge is present to our East

Lols Gavin, how can the GFS show a monster 955mb low off the Eastern seaboard at day 5 and ECM show the same low with a pressure of 1005mb

Edited April 2, 2013 by Captain shortwave

[Summer Sun]

After the "Grey" Easterly, the breakdown seems slower and potentially with a warmer outcome as a strong ridge is present to our East

Lols Gavin, how can the GFS show a monster 955mb low off the Eastern seaboard at day 5 and ECM show the same low with a pressure of 1005mb

Exactly this is what I'm saying ECM is taking its own route currently GFS and UKMO both have a low of 955mb and 975mb respectively off the Eastern seaboard yet ECM has nothing to that extent

Edited April 2, 2013 by Gavin.

[Captain Shortwave]

Exactly this is what I'm saying ECM is taking its own route currently GFS and UKMO both have a low of 955mb and 975mb respectively off the Eastern seaboard yet ECM has nothing to that extent

Even the ECM Ens have pressure at 995mb for that low, it's pretty much saying no to a major wind event over newfoundland. Unfortunately we know all to well the GFS can make Phantom storms, unfortunately it has an even worse record at picking up correct ones like Hurricane Sandy and the winter storm 2 months back over the North East states.

[Summer Sun]

T186 see's the low tracking across the north of Scotland

This results in a spell of rain moving north to south

t252 has the high edging up again

Anyone heading to Spain or Portugal next week look like seeing some warm settled weather with the Azores high finally getting its act together

Edited April 2, 2013 by Gavin.

[egret]

as promised, my view on a pattern change

Pattern change prediction-2 April 2013.pdf

Thanks John, as ever a very carefully considered and informative post - I really enjoy reading these and feel I learn a bit more each time!

What do you feel is (are) the main driver(s) which are triggering the change from what seems to have been a very stubborn (stable) situation ?

[johnholmes]

Thanks John, as ever a very carefully considered and informative post - I really enjoy reading these and feel I learn a bit more each time!

What do you feel is (are) the main driver(s) which are triggering the change from what seems to have been a very stubborn (stable) situation ?

thank you

I have to say I don't know, maybe someone like chio or Lorenzo who have a better grasp of things further out than I do might be able to answer that. My limit is really to MJO, AO, NAO etc downwards in time scales - sorry.

Edited April 2, 2013 by johnholmes

[mushymanrob]

once we rid ourselves of this troublesome block (modified historical referance there lol) its looking like 'normal' taking over (at last). that isnt sunny and warm all the way, and anything like that is in deep fi (as the good old gfs was showing for the past 6 summers <_< ). the outlook is changable, temps hovering around or just below average (but still normal). itll be wetter too, with some april showers between more organised rain band. it feels great in the sun today, out of the wind, so i reckon good old normal april weather will be very nice to be out in, between the rainy bits!

cant wait to smell the fresh emerging vegetation... springtime air is aromatherepy to me!

[Frosty.]

The Gfs 06z shows the uk out of the fridge by next monday with temps beginning to approach average but still a little on the cool side with temps of 10-11c, but milder further west/southwest nearer 12-13c, by tuesday the uk is bathed in mild air within a warm front sector with temps widely up to 13-14c which will feel very mild but we are not fully out of the woods in terms of colder weather, the airmasses chop and change with some polar maritime incursions, even brief flirts with arctic air further north but the most important thing is that the very cold, very prolonged cold spell is on the way out, the dying embers this weekend with the main change arriving on sunday as unsettled weather spreads from the west, the cold air shunted east into the north sea and beyond by the 8th april. Next week looks generally unsettled and breezy/windy at times with spells of rain swapping with sunshine and showers, the wettest, windiest weather across nw britain with pressure rising a touch across the south later next week, beyond next week the 6z shows a settled spell with a risk of overnight frosts but fine with some sunshine.

Edited April 2, 2013 by Frosty039

[chionomaniac]

thank you

I have to say I don't know, maybe someone like chio or Lorenzo who have a better grasp of things further out than I do might be able to answer that. My limit is really to MJO, AO, NAO etc downwards in time scales - sorry.

The reason that I have suggested a change for mid April is due to a change in stratospheric conditions following a long spell with negative mean zonal mean winds. Now we are seeing a postive surge of mean zonal stratospheric winds propagating to the troposphere and aligning to a favourable MJO for an increase in the PV strength and an El Nino-ish base atmospheric GWO state. The MJO is the one to watch now as if we see an expected increase in amplitude (especially into phase 5) then we may start to see the settled conditions that all are hoping for.

[Summer Sun]

The GFS ensemble continues with its upward trend which is about time

[Frosty.]

The latest met office update still retains elements of wintry weather in the outlook but the main cold spell is heading for the exit this weekend, the ecm 12z last night has been the trend setter for today's model output so far since the ecm was quickest to end the cold spell. However, although we will be entering a milder regime next week, there will be colder intervals embedded within the more springlike pattern with polar maritime incursions bringing wintry showers at times to northern hills with snow on the higher hills and mountains of northern britain next week, especially early in the week and then beyond midweek, if I had to pick a particularly mild day next week I think it would have to be tuesday as the uk will probably be sandwiched within the warm sector of a depression in that timeframe with temps dipping somewhat beyond then but the backbone of this epic cold spell will be well and truly broken by sunday/monday.

Edited April 2, 2013 by Frosty039

[UV-RAY]

The latest met office update still retains elements of wintry weather in the outlook but the main cold spell is heading for the exit this weekend, the ecm 12z last night has been the trend setter for today's model output so far since the ecm was quickest to end the cold spell. However, although we will be entering a milder regime next week, there will be colder intervals embedded within the more springlike pattern with polar maritime incursions bringing wintry showers at times to northern hills with snow on the higher hills and mountains of northern britain next week, especially early in the week and then beyond midweek, if I had to pick a particularly mild day next week I think it would have to be tuesday as the uk will probably be sandwiched within the warm sector of a depression in that timeframe with temps dipping somewhat beyond then but the backbone of this epic cold spell will be well and truly broken by sunday/monday.

All good things must come to an end Frosty, it's been a remarkable month and one which I'll never forget. Roll on winter!!

[pip22]

The latest met office update still retains elements of wintry weather in the outlook but the main cold spell is heading for the exit this weekend, the ecm 12z last night has been the trend setter for today's model output so far since the ecm was quickest to end the cold spell. However, although we will be entering a milder regime next week, there will be colder intervals embedded within the more springlike pattern with polar maritime incursions bringing wintry showers at times to northern hills with snow on the higher hills and mountains of northern britain next week, especially early in the week and then beyond midweek, if I had to pick a particularly mild day next week I think it would have to be tuesday as the uk will probably be sandwiched within the warm sector of a depression in that timeframe with temps dipping somewhat beyond then but the backbone of this epic cold spell will be well and truly broken by sunday/monday.

Whatever the GFS say, it is sucks to me. I was hoping for a continued cold,sunny, dry spell to hold on to atleast mid-April. Everytime I went on holiday to Wales, it is always pouring down with rain with gales!!

Can someone is there any models showing better weather next week besides GFS?

Edited April 2, 2013 by pip22

[cold snap]

well this morning i think the incoming pattern change is clear to see.

This is my last past this winter ,its been the most exciting long winter model watching ever for me.

Cold snap and out.

[Summer Sun]

The ECM Birmingham ensemble continues its upward trend with average temperatures by the end

The minimum temperature gets above average by the end of its run

Rainfall hits its peak on the 9th before dropping back down to average and then below average again

[Frosty.]

Whatever the GFS say, it is sucks to me. I was hoping for a continued cold,sunny, dry spell to hold on to atleast mid-April. Everytime I went on holiday to Wales, it is always pouring down with rain with gales!!

Can someone is there any models showing better weather next week besides GFS?

I think all the models are showing an unsettled spell throughout next week to varying degrees with depressions tracking in with milder air but then a backwash of colder air from the west or northwest with sunshine and showers, wintry on hills with slight frosts in the quieter intervals but sunday onwards looks generally unsettled with temps recovering to average at times, sometimes rather below average with the odd very mild day here and there.

[Purga]

Whatever the GFS say, it is sucks to me. I was hoping for a continued cold,sunny, dry spell to hold on to atleast mid-April. Everytime I went on holiday to Wales, it is always pouring down with rain with gales!!

Can someone is there any models showing better weather next week besides GFS?

The P20 run from the GEFS is a better one to keep you dry for a while.

Then something very tasty right at the end

A pipe dream really but still a faint option.

[Polar Maritime]

We do seem to now be heading out of the severe record breaking cold/snowy spell we have all had to endure, and back to something more akin to April North/South split ie Polar Maritime attacks from the N/W, with milder interludes trying to push in from the South. A real mixed bag coming up, something for everyone at least !

Edited April 2, 2013 by Polar Maritime

[No Balls Like Snow Balls]

The P20 run from the GEFS is a better one to keep you dry for a while.

Then something very tasty right at the end

A pipe dream really but still a faint option.

I am sure that really confuses the person asking the question. I am sure 1 ensemble member way off in willy wonka world is of no real use.

Edited April 2, 2013 by No balls like Snow Balls

[Purga]

NAVGEM still looking OK for early next week

Could we get some snow on the leading edge as the system slips SE?

[Panayiotis]

Well the CFS is one to awe over starting from the 13th to the 24th:

However before that a brief spell of wetter weather for all especially the NW.

[No Balls Like Snow Balls]

NAVGEM still looking OK for early next week

Could we get some snow on the leading edge as the system slips SE?

TBH i don't think even the mildies straw clutch this much by showing the NAVGEM LOL

Edited April 2, 2013 by No balls like Snow Balls