Model Output Discussion 31/03/14 onwards.

[gottolovethisweather]

I'd be surprised if those 3 am maximum temperatures of -3C shown in SS's chart earlier don't get watered down in the end, that's VERY cold for beginning of May nighttime.

 

Liking the look of building High Pressure into next (Bank Holiday) weekend, if that modelling verifies many of us could see pleasant daytime conditions -- albeit not spectacular or anything.

 

Yes they could get watered down but equally who knows, it certainly is worth the heads up though. To get a definite change of weather type, we need to shift the troughing as I don't like these "stuck in a rut" patterns. The HP influence to which you refer is still a distinct possibility around the end of April. Should it start showing up mid-term (t+144 onwards) consistently across runs and matching 12z's or 00z's from the GFS, then I will personally take note.

Edited April 25, 2014 by gottolovethisweather

[phil nw.]

Hi Phil, Thanks for this. I know it is still valid discussion but I had been left wondering what the weather was likely to do next week, given that most of the focus (as often is the case) is on synoptic patterns some t+168 hours away. So a continuation of cool wet showery interludes (aside from today's deluge) and fleeting glimpses of warmer sunnier spells looks the way of things. I won't even reserve judgement on the next Bank Holiday weekend until next Monday's and Tuesday's charts reveal themselves as it could go either way.

Yes it looks like drying up but cooling from the north after mid-week.

Only my interpretation of the latest outputs of course but after the initial build of the Azores high come the week end the further north you are the more likely it would turn unsettled early the following week but it's too far away yet for clarity as you suggest.

What i do like though is the trend to weaken and move the jet position further north with time which would help keep more settled weather around the south of the UK.

[gottolovethisweather]

Yes it looks like drying up but cooling from the north after mid-week.

Only my interpretation of the latest outputs of course but after the initial build of the Azores high come the week end the further north you are the more likely it would turn unsettled early the following week but it's too far away yet for clarity as you suggest.

What i do like though is the trend to weaken and move the jet position further north with time which would help keep more settled weather around the south of the UK.

 

Cheers, my focus is looking for any dry weather turning up in the nearer timeframe as I have to pick my days carefully for my current occupation. The Azores high hasn't moved too far away from the Southern section of the UK for a few weeks so maybe this rainier interlude was inevitable, just how long will it last is questionable?

 

The Berkshire 06z ensembles spreads look unsettled with hints of High Pressure ridging in into early May as you suggest and as have others.

 

 

Sorry about all these edits, but the upside to this is IF any warmer weather gets dragged into the equation, it could get very interesting from a convective perspective as well.

Edited April 25, 2014 by gottolovethisweather

[knocker]

Yes it looks like drying up but cooling from the north after mid-week.

Only my interpretation of the latest outputs of course but after the initial build of the Azores high come the week end the further north you are the more likely it would turn unsettled early the following week but it's too far away yet for clarity as you suggest.

What i do like though is the trend to weaken and move the jet position further north with time which would help keep more settled weather around the south of the UK.

 

True and it's pretty weak next week anyway.

[Gibby]

Hi Guys Just a quick off topic post to tell you that despite my family health dilemmas which have far from gone away I have resumed my website services including model output summaries to keep my mind active and away from health issues. It looks like High pressure at Northern latitudes is continuing to feature in current output. Lets hope this pattern is not maintained through the Summer as it may end up being being quite wet at times.

[Polar Maritime]

The GFS is showing -6 -7 850's spilling over all of Northern UK and North Wales on the 2nd, With parts of the Scottish Highlands maybe getting it's last covering of Snow before Spring proper arrives. Certainly an unsettled turn of the Month coming up, and feeling much colder especially the further North you live, But of course there is plenty of time for change in detail at this range.

 

Edited April 25, 2014 by Polar Maritime

[Milhouse]

The key to how soon it turns warmer will be the direction in which next weeks low pressure heads. The GFS 12z has it loitering over the North Sea before slipping south into France. This means the approaching high is unable to build across southern England. Instead it builds over Scotland leaving the UK in a cool NE wind. The ECM 0z on the other hand has the high pushing in in a much more favourable position for warmth. No low pressure over Europe restricting its movement eastwards.

[Summer Sun]

Before we get to the colder air next week will start on a warm note for many with somewhere in the south possibly getting to around 22 or 23c by Tuesday deepening on cloud cover

 

 

Wednesday we see temperatures starting to fall in Scotland but it remains warm in the east cloud deepening we could hit the low 20's somewhere

 

 

By Thursday the cooler air continues to track south into the north of England Midlands south holds onto another warm day though temps would be down on the previous days

 

 

By early Friday the risk of frosts increases these are the maximum temps day time temps are lower for all

 

 

Into Saturday and we see the frost risk continuing though temperatures are higher than the 06z (see page 35)

 

 

Tonight's ECM continues to show pressure rising later next week from the west though Scotland could become more prone to unsettled weather later before this transfers UK wide for bank holiday Monday

 

 

Still a lot to be resolve yet for how long any pressure rise may last the GFS ensemble looks pretty settled for the BH weekend with big differences between the ECM op and the GFS ensemble on BH Monday

 

Edited April 25, 2014 by Summer Sun

[Winter Cold]

well the final month of meteorological spring continues to be shown to start cool for us all:

 

 

I dont see high pressure staying for long either to be honest later next week. This looks like a cool and wet bank holiday Monday to me:

 

[Frosty.]

A nice burst of Arctic air pushing south from T+144 hours on tonight's Ecm 12z op run, sub -5 T850 hPa with showers turning to snow across hills in the north and occasionally wintry to lower levels in the heaviest showers elsewhere, hail and sleet with rumbles of thunder and widespread overnight frosts but feeling pleasant in the sunny spells. Although temperatures then recover somewhat, the run ends with a cool and cyclonic pattern bringing sunshine and heavy showers, rather like we have now but with lower temperatures, nearer the low teens celsius for the south, struggling to reach above 10c across northern uk. By early may standards, I would currently call the second half of next week wintry, especially for the north.

[Summer Sun]

I spoke a short time ago regarding cloud cover earlier next week and how high the temps could get well here is a closer look

 

Monday looks quite cloudy away from the west but it should be warm across the south regardless of cloud cover similar for the north though we do have a noticeable cooler zone

 

 

Now by Tuesday cloud looks thinner in the south and SE if so temperatures could really respond to around 23c if it does break

 

 

Mid week it should start bright in the east but cloud is shown to gradually increase during the afternoon though the far south east could remain brighter with some western parts also brightening up again its in the east where temperatures hold up with the low 20's possible if it stays bright long enough

 

 

Thursday looks cloudier for just about all

 

 

So a mixed week coming up warm to start turning cooler from the north on Wednesday but if the cloud does lift long enough we could see the warmest day of the year so far which is currently 21c

 

Tonight's ECM ensemble still points to a fairly settled BH Monday unlike the op

 

Edited April 25, 2014 by Summer Sun

[knocker]

The ECM ens upper air is much the same as previous for the holiday weekend with a ridge in the Atlantic to the west and cold air to the NE.This sneaks through to the UK on Thursday but it is cut off by the weekend by a slack anticyclonic set up over the UK giving cool settled weather.

Edited April 25, 2014 by knocker

[knocker]

Morning snapshot.

Edited April 26, 2014 by knocker

[bluearmy]

Interesting outlook for bh w/end

The ens show a slowly settling down scenario with lower heights to our ne and pressure building across the uk from the wsw. However, the ops are continuing to bring a depression across us from the nw. Is the higher res of the ops picking the right solution or will the ens prove to be closer as they should at this range? I would be surprised if this feature didn't verify but it may well run it's track further to the east.

[knocker]

Yup. The ECM ops is going with the build up of high pressure dominating Saturday and Sunday and England on Monday with the low to the north impacting on Scotland on the Monday. Haven't seen the ens yet.

[knocker]

Interesting outlook for bh w/endThe ens show a slowly settling down scenario with lower heights to our ne and pressure building across the uk from the wsw. However, the ops are continuing to bring a depression across us from the nw. Is the higher res of the ops picking the right solution or will the ens prove to be closer as they should at this range? I would be surprised if this feature didn't verify but it may well run it's track further to the east.

 

Regarding the ECM ens there is no obvious breakdown with the settled outlook. The colder air to the NE stretches right down just to the east of the UK with the ridge to the west. No sign of the depression and the UK in a slack anticyclonic area at least until Tuesday. It portends towards a fairly quiet but quite chilly weekend with cloud amounts depending on quite where the high pressure is situated. That's the theory anyway.

[Summer Sun]

ECM ensemble once more this morning is showing pressure rising later next week and through the bank holiday weekend

 

 

By day 10 both the GFS and ECM ensembles look pretty close with the placement of the high

 

 

UKMO seems to be following the others this morning at t144 with a steady rise in pressure from the west

 

 

Next week still looks like it will start quite warm before temperatures gradually fall from the north on Thursday with Friday a cooler day for all, if we get some lengthy spells of sunshine we could see temps in the low 20's for some southern and eastern parts but that is really dependent on cloud cover

 

 

 

[Frosty.]

The Gfs 06z op run shows relatively much colder air from the arctic pushing south later next week, reaching scotland by midweek and then the rest of us soon after once a band of rain has cleared south, overnight frosts becoming more widespread and a mix of sunshine and showers by day, heavy and thundery with hail and even a risk of sleet and wet snow across northern hills / mountains and perhaps on higher ground further south in the heaviest showers. The 6z then reloads the unseasonal cold pattern from the north/nw into mid may, synoptically it's wintry but the strong sunshine would still make it feel pleasant, especially where winds are lighter....but a definate nip in the air is on the way.

[knocker]

The GFS for the weekend is mainly dominated by high pressure. By Sunday it is centred SW of the UK briefly allowing a trough to poke it's nose into N. Ireland and NE Scotland but it's a transient feature. Assuming (and we all know about that) the ECM ens and the last GFS are correct regarding the high pressure the orientation is of some relevance regarding the weather apart from the fact it won't be that warm. I'll phone a friend later in the week.

 

This afternoon's snapshot

Edited April 26, 2014 by knocker

[Summer Sun]

Looks like a settled end to next week feeling pleasant in the sunshine but cold over night with frosts still looking likely

 

 

Next week starts warm with Tuesday looking the warmest day

 

 

Turns cooler in the north on Wednesday staying warm for the south though it could be wetter

 

 

The cooler air in the north spreads south by Thursday which leads to a frost risk into Friday

 

 

Temperatures do recover by day over the weekend but fall again overnight with a continued frost risk

[Winter Cold]

Very different GFS 12z tonight, it increases the influence of the trough coming down and actualy progresses it south west accross the UK and maintains us in a cool situation for at least a week from next Friday:

 

[IDO]

Yes the models have been spot on with regard to the coming week, for a slack flow, maybe not as meridional as expected due to the AH keeping the pattern flatter. Cold air, as predicted for a while on the march south, through delayed, but Thursday has been the call for a few runs now, The models then disagree from then.

 

GFS op and control have the ridging equating to an Icelandic high by T144:

 

    

 

Perfect winter synoptics with the UK on the cold side of the trough, so by T264 we are still in a cold flow:

 

 

 

Staying relatively cold till the end of the run, T324: 

 

However UKMO has the high at T144 over the UK: 

 

And GEM close to the NW coast of Scotland: 

 

They will lead to the trough and associated cold air escaping south further east, into continental Europe.

 

GEM at T240:   

 

Looking at the GEFs, by T192 they are all over the place and I also suspect the 12z op is in the coldest 10% of its ensembles.

 

We have had inter model and cross model chopping and changing on this for some time so very uncertain as to what happens after the May Bank Holiday weekend.

[Polar Maritime]

Yes I,D,Of.. The Models have handled this up-coming Pattern very well indeed, And the GFS is certainly showing some very unsettled/wet and cool charts on this evenings run, The PV is going to take a real hammering over the next few weeks, with Heights pushing North more or less from next Wednesday onwards & through-out the rest run.

 

Edited April 26, 2014 by Polar Maritime

[I remember Atlantic 252]

Yes I,D,O.. The Models have handled this very well indeed and the GFS is certainly showing some very unsettled/wet and cool charts on this evening run, The PV is going to take a real hammering over the next few weeks with Heights pushing North more or less from next Wednesday onwards & through-out the run.

 

 

Snow for you, but not for the majority of us, too low most members

[Polar Maritime]

Snow for you, but not for the majority of us, too low most members

 

Who mentioned Snow? :lol:

 

Maybe.. Who knows at this time scale, The Highlands will certainly see some that's for sure, but then again evaporative cooling can be a big unforeseen player at this time of year.

Edited April 26, 2014 by Polar Maritime