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Model Output Discussion - 15th April Onwards


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Posted
  • Location: Manchester
  • Location: Manchester

An easterly would probably not be that chilly though with the continent looking set to warm up- GFS is showing some warm uppers in FI. I'm surprised that people aren't taking this very seriously- there does appear to be a change on the cards. Indeed going by GFS there could be some very warm air coming in off the continent in such a setup, and we only need the trough to move slightly further westwards for the whole of the UK to experience much warmer uppers.

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Posted
  • Location: Keyingham, East Yorkshire
  • Weather Preferences: Spanish plumes, hot and sunny with thunderstorms
  • Location: Keyingham, East Yorkshire

An easterly would probably not be that chilly though with the continent looking set to warm up- GFS is showing some warm uppers in FI. I'm surprised that people aren't taking this very seriously- there does appear to be a change on the cards. Indeed going by GFS there could be some very warm air coming in off the continent in such a setup, and we only need the trough to move slightly further westwards for the whole of the UK to experience much warmer uppers.

Exactly. I am seeing some very warm temps over central Europe in FI on the GFS 12z. In this case an easterly affecting the UK would be far from chilly. A chilly easterly/North easterly is often associated with low pressure over Europe with winds coming over the cold side of the low. There are very few ensemble members which show this outcome in FI.

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Posted
  • Location: Redbourn,Herts AL3. 122M ASL
  • Weather Preferences: Hot summers, Storms and epic cold snowy winters
  • Location: Redbourn,Herts AL3. 122M ASL

Exactly. I am seeing some very warm temps over central Europe in FI on the GFS 12z. In this case an easterly affecting the UK would be far from chilly. A chilly easterly/North easterly is often associated with low pressure over Europe with winds coming over the cold side of the low. There are very few ensemble members which show this outcome in FI.

Very much so, From memory last year Central Europe was under a very sluggish cool flow. The 500 anomilies showed very little change,Im sure it was JH that stated untill Europe warms up,The UK will stay under the same conditions. However we cant rule out a warmer flow as this would very much indicate a pattern change and im sure most would welcome.

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Posted
  • Location: Keyingham, East Yorkshire
  • Weather Preferences: Spanish plumes, hot and sunny with thunderstorms
  • Location: Keyingham, East Yorkshire

Exactly. I am seeing some very warm temps over central Europe in FI on the GFS 12z. In this case an easterly affecting the UK would be far from chilly. A chilly easterly/North easterly is often associated with low pressure over Europe with winds coming over the cold side of the low. There are very few ensemble members which show this outcome in FI.

And just as i say that the 18z throws up a northeasterly in FI unsure.png . But what i will say is that the ensemble mean indicates a good chance of a southerly flow for the beginning of May.

http://www.wetterzentrale.de/pics/Rz500m14.html

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Posted
  • Location: Lincoln, Lincolnshire
  • Weather Preferences: Sunshine, convective precipitation, snow, thunderstorms, "episodic" months.
  • Location: Lincoln, Lincolnshire

Over the coming days many of us will have a fair amount of persistent frontal type rainfall over the next couple of days, with low pressure meandering about over southern areas and some slow-moving fronts. In places where the sun breaks through, some heavy thundery showers will develop.

As we head into Friday and the weekend the low pressure looks set to slowly fill out over the country with no real "backups" from the Atlantic, so we will shift into a more straightforward sunshine-and-showers regime with the heaviest and most thundery showers concentrated in eastern England and possibly south-eastern Scotland. It is notable that the recent emphasis on sunshine and showers has allowed sunshine totals over England and Wales (according to Philip Eden at Climate-uk) to creep slightly above the 1981-2010 average, and we might just about stay there during the coming week despite a couple of cloudier days to come initially.

Into next week, it does look like turning warmer from the south- so we may well see that April CET kicked up towards average, as has happened in most recent Aprils that were cool up until around the 20th (1998, 2000, 2008). The progged setup resembles the "Euro high, Atlantic trough" setup that we sometimes see in summer, with a high chance of seeing either sunshine and thundery showers under returning polar maritime air (as happened on the 18th-24th April 2000) or chances of a "Spanish plume" type regime. A word of caution though, sometimes the setup can leave large areas of the country under slow-moving Atlantic fronts, depending on the precise positioning of the low pressure to the west.

I don't see any convincing evidence of the weather turning more settled over the coming couple of weeks, but the odds strongly favour warmer temperatures as we head through next week.

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Posted
  • Location: Kings Norton, West Midlands
  • Weather Preferences: Thunderstorms, Cold & Snowy
  • Location: Kings Norton, West Midlands

Well hopefully in line with 2006, then June/July can be left to the warmth and sun!

There is no correlation between Spring & Summer.

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Posted
  • Location: Napton on the Hill Warwickshire 500ft
  • Weather Preferences: Snow and heatwave
  • Location: Napton on the Hill Warwickshire 500ft

There is no correlation between Spring & Summer.

Surely one always follows the other ?

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Posted
  • Location: just south of Doncaster, Sth Yorks
  • Location: just south of Doncaster, Sth Yorks

beyond the next 3-7 days-what next?

The comments below are my notes over the last 24 hours regarding both NOAA and the ECMWF-GFS predictions

Tue 17 april

Ec-gfs

Marked trough still on both and gfs has ridge over top of it – ec just a suggestion of it

Ec centre trough is about 10w with gfs still e of this about w of meridian!

So both have edged it west-ridge to e less straightforward, gfs is quite flat but with the separate thing over top of trough not connected, ec has ridge sort of across top from eastern ridge

All a bit messy

Overall trough is edging west but unsure of ridge east of it?

West of all this and ec has more ridge than gfs with centre 40-50w gfs is 10 or more east of this and less pronounced, trough on both over eastern seaboard and similar on both further west

noaa

6-10 day 8-14 day out to 1 may

Both show –ve area still moving s/se, this time especially 8-14 which shows it centred nw of nw Iberia and trough a touch w of 10 w

Wait for the issues wed and IF similar to last 2-3 days then comment on it to net wx

Note also the outlook by uk met??

Wed 18 april

Ec-gfs

And both keep the trough moving west-differences in placing and size of +ve area and its ridge to east

Gfs makes more of a ridge with ec showing a flatter idea, indeed no ridge at all really, similar on both further west over atlantic and america although far west ec has trough somewhat different

Overall the trough is being moved west

On ec/gfs average 4 days ago it was around the meridian, 4 days later its predicted to be about 15w, so 15 degrees in 4 days, ridge is less easy to comment on.

So overall it seems fairly clear that the trough, currently over the top of the country, is going to move west of it, be it west or south west. As to east of the UK then the ridge situation is far from clear although there is reasonable evidence to suggest it is predicted to build east of the country. This will lead to a 500mb flow from south of west possibly south of east rather than the north of west it currently is. It will have a knock on effect to the temperatures, raising them, but the actual weather is unclear at the moment.

jh

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Posted
  • Location: Derbyshire Peak District South Pennines Middleton & Smerrill Tops 305m (1001ft) asl.
  • Location: Derbyshire Peak District South Pennines Middleton & Smerrill Tops 305m (1001ft) asl.

Looking at the GFS this morning things pretty much looking like more of the same for the next 7-10 days unsettled and cool, if anything maybe turning a touch cooler at the weekend from the N/E.

gfs-0-102.png?0

At the end of the run and the turn of the month, We could have some nice warm air pumped up from the South, with temps in the mid 20s. And the chance of some storms, all seems to go along with the MET outlook. But it's a long way off yet, and things could very well change as we all know.

gfs-9-276.png?0

gfs-0-336.png?0

While the ECM is still showing a cool and unsettled turn of the month.

ECM1-240.GIF?18-12

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Posted
  • Location: Home near Sellindge, 80m/250feet, 5miles from Coast
  • Weather Preferences: Severe Storms and Snow
  • Location: Home near Sellindge, 80m/250feet, 5miles from Coast

Looking at the GFS this morning things pretty much looking like more of the same for the next 7-10 days unsettled and cool, if anything maybe turning a touch cooler at the weekend from the N/E.

At the end of the run and the turn of the month, We could have some nice warm air pumped up from the South, with temps in the mid 20s. And the chance of some storms, all seems to go along with the MET outlook. But it's a long way off yet, and things could very well change as we all know.

gfs-0-336.png?0

While the ECM is still showing a cool and unsettled turn of the month.

If you like chilly winds from the north sea then sure with temps pegged back to 13c on the coast, Sometimes I hate it here :p... I remember when I went to the isle o sheppy for a holiday and the temps said 21C yet with that nagging wind it felt much colder :(

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Posted
  • Location: London, UK
  • Weather Preferences: MCC/MCS Thunderstorms
  • Location: London, UK

There is no correlation between Spring & Summer.

The correlation between Spring and Summer is a natural one, that occurs. It's very similar to the one we had last year in the sense that. Settled weather for prolonged periods, normally means unsettled period for prolonged periods. (weeks, not months like we have seen with the Azores high) after. Sometimes this doesn't happen, but when obviously people say crap spring, they should get a fairly decent Summer if the weather patterns (wants to balance each other out). That's my take on it.

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Posted
  • Location: Chelmsford
  • Weather Preferences: Hot and dry summers with big thunderstorms.
  • Location: Chelmsford

beyond the next 3-7 days-what next?

The comments below are my notes over the last 24 hours regarding both NOAA and the ECMWF-GFS predictions

Tue 17 april

Ec-gfs

Marked trough still on both and gfs has ridge over top of it – ec just a suggestion of it

Ec centre trough is about 10w with gfs still e of this about w of meridian!

So both have edged it west-ridge to e less straightforward, gfs is quite flat but with the separate thing over top of trough not connected, ec has ridge sort of across top from eastern ridge

All a bit messy

Overall trough is edging west but unsure of ridge east of it?

West of all this and ec has more ridge than gfs with centre 40-50w gfs is 10 or more east of this and less pronounced, trough on both over eastern seaboard and similar on both further west

noaa

6-10 day 8-14 day out to 1 may

Both show –ve area still moving s/se, this time especially 8-14 which shows it centred nw of nw Iberia and trough a touch w of 10 w

Wait for the issues wed and IF similar to last 2-3 days then comment on it to net wx

Note also the outlook by uk met??

Wed 18 april

Ec-gfs

And both keep the trough moving west-differences in placing and size of +ve area and its ridge to east

Gfs makes more of a ridge with ec showing a flatter idea, indeed no ridge at all really, similar on both further west over atlantic and america although far west ec has trough somewhat different

Overall the trough is being moved west

On ec/gfs average 4 days ago it was around the meridian, 4 days later its predicted to be about 15w, so 15 degrees in 4 days, ridge is less easy to comment on.

So overall it seems fairly clear that the trough, currently over the top of the country, is going to move west of it, be it west or south west. As to east of the UK then the ridge situation is far from clear although there is reasonable evidence to suggest it is predicted to build east of the country. This will lead to a 500mb flow from south of west possibly south of east rather than the north of west it currently is. It will have a knock on effect to the temperatures, raising them, but the actual weather is unclear at the moment.

jh

Thanks John but is there any teleconnections backing up this change.

Yesterday for example MJO was still progged to head back to phase 8, surely this isn't great?

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Posted
  • Location: London, UK
  • Weather Preferences: MCC/MCS Thunderstorms
  • Location: London, UK

Also just wondering, the weather looks to become slightly warmer... but has anyone noticed the colder H500 temperatures NE of Scandi??

npsh500.png

With a southerly tracking jet stream, and a Greenland high... I wonder!!

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Posted
  • Location: Derbyshire Peak District South Pennines Middleton & Smerrill Tops 305m (1001ft) asl.
  • Location: Derbyshire Peak District South Pennines Middleton & Smerrill Tops 305m (1001ft) asl.

Also just wondering, the weather looks to become slightly warmer... but has anyone noticed the colder H500 temperatures NE of Scandi??

npsh500.png

With a southerly tracking jet stream, and a Greenland high... I wonder!!

Yes some storm potential there, if we can manage to get some warm air pumped up from the south. Otherwise more of the same...

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Posted
  • Location: Heswall, Wirral
  • Weather Preferences: Summer: warm, humid, thundery. Winter: mild, stormy, some snow.
  • Location: Heswall, Wirral

I can't help but feel that we are about to embark on one of those 'chasing the rainbow' adventures regarding warmth and easterlies in the unreliable time frame. I can't really see this pattern shifting very soon, it looks quite set, very similar in fact to those patterns of the last 5 years which were also fairly set for some time. The overall pattern is still with us, and will remain so for some time I suspect.. the broad synoptic of high pressure and slack low pressures in our vicinity reinforces this somewhat (ie, 2007 for example).

Summer-type weather on hold I think, but it'll come soon enough, provided the synoptics don't 'lock in'.

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Posted
  • Location: Derbyshire Peak District South Pennines Middleton & Smerrill Tops 305m (1001ft) asl.
  • Location: Derbyshire Peak District South Pennines Middleton & Smerrill Tops 305m (1001ft) asl.

I can't help but feel that we are about to embark on one of those 'chasing the rainbow' adventures regarding warmth and easterlies in the unreliable time frame. I can't really see this pattern shifting very soon, it looks quite set, very similar in fact to those patterns of the last 5 years which were also fairly set for some time. The overall pattern is still with us, and will remain so.. the broad synoptic of high pressure and slack low pressures in our vicinity reinforces this somewhat (ie, 2007 for example)

I agree very much so, all due to the jet stream position. We seem to be getting more Northern Blocking during Spring and early summer.

Edited by Polar Maritime
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Posted
  • Location: Lincoln, Lincolnshire
  • Weather Preferences: Sunshine, convective precipitation, snow, thunderstorms, "episodic" months.
  • Location: Lincoln, Lincolnshire

I don't think the "spring/summer balancing each other out" relationship really works- if it does it is only a slight correlation.

Also, while low pressure is correlated with cloud and rainfall in the summer half-year, the relationship is nowhere near as clear-cut as many people think. It is certainly possible to get mainly hot dry sunny weather without a prolonged fat area of high pressure (e.g. Julys 1976 and 1995) or mainly cool cloudy weather despite prolonged high pressure (e.g. much of England during June 1988).

Back to the upcoming weather, and after more in the way of frontal activity during today and tomorrow (though still with an emphasis on sunshine and showers for many, e.g. much of Scotland and southern England today) we look like settling into a straightforward sunshine-and-showers regime between Friday and Monday. The precise distribution of showers will depend on the precise positioning of the low pressure, but it may well prove to be a more "active" convective period for eastern areas in particular than last week's one, with hail and thunder fairly widespread.

Into late next week the model outputs are currently suggesting a cyclonic/southerly regime with low pressure stalling just to the west of us. That, too, can give us sunshine, showers and thunderstorms at this time of year, although depending on precisely where the low stalls, we may get some slow-moving Atlantic systems with belts of more continuous rain, with bright showery weather to the west and hot sunny weather out on the near-Continent, so it remains to be seen what weather we'll get from it.

Robbie Garrett's post about the Greenland High had me thinking, "possibility of another switch-around?", as we have the hot southerlies close by over Europe but also cold and potentially wintry northerlies on the eastern flank of the Greenland High, and it is certainly a possibility, but an outside one IMHO at this stage.

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Posted
  • Location: just south of Doncaster, Sth Yorks
  • Location: just south of Doncaster, Sth Yorks

Thanks John but is there any teleconnections backing up this change.

Yesterday for example MJO was still progged to head back to phase 8, surely this isn't great?

It depends on what time scales you use Alex. The 500mb anomaly charts out to about D+16-17 from about D+6-7. The MJO from late in the 500mb period out to 3 weeks or so IF its giving good guidance.

You need to ask the experts on this but I tend not to have much belief in the correlations of MJO predictions to 500mb patterns when the MJO is predicted to be close by the origin regardless of what phase its predicting?

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Posted
  • Location: st albans
  • Location: st albans

JH comments on the expected movement southwest of the trough as we approach month end. the past 24 hours has lessened the chances of a transient 'plume' type scenario with any notable warmer than average uppers pushed to our east. the trough holding a little firmer as the modelling comes into a shorter timeframe. currently, i expect the trough to hang around a little longer than the ops currently show. the further south and east you are, the less its influence. temps will recover towards normal but i dont think we will see anything particularly warm although a day of upper sixties/low seventies cannot be ruled out, if we see a well placed warm sector.

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Posted
  • Location: Manchester
  • Location: Manchester

I don't get this idea that it's going to be 'more of the same'. Low pressure is moving slightly to the west rather than being slap bang on top of us so this is a clear difference. Surely if the potential is there for warm air to move in, this is not more of the same as temperatures have been average to below for over 2 weeks now.

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Posted
  • Location: Live Haddenham (Bucks). Work Heathrow Airport
  • Location: Live Haddenham (Bucks). Work Heathrow Airport

There is no change within the next 5 days and change after this is subject to change lol. From what I can see it may just maybe go from cool and unsettled to slightly warmer/warm and unsettled, I cannot see any long term settled period showing at the moment.

Edited by No balls like Snow Balls
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Posted
  • Location: London, UK
  • Weather Preferences: MCC/MCS Thunderstorms
  • Location: London, UK

Robbie Garrett's post about the Greenland High had me thinking, "possibility of another switch-around?", as we have the hot southerlies close by over Europe but also cold and potentially wintry northerlies on the eastern flank of the Greenland High, and it is certainly a possibility, but an outside one IMHO at this stage.

, I am inclined to believe the possibility the Greenland high is going to be rather influential, or possibly a Scandinavian high.. CFS model runs have shown a spanish plume end of month (hot air tracking from Africa??), with unsettled weather from the west, then a resurgence from the north east. Probably rather inline with what I expected for May.

High pressure over central eastern europe and northern greenland, also mid atlantic. We could actually get stuck in an unsetlled but very mild regime. (the difference is the temperatuers, not the weather in terms of percipitation remaining the same)

The start of May looks likely to remain unsettled with a continuation of showers or longer spells of rain, although there should also be some drier and brighter interludes. Temperatures will generally be close to or slightly above the seasonal average. Later in the first week of May, conditions may turn more settled across southern England for a time, with a greater chance of some drier and sunnier weather than of late. Further north, it looks likely to stay unsettled with further rain at times, particularly across northwest England as well as northern and western parts of Scotland.

The CFS is predicting this quite well, at the moment... with most of the showers coming off a LP in the Biscay region.

cfs-0-354.png?00

cfs-1-300.png?00

Looking at solely the CFS for long term indications, and I am just going by my level of knowledge and no means of this is of professionalism quality, but I really do think that it will be very mixed.... some settled conditions, every now and again some troughs into the western edge of Britain. With high pressure not to far away.

I could be wrong, but it does looks very very nice for Summer come early/mid June. with low pressure stuck to the south west of the UK (bay of biscay) and high pressure over most of western Europe. But this should keep precipitation well up, most likely from regular Thunderstorms.

Not sure the update times regarding the CFS, but it no longer shows low temperatures mid-may from a north easterly.

I mean it's far away but for the majority of the run this is what it keeps trying to do an eventually ends at this.

cfsnh-0-1074.png?00

cfsnh-2-1074.png?00

cfsnh-3-1074.png?00

The models very keen on a southerly tracking jetstream, so for people looking for a mega pattern change (Azores high being a pest) can look again. It's clearly a mid atlantic ridge at the moment. Just where it belongs.

Edited by Robbie Garrett
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Posted
  • Location: Lincoln, Lincolnshire
  • Weather Preferences: Sunshine, convective precipitation, snow, thunderstorms, "episodic" months.
  • Location: Lincoln, Lincolnshire

High pressure over central eastern europe and northern greenland, also mid atlantic. We could actually get stuck in an unsetlled but very mild regime. (the difference is the temperatuers, not the weather in terms of percipitation remaining the same)

I think that's a fair assessment and answers the questions raised in the last few posts.

A continuation of unsettled weather doesn't necessarily signify more of the same- indeed as I noted in my previous post, even some notably warm dry sunny months have periods of 'unsettled'-looking synoptics. For instance the trough drifting out into the Atlantic could keep us with sunshine and showers but concentrate showers more towards western areas, it could give us some dry sunny interludes (if we get enough of a continental influence), or it could turn the weather wet and cloudy with slow-moving fronts, to quote just three examples of possible changes. It's quite interesting to see the models struggling with precisely how far west and south the Atlantic trough retreats, as this will be what determines the weather we get into the last week of April.

At present it is too far out in my opinion to be able to say what the outcome will be weather-wise, other than that sunshine and showers looks to be the odds-on favourite across England and Wales until at least next Monday with Scotland prone to occasional longer outbreaks of rain from weak fronts on the northern flank of the low pressure.

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Posted
  • Location: London, UK
  • Weather Preferences: MCC/MCS Thunderstorms
  • Location: London, UK

I think that's a fair assessment and answers the questions raised in the last few posts.

A continuation of unsettled weather doesn't necessarily signify more of the same- indeed as I noted in my previous post, even some notably warm dry sunny months have periods of 'unsettled'-looking synoptics. For instance the trough drifting out into the Atlantic could keep us with sunshine and showers but concentrate showers more towards western areas, it could give us some dry sunny interludes (if we get enough of a continental influence), or it could turn the weather wet and cloudy with slow-moving fronts, to quote just three examples of possible changes. It's quite interesting to see the models struggling with precisely how far west and south the Atlantic trough retreats, as this will be what determines the weather we get into the last week of April.

At present it is too far out in my opinion to be able to say what the outcome will be weather-wise, other than that sunshine and showers looks to be the odds-on favourite across England and Wales until at least next Monday with Scotland prone to occasional longer outbreaks of rain from weak fronts on the northern flank of the low pressure.

Yeah, that's what I thought. Right now the trough is over us, so I take with a trough being to the west of us, it means and of the 3 you have just mentioned in terms of a definitive pattern change. The ideal position, for those wanting warm/humid thundery weather is pretty much south west of us is it not?? (bay of biscay) which would provide warm temperatures yet a very very stormy outlook = unsettled.

I've also noticed with the models, they show southern europe remaining fairly wet... I take it this is because of possibly thundery weather?? But does the models actually calculate this?? surely not?? It's not high high pressure but, still precipitation from where?? across spain etc...

Whilst not the definitive pattern we are entering into Summer, but odds are on with a pattern like we have know, it's more likely to be better (doesn't mean settled) for Summer. What we have now isn't this a classic summer pattern anyway??

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