Model Output Discussion

[mushymanrob]

a mixed bag from the models this morning, nothing inspiring at all, only the gfs in fi brings anything like 'summery' weather. the fax is pretty dire tbh, and raises concerns, i cant see any quick return to settled from this chart and of course theres the spectre of 3 washout summers haunting us.... will there be a fourth? has the dry theme gone? maybe...

[TEITS]

a mixed bag from the models this morning, nothing inspiring at all, only the gfs in fi brings anything like 'summery' weather. the fax is pretty dire tbh, and raises concerns, i cant see any quick return to settled from this chart and of course theres the spectre of 3 washout summers haunting us.... will there be a fourth? has the dry theme gone? maybe...

Morning Mushy.

Certainly no prolonged heatwaves in the models but they could be much worse. The model output this morning suggests the weather will settle down into this weekend possibly extending into the following week. This rise in pressure is supported by the ECM plus the GEFS ensembles.

http://charts.netweather.tv/ensimages/ens.20100607/00/prmslCambridgeshire.png

So after an unsettled week the weather is likely to become dry, settled with sunny spells with temps possibly between 19-23C if this rise in pressure occurs.

[Cecil Hogmanay Melchett]

Morning Mushy.

Certainly no prolonged heatwaves in the models but they could be much worse. The model output this morning suggests the weather will settle down into this weekend possibly extending into the following week. This rise in pressure is supported by the ECM plus the GEFS ensembles.

http://charts.netweather.tv/ensimages/ens.20100607/00/prmslCambridgeshire.png

So after an unsettled week the weather is likely to become dry, settled with sunny spells with temps possibly between 19-23C if this rise in pressure occurs.

im actually getting quite optimistic now teits.After this wee the signs are an azores high will ridge towards the

uk,ecm this morning is looking nice.

[Kentish Kiwi]

Ignoring FI and its unlikely transformation to high pressure, the realist timeframe look very cool and very wet with temperatures in many parts in the daytime 4-8C below average.

If this unravels and gets momentum then despite the warm start to June it could well be as bad as last year maybe one of the coolest/wettest in the series.

Bit early I know but its a very real possibility.

Interesting that you believe high pressure asserting itself is unlikely. From the latest runs (I know they have been chopping and changing quite regularly of late) there seems to be broad, general agreement from the big three; ECM, UKMO and GFS, that high pressure to the west will begin to ridge eastwards by around +144 after the northerly incursion.

I know it is 'very much FI and likely to change somewhat' but there is strong similarity between the ECM and UKMO at that +144 timeframe (the ECM showing the nicest evolution and ironically the GFS 06z, having been so keen on high pressure domination in FI recently, showing the poorest outlook in early FI although still very similar in nature) and it would seem likely from that evolution the most likely would be Azores high continuing to ridge eastwards over the UK, much as we have seen happen over the last few weeks.

If this were to occur, the recent pattern of one week unsettled with northerly winds, next week settled and warm as the Azores high ridges over the UK, which will have re-occurred repeatedly for almost a month, would surely be something to take note of. Maybe more of a traditional UK summer pattern...?

Edited June 7, 2010 by Kentish Kiwi

[Thundery wintry showers]

High pressure usually means settled weather but there is often an over-simplistic tendency to think "high pressure, therefore settled, therefore warm and sunny", but in reality the "warm and sunny" part is dependent on the positioning of the high. Airmass origin is less of an issue because a "cloudy" high tends to become a "sunny" one once the strong June sun burns off the stratocumulus within a couple of days, but you can still get a fair amount of cloud and suppression of temperatures off the sea. On the ECMWF the high is mostly situated over the NW allowing a rather cool cloudy looking NE airflow to affect eastern England. By T+240 the high fully asserts itself and so it would become warm and sunny for all by then.

GFS goes for more of a NW'ly type. It turns cloudy and fairly wet for a time next weekend followed by a couple of showery days and then high pressure asserting over the UK promising warm dry sunny weather, but in both cases the warm sunshine looks to be well out in FI. It could happen, but there is a lot of uncertainty to get through before we reach it.

In the nearer term we are still looking at a few days of dull cold weather for much of the country, but northern Scotland may stay relatively dry and bright, while southern England still has a chance of sunshine mixed with thundery showers for tomorrow and Wednesday.

[TonyH]

The 18z is rather uninspiring, with very little in the way of interest unless you prefer a cool-cold and wet scenario. Ignoring FI and its unlikely transformation to high pressure, the realist timeframe look very cool and very wet with temperatures in many parts in the daytime 4-8C below average.

If this unravels and gets momentum then despite the warm start to June it could well be as bad as last year maybe one of the coolest/wettest in the series.

Bit early I know but its a very real possibility.

When are such below average maxima suggested? That would mean just 12-16c in the Midlands then. I even doubt whether they will be as low as 16c on any day this week. Also 'very wet' will probably only happen on a local rather than widespread basis owing to the showery nature of much of the week. Unlikely that June will turn out cooler than average given such a warm first week, and that we are still in the warming process of early Summer.

Edited June 7, 2010 by Tonyh

[Thundery wintry showers]

John Holmes often points out that the GFS tends to underdo maxima by 2-3C or so. Remember that average maximum temperatures reach 20C only in the London area- for most parts of the country 18C is typical, and in parts of the north, particularly around the coasts, 16 or 17C is the norm.

Thus, with maxima for most of the week hanging around 15-18C with perhaps the odd 13 or 14C near North Sea coasts, it doesn't look like daytime temps will be falling more than a few degrees below average at any stage. In addition the overnight minima will often be a little above the average.

[TonyH]

John Holmes often points out that the GFS tends to underdo maxima by 2-3C or so. Remember that average maximum temperatures reach 20C only in the London area- for most parts of the country 18C is typical, and in parts of the north, particularly around the coasts, 16 or 17C is the norm.

Thus, with maxima for most of the week hanging around 15-18C with perhaps the odd 13 or 14C near North Sea coasts, it doesn't look like daytime temps will be falling more than a few degrees below average at any stage. In addition the overnight minima will often be a little above the average.

Indeed, I was giving the benefit of the doubt somewhat- the average max in Coventry is just 19c:

Bablake WS

That makes widespread 4-8c sub normal maxima even more unlikely and even more misleading to quote in this thread (11-15c maxima most unlikely this week in Coventry), that would be very cool for June. Today is fairly warm, Tuesday/ Wednesday will be warmish sunny intervals and showers so maxima close to average, and uncertainty after this (more rain or mainly dry), but such very cool conditions unlikely.

[SP1986]

By the way none of what I wrote was my opinion as such, it was largely based on what I saw on the models. FWIW I realise the GFS underestimates maximum sometimes in certain situations and such maxima predicted by the GFS is only likely to come off in areas where rainfall is heaviest. The GFS does have an uncanny ability to predict the most severe scenarios over a large land area rather than the localised areas which is more usually the case.

We often see this with it's rainfall and temperatures predictions, but upon working it out most people can usually find a closer estimate to a more realistic outcome based on both experience of normal conditions in that situation and also their own local climatic conditions in those situations

[Eugene]

It's going to feel really miserable under brisk northeasterly winds and heavy rain for the midlands and especially southeast england on thursday into friday, looks potentially nasty in the far southeast.

http://www.wetterzen...cs/Rtavn781.png

http://www.wetterzen...cs/Rtavn784.png

http://www.wetterzentrale.de/pics/Rtavn7817.png

http://www.wetterzen...cs/Rtavn841.png

Edited June 7, 2010 by Eugene

[Eugene]

Drying up by the weekend with a strong mid atlantic ridge and a relatively cool light northerly flow, could be quite cool at night if the cloud clears which is debatable.

[Alex95]

Drying up by the weekend with a strong mid atlantic ridge and a relatively cool light northerly flow, could be quite cool at night if the cloud clears which is debatable.

I'd take that anyday!

From what I see it will be quite cool and wet at the end off the week, followed by a drier weekend with chilly nights as you say, then next week might warm up a bit. This summer is pretty close to perfect at the moment for me - there has been a good range of weather types so far, with the emphasis firmly on drier and, at times, warmer weather, but hot spells have been short and relatively frequent. 2006 was nice but it got a bit excessive, and I prefer variety as long as there is more 'good' weather than not so good as has been the case so far this year.

Edited June 7, 2010 by alza

[picog]

When are such below average maxima suggested? That would mean just 12-16c in the Midlands then. I even doubt whether they will be as low as 16c on any day this week. Also 'very wet' will probably only happen on a local rather than widespread basis owing to the showery nature of much of the week. Unlikely that June will turn out cooler than average given such a warm first week, and that we are still in the warming process of early Summer.

The max today here has been 15.7C, so 12-16C for the midlands may not be an over exaggeration.

[SP1986]

Unless upper air temperatures are rather low with low thickenesses (Below 533 dam & 0 to -5C at 850hPa), it's unlikely there will be chilly nights, (whatever chilly nights entails).

Furthermore it looks cool by day probably a few degrees below average, and by night perhaps 1-2C below average but away from prone cold spots still in double figures.

I'm still extremely sceptical about any rebuilding of high pressure for any length of time, despite the continued them emerging from the models.

[lukemc]

Unless upper air temperatures are rather low with low thickenesses (Below 533 dam & 0 to -5C at 850hPa), it's unlikely there will be chilly nights, (whatever chilly nights entails).

Furthermore it looks cool by day probably a few degrees below average, and by night perhaps 1-2C below average but away from prone cold spots still in double figures.

I'm still extremely sceptical about any rebuilding of high pressure for any length of time, despite the continued them emerging from the models.

Why are you not confident about HP rebuilding? Surely if we do have a cooler and more unsettled period thier is nothing IMO in the way of high pressure building sooner rather than later even in quite poor summers we have had HP dominated spells mid summer like last year at the end of June/beginning of July or in 2008 in mid-late July so even if an unsettled pattern where to continue a rebuild of HP should be just as likley.

I do have a question regarding the "mid atlantic high" scenario - reading posts on this forum seems to suggest that it is to be associated with poor weather in the summer but is that always the case? Surley it could either ridge across us, merge with the Azores high or even a Euro high to give us a warm or even hot settled spell so when the likes of GP mention the Mid Atlantic High do they take that possibility into account?

Luke

[❄️❄️❄️❄️❄️❄️❄️❄️❄️]

Could be a wet week, but these things usually change.

Edited June 7, 2010 by RAIN RAIN RAIN

[TonyH]

Cant see those almost 4 inches coming off in the south, perhaps very locally due to thundery downpours. 50mm would be nearer the mark generally for the south of England.

[Eugene]

Good to see a drying trend if rather cool for early next week, hopefully no more moaning about the warm nights.

http://www.wetterzentrale.de/pics/MT8_Manchester_ens.png

http://www.wetterzentrale.de/pics/Recm1201.gif - Some nice mid atlantic ridging on ECM 12Z, looks very similar to GFS so far with fresher cooler air moving over the country.

[patrickshere]

http://91.121.94.83/modeles/gens/graphe_ens3.php?x=306&ext=1&y=141&run=12&ville=Londres&runpara=0

Not sure if any of you noticed the parallel run, for this wed and thur suggesting very little rainfall? Is the parallel run completely innacurate at the moment? Seems a bit bizarre to me. It's completely out on its own.

[TonyH]

http://91.121.94.83/...ndres&runpara=0

Not sure if any of you noticed the parallel run, for this wed and thur suggesting very little rainfall? Is the parallel run completely innacurate at the moment? Seems a bit bizarre to me. It's completely out on its own.

I think it depends on how far the Low' s influence extends the predicted rain area for Thursday away from the SE- could reach possibly into the Midlands but uncertain.

[Cecil Hogmanay Melchett]

Very pleased with this evenings output.

UKMO 144H

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

ECM

http://www.wetterzentrale.de/pics/Recm1681.html

followed by

http://www.wetterzentrale.de/pics/Recm1921.html

This has been quite consistent on ecm and altough we have 4 or 5 poorish days coming up im starting to think a warm spell is coming next week.

[patrickshere]

I think it depends on how far the Low' s influence extends the predicted rain area for Thursday away from the SE- could reach possibly into the Midlands but uncertain.

Yeah, looking through the precipitation forecast on the parallel it's always kept east and south.. Just a very lucky skirt around in that instance I guess. Would love it to be true.

[bluearmy]

http://91.121.94.83/modeles/gens/graphe_ens3.php?x=306&ext=1&y=141&run=12&ville=Londres&runpara=0

Not sure if any of you noticed the parallel run, for this wed and thur suggesting very little rainfall? Is the parallel run completely innacurate at the moment? Seems a bit bizarre to me. It's completely out on its own.

the parallel keeps the precip just to the se of london and mainly on the continent. the ecm 12z also is less bullish on thursdays rainfall over london, keeping it mainly over kent/sussex and then east anglia. however, it brings a deluge fri with a secondary depression moving ne. will be worth looking at the meteogroup ecm ens later to see just how much that would drop in mm.

following on from stephens earlier musings re higher heights, i can see that the iberian trough may mean lower heights persisting around the sw of the uk but somewhere will fall under ridging from either the mid atlantic high or eastern euro high.

[Glacier Point]

I do have a question regarding the "mid atlantic high" scenario - reading posts on this forum seems to suggest that it is to be associated with poor weather in the summer but is that always the case? Surley it could either ridge across us, merge with the Azores high or even a Euro high to give us a warm or even hot settled spell so when the likes of GP mention the Mid Atlantic High do they take that possibility into account?

Luke

Think of summer patterns being an option between three high pressure centres -

1) Azores ridge / positive NAO

2) Euro High

3) Mid Atlantic ridge / negative NAO

These tend to be mutually exclusive as they essentially represent different longwave patterns. Therefore, if the mid Atlantic ridge becomes dominant, the other two do not as mean features. The current SSTA profile in the Atlantic and underlying global wind pattern associated with falling angular momentum (La Nina) are most likely to be manifested by the mid Atlantic ridge solution with the other two being very unlikely on a sustained basis.

If the mid Atlantic ridge is big enough, then yes, oscillations in the wind patterns can edge the high towards the UK although the conditions will be less optimal for sustained high temperatures as the airmasses will originate from the North Atlantic rather than the sub-tropical belt.

Global angular momentum continues to fall as La Nina takes hold. A notable trend has been for frictional torques and the Southern Oscillation Index (SOI) to be indicative of falling angular momentum over the last few weeks dragging the global wind oscillation into a low angular momentum base state.

As frictional and mountain torques begin to reverse and add some westerly flow, we should expect the high to edge eastwards towards the UK. However, it is very uncertain as to how far east the centre of the high will get and odds against it becoming centred far enough east to sustain a warm drag of southerlies - the factors drawing the ridge back west are too strong this year.

So long as the SOI and angular momentum continue to show La Nina tendency, that ridge in the Atlantic will do two things:

1) it will become even more obvious;

2) it will edge westwards allowing weather fronts to drop over the top of the high.

[rmc1987]

Good to see a drying trend if rather cool for early next week, hopefully no more moaning about the warm nights.

http://www.wetterzentrale.de/pics/MT8_Manchester_ens.png

http://www.wetterzentrale.de/pics/Recm1201.gif - Some nice mid atlantic ridging on ECM 12Z, looks very similar to GFS so far with fresher cooler air moving over the country.

Good heavens, people moaning about warm nights. When did they occur? Well they'll soon be moaning at the wetter cooler and cloudier weather. The whole run to me looks cool so we could be waiting some time to see any decent warmth.

I know I'll be moaning about it lol, we get too much of this. Ah such is the Great British weather ;-(

Edited June 7, 2010 by rmc1987