Model Output Discussions 12z 08/03/17

[Man With Beard]

2 hours ago, Summer 1976 said:

The ECM is being ridiculous this evening. I'm sure the whole lot will collapse in time for June

It's following on from a trend that GFS picked up on a few days ago. That Greeny high looks hungry. Not confident about much May warmth now! ECM T264 / T288 if following on logically from T240 possibly looking at some record cold for the time of year - at least a record for recent years??

Still there's the hope that the ECM will have gotten another easterly wrong ... I'm not so sure this time though.

[Frosty.]

Tonight's Ecm 12z ensemble mean is also strong on the retrogression of the high to greenland and lowering heights to the NE. In winter these charts would be potentially dreamy for coldies but in May I can't imagine steve murr will be ramping them up!.

[snowray]

1 hour ago, Man With Beard said:

It's following on from a trend that GFS picked up on a few days ago. That Greeny high looks hungry. Not confident about much May warmth now! ECM T264 / T288 if following on logically from T240 possibly looking at some record cold for the time of year - at least a record for recent years??

Still there's the hope that the ECM will have gotten another easterly wrong ... I'm not so sure this time though.

Of course it won't be wrong, it's May not January!

[knocker]

The gfs this morning for the next ten days is not terrible complicated.

A showery regime for Sunday and Monday before the amplification and surge of the high pressure in the vicinity of the UK. By Tuesday the centre of the high Pressure is west of Norway and Britain is already in an easterly regime, particularly the southern half with showers quite likely in the east

This easterly regime remains in place for the rest of the week but the high pressure moves slowly west which allow the Atlantic trough and associated surface lows to slip in the other direction

This eastward tracking of the lows over France is then nipped in the bud by some more amplification and another burst from the high pressure, So in a nutshell a dry easterly regime for the week with temps around average but tending cooler on the east coasts. The far south could just be impacted by the systems tracking east into France,

A quick look further ahead and the HP does eventually retrogress to the Greenland area and with the Canadian lobe zapped the troughs to the east and south west become increasingly influential and by the end of the 14 day period perhaps more zonalty and low pressure in the eastern Atlantic.

Edited April 28, 2017 by knocker

[Frosty.]

By the end of the Ecm 00z, the low to the southwest helps to start pumping warmer more humid continental air up from southern Europe, in fact western europe generally starts to warm up as time goes on. It's an improving run, high pressure becomes the main player from around next midweek with generally dry and fine weather, a cool Easterly breeze for a while but inland it should feel pleasantly warm in the strong early May sunshine..coolest on eastern coasts and there would be variable amounts of cloud.

Edited April 28, 2017 by Frosty.

[Frosty.]

The Ecm 00z ensemble mean is more retrogressive than the op and similar to last night's 12z but at least the uk becomes generally fine with high pressure or at least strong ridging from next midweek until the end of the run with variable amounts of cloud and spells of strong early May sunshine..so, after a changeable BH weekend it's set to become fair.

Edited April 28, 2017 by Frosty.

[mb018538]

Is it just me....but looking at the models,  don't see where the BBC keep getting their forecasts for high teens next week from? The output all shows cool E/NE winds dominating by midweek. GFS temp forecasts are for low-maybe mid teens at best, which looks much more likely to me given the keen breeze off the north sea and low 850s. Coastal and eastern areas could really struggle with low cloud.



12c, sub-zero 850s, and low cloud plaguing the country. Yet go on to the BBC website for next Thursday and it says 17c and sunny spells for London? The 00z was one of the colder options, but not without support, and the ECM is similar.

[Singularity]

While the stratosphere does not tend to drive our weather all that directly at this time of year, I do wonder if this 'left-over' pattern of lower stratospheric heights on the Eurasian side and higher on the Canadian side is not helping with respect to the positioning of the major blocking features.

This should only be having a slight influence though, particularly when considered in comparison to that of some Pacific MJO activity which has gained some support from the ECM ens. lately in a move toward GEFS that could change the tone of future longer-range updates should it remain in the projections. On the other hand, the link between this activity and blocking to our N/NW weakens substantially from April to May so a relaxation of such a blocking pattern could be anticipated from that.

On Wednesday @knocker asked me which models are showing Arctic blocking for May as a whole - I'm infrequent on here these days so a bit late in response but here goes; I was referring to the likes of GFS and ECM and extrapolating a pattern of Arctic blocking forward from there. The strength of the pattern suggests persistence is likely until at least mid-May which should be long enough to do some harm to the Arctic sea ice. Admittedly this does require the assumption that the models are right to produce such extensive blocking across the Arctic to begin with, but the signals have been remarkably consistent over the past week or so. It also assumes that the blocking highs will bring a lot of clear skies, which is not guaranteed as 2013 proved with an abundance of mist and fog that shielded the ice from the sun's rays under the highs. They were more slack than is currently being predicted for early May, though, so the calm conditions needed for mist and fog are less likely to occur.

[Andover]

Really cold next weekend if this GFS is anything to go by, away from Northern Scandinavia we will be the coldest in Europe with plenty of rain about too.

[Frosty.]

26 minutes ago, Andover said:

Really cold next weekend if this GFS is anything to go by, away from Northern Scandinavia we will be the coldest in Europe with plenty of rain about too.

Charts?

[knocker]

Pretty good agreement between last night's NOAA and the GEFS and EPS anomalies this morning.

All have the Canadian lobe declining as the high cell created by the midweek amplification retrogresses towards Greenland and the Russian lobe  and trough to the east becoming more influential  The result of the aforementioned amplification is high pressure to the north drifting west and low pressure to the south west drifting east, Thus the the probability is of the UK staying under the influence of the high pressure and remaining dry under the easterly winds, backing NE/N as the high retreats. Temps varying around the average.

The consensus in the later period would appear to be positive anomalies and some ridging in the NE Canada/Greenland region, a very inactive Atlanti with low pressure to the south west and the trough to east taking closer order. The percentage play from here is for low pressure to become more established in the eastern Atlantic with the upper flow in a more SW quadrant with colder air to the east, But different interpretations are all too obvious, one being the trough to the east sneaking further west.But temps do not look as is if they will push much above average unless a more southerly fetch is forthcoming which is another possibility.

[Summer Sun]

The trend still appears to be an upward one if the beeb are correct

Edited April 28, 2017 by Summer Sun
Fixed text after it vanished not sure why

[Frosty.]

There's some snow on the Gfs 6z

Edited April 28, 2017 by Frosty.

[weatherguru14]

7 minutes ago, Summer Sun said:

The trend still appears to be an upward one if the beeb are correct

But that is no doubt for  about  5% of the UK in  probably the tip of  the south east.. That's where the bbc  are no being honest  they don't mention where exactly its going to be. Just  a smoke screen.

[knocker]

This morning's ecm for 12z Sunday has a whole swathe of temps in the 16-20C range for England and Wales with 20C being quite extensive in the east Midlands and East Anglia.

[Frosty.]

I have a feeling the Gfs 6z operational will be a cold / unsettled outlier..The outlook for the next few weeks doesn't appear to be anything like as bad as that..indeed, the latest MO update is just as good as yesterday regarding high pressure and gradually warmer temperatures.

Edited April 28, 2017 by Frosty.

[Cheshire Freeze]

51 minutes ago, Frosty. said:

I have a feeling the Gfs 6z operational will be a cold / unsettled outlier..The outlook for the next few weeks doesn't appear to be anything like as bad as that..indeed, the latest MO update is just as good as yesterday regarding high pressure and gradually warmer temperatures.

GFS 6z turns very wet deeper into FI through the pattern I mentioned as a possibility the other day i.e LP encroaching up from the SW. A real risk whilst you've got heights around Greenland. 

On the other hand, if we saw HP migrate even further W (towards the Canadian side) it would encourage ridging up through (and possibly just to the E) of the UK.

[Scorcher]

A better run from the GFS 12Z this evening- later on in the run, the area of low pressure stalls further west in the Atlantic. This could allow us to draw up some warmer air from the south and also allow high pressure to build in a more favourable position for the UK.

Not a terrible run further west in the reliable time frame either. The BBC are very confident that areas further west will see plenty of sunshine from Tuesday onwards, although temperatures will be nothing special even in the west, probably mid teens at best.

[stodge]

59 minutes ago, Scorcher said:

A better run from the GFS 12Z this evening- later on in the run, the area of low pressure stalls further west in the Atlantic. This could allow us to draw up some warmer air from the south and also allow high pressure to build in a more favourable position for the UK.

Not a terrible run further west in the reliable time frame either. The BBC are very confident that areas further west will see plenty of sunshine from Tuesday onwards, although temperatures will be nothing special even in the west, probably mid teens at best.

GEM 12Z is much colder at the end with a N'ly wind for us all. The battle between the colder and warmer air flows looks set to be joined in the middle of the second week of the new month.

Looking at the 12Z GEFS and admittedly right out at T+312, the OP looks on its own and the colder option of having LP close to or over Scandinavia looks the majority option. 

Obviously very early days and plenty of runs needed.

Strong cross-model agreement out to T+168 however - roll on the easterly !!

 

 

[Frosty.]

Roll on the easterly? who on earth wants an Easterly in May! Cool cloudy north sea filth..no thanks.

Edited April 28, 2017 by Frosty.

[Matthew.]

It's alright for some

[Snowy L]

Models on the face of it look terrible, low pressure over the UK over the weekend and then high pressure moving towards Greenland, but looking in detail it's not bad at all. During the day it will be fine this weekend with rain coming Sunday night for most and as for the high pressure retrogression next week, the Northeasterly doesn't quite get there in full flow. Strong winds also doing us a favour so that we're not stuck with low cloud which is typical of most easterlies.

[Fourty Point Three Degrees]

This blocking HP over Greenland looks like it could take some shifting and I'm glad we're getting it now rather than in June.  May will be a month of switching between E'lys and N'lys  with LP skimming the far South.

[knocker]

Once the dance of the shallow lows is out of the way tomorrow (a showery, cloudy, day for many). the amplification gets underway Tues/Weds with the upper trough disrupting (note cut off low to the south east), and the high pressure surging. Thus by 00z Wednesday we have high pressure centred west of Norway, low pressure eastern France and the easterly regime underway So mainly dry weather with temps hovering around average or just below.

But this easterly regime is relatively short lived. The high pressure drifts west to the Iceland area and Atlantic troughs track east from the WSW into France and this could well bring some showery rain into the south and back the light flow a tad further north.

By Sunday we very much have an analysis that has been indicated by the anomalies with low pressure to E/SE the main high continuing to retrogress to the Greenland/Iceland area and with  further low pressure to the SW the UK is virtually in a col. Not an unpleasant position with little wind, dry with variable cloud and temps generally around average.

So all in all not a bad week in prospect, remaining dry and although the temps are not any great shakes pleasant enough. But what next as there are options aplenty? will the trough to the east edge closer and bring cooler northerlies or the Atlantic trough edge further west and a warmer SW drift? Or indeed is the situation primed for another little surge of the high pressure over the UK?

Editt

This morning's GEFS is indicating a NW, backing W, upper flow with maybe the trough to the east taking closer order.

Edited April 29, 2017 by knocker

[Matthew.]

The easterly wind looks lighter on UKMO this morning with the Hp a little closer to the country from Wednesday.

Edited April 29, 2017 by Summer 1976