Model Output Discussions 12z 08/03/17

[knocker]

Once the low pressure, currently over southern England, moves into France taking the wet weather with it, apart maybe for the far south east, then the transition to a dry easterly can get underway. At least the last couple of days has seen 30-50mm in parts of Devon and Cornwall.

This dry weather, with quite strong easterlies at times in places, more or less stays in place until around, and including, the weekend with the odd low spawned from the trough to the south west brushing the south west tip. Temperatures during the week will vary longitudinally with the western half being around average and the eastern more on the cool side for obvious reasons but feeling quite warm if any cloud dissipates.

Towards the end of the weekend the high pressure to the north starts to retrogress, it has been sign posted for quite a time, and thus we begin the transition to the next phase with the troughs to the east and south west taking closer order. Thus by Tuesday the UK is in a very slack north easterly drift which very quickly becomes the UK sitting in a col with the cold trough to east where hopefully it will remain in future runs

You can see where the anomalies are going with this by glancing at last night's NOAA and this morning's GEFS but I think the detail of this transition will take a few runs to sort.

Edited May 1, 2017 by knocker

[knocker]

Although the ecm naturally varies in detail from the gfs they are on the same page and it ends with an analysis not at odds with the above anomalies. it has the main trough to the east with a shallow subsidiary over the UK which has phased in  with the trough to the south west. Thus unsettled showery weather with temps a little below norm. This is of course subject to change.

Edited May 1, 2017 by knocker

[stodge]

2 hours ago, knocker said:

Although the ecm naturally varies in detail from the gfs they are on the same page and it ends with an analysis not at odds with the above anomalies. it has the main trough to the east with a shallow subsidiary over the UK which has phased in  with the trough to the south west. Thus unsettled showery weather with temps a little below norm. This is of course subject to change.

I do agree we are seeing the probable end of the NE flow early next week but I'm far from clear as to the evolution from there. I quite like the GFS Control option of drawing the trough up from the SW and I think that more plausible than the OP at this time. 

The other possible is the ECM where a pool of stagnant cold air gets trapped over the UK - this has happened many times in May and brings showery days and cool nights with little or no wind. Indeed, it might be the outcome if the col becomes established.

Either way, I think a more unsettled evolution is the way ahead into the middle of next week.

[damianslaw]

A benign outlook for the foreseeable, and a highly abnormal synoptic pattern as well, with the atlantic dead in the water, and everything moving east to west as opposed to west to east - full on retrogressive pattern, always noteworthy, but perhaps more likely now than at any other stage in the year. The east will see a very dull spell of weather, with a nagging chilly easterly wind and perhaps some spits and spots of rain. Sheltered western spots will do best - again often the case in May when we have easterlies. I think May is our most easterly month, and April our most northerly?

Longer term - heights will sit to the NW, but it looks like a weak trough will become unstuck over the country under rather cold uppers, so a probable change to something more unsettled before mid month with perhaps the first significant precipitation in some parts for many weeks - I was out walking yesterday and the ground is very dry, many streams are bone dry or just a light trickle. 

[MP-R]

49 minutes ago, damianslaw said:

I think May is our most easterly month, and April our most northerly?

 

Quiet possibly. May just beats August as most thundery month of the year in my location, not least because we do well out of anything between SSE and NNE. Today is no exception.

[Summer Sun]

GEM shifts the low a good bit further east compare to the 00z in the latter stages of its run

12z

00z

[Summer Sun]

The latest ECM weeklies issued this morning show temperatures widely below average for northern Europe next week this probably extends to the UK though we may be only just below average

Weeks 3 and 4 see temps recovering but rainfall also increases which may well indicate more of a southwesterly flow setting up - towards the end of the month indications are it may well turn drier again for the south

 

[snowray]

Well here we go again, very wintry chart even for early May, Brrrrrrrrr!

[ANYWEATHER]

Evening All and I hope you have had a great Bank Holiday Both ecm and gfs ops show next week a Potent cold spell from the Artic at some point! So the models have not shied away from that scenario, if that occurs expect some amazing convection , similar to what we had last week, with rain, sleet and snow , hail and thunder and perhaps a tornado. The air will be very unstable , and with strong sunshine and very cold uppers expect pyrotechnics So the general theme of dry weather still looks likely ,but unfortunately some potent late frostsAnd this goes for the south too

Edited May 1, 2017 by ANYWEATHER

[knocker]

The ten day anomalies are all in pretty good agreement this evening

A trough over the eastern seaboard with the high pressure now in the NW Atlantic/Greenland area but still ridging east towards the UK with the cut off upper low to the south of that. The latter and the other trough to the north east of the UK would appear to be the key players as we move forward into the next pattern change. The precise timing on how these two troughs Phase/interact will determine the detail that the det. runs will need  to sort. The ecm chart at day 10 is possible way forward with the Atlantic becoming very meridional with ridging into Greenland and the now combined trough orientated NE/SW across the UK with the latter in W/SW flow. This would portend some unsettled cool weather with temps a little below average in a slow moving surface pressure area.

Moving into the later period is not too enlightening although they all agree on the general these of ridging into Greenland and a trough in the eastern Atlantic but the EPS makes less of the former and more of the latter than the other two. So as a general observation continuing changeable with temps still a little below average.

Edited May 1, 2017 by knocker

[knocker]

The transition to the easterly regime gets underway today with the low pressure to the south slipping into Germany and the high pressure west of Norway becoming more organized and influential. This remains the case until the weekend as the high cell tracks slowly west and troughs breaking off from the Atlantic trough east into France. Thus not a bad week for the UK with much dry weather perhaps becoming fairly windy in the south and temps around average. Of course the latter needs qualify as there will be a fair bit of east/ west variability with the former being a tad cooler. Where there is cloud clearance, particular in the west it will feel very pleasant.

From this point things get a little more complicated as has been indicated by the anomalies. The trough to the east is taking closer order as the high pressure declines and the flow over the UK backs and becomes very light  Still remaining dry and temps generally maybe just a little cooler but still not far from the norm

From this point the upper trough spreads it's wings further west and south west, phasing with out old friend the cut off low to the south which on the surface translates to a large low pressure area in the eastern Atlantic spreading east. Thus more unsettled weather for the UK but not by any means drastic with a light southerly/SE drift and temps correspondingly a little warmer

This morning's GEFS not adverse to this

Edited May 2, 2017 by knocker

[knocker]

Although on the same page the detail is obviously different with the ecm towards the end of the run with a much deeper low to the north west. The detail vis the transition to a complex low pressure area in the eastern Atlantic remains to sorted but there is nothing very untoward lurking in the woodshed.

[snowray]

ECM has now dropped the arctic blast for D8/9, no surprises there. Ensembles looking much better, things warming up nicely and also a settled period coming up by the looks of things.

 

Manchester and London.

[bluearmy]

Very interesting re next week. Extended ens have been solid on extending the scandi trough se across the uk to meet the Azores low. As we get to the all important 7/8 day timeframe on this evolution, we begin to see signs that the system developing around Iceland will possibly dive south further West and introduce a more southerly flow across us. If this does indeed happen then it mirrors previous solutions over the past month or so where a predicted nw euro trough has been corrected southwest - watching this with a lot of interest as it offers an insight into what may be ahead for us as we head towards summer re possible plumes  

[Frosty.]

3 hours ago, bluearmy said:

Very interesting re next week. Extended ens have been solid on extending the scandi trough se across the uk to meet the Azores low. As we get to the all important 7/8 day timeframe on this evolution, we begin to see signs that the system developing around Iceland will possibly dive south further West and introduce a more southerly flow across us. If this does indeed happen then it mirrors previous solutions over the past month or so where a predicted nw euro trough has been corrected southwest - watching this with a lot of interest as it offers an insight into what may be ahead for us as we head towards summer re possible plumes  

According to the pros, next week will become colder and unsettled with gales in the n / e with overnight frosts.

Edited May 2, 2017 by Frosty.

[Summer Sun]

41 minutes ago, Frosty. said:

According to the pros, next week will become colder and unsettled with gales in the n / e with overnight frosts.

Must admit @Frosty. I was a bit surprised by that update stating gales next week that high is gonna take some shifting

Here's UKMO, GFS & ECM at t168

Edited May 2, 2017 by Summer Sun

[Scorcher]

1 hour ago, Frosty. said:

According to the pros, next week will become colder and unsettled with gales in the n / e with overnight frosts.

The same pros that predicted very warm conditions for this week? 

Just looking at the models today and yesterday evening, they seem to be backing away from the colder spell. Fingers crossed this is the case.

[Summer Sun]

UKMO shows the high maintaining it's grip on the UK as we start next week as with this week it will be pleasantly warm in the sunshine but always cooler if you are stuck under cloud

[Scorcher]

Again west will be best looking at that chart- we've had a lovely day here for most of today and managed 16C. Slightly above average for the first week of May. It's certainly looking very dry for most for the foreseeable future.

[northwestsnow]

Lovely looking ukmo posted above.Certainly a very dry 5 to 7 days coming up and for the first part of it west is best i would imagine, hoping the cold blast next week gets shunted east as is often the case..

[lassie23]

Too late/early for cold blasts now, we will hopefully see a cold arctic blast when needed, hopefully in November.

[phil nw.]

Modeling showing a pattern not uncommon in Spring as the Polar Vortex breaks up.

UKMO at T120hrs

Everything coming from the east as the bulk of the Vortex situates over the Siberian side leaving a blocking high pressure to our north.

A cool easterly flow off the North Sea down the eastern coastal strip with cloudier spells here but looking brighter and somewhat warmer the further west you are.The overall dry conditions seen in April looks like continuing for the next week at least. 

[Summer Sun]

It's nice to see the real cold 850's of a few day's back now struggling to make it down to us still chilly in any cloud yes but not too bad in some sunshine

As for the gales the met office are suggesting next week I still can't see it happening yet

Edited May 2, 2017 by Summer Sun

[Matthew.]

4 hours ago, northwestsnow said:

Lovely looking ukmo posted above.Certainly a very dry 5 to 7 days coming up and for the first part of it west is best i would imagine, hoping the cold blast next week gets shunted east as is often the case..

By the looks of it the SE into Yorkshire have the worst of the cloud the next few days close to that front. North and West of that wall to wall sunshine but quite a breeze.

[Summer Sun]

Nothing too cold on offer this morning with GFS for the most part keeping the colder air at bay with any inroads it makes very short lived with some rain at times

ECM keeps any chiller air to D9 or 10