Model Output Discussions 12z 08/03/17

[Summer Sun]

Little change from UKMO with pressure building for the weekend (makes a change) maybe some rain at first in the south but this should diminish as the weekend progresses

Pleasant enough by day but cold overnight we could see some big temperature ranges during this period between the afternoon peak & overnight peak

[Frosty.]

11 minutes ago, Summer Sun said:

Little change from UKMO with pressure building for the weekend (makes a change) maybe some rain at first in the south but this should diminish as the weekend progresses

Pleasant enough by day but cold overnight we could see some big temperature ranges during this period between the afternoon peak & overnight peak

Indeed, some marked diurnal temperature variations with pleasantly warm days followed by slight overnight frosts..lovely spring weather under high pressure.

Edited March 20, 2017 by Frosty.

[Frosty.]

Very nice Gem 12z from later this week if you like high pressure with temps becoming pleasant by day in the strengthening late march sunshine but then turning chilly overnight under clearer skies with slight frosts and fog patches. It's only towards the end of the run when there are signs of an atlantic intrusion but probably only briefly.

Edited March 20, 2017 by Frosty.

[Frosty.]

The Ecm 12z shows high pressure building in later this week but it becomes positioned in such a way as to allow colder air to feed in across the SE in particular with a chilly NEly breeze setting in but for most of the uk it's an improving picture after the next few days, at least for a time..The 00z was much nicer than this but the outcome could still be much better like the Gem shows..The Ecm does improve during next week I'm pleased to say and ends pleasantly milder and blocked.

Edited March 20, 2017 by Frosty.

[Summer Sun]

ECM shows colder air getting into the SE unlike UKMO

[Scorcher]

24 minutes ago, Frosty. said:

The Ecm 12z shows high pressure building in later this week but it becomes positioned in such a way as to allow colder air to feed in across the SE in particular with a chilly NEly breeze setting in but for most of the uk it's an improving picture after the next few days, at least for a time..The 00z was much nicer than this but the outcome could still be much better like the Gem shows..The Ecm does improve during next week I'm pleased to say and ends pleasantly milder and blocked.

 

On this occasion I'm really hoping the ECM is wrong in its positioning of the high- the UKMO is certainly much closer to the GFS. It's really quite a poor run from the ECM compared to previous runs- we would even be struggling temperature-wise by day into the weekend if that run came off. I imagine it could be rather cloudy for most as well with the high too far west and that NE flow.

[Frosty.]

1 minute ago, Scorcher said:

On this occasion I'm really hoping the ECM is wrong in its positioning of the high- the UKMO is certainly much closer to the GFS. It's really quite a poor run from the ECM compared to previous runs- we would even be struggling temperature-wise by day into the weekend if that run came off. I imagine it could be rather cloudy for most as well with the high too far west and that NE flow.

Yes I would much prefer the 00z version with high pressure centred over the uk..which could still be the eventual outcome anyway..fingers crossed.

[Scorcher]

Just now, Frosty. said:

Yes I would much prefer the 00z version with high pressure centred over the uk..which could still be the eventual outcome anyway..fingers crossed.

Let's hope this run is just an outlier. I am always concerned when it's the ECM that begins to change tune though, as it is generally the most reliable of the main models as we know.

[Frosty.]

2 minutes ago, Scorcher said:

Let's hope this run is just an outlier. 

Yes let's hope so, the Ecm 12z ensemble mean will give us a better idea, the 00z was very pleasant.

Edited March 20, 2017 by Frosty.

[knocker]

Yes it's quite interesting how the ecm did this and it's so dependent on being that precise I wouldn't be overly concerned. It has sneaked an upper trough around the top of the ridge and nips it SE to phase with the low pressure to the south before the Azores ridge can cut it off at pass Thus for a time there is a low pressure area to the SE before the HP reasserts itself but it does once again open the channel around the high

Edited March 20, 2017 by knocker

[knocker]

Well the EPS 850mb mean and wind vectors is not liking the trough running around like that and shuts the door on the ingress of cooler air with the ridge becoming influential.

Edited March 20, 2017 by knocker

[Frosty.]

On the face of it, the GEFS 12z mean is smooth sailing into a pleasant anticyclonic outlook, even more bullish than the earlier runs today..hopefully a good spell of weather is on the way.

Edited March 20, 2017 by Frosty.

[knocker]

Interesting this evening NOAA appears to quite like a negatively tilted trough mid Atlantic with some positive anomalies and some NW ridging in the Iceland area. Something which the GEFS and EPS are not keen on so I'm not quite sure what to make of that. I would still think the percentage play is for the Azores to be ridging in the vicinity of the UK getting towards the end of the period.

[phil nw.]

It's certainly looking promising for much better weather by the weekend, looking at all 3 main runs, with a building high modeled across the UK.

T120 hrs 

 

Looking through the ens outputs shows some mid-latitude blocking extending well into next week with a lot of dry weather about.

Some variations in the exact orientation of the block within the ens but the general theme of a split jet such as here at t144hrs seems the ongoing outlook.

It's doesn't look like being exceptionally mild though with some of the colder air from this week still trapped around the UK so some night frosts later this week as skies clear.Days should feel pleasant enough though in the sun.

[Frosty.]

Tonight's Ecm 12z ens mean paints a nice settled picture from later this week onwards with high pressure taking over bringing variable cloud and pleasant sunny spells and chilly nights where clearer skies occur with slight frosts and fog patches.

Edited March 20, 2017 by Frosty.

[Scorcher]

41 minutes ago, Frosty. said:

Tonight's Ecm 12z ens mean paints a nice settled picture from later this week onwards with high pressure taking over bringing variable cloud and pleasant sunny spells and chilly nights where clearer skies occur with slight frosts and fog patches.

That certainly looks better than the op run, it would be nice to have that high pressure further east though. Perhaps it will become warmer over time as this gradually happens. There is always the risk of fog at this time of year with high pressure directly over the UK, although this risk is diminishing with the sun gaining in strength now.

[knocker]

Quite interesting to note the EC46 mean update last night. It slips into the Atlantic trough more zonal routine that the EPS has been indicating at the end of the month but it is but a brief interlude. By the 3rd of April a rapid pattern change is underway involving the vortex emphasis switching once again to Canada/Greenland and the initiation of renewed amplification in the Atlantic involving the trough in the west and the Azores in the east. This last around a week to the 9th before normal service is resumed. If this is anywhere near correct it would portend a quite pleasant start to April being dry and temps above average.

Edited March 21, 2017 by knocker

[knocker]

The GFS this morning. The unsettled low pressure regime lasts another couple of days before giving way to the Azores on Friday.

In one shape or another this high pressure remains influential until the end of March when it tends to get suppressed allowing the Atlantic to ingress the northern half of the UK. However the orientation and position of the HP will be crucial when it comes down to the detail vis wind, cloud, diurnal temp variation. This is illustrated quite well with the chart for next Monday with the centre of the high cell away to the NE and thus a fresh south easterly regime.

Only to become this by Thursday.

So in a Sidney nutshell becoming dry, quite pleasant and temps possible a little above average but a quite large diurnal variability.

EDIT

Nothing much to add vis the ecm, Starting to push Atlantic fronts in by the 30th

Edited March 21, 2017 by knocker

[Sky Full]

Just wanted to put these two charts up this morning:

  

Not a huge difference between them really.  The first one is this mornings GFS for tomorrow (+24hr) which is unlikely to change much now.  The second is the prediction made by the GFS on the 9th March for the same time tomorrow - that's 312 hours ahead.  I don't think that's a bad result allowing for the details which could not possibly be predicted that far ahead.  If we could expect this kind of accuracy even 50% of the time, think how that would transform forecasting!

 

 

[mb018538]

ECM looks lovely this morning. As a few others have said, risk of big diurnal variations coming up, with some cold nights and pleasant days. Hopefully we should see some sun with winds coming from the near continent bringing dry air.

[Frosty.]

Much improved Ecm 00z in terms of temperatures and sunshine potential with high pressure slowly drifting further east enabling a milder / warmer continental flow..hope this trend locks in. Still some chilly nights but increasingly pleasant days..very spring like.

Edited March 21, 2017 by Frosty.

[mb018538]

Darren Bett mentioned the same last night....if we get the high over the UK, but wafting some of that southerly air towards us, I think we will see a 16-18c max somewhere by later next week.

[Frosty.]

6 minutes ago, mb018538 said:

Darren Bett mentioned the same last night....if we get the high over the UK, but wafting some of that southerly air towards us, I think we will see a 16-18c max somewhere by later next week.

Fingers crossed, didn't like last night's Ecm operational with that chilly cloudy NEly but the mean looked better..always good to have the Ecm on-board, surely most of us fancy some proper spring warmth!

Edited March 21, 2017 by Frosty.

[Frosty.]

Nice ukmo 00z for the weekend into next week with high pressure becoming centred over the uk..very pleasant days followed by chilly nights.

[Frosty.]

Nice Gem 00z too, high pressure here we come.