Model Output Discussion 26/08/2012

[Frosty.]

12z brings in the dreaded PV, monstrous in FI. No wonder its quiet in here.

BFTP

Still 2 months to winter so i'm not concerned what individual op runs are showing, the medium and longer range outlook is very unclear at the moment, I will only become concerned if a euro high sets up like last autumn and refuses to budge for 2 months.

[SMU]

Still people looking at the models hoping for that Euro high-

Its not coming people-

It wasnt coming 3 days ago & isnt coming tonight for 6-8 days time-

In the short term 1-5 days we have a jet that runs at WORST west east, then the next bout of energy will try to move SE across iceland under greenland-

the Euro high has been weak this year- we MAY see fleeting glimpses of it- however we are talking about the extreme south of the UK- As we are now heading into October the mean location of the polar front is edging back south- & for that reason we are really running out of the sands of time on any warm from the south

I would give it a 10% chance of any MAJOR influence from the south in the next 10 days-

As it stands where October tends to start quite warm I expect a cold anomaly for the time of the month CET wise when we hit the 10th...

the highest chance of warmer weather is a retrograde euro high towards Scandi- thus nice in the S/SW-

S

[Gibby]

Good evening. Here is the latest look at the output from GFS, UKMO and ECM.

All models continue to show a low pressure influence from a position North of Scotland with a strong Westerly wind blowing for much of the time with showers and longer periods of rain rushing East on the breeze on all days for all areas.

GFS then shows a further unsettled day on Saturday with a hangback of cloud over Southern England with some rain lasting into Sunday and Monday. In FI high pressure from the Atlantic steers Atlantic fronts down over the UK, largely affecting more Northern and Eastern areas with some dry, typically Autumnal weather likely at times further SW though even here some rain is likely at times.

The GFS Ensembles show the operational as a cold outlier in the South for Southern locations. the overall mean for the 850's take a mild blip next week before returning to levels close to or a little below the long term mean. Rainfall is indicated at all points of the run from locations North and South indicating the most likely outcome remaining changeable.

The Jet Stream blows East across Northern Britain currently. It slips slowly South over the coming days to a position South of Britain by midweek. Further out and a split in the flow looks likely with a Northern arm blowing well North of the UK and one exiting the Staes to a point near the Azores next weekend and beyond.

UKMO at noon on Saturday show High pressure transferring over Britain through the day with a dry and fine mid Autumn day with some sunny spells by day but some mist, fog and frost issues possible overnight.

ECM shows High pressure too at 144hrs, moving away SE quite quickly though in the following days as deep Atlantic Low pressure steers strong South or Southwest winds back into the UK with troughs delivering rain to many, as usual in these situations the heaviest in the North and West.

In Summary the weather still looks mixed from the models as we move beyond this week. There is a slight closing of the gap between GFS and ECM in as much as they both show unsettled weather in their extended outputs. It's the way in which they deliver it that differs. GFS likes the idea of an mid Atlantic High suppressing an old Azores Low while steering Low pressure over the top and down over the UK from the NW in often cool and rather chilly winds. ECM on the other hand shows a mid Atlantic Low with attendent milder and wetter SW winds affecting the UK soon after the start of next week. A lot of sorting out in the models to keep us interested over the next few days.

[BLAST FROM THE PAST]

Still people looking at the models hoping for that Euro high-

Its not coming people-

It wasnt coming 3 days ago & isnt coming tonight for 6-8 days time-

In the short term 1-5 days we have a jet that runs at WORST west east, then the next bout of energy will try to move SE across iceland under greenland-

the Euro high has been weak this year- we MAY see fleeting glimpses of it- however we are talking about the extreme south of the UK- As we are now heading into October the mean location of the polar front is edging back south- & for that reason we are really running out of the sands of time on any warm from the south

I would give it a 10% chance of any MAJOR influence from the south in the next 10 days-

As it stands where October tends to start quite warm I expect a cold anomaly for the time of the month CET wise when we hit the 10th...

the highest chance of warmer weather is a retrograde euro high towards Scandi- thus nice in the S/SW-

S

Indeed Steve, as my earlier post states I tend to agree an outcome where pressure is higher to our N/NE , I'm just doing a little prodding re PV to get folk posting on here.

BFTP

[Geordiesnow]

Despite what Steve says, there is more of a trend for the Euro high to develop which could in turn warm things up as we head into the latter part of next weekend, how long it affects us and in what way is quite uncertain at this moment in time.

Quite a cool week coming up and at times quite wet but nothing exceptional from what I can see, any rainfall will be showery in nature apart from that front on Tuesday but even this could provide some interest for convective lovers so again, those in the North West could have an interesting week whilst those in the East it will be more drier and sunnier.

Regarding the PV, we are at the time of year where it will naturally form over Greenland anyways, obviously for those looking for cold set ups, in general we don't want it to remain there during the winter for long periods of time but at this moment in time, its not a concern at all.

[BLAST FROM THE PAST]

Geordiesnow

There is one problem, over past 3 years our weather has got into 'ruts' which have lasted for very lengthy periods with recurring themes, for me I would rather it didn't dig in. So something to watch out for over next 4-5 weeks.

BFTP

[damianslaw]

BBC/Met office obviously uncertain with things at present as illustrated in this evening's countryfile forecast. The uncertainty is due to the remains of hurricane nadine , which continues to languish in the mid atlantic. The BBC hinted it could spawn a secondary low feature once again and get caught up in the jetstream delivering a wet windy spell at the weekend. It is a very plausible outcome, the ridge developments being shown by ECM/GFS for later in the week looks a rather lacklustre weak affair, and it wouldn't take much for lower heights to rapidly develop to our SW squeezing out the ridge..

I believe the reliable timeframe is rather short at the moment - and there are many possibilities once we get to Friday.. with this in my mind don't be surprised to see sudden short-term developments in the forecasts this coming week.