Model output discussion 14/04/18

[Singularity]

As alluded to in recent days, while the forcing mechanisms are on the change, we can expect a bit of a shake-up to our pattern. 

The hope is that the forcing aligns such that ridges from the Azores bring an end to the more changeable conditions by around mid-month (sometime in the period 12-18 June). Note the sizeable leeway there - and I see Tamara's just weighed in with an estimate at the later end which I concede to be the more realistic exception giving the most likely timing of MJO movements, tropical Pacific SST changes and resultant GLAAM/GWO behaviour.

I can certainly live with a more changeable 8-10 days if conditions become predominantly fine for the rest of the month and on through July. Better, in my opinion, than being stuck in a pattern that's brought an increasingly large number of cloudy, very muggy days to many parts of England, and threatens large amounts of rain if LP to the south drifts too close and/or develops too much.

[davehsug]

All very unfortunate for those of us holidaying on the West coast next week! Seeing weeks of beautiful weather before and potentially after is particularly galling. Still time for small changes, that could make a big difference.

 

[mb018538]

3 minutes ago, davehsug said:

All very unfortunate for those of us holidaying on the West coast next week! Seeing weeks of beautiful weather before and potentially after is particularly galling. Still time for small changes, that could make a big difference.

 

It's unfortunate, but it's quite rare in the UK to get an extended period of weather where the west fares much better than the east. It had to end at some point!

As others have alluded to, we've flip-flopped with model uncertainty the last few days, and they have started to lean towards an unsettled period again. Not a problem as such - all UK summers will have an unsettled period at some point - its where we end up after that's the key. I take heart from posters such as Tamara saying that teleconnections look favourable for the UK in the longer term, so we will see how things pan out.

Edited June 5, 2018 by mb018538

[I remember Atlantic 252]

4 minutes ago, davehsug said:

All very unfortunate for those of us holidaying on the West coast next week! Seeing weeks of beautiful weather before and potentially after is particularly galling. Still time for small changes, that could make a big difference.

 

but a relief to those holidaying in eastern areas, or anyone foolish enough to holiday here

[Frosty.]

20 minutes ago, I remember Atlantic 252 said:

but a relief to those holidaying in eastern areas, or anyone foolish enough to holiday here

You're always moaning! looking at the models there's plenty of decent early summer weather to come before it potentially turns more unsettled.

[davehsug]

27 minutes ago, I remember Atlantic 252 said:

but a relief to those holidaying in eastern areas, or anyone foolish enough to holiday here

A look at the 6z so far suggests a limpet UK low and the perennial NW wind which has plagued summers away from the South these past few years. Be careful what you wish for!

[Guest]

GFS going down the 'return of the westerlies' route on the 06Z run, by 240hrs with the Azores high stuck in Biscay it leaves the door open to a flat or NW/SE slanted Jet aimed at the UK. Just remember some of the best spring weather recently has occurred in years with some utterly terrible summers (2007,2012) lets hope 2018 doesn't follow suit.

[Matthew.]

50 minutes ago, I remember Atlantic 252 said:

but a relief to those holidaying in eastern areas, or anyone foolish enough to holiday here

Remember we have to pay for the first 3 weeks of sunshine in May with 3 weeks of dull by the time we finish. Whereas the west has had it more the other way round Many good summers don’t get going till the last third of June so we wait and see

[Man With Beard]

EC clusters this morning a further turn to mobility for D8-D10 - we now have 29 in the unsettled cluster, and 22 in the settled one (this was the other way round yesterday)

Once we get up to about 35 in the unsettled cluster, then we can start calling a pattern change more confidently (whether brief or extended). I don't think we are there yet. Though northern areas look unlikely to escape some sort of unsettled period around mid-month if the T300 chart is accurate:

Yesterday's clusters were not quite as unsettled, so need to see a couple more runs to firm up prospects.

[mushymanrob]

15 hours ago, Quicksilver1989 said:

Given how wrong the anomaly charts were last time I'd saw a warm and muggy SE'ly is the more likely option then!

That chart you post for the 29th on May 21st was remarkably close to the actual chart!

thats true.... but we still didnt get the heatwave did we, so whilst my interpretation of them wasnt correct, the conditions we got WERE.

interestingly though.... all models now agree with what the noaa's had been predicting for 3 days. the ecm, the gfs, the ecm/gfs anomalies. the noaa's have yet again been proven to be the better model for this timeframe.

 

[Djdazzle]

The NOAA hasn’t been proven as the best model yet because it hasn’t happened!

[johnholmes]

46 minutes ago, Djdazzle said:

The NOAA hasn’t been proven as the best model yet because it hasn’t happened!

 

My comment about the 500 mb charts is based on watching them for years 365 days a year. When they show consistency along with EC-GFS then they are much more reliable than the 2x or 4x synoptic outputs at similar ranges.

Of course they are not infallible nothing in meteorology is, that is the beauty of trying to follow or predict it for some of us.

 

[mushymanrob]

1 hour ago, johnholmes said:

 

My comment about the 500 mb charts is based on watching them for years 365 days a year. When they show consistency along with EC-GFS then they are much more reliable than the 2x or 4x synoptic outputs at similar ranges.

Of course they are not infallible nothing in meteorology is, that is the beauty of trying to follow or predict it for some of us.

 

it was Johns observations on these charts several years ago that 'converted' me to them (as highlighted in the post above). the noaa ones in particular.  if you really want to know whats most likely to happen, then these charts are the best. they dont vary as much as the ops which might make them a bit boring for some people. but if you get the upper flow right, then the surface conditions are easier to get right too ... no?..

well it works for me most of the time, viewing those will point you to which of the op runs are most likely to be nearer the mark.  but of course if you enjoy the variability of the ops, and like being led up the garden path sometimes, then thats fine lol.

as for it 'not happening yet' , true, but when the noaa anomaly charts have been consistent and other model suits have been slow to fall in line, before eventually agreeing, i for one will not place any monies on this outcome being inaccurate! much as i do not want it, a period of low pressure dominance in some form (detail to be resolved) for next week is now pretty likely imho, unless these charts change, which sadly, is unlikely.

[swebby]

3 hours ago, Alderc said:

GFS going down the 'return of the westerlies' route on the 06Z run, by 240hrs with the Azores high stuck in Biscay it leaves the door open to a flat or NW/SE slanted Jet aimed at the UK. Just remember some of the best spring weather recently has occurred in years with some utterly terrible summers (2007,2012) lets hope 2018 doesn't follow suit.

Agree and I do like that "return of the westerlies" term (coined by TWS if memory serves?) and as we head towards the solstice a more unsettled theme is being hinted at by the models. To my mind, it's common for UK to be under the influence of LP around the solstice and it's what happens come July and the behaviour of the Azores high that is more important to our summer prospects.

In regards to good spring weather equalling wash out summers - it's a very unscientific approach on my part but it is prolonged very dry spells in April that give me the heebie jeebies (i think 2007 and 2012 have such examples).  Fortunately this April was not one of those, so while it may not mean this summer will be "scorchio"  it does at least mean i feel a bit more confident that we are not going to have a record breaking wash out..

[carinthian]

1 hour ago, swebby said:

Agree and I do like that "return of the westerlies" term (coined by TWS if memory serves?) and as we head towards the solstice a more unsettled theme is being hinted at by the models. To my mind, it's common for UK to be under the influence of LP around the solstice and it's what happens come July and the behaviour of the Azores high that is more important to our summer prospects.

In regards to good spring weather equalling wash out summers - it's a very unscientific approach on my part but it is prolonged very dry spells in April that give me the heebie jeebies (i think 2007 and 2012 have such examples).  Fortunately this April was not one of those, so while it may not mean this summer will be "scorchio"  it does at least mean i feel a bit more confident that we are not going to have a record breaking wash out..

I think we have to be a bit cautious regarding the timing of the return of the westerlies. Of course its going to happen sometime sooner than later. However, here lies the problem ( timing ) Todays GFS runs have indicated that route by 240t, but in my experience it is fairly rare for a locked weather pattern to be blown away so quickly. The recent pattern over Europe/ UK has been profoundly stubborn as borne out by some extremes in weather over the past 3 months and drastic changes in the overall pattern ( flow from all points East ) has just not happened, even when longer term forecasts ( UKMO ) had some weeks ago suggested a maritime cooler regime to affect the NW and Azores linked weather to affect the SE. The domination of the block /ridging to all vectors to the north and low heights  over Europe / Iberia has been quite a feature.

C

[Uncle_Barty]

2012 went downhill from as early as the 9th April.

Even the best of summers have an unsettled spell at some point - 1976 had a somewhat unsettled mid-part of June, 1989 had a horrid spell in the 1st half of June (coinciding with the 2 weeks I had off being the only time I got...) and 2003 had a dodgy spell in late July.

Not too concerned at the moment, given Tamara's words in recent days, but the fact that it's an "8" year is always at the back of my mind 

[Fourty Point Three Degrees]

4 hours ago, Alderc said:

GFS going down the 'return of the westerlies' route on the 06Z run, by 240hrs with the Azores high stuck in Biscay it leaves the door open to a flat or NW/SE slanted Jet aimed at the UK. Just remember some of the best spring weather recently has occurred in years with some utterly terrible summers (2007,2012) lets hope 2018 doesn't follow suit.

2012 was nothing special in terms of best spring weather. It was a terrible Spring and Summer put together but only with some nice blips around the last week of May and July. The jet stream was always quick at diving back south, this year it seems keen on diving north.     

2012 was also the end of a drought period, this year could be the beginning of one - it has after all been a while since there was a hydrological drought

 

[cheese]

5 hours ago, davehsug said:

A look at the 6z so far suggests a limpet UK low and the perennial NW wind which has plagued summers away from the South these past few years. Be careful what you wish for!

It's a small price worth paying to cut off this seemingly never-ending North Sea flow, and the Pennines offer us some protection anyway so most of any rain should be kept to the west where it belongs.

[Derecho]

5 hours ago, mushymanrob said:

thats true.... but we still didnt get the heatwave did we, so whilst my interpretation of them wasnt correct, the conditions we got WERE.

interestingly though.... all models now agree with what the noaa's had been predicting for 3 days. the ecm, the gfs, the ecm/gfs anomalies. the noaa's have yet again been proven to be the better model for this timeframe.

 

Aye the NOAA charts will be closer to the mark this time but I reckon we will probably see low pressure a bit further north.... or at least I hope...

Cooler uppers returning seem likely after Sunday and with a cool North Atlantic temperatures won't be particularly warm. With a westerly regime setting up the chance of heat remains restricted to Spanish plumes, only problem is there hasn't really been any heat in Spain in recent weeks!

Lets hope the models are overdoing the strength of the jet later next week and the Azores high ridges across us instead, don't think too many people will complain at that

Edited June 5, 2018 by Quicksilver1989

[Singularity]

The latest GFS run goes out of kilter with the others by 5 day's range, as it develops LP significantly more during the weekend and moves it further north and west than UKMO goes with, and further north than GEM goes with. Only the UKMO solution keeps long and often heavy spells of rain away from much of England though... and GFS produces an absolute deluge, so it's something to keep an eye on.

The GFS run then loses a lot of credibility by days 8-9 in my book, having taken the jet stream to the sort of strength nearly always restricted to the winter months and only intermittently even then. I'm in no way saying it can't happen, but this solution stinks of zonal bias to me and I anticipate a more sluggish and messy deterioration of the pattern as we move into the interchanging period. Much as @carinthian suggested earlier .

...but to be fair to GFS, it doesn't keep that rampant jet going for long;

 

Note the jet digging down a good way in the mid-N. Atlantic. That's the manner of development to look out for as the forcing switches in favour of ridging or even fully displacing the Azores High in our direction - though it may not be as pronounced at that to begin with (the models have a habit of responding too rapidly to changes in forcing).

The run works out nicely if you enjoy a run of high temperatures;

 

The shuffling of the deck may re-open routes to 'proper heat', the likes of which we've pretty much seen the doors closed on since the Azores-Scandinavia ridging pattern morphed into an Azores-Iceland ridging pattern. This run does seem a bit overly dramatic for the first time of asking though!

 

[I remember Atlantic 252]

1 hour ago, cheese said:

It's a small price worth paying to cut off this seemingly never-ending North Sea flow, and the Pennines offer us some protection anyway so most of any rain should be kept to the west where it belongs.

Yes, and hopefully will only last a few days, another good FI on the GFS

[Mike Poole]

Given what we think we expect, I think I'll take the GEFS 12z.  Yes, westerlies and unsettled weather at T240:

Edit, please click the above chart and see it is NOT the one the thumbnail shows, I think it might be yesterday's, this  sort of thing is just annoying. 

But strong hints of a resurgence of the higher pressure at the end of the run:

Given long range signals, models and the Met Office long range forecast, I still think this bodes well for a decent summer.

Edited June 5, 2018 by Mike Poole

[Frosty.]

The 12z models are firming up on a more unsettled cooler interval from the atlantic next week but if it was then followed by this from the Gfs 12z..it would be a small price to pay for the rich rewards shown late in low res...now that's a plume

Edited June 5, 2018 by Frosty.

[Gordon Webb]

11 minutes ago, Frosty. said:

The 12z models are firming up on a more unsettled cooler interval from the atlantic next week but if it was then followed by this from the Gfs 12z..it would be a small price to pay for the rich rewards shown late in low res...now that's a plume

well the first 16 words were realistic

[Matthew.]

11 minutes ago, Frosty. said:

The 12z models are firming up on a more unsettled cooler interval from the atlantic next week but if it was then followed by this from the Gfs 12z..it would be a small price to pay for the rich rewards shown late in low res...now that's a plume

30c easy there Frosty