model discussion Model output discussion 11th July onwards

[Singularity]

The Atlantic low has shifted back west now, in fact GFS has adjusted by a considerable margin at just 5 days range.

This adds to the interest as the AAM cycle reaches the declining stage and the summer NAO tends toward negative. Sometimes, this takes a shape loosely akin to a ‘west-based’ negative winter NAO, if there’s an Atlantic low west of the UK.

Key difference to winter is that said low tends to break down into smaller, potentially cut-off lows. Whether they then stall to the west of Europe or not then determines whether the UK sees some very warm or hot (e.g. GFS 12z in south, yesterday’s ECM 12z more widely) or unseasonably cool (ECM 00z) weather.

[Frosty.]

Well this would be quite stunning wouldn’t it considering the gloom and doom in here of the last few days?!...ok, I realise we are not home and hosed but I did mention first thing this morning regarding this possible evolution that the rank outsider sometimes wins!!!

   

[Methuselah]

To use a term that's usually reserved for the winter months: the GFS12Z is screaming 'POTENTIAL' at Day 10!

    

[Mike Poole]

ECM T144 a little further east with the low than the UKMO at same time:

But those who are calling a NW/SE split here are looking on the money.  Which is an improvement on the model output a couple of days ago.  It looks like the kind of run that we saw on ECM 12z yesterday and GFS 18z with the low held out west more is gaining in traction today.

[Frosty.]

This is variations on the same theme from the ECM 0z / 12z operational today, so much heat indicated further south across mainland Europe, it wouldn’t be too much of a surprise to me if southern / southeast England gets at least a little taste of it too..and the mighty Gfs is now on board..until the 18z at least!  

 

[stodge]

Evening all

With everyone of my acquaintance convinced we're having a heatwave in the second part of the month, I thought it was time I luxuriated in these wonderful heat-ridden charts with endless days of HP and 20c 850s and daytime maxima in the 30s.

Apparently.

Let's see where the T+240 850s take us tonight - GFS OP. GFS Control, GEM, JMA and ECM respectively

GFS OP the most bullish for heat and that's far from discouraging at present with a brief push of +16 850s across the south and south east but other models keep the heat well to the south and south east suggesting (for now) the Atlantic LP will be too close to advect any hot air from Iberia.

Back to the 500s and the T+360 charts from GFS OP and Control and the 06Z monthly CFS run:

There's a couple of things to note for this observer - first is the continued signal for heights to sit to the north or north east - we've been here for much of the summer and the pattern which has helped the north and west of Britain seems set to continue. I also note the hint of tropical energy on GFS OP - this isn't the first run to feature a "fish" storm which recurves far to the east of land and thus carries a lot of energy back into the lower mid Atlantic. I think this is what we will need to kick the pattern a little and bring HP forward into the British Isles and NW Europe. It's not an unusual late summer/early autumn pattern.

[Mike Poole]

Spread is telling on the ECM ensembles at T240:

On average the trough is to our west, and the deep blues showing lower uncertainty and more likely settled conditions demark the NW and SE split as suggested earlier.  

Edited August 7, 2021 by Mike Poole

[Methuselah]

Seeing as there's only limited support (for the operational run) among the GEFS 12Z ensembles, I'll be reining in my expectations until about Tuesday:

    

[Mike Poole]

ECM clusters T192-T240:

This looks to me to be on a bit of a knife edge here.  Clusters 1 and 2 have the trough to our west, but there’s not much in terms of heights over the UK, just enough.  They account for 64% of the probability, so clearly that figures in the spread plot I posted earlier.  Cluster 3 is the one we don’t want…this was more prevalent on previous runs (I think) so hopefully on the decline.  

Cluster 4 is the scenario that @summer blizzard mentioned earlier with the northerly, but just 14% chance of that.

Having viewed the models over the last few days, I think the old saying ‘the trend is your friend’ hits home - the outlook for the second half of August is improving, but just not very fast right at the moment.  

Edited August 7, 2021 by Mike Poole

[fellmike]

7 hours ago, jon snow said:

Well this would be quite stunning wouldn’t it considering the gloom and doom in here of the last few days?!...ok, I realise we are not home and hosed but I did mention first thing this morning regarding this possible evolution that the rank outsider sometimes wins!!!

   

Your posts  are always interesting and humorous and very clear to understand 

 

[Man With Beard]

Best ECM of the summer this morning, some hot weather if this comes off:

[mb018538]

On 08/08/2021 at 07:55, Man Without Beard said:

Best ECM of the summer this morning, some hot weather if this comes off:

Interesting that all 3 show the low stalling and cutting off this morning - settled weather via the back door if you like. As you say MWB, it would be another dose of summer if this happens, as it scoops a load of warm air our way. Can’t even say the ECM is an outlier as the GFS and GEM both show the same. One to watch!

Edited August 8, 2021 by mb018538

[East_England_Stormchaser91]

ECM is a cracker for most this morning. If we can sustain that cut off low out to the West, we could well tap into some hot temperatures come next weekend. Iberia, S France and NW Africa look to be going into the oven during this coming week. 

[Scorcher]

48 minutes ago, mb018538 said:

Interesting that all 3 show the low stalling and cutting off this morning - settled weather via the back door if you like. As you say MWB, it would be another dose of summer if this happens, as it scoops a load of warm air our way. Can’t even say the ECM is an outlier as the GFS and GEM both show the same. One to watch!

Yes this is what I was saying only a couple of days back- you and a few others were getting very negative about the output. You'd think summer was over if you stumbled across this thread with no knowledge of the models a day or two back. At this time of year you don't necessarily need an outstanding overall pattern to produce warm/hot days. Very slight alterations can lead to big differences in temperature.

[mb018538]

On 08/08/2021 at 08:51, Scorcher said:

Yes this is what I was saying only a couple of days back- you and a few others were getting very negative about the output. You'd think summer was over if you stumbled across this thread with no knowledge of the models a day or two back. At this time of year you don't necessarily need an outstanding overall pattern to produce warm/hot days. Very slight alterations can lead to big differences in temperature.

Yeah for sure - I was more making the point that global patterns don’t really favour a settled NW Europe regime. They still don’t, but it doesn’t exclude stuff like this happening. Last august was the same….very unsettled on the whole and we managed to wangle that crazy hot spell out of nowhere.

Im always happy to be proved wrong. If we get a nice stalled low and a run of warm days as a result, I’ll be ecstatic!  

[Man With Beard]

Looking at the individual ECM ensembles at D8 brought me back down to earth a little. The stalling trough to the west is probably a little more likely than other scenarios, but only just. Could still end up with a north westerly after D7, or another UK low. But the trends are good.

[mushymanrob]

Heres the current 8-14 day NOAA 500mb mean chart... i think most of us would hope its inaccurate, but i wouldnt bet any money on that. Its looking cool but not overly unsettled after next weekend, thus dashing the hopes of those of us hoping for a lengthier spell of summery weather (as in sunshine and warmth).



 

[Scorcher]

47 minutes ago, mb018538 said:

Yeah for sure - I was more making the point that global patterns don’t really favour a settled NW Europe regime. They still don’t, but it doesn’t exclude stuff like this happening. Last august was the same….very unsettled on the whole and we managed to wangle that crazy hot spell out of nowhere.

Im always happy to be proved wrong. If we get a nice stalled low and a run of warm days as a result, I’ll be ecstatic!  

Yes I was going to mention last August. There is also a lot of quite extreme heat building in the south of Europe next week- could be very interesting if we get lucky with the setup over the next 10 days or so.

[northwestsnow]

Next week suddenly looking dry ,warm and settled for many...

[mb018538]

We’d better not get too giddy - ecm 00z is an outlier for 500 heights, pressure and 850s this morning. All way above the ensemble mean. GFS also above the mean. Very finely poised.

 

[summer blizzard]

The balance does seem to have shifted from yesterday morning towards the GEM/Euro plume attempt. GFS is the holdout at day 10.

[mb018538]

Think the 6z run didn’t get the memo…goes the other way instead with cooler air winning out. To be fair it looks more like the noaa anomalies…

[Iceaxecrampon]

3 hours ago, northwestsnow said:

Next week suddenly looking dry ,warm and settled for many...

I'm sailing on Windermere 15th August.

What are the chances? - a light breeze would be beneficial.

GFS Please be nice.

GFS Please be nice.

GFS Please be nice.

GFS Please be nice.

GFS Please be nice.

 

[mushymanrob]

2 hours ago, mb018538 said:

Think the 6z run didn’t get the memo…goes the other way instead with cooler air winning out. To be fair it looks more like the noaa anomalies…

Yep, it does.. 

[kold weather]

7 hours ago, mushymanrob said:

 

Whats interesting is even the 00z ECM which had a decent 00z run actually wasn't very far removed from that pattern shown above. It would only take a weak main core to be located to the west (and perhaps a little more north) and the other low area to be a little weaker for that to turn into something very useable and something similar to the ECM/GEM pattern.

The one downside is its a pattern that is highly unlikely to sustain, we'd still have to deal with breakdowns and probable LP attacks from the SW (which could be thundery possibly).

I'd hate to call it at the moment, its a classic pattern that could go hot if all the pieces line up, but also has a fair chance of being utterly horrid if we get real unlucky. My guess is HP will build in somewhat but eventually it will lift NE, weakening, and we'll end up into a LP train again for a few days, followed by a rinse and repeat job.