Model Output Discussion 18z 28/07/13

[Frosty.]

The GEFS 00z mean shows temperatures soaring in the next 5-7 days with very summery weather returning through the week ahead, initially across the south and then spreading north and west, the northwest corner of the uk has an unsettled blip midweek before high pressure takes control again, the large anticyclone slowly becomes centred to the east of the uk which enables very warm and sultry air to drift north from the near continent but the anticyclone continues to slowly drift east and this allows a weakness to push northeast by next weekend, with all the very warm and muggy air across the uk and with the pressure leaking away, this is the perfect recipe for thunderstorms to break out by next weekend but with hot and hazy sunshine in between and some areas would miss the storms and stay hot and hazy but the mean shows a depressed pattern next weekend with a storm risk, thereafter, the pattern remains very slack and we would continue in a warm and muggy feeling sunshine and heavy thundery showers type pattern but with temperatures back down into the low to mid 20's c rather than the high 20's to low 30's celsius which look likely during the second half of the week ahead, I think mid 80's or even high 80's to low 90's F is possible, at least for the south/se later in the week but for many other areas, high 70's to low 80's F is likely, making it a very warm or hot spell for many.

Edited August 18, 2013 by Frosty039

[bluearmy]

Which bit ba?

the bit where you stated 'low pressure looks set to return' for bh weekend.

[draztik]

The eps ecm control model from t240 to 360, shows very cool air over the UK by the end of its run, with 5 uppers over the SE and near 0 over Scotland, NI and Northern England. As for the "hot" spell by midweek, it appears to be rather brief, before cooler and unsettled weather move in.

[Captain Shortwave]

UKMO and ECM seem to agree on the low for the bank holiday weekend and personally would favour that over the GFS solution because of the set-up and the GFS has it's weaknesses in set-ups like the one here.

I'm really surprised by the differences in uppers between the GFS and ECM, the GFS would have temperatures reaching close to 30C whilst the ECM would be struggling to make the mid-twenties off charts which on the surface look pretty similar.

^ECM mean still has the jet north of the UK by day 10 so I am struggling to understand how one can conclude that the weather will be cool and unsettled after the coming week

Edited August 18, 2013 by Captain shortwave

[bluearmy]

 

^ECM mean still has the jet north of the UK by day 10 so I am struggling to understand how one can conclude that the weather will be cool and unsettled after the coming week

 

agreed although as we saw in frrst week aug, a projected plume of +15c uppers at D8 became a reality of fresher air @ +5c as the trough dug well into france.

[Frosty.]

 

^ECM mean still has the jet north of the UK by day 10 so I am struggling to understand how one can conclude that the weather will be cool and unsettled after the coming week

And so does the GEFS 00z mean, the PFJ remains well to the north of the uk, across iceland or even further north, looping across from canada across to greenland and then into northern scandinavia, so the uk would at the very least remain warm and probably better than that.

[Tamara]

And so does the GEFS 00z mean, the PFJ remains well to the north of the uk, across iceland or even further north, looping across from canada across to greenland and then into northern scandinavia, so the uk would at the very least remain warm and probably better than that.

Yes agreed. There is a lot of uncertainty over this shallow low for the weekend - with pressure remaining high in a sandwich just to the north and west of it the chances are reasonable it will be squeezed out as pressure re-builds from the west and the instability associated with it is pushed off east into central europe. That will likely re-set the pattern and keep the jet stream to the north of the UK. Probably relatively cooler and fresher after the very warm weather late this week - but still very pleasant

 

[shedhead]

the bit where you stated 'low pressure looks set to return' for bh weekend.

Well all three show the presence of LP to one degree or another come the weekend ba, so suggesting it looks set to returns seems fair enough to me right now.  Clearly the precise evolution is uncertain at this stage, as is where we go thereafter, which is why I suggested waiting a few days before drawing to many conclusions about the following week.

 

 

GFS

 

ECM

 

 

UKMO

Edited August 18, 2013 by shedhead

[bluearmy]

thats yesterday's 00z naefs tamara

 

just to show where we've come between saturday mornings ens and today, comparing naefs for same timepoint:

 

heights, uppers and height spread

 

                                               

 

                                               

 

 

not difficult to see why some are rather less enthused than yesterday. ecm in broad agreement and was always less keen on an uninterrupted return of summer via its spreads. 

 

the overall point is that ens means have changed a fair bit in 24 hours so to assume this is what they will look like come tuesday would be a big step. that also applies to the ops this morning which all show a trough encroaching into the uk to some degree (as per shed's post).

Edited August 18, 2013 by bluearmy

[DR(S)NO]

The eps ecm control model from t240 to 360, shows very cool air over the UK by the end of its run, with 5 uppers over the SE and near 0 over Scotland, NI and Northern England. As for the "hot" spell by midweek, it appears to be rather brief, before cooler and unsettled weather move in.

Really? Unless im reading the wrong charts the "hot" spell appears far from brief....i can see temps ranging from 24c to 28c quite widely across England from Tuesday thru Sunday.That doesnt appear too brief to me.

[Methuselah]

Well all three show the presence of LP to one degree or another come the weekend ba, so suggesting it looks set to returns seems fair enough to me right now.  Clearly the precise evolution is uncertain at this stage, as is where we go thereafter, which is why I suggested waiting a few days before drawing to many conclusions about the following week.

 

 

GFS

 

ECM

 

 

UKMO

So they're all agreed on fairly warm and, to varying degrees, not completely dry weather then?

[shedhead]

Really? Unless im reading the wrong charts the "hot" spell appears far from brief....i can see temps ranging from 24c to 28c quite widely across England from Tuesday thru Sunday.That doesnt appear too brief to me.

As always it's worth noting DR(S)NO that not everyone lives in England. How long do you see the hot spell being across Scotland and N Ireland?

Edited August 18, 2013 by shedhead

[J10]

There have been a few times this summer that low pressure has attempted to nudge in from the South West in such scenarios and they haven't materialised to spoil the fun, I think the first occasion that this was forecast was Early June but the High reestablished itself and the first 10 days were glorious.

 

http://meteociel.com/modeles/archives/archives.php?day=5&month=6&year=2013&hour=0&map=0&mode=0

http://meteociel.com/modeles/archives/archives.php?day=7&month=6&year=2013&hour=0&map=0&mode=0

http://meteociel.com/modeles/archives/archives.php?day=9&month=6&year=2013&hour=0&map=0&mode=0

 

When a breakdown similar to that of today's GFS was originally suggested.

 

The start of August which did give buckets of rain was more of a plume rather any HP over the UK.

 

In any case, A much better end to august is on the cards than is normally the case.

 

I made this post yesterday, slighlty ameneded to clean out old references.

 

And my point about low pressure from the south not making that much inroads at other times this summer holds true. 

 

Last post of the monring from me, off out to enjoy today's decent weather.

Edited August 18, 2013 by J10

[summer blizzard]

Well all three show the presence of LP to one degree or another come the weekend ba, so suggesting it looks set to returns seems fair enough to me right now.  Clearly the precise evolution is uncertain at this stage, as is where we go thereafter, which is why I suggested waiting a few days before drawing to many conclusions about the following week.

 

 

GFS

 

ECM

 

 

UKMO

Personally i think they all look crap. Showery and humid.

[shedhead]

So they're all agreed on fairly warm and, to varying degrees, not completely dry weather then?

That is one way to look at things, but that could also be said of the past week. One thing is certain though, IF ECM and UKMO verify we're looking at nothing particularly special and if GFS verifies we're looking at something pretty unsettled, especially across the north and west.

[Frosty.]

Personally i think they all look crap. Showery and humid.

Personally I think they all look fantastic, it's the ultimate summer weather during the next 7-10 days..BRING IT ON I SAY 

[Captain Shortwave]

To be honest the coming week looks good, the bank holiday weekend will need a lot more runs as a low like the one projected is going to be a pain to get right. Thursday and Friday look warm-hot across the uk 

Edited August 18, 2013 by Captain shortwave

[lorenzo]

So a warm up of sorts is pretty much decided on, the longevity seems to be the key issue awaiting resolve.

 

The ensembles are an interesting look this morning, some healthy variance around the UK in 850 temps. GFS operational on the warm side initially.  First chart is the 850s, had a chuckle when I saw the 15% chance of snow for August 31st ! Although it looks like there is something altogether wrong with the chart at this time frame.

 

Next up the pressure ensembles, which resemble an attempt by someone who has had too much coffee getting set loose on an etch a sketch. 

 

Is GFS 06z continuing with a warm outlier on it's operational run here. Definitely a divide across the UK evident here with upper temps.

 

06z has a fearsome reputation for being total cannon fodder however here at day 5 it is holding up well against the other 3 runs of this model, have they been tweaking GFS over summer due to the stunning fall off in reliability earlier in the year.

 

Latest 72 hr Jet pattern from UKMO interesting that that energy currently over America is dissipated. GWO phase 2 forecast, composite here.

 

 

Looks like either a nice warm up and/or some great storm potential, good chart watching either way. 

 

 

 

 

[East_England_Stormchaser91]

Some of these scenarios look very familiar to that of the end of August 05. 30-31c and then going out with the best thunderstorm I have ever seen in the UK on the night of the 31st. Of course, who said it can't happen again

[shedhead]

Actually if the ECM and UKMO verified the north would probably have a fantastic bank holiday weather-wise, Away from eastern coasts where there might be some low cloud.

Agreed CS, the north could ultimately do very well out of this IF things develop as ECM and UKMO suggest.  However, hot it won't be and we look at GFS the BH weekend there looks very ordinary...not that it is a BH in Scotland of course.

Edited August 18, 2013 by shedhead

[Tamara]

thats yesterday's 00z naefs tamara

 

just to show where we've come between saturday mornings ens and today, comparing naefs for same timepoint:

 

heights, uppers and height spread

 

naefs-1-0-192.png                       naefs-1-1-192.png                          naefs-6-0-192.a.png

 

naefs-1-0-180.png                       naefs-1-1-180.png                          naefs-6-0-180.png

 

 

not difficult to see why some are rather less enthused than yesterday. ecm in broad agreement and was always less keen on an uninterrupted return of summer via its spreads. 

 

the overall point is that ens means have changed a fair bit in 24 hours so to assume this is what they will look like come tuesday would be a big step. that also applies to the ops this morning which all show a trough encroaching into the uk to some degree (as per shed's post).

Yes, that was my mistake  I saw the suite pre t180 had updated and believed that the 10 day chart had too.

 

To be honest though, and reading between the lines now, and as I was yesterday, it doesn't change my thinking at all, and the updated NAEFS data merely reflects the fact that conditions may become rather cooler and fresher from the Bank Holiday onwards - but still pleasant enough with a High pressure ridge looking reasonable to return just the same. Based on present information.

 

Edit: I cut and paste the updated NAEFS chart for day 10 and it reverts to yesterdays for some reason. Grrr!

 

Ah, there we are...

 

 

 

The move towards the trough this weekend has increased this morning, but then this was always a possibility yesterday - albeit the chances of it happening seemed less. Much as you posted might be possible yourself and which I agreed with. We can only make judgements based on the information that is present at that time

 

I still think there is plenty of time for more changes in respect of this weekend yet - hence why I said ealier on it would be wise not to try and put any detail on it.

Edited August 18, 2013 by Tamara Road

[draztik]

Really? Unless im reading the wrong charts the "hot" spell appears far from brief....i can see temps ranging from 24c to 28c quite widely across England from Tuesday thru Sunday.That doesnt appear too brief to me.

honestly, if you had seen some posts earlier in the week, you'd be forgiven for thinking a July heatwave was on the way! The shortwave which affects the northern UK appears to be the spoiler, which disrupts the hp's dominance. Also, even if we see those warm temps you suggest, we may also see a fair amount of cloud too. All in all, we will get a lot of useable weather, but no heatwave on the way Edited August 18, 2013 by draztik

[shedhead]

Well IF the 06 GFS verifies there could well be some EPIC weather around come the weekend if heavy, thundery rain/showers float you boat.

 

 

 

 

Edited August 18, 2013 by shedhead

[Polar Maritime]

honestly, if you had seen some posts earlier in the week, you'd be forgiven for thinking a July heatwave was on the way! The shortwave which affects the northern UK appears to be the spoiler, which disrupts the hp's dominance. Also, even if we see those warm temps you suggest, we may also see a fair amount of cloud too. All in all, we will get a lot of useable weather, but no heatwave on the way

 

That's because the charts last week have changed in detail a little. Which is very normal.

Edited August 18, 2013 by Polar Maritime

[mushymanrob]

honestly, if you had seen some posts earlier in the week, you'd be forgiven for thinking a July heatwave was on the way! The shortwave which affects the northern UK appears to be the spoiler, which disrupts the hp's dominance. Also, even if we see those warm temps you suggest, we may also see a fair amount of cloud too. All in all, we will get a lot of useable weather, but no heatwave on the way

erm, you were the only one mentioning heatwave, and that was used to dismiss the coming spell of warm/hot weather. in fairness though some runs DID suggest heatwave with the 15c upper over most of southern uk.