Model Output Discussions 12z 03/05/2016

[Frosty.]

I know I get called a hopecaster but I think there is hope, the Gem 12z turns into a cracker and the GEFS mean has improved for the third time today, the 12z mean shows a decent spell of warm Azores high / ridge settled weather across at least England and Wales and perhaps up into northern uk as well, they are good charts. The transformation between the Gem 00z cool and unsettled to very warm and settled on the 12z is staggering!

[Man With Beard]

It's been a dramatic, tense, action-packed day on the models.

It started with that quite promising ECM 00Z at T240, with an extra trough in the Atlantic holding back the forces of Greenland and allow the advance of the Euro heat army:

before the ECM threw in perhaps the scariest T240 chart of the summer this evening - potentially as cold as could be three days after this as the low swings down from Iceland:

The GFS, on the other hand, has been showing very good though not exceptionally hot weather after T200, and perhaps that proper anti-cyclone at last coming in. The GEM joins in:

  

In the closer time-frame, it's touch and go for next weekend between trough and ridge domination. In contrast to yesterday, it is actually the deeper areas of low pressure leading to better high pressure scenarios for the 6th/7th

  

Verdict? Come back tomorrow and look again

 

[Frosty.]

The Ecm 12z looks changeable / unsettled with sunshine and showers, some thundery and during the first half of the week ahead, spells of persistent rain spreading from the w/sw  but later in the week indicates a weak ridge pushing into the south bringing at least a short spell of fine and warm, sunny weather further south. As for temperatures, there isn't anything I would call cool until day 10, most days have temps close to where we would expect them in early August and at least a few potentially very warm and probably humid days across the south of the uk when temps could reach 80F+ depending on sunshine amounts but possible thunderstorm risk too in the south of the uk by the end of next weekend before it turns fresher by T+240...a mixed bag.

[knocker]

The ecm has a frontal system arriving late Monday into Tuesday associated with the depression 500 miles to the west of N.Ireland. This brings rain to the south for a change but quickly nips through followed by the main depression moving east to be over N/ Ireland by 12z Wednesday bringing some wet weather into Scotland with the rest of the UK in a showery westerly. The depression then moves east some more to be over central Sweden by Saturday and in the process leaves the UK in a light showery NW but to be quickly followed by more systems running in from the west at the beginning of the following week. A bit of a dogs dinner at the end. So all in all very changeable with temps varying around the average.

Edited July 30, 2016 by knocker

[phil nw.]

Yep much the same from the models this evening with the changeable and sometimes rather cool theme continuing.

The pressure anomalies still with the cool westerly theme.This rather disappointing pattern still allows transient ridging from the Azores high though so some decent weather at times especially further south,although real heat is held at much lower latitudes over S.Europe.  

[Frosty.]

3 minutes ago, phil nw. said:

although real heat is held at much lower latitudes over S.Europe.  

And yet the Gem and Ecm 12z show potential for hot days across southern UK later next week, especially the Gem which becomes anticyclonic.

[knocker]

1 minute ago, Karl. said:

And yet the Gem and Ecm 12z show potential for hot days across southern UK later next week, especially the Gem which becomes anticyclonic.

Wouldn't have said the ecm does

[Frosty.]

Just now, knocker said:

Wouldn't have said the ecm does

Perhaps very warm then...mid to upper 20s c in the s / se

[phil nw.]

Just looking at the GFS ens graphs for Warks- as already discussed no great heat with temperatures around or just a shade below average at times. In spite of the rather poor looking pattern however rainfall amounts look quite small over the next 2 weeks.

Not a terrible outlook with i am sure reasonable weather about but probably days of wall to wall sunshine would be few with a lot of cloud drifting across the UK off the Atlantic westerlies. 

 

 

[Frosty.]

6 minutes ago, knocker said:

Wouldn't have said the ecm does

Perhaps very warm then...mid to upper 20s c in the s / se

I'm cheering for the Gem 12z...long shot or not!

[knocker]

19 minutes ago, phil nw. said:

Yep much the same from the models this evening with the changeable and sometimes rather cool theme continuing.

The pressure anomalies still with the cool westerly theme.This rather disappointing pattern still allows transient ridging from the Azores high though so some decent weather at times especially further south,although real heat is held at much lower latitudes over S.Europe.  

Yes Phil this pressure rise in the west/central Atlantic isn't doing us any favours.although it might late in the period if it moves far enough east.

[phil nw.]

4 minutes ago, knocker said:

Yes Phil this pressure rise in the west/central Atlantic isn't doing us any favours.although it might late in the period if it moves far enough east.

Yes just scanning the GFS/GEM ens and they do indicate some encroachment by the AH for a while around day10 but then shifts back west again.The ECM op this evening doesn't want to know and looks pretty unsettled at T240 quite frankly.Let's see what the ECM ens say.

 

[Man With Beard]

Just now, phil nw. said:

Yes just scanning the GFS/GEM ens and they do indicate some encroachment by the AH for a while around day10 but then shifts back west again.The ECM op this evening doesn't want to know and looks pretty unsettled at T240 quite frankly.Let's see what the ECM ens say.

 

A very simplistic view but I'd have to back the GFS over the ECM when it comes to mid-Atlantic heights, if the trends shown continue on each model - ECM too prone to overdo them in my subjective opinion.

Of course the situation is complicated by a "will it won't it" on whether another low will get through the Atlantic train between T168-T216, which changes the game either way.

[Frosty.]

Tonight's Ecm 12z ens mean is lacking in detail but what there is doesn't indicate anything settled, trough influence rather than ridge which is more in line with the Ecm 12z operational run. I said I was backing the Gem 12z but logic says back the more unsettled scenario which has been the form horse all summer so far!

 

[knocker]

1 hour ago, Man With Beard said:

A very simplistic view but I'd have to back the GFS over the ECM when it comes to mid-Atlantic heights, if the trends shown continue on each model - ECM too prone to overdo them in my subjective opinion.

Of course the situation is complicated by a "will it won't it" on whether another low will get through the Atlantic train between T168-T216, which changes the game either way.

I'm afraid I don't understand that. Why should a surface feature at that range on one model change the game when the upper air is the main driver?

Edited July 30, 2016 by knocker

[knocker]

The ecm anomaly continues the theme, also peddled by NOAA and to a lesser extent the GEFS and previous EPS runs of height rises in mid Atlantic which realigns the trough to a neutral position over the UK thus veering the upper flow and generally temps a little below average. In the ext period this continues with everything moving east so towards the end of the period the UK may well come under the influence of the Azores HP

[Frosty.]

1 minute ago, knocker said:

The ecm anomaly continues the theme, also peddled by NOAA and to a lesser extent the GEFS and previous EPS runs of height rises in mid Atlantic which realigns the trough to a neutral position over the UK thus veering the upper flow and generally temps a little below average. In the ext period this continues with everything moving east so towards the end of the period the UK may well come under the influence of the Azores HP

One thing I've noticed about the ext period is the mention of large swings in temperature which at least indicates some very warm or even hot potential as well as cool and average so something for everyone in the next four weeks I would think.

[Man With Beard]

21 minutes ago, knocker said:

I'm afraid I don't understand that. Why should a surface feature at that range on one model change the game when the upper air is the main driver?

The difference between the ECM 00Z and 12Z at T240 illustrate my point. 

[mb018538]

Basically it looks crud again, with no real positive signs to latch onto as of yet. Nice warm sectors come and go with each run, but the overriding pattern is an unfavourable one.

[Nouska]

25 minutes ago, Man With Beard said:

The difference between the ECM 00Z and 12Z at T240 illustrate my point. 

The 00Z mean was not good either, closer to the 12Z run - waiting for the afternoon run to update. Looking at the EC32, second week of August has a positive temp anomaly but I'm taken by the huge precip anomaly (week three) for the western Med area. Is that suggestive of a jet stream well south?

  

Edit to add the 12Z mean at +288 hours - not as bad as the 240 hour chart indicates and flattens out completely by the end of the run.

 

Edited July 30, 2016 by Nouska

[Frosty.]

The difference between the GEFS / ECM 12z mean is staggering, the Gefs indicates a robust Azores ridge for several days whereas the Ecm is trough dominated..the plot thickens!

[knocker]

46 minutes ago, Man With Beard said:

The difference between the ECM 00Z and 12Z at T240 illustrate my point. 

I fail to see how but in fact you didn't answer my perfectly reasonable question. You appear to be arguing that changes of interpretation by two deterministic runs, within the long wave pattern. can indicate a possible game changer. I just don't see why this should be the case for the reason I've already stated. I should add that it's around this time period that the upper air is changing from a positively tilted trough mid Atlantic to the aforementioned height rises. The det, runs may well struggle.

Edited July 30, 2016 by knocker

[knocker]

10 minutes ago, Karl. said:

The difference between the GEFS / ECM 12z mean is staggering, the Gefs indicates a robust Azores ridge for several days whereas the Ecm is trough dominated..the plot thickens!

They are not that different

[knocker]

For the second week in August the EC32 means says very much what tonight's EPS says.

[knocker]

Today a mainly fine day in England and Wales with showers in Northern Ireland and Scotland. Rain spreading into England and Wales overnight and into tomorrow.

The GFS this morning.

Rain from the frontal systems tomorrow and Tuesday clears away to southern Scandinavia by Wednesday with the main low moving east into Scotland bringing rain, and probably windy, to the area whilst England and Wales are in an unstable westerly. The low fills and wanders NE leaving the UK in a slack, showery, area of low pressure at the end of the week before a new low tracks NE into Scotland on Sunday bringing more rain there whilst again England and Wales are in an unstable westerly. This moves away NE and the Azores HP ridges in at the beginning of next week. All in all a pretty changeable outlook for ten days with once again Scotland and the north copping the worst of the weather and the south benefiting from the longer sunny intervals. Temps varying around the average.