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Model output discussion - summer rolls on


Paul

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Posted
  • Location: NR Worthing SE Coast
  • Location: NR Worthing SE Coast
21 minutes ago, mb018538 said:

I'd be wary about writing the summer off just yet! It looks nailed on that once we get to Wednesday next week the hot weather will be moved away by low pressure for a time. However, it doesn't look desperately unsettled - and by no means a wash out. ECM ensembles & met office long ranger still going for something more settled as we head through August. To be honest, even if the rest of August didn't offer much, we've still had another week of temperatures in the high 20s/low 30s....which beats most of the terrible August months we've had in recent years regardless. What a summer!

Yes hot till Wednesday ,but even after that doesn’t look very wet or unsettled for a lot of the country,despite what  some posters would have you believe earlier this week with all this talk of low pressure and rain for next week for most.

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Posted
  • Location: Castle Black, the Wall, the North
  • Weather Preferences: Spanish Plumes, Blizzards, Severe Frosts :-)
  • Location: Castle Black, the Wall, the North

Certainly the ukmo 00z shows a marked change to cooler nationwide later next week and much sooner than that further n / nw.

UW144-7.gif

Edited by Frosty.
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Posted
  • Location: Cambridge, UK
  • Weather Preferences: Summer > Spring > Winter > Autumn :-)
  • Location: Cambridge, UK

240-777UK.GIF?03-0

NW of Scotland looking very wet over the next 10 days. Heavier ppn over the Cumbrian fells too. Turning drier the further south and east you head. Parts of the S/SE may see no rain again for the next 10 days. Typical of the set up really.

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Posted
  • Location: Castle Black, the Wall, the North
  • Weather Preferences: Spanish Plumes, Blizzards, Severe Frosts :-)
  • Location: Castle Black, the Wall, the North

All the models show a cool down next week, even the SE is down to the low 20's celsius after next midweek and a good deal cooler than that further NW. Most of the rain next week is further n / nw but week 2 is wetter everywhere according to the Gfs 00z operational..not saying it's going to play out like that but it's what the latest models are showing which is a spell of more average conditions, indeed below average across the far NW.

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Posted
  • Location: Drayton, Portsmouth
  • Location: Drayton, Portsmouth

The last two EC clusters actually saw the middle of August recovering. Generally, hot until 7th, then 8th-13th are unsettled north / changeable south, then 14th-18th are *probably* more settled again especially further south and east (and potentially hot once more), just a small risk of the trough from the previous week dragging its heels. I'll post more tonight :)

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Posted
  • Location: Castle Black, the Wall, the North
  • Weather Preferences: Spanish Plumes, Blizzards, Severe Frosts :-)
  • Location: Castle Black, the Wall, the North

Looking at the Ecm 00z ensemble mean, certainly a change to cooler more changeable westerly type atlantic pattern next week although early next week looks hot for the SE quarter of england..hints that the azores high could ridge in post T+240 hours.

EDM0-144.gif

EDM1-144.gif

EDM0-168.gif

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EDM0-192.gif

EDM0-240.gif

EDM1-240.gif

Edited by Frosty.
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Posted
  • Location: Bristol
  • Weather Preferences: High pressure, snow + alll extremes of weather
  • Location: Bristol

The GFS 06z is continuing the trend of toning down the depth of the trough next week.

The core of the low not making landfall in Scotland before moving away.

 

By 168hrs the Azores high is nosing in again, I think the breakdown has been toned down in the last 24hrs.

 

26F97EA8-53E8-4F1A-8DB3-287EA09BCEF5.jpeg

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Posted
  • Location: Yateley, NE Hampshire (Berks/Surrey borders)
  • Location: Yateley, NE Hampshire (Berks/Surrey borders)
5 minutes ago, Craig84 said:

The GFS 06z is continuing the trend of toning down the depth of the trough next week.

The core of the low not making landfall in Scotland before moving away.

 

By 168hrs the Azores high is nosing in again, I think the breakdown has been toned down in the last 24hrs.

 

26F97EA8-53E8-4F1A-8DB3-287EA09BCEF5.jpeg

Yes by T192 we have a UK high. Encouraging signs, but only one run and all that...

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Posted
  • Location: Castle Black, the Wall, the North
  • Weather Preferences: Spanish Plumes, Blizzards, Severe Frosts :-)
  • Location: Castle Black, the Wall, the North

Not a bad Gfs 6z operational, a few blips for sure but plenty of high pressure and warmth through the run, especially across england and wales..much better than the 00z as far as most of low res is concerned.

06_204_mslp500.png

06_252_mslp500.png

06_252_uk2mtmp.png

06_276_mslp500.png

06_276_uk2mtmp.png

06_372_mslp500.png

Edited by Frosty.
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Posted
  • Location: New Forest (Western)
  • Weather Preferences: Fascinated by extreme weather. Despise drizzle.
  • Location: New Forest (Western)

This morning we've seen GFS introduce for two runs in a row more ridging back across the UK next Friday than the preceding run had, while suppressing the Azores high a bit more too.

It was a very tentative adjustment by the 00z, but the 06z has acted more boldly. 

h850t850eu.png h850t850eu.png

By day 10 (right-hand chart), it's almost got the pattern back around to the first step of the August El Nino GWO cycle - it just needs to have that trough by Newfoundland a thousand or so miles further southeast. Sounds like a lot of adjustment to make, but at that range, it's really not.

A faster arrival of that trough and resultant further displacement of ridging through the UK is also feasible, as you have the Pacific-into-US acceleration contrasting with the Atlantic deceleration (reduced westerly momentum at the mid-high latitudes).

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Posted
  • Location: Eastbourne and Larnaca,Cyprus .
  • Location: Eastbourne and Larnaca,Cyprus .

I can’t see anything in terms of extreme heat for the UK from the current spell , low thirties possible but hard going to see mid reached. 

The plume over Iberia really needed a digging low to the west to help pull that right into the UK .

Currently the extreme heat looks like staying over the Channel skirting ne. 

Before the mid week change we do see a dip in the jet to the west with a downstream jump ne but the warmest 850s look like again staying over the Channel.

I’m sure it’s hot enough for those that like the heat and personally I’ll be glad to see something cooler next week.

Edited by nick sussex
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Posted
  • Location: Castle Black, the Wall, the North
  • Weather Preferences: Spanish Plumes, Blizzards, Severe Frosts :-)
  • Location: Castle Black, the Wall, the North

Overall, a decent GEFS 6z mean, sure there's a cooler more changeable blip for a time next week  but southern uk quickly recovers towards the end of next week onwards thanks to weak heights extending up from the azores with predominantly fine and pleasantly warm conditions returning, generally cooler and more changeable across northern uk. .a typical n / s split..and back to the reliable timeframe there's a hot weekend and early next week for the s / se to enjoy / endure depending on your point of view.

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Edited by Frosty.
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Posted
  • Location: Peterborough
  • Weather Preferences: Snow and frost in the winter. Hot and sunny, thunderstorms in the summer.
  • Location: Peterborough

Just had a quick glance at the morning runs, the ECM does seem slower to break the heat over Europe down with probably another very warm to hot day across central/southern England on Tuesday so still some interest in how the breakdown happens and how much warmth and thundery potential there still is during the first half of next week. Longer term, to me probably a north/south split is the general trend but obvious some warmer and cooler spikes are likely if we can get some more amplification.

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Posted
  • Location: Castle Black, the Wall, the North
  • Weather Preferences: Spanish Plumes, Blizzards, Severe Frosts :-)
  • Location: Castle Black, the Wall, the North

Looking at the ukmo 12z, the s / se stays hot into early next week with isolated thunderstorms breaking out but it's increasingly cool and changeable further n / w and eventually all areas freshen up with a westerly airflow but notice the azores high throwing a ridge towards the south by T+144 hours.

UW72-7.gif

UW96-7.gif

UW120-7.gif

UW120-21.gif

UW144-7.gif

UW144-21.gif

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Posted
  • Location: Drayton, Portsmouth
  • Location: Drayton, Portsmouth

Just to add to my earlier post - here's the last three sets of EC clusters for 16th August (so mid - August). Far more building ridges that impact the UK than those favoring a trough - the latest in particular. 

ec-ens_nat_z500scenarios_2018080200_336.

ec-ens_nat_z500scenarios_2018080212_324.

ec-ens_nat_z500scenarios_2018080300_312.

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Posted
  • Location: just south of Doncaster, Sth Yorks
  • Location: just south of Doncaster, Sth Yorks
1 hour ago, Tamara said:

Data/substance to validate the workings of the Global Synoptic Dynamical Model is readily updated and available each day. Here is a current example to show it working in real-time and how it becomes interpreted by NWP from upstream

To do so, its necessary to return to the frictional chart plot posted the other day and use a grab from weather satellite imagery in the Pacific to illustrate the development of -ve frictional as shown in the GSDM plot around 20N. The plot clearly also shows the last -ve frictional torque wind anomaly (in blue) that occurred around the similar location during the bigger trade wind burst in June.

I'm not sure that the satellite image will show when posted beyond a still image (?) but the full real-time moving image can be seen from the main link. Anyway, from the imagery the storm cloud is depicted heading north westward from the tropics in association with a current uptick in trade winds which are scrubbing out some of the westerly wind bursts in association with recent passage of MJO activity. Also visible is Hurricane Hector south of Hawaii.

2018-08-03.thumb.png.8c2855dfa917d504441b334410c03b91.pngu_anom_30.5S-5N.thumb.gif.d9f9dcc1e93547cd14cd596cecb7f211.gif1449259569_2018-08-03(5).thumb.png.bbb07358c9c68569e559d6ec98aa44b5.png

The poleward fluxing of the activity in the Western Pacific is driving the -ve frictional torque where it meets the westerly winds on the poleward side of the jetstream. The result of the fluxing of energy is to amplify the Pacific Jetstream and drive disturbances downstream across North America. Further downstream in the Atantic, the pattern manifestation is an Atlantic ridge.

The effect of the -ve tendency fluxing in the tropical Pacific is is for atmospheric angular momentum tendency to register it as a fall - due to greater net easterly winds being added to the atmospheric circulation than westerlies at the given time

2039614688_2018-08-03(2).thumb.png.9f74352b1508937e31cd6c915cbc68cf.png

 

Taking into account the lifespan or wavelength of the frictional torque, then extra tropical lag will entail the Atlantic ridge pattern and trough solution next week as greater energy is directed into the polar jet downstream from North America.. 

However, with the El Nino standing wave developing in the East Pacific and associated low frequency tropical signal defaulted there, total AAM (allowing for the fall in tendency) in the global circulation remains close to average with much less scope to fall back than June/July - ahead of future further rises

 

9208277_2018-08-03(4).thumb.png.bce0ed6d2be58f0ecd86afec7ff6fcba.png

 

it is a matter of time before the tropical signal re-emerges to scrub out the trade burst, de-amplify the Pacific and return to the pattern that continues to further establish the El Nino configuration across the Pacific 

DjpD-gTV4AIdDUk.thumb.jpg.e905ea8d3158317feeeb835c5d89e53d.jpg

 

 - and the return of the Atlantic trough and downstream ridge beyond the mid month period.

So the whole point of this analysis, and all other analysis before it is the breakdown of the tropical and extra tropical interaction within a changing ENSO regime that has bearing on evolving synoptic patterns through ocean/atmosphere coupling - and not the ENSO regime itself in isolation.

 

 

 

In very simplified terms Tamara, are you saying that using the GSDM you anticipate that the upper air pattern we have seen in the eastern Atlantic-UK-Europe much of the summer so far, is going to return sometime around the mid month period?

 

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Posted
  • Location: Lincolnshire - 15m asl
  • Weather Preferences: Frost and snow. A quiet autumn day is also good.
  • Location: Lincolnshire - 15m asl

Afternoon all - back from holiday (which was hot  ) to a UK that is still pretty warm (  ) but to a distant countdown to autumn (  )

On a more serious note....where are we with the shift to El Nino and timing of coupling to the atmosphere? Without back copying my very infrequent posts earlier in the summer my only real interest at the moment has been to ascertain the likelihood of a coupling before summer's end or whether we would need to wait until September. I had a lingering sense that the pacific temperature profile wasnt warm enough to force an atmospheric response yet, and that a slow moving MJO might be too slow to help add a westerly input in the tropical pacific. I mentioned the pattern might, therefore, flatten out through August.

One thing I'm going to have to do is find some new tools for the next winter season, because my links/bookmarks seem to be drying up and failing, and getting free access to GSDM plots is becoming difficult - but 2 images worth posting from the functioning links I do have:

2018080300_cfsv2_aam_fcst.png

Global relative AAM (GLAAM) would appear to be stabilising longer term at around +1 according to these CFS plots. Consistently any dip to 0 or below is being seen as temporary as we work through August.

 

twc_globe_mjo_vp200.png

Our current MJO is of reasonable amplitude, and by the end of August has worked its way into the pacific phase 7to add convective westerly anomalies into the mix. 

Conclusion? The pattern is going to flatten out a bit because we have lost the AAM spike that went from -2 and +2 in short order and forced the meridionality we are now seeing. However if AAM stabilises at +1, the MJO makes progress through sympathetic warm waters and the Nino profile continues to build, then I think we have our Nino coupling before we get to the start of the next school term. It may even be in place now. This would enhance the probability of warm weather returning given the current position of a rebuilding Azores/Bermuda High. However probably not as warm as we have seen because AAM will be purring along rather than spiking.

What does this mean for the autumn? That's the hobby based thinking I'm shortly about to get underway as this summer fades out...

Edited by Catacol
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Posted
  • Location: Wildwood, Stafford 104m asl
  • Weather Preferences: obviously snow!
  • Location: Wildwood, Stafford 104m asl

that low need watching WH? hate that setup, or just a one off bad run from GFS?

we'll see though if other models, or anymore GFS runs go with it, dread it hope it's wrong

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Posted
  • Location: Catchgate, Durham,705ft asl
  • Location: Catchgate, Durham,705ft asl
13 minutes ago, Weather-history said:

Not sure if GFS 12z loses the plot after 152hrs with that low in the North Sea but it gives a hell of a washout to East Anglia.

 

Over 5 inches of rain in just over a day!

 

174-777UK.thumb.GIF.9eaf6731d529db2c1bb852bf9a353189.GIF

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Posted
  • Location: Irlam
  • Location: Irlam
23 minutes ago, I remember Atlantic 252 said:

that low need watching WH? hate that setup, or just a one off bad run from GFS?

we'll see though if other models, or anymore GFS runs go with it, dread it hope it's wrong

Has happened before. Interesting to see Norwich's rainfall ensembles.  

NOAA_1_1996082800_1.pngNOAA_1_1996082906_1.png

Edited by Weather-history
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Posted
  • Location: chellaston, derby
  • Weather Preferences: The Actual Weather ..... not fantasy.
  • Location: chellaston, derby
45 minutes ago, johnholmes said:

In very simplified terms Tamara, are you saying that using the GSDM you anticipate that the upper air pattern we have seen in the eastern Atlantic-UK-Europe much of the summer so far, is going to return sometime around the mid month period?

 

Gfs 12z seems to be suggesting that in f.i.

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