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Model output discussion - August hot spell - how hot, how long?


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3 hours ago, johnholmes said:

If it was mid winter this forum would be pretty lively.

The relevant contour all the way back into the Arctic Circle. So for now not all that hot I would imagine and with a large and barely moving trough over the UK not especially sunny and dry!

 

I understood your point the other day about successful interpretation of these charts requiring a good dose of experience, as well as your point about it being a moving average and needing to be understood in that context.

With that in mind, do today's charts not show a striking shift from yesterday's? Seems quite a dramatic shift North and East by that low pressure.

Separately, I wonder if you can shed any light on how these NOAA anomaly charts are actually produced? Is there another suite of model runs which is aggregated and summarised this way? Or is the underlying data/method completely different?

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6 hours ago, wellington boot said:

I understood your point the other day about successful interpretation of these charts requiring a good dose of experience, as well as your point about it being a moving average and needing to be understood in that context.

With that in mind, do today's charts not show a striking shift from yesterday's? Seems quite a dramatic shift North and East by that low pressure.

Separately, I wonder if you can shed any light on how these NOAA anomaly charts are actually produced? Is there another suite of model runs which is aggregated and summarised this way? Or is the underlying data/method completely different?

Low Pressure returns image.thumb.png.5c95610841a24fd2d1ecba00f062ae69.png and jet stream fires up at + 8 day range image.thumb.png.c91e2aefa700d1675e74d3ef460258fa.pngimage.thumb.png.3afea05935d9a55a3788e03e9e7f4fcf.png Uk left on cold side of the much more powerful jet that exits Canada and our old friend the Iceland low sweeps across the UK bringing temperatures down to just 13 in Northern England and North Wales. image.thumb.png.cd4dabe1c181b5faa178324a63a6c774.pngimage.thumb.png.d51006da69740e35e1004e14ac82473f.png Summeimage.thumb.png.ae15dbb8811fc0c3b9afca33d75f1412.pngr ends next Tuesday 18th August.  Week commencing 24th August looks distinctly cool and wet!     

image.pngimage.thumb.png.34d2fcc70f76741263a086b40bf754e2.pngimage.thumb.png.d1b7b2000680a604683018d74b569791.png

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Edited by NApplewhite
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Well - the last of the truly hot days today, with mid 30s again likely if the storms stay away in the SE.

Tomorrow could see 30c hit again across East Anglia/SE corner in between any storms and longer rainy periods. Friday and into the weekend we slowly drift towards a much more unsettled period of low pressure domination, with temperatures coming back down to normal along with spells of rain. Much more akin to what we've had for most of summer 2020, and probably quite likely to see us out until the end of the month.

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Looking 👀 at GEFS 0z mean the last third of August could be bordering on or indeed autumnal?...of course we should remember that it’s not all about what the GEFS shows, it’s merely a cog in the wheel.😜

6317B1B4-0F4F-45E2-B85A-21B7C5F89674.thumb.png.cdcf32a40ec1aa388c6c3a43ae90baf7.pngECA9B764-C6C9-47B1-B583-685B0614F659.thumb.png.a5a403b0f2856f157bc048ae2bc3ef68.pngCB611C4D-6455-475C-B477-54A618A50F61.thumb.png.a8eae54a81fa488219eab12aa6144257.png400D2848-8940-4D05-BBC8-AB538E210A2E.thumb.png.e3123e4c71fdc283a4712f79fe5b19c1.png5311E7B7-AA13-496C-9983-FBF6DA908C54.thumb.png.9a57f35b391faf4a626ffa76ff5bddd1.pngAEE8BB6E-C734-4468-BE8C-82498C7CA8FF.thumb.png.29353aac70778a46443b4fdeaeda4171.png

 

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28 minutes ago, JON SNOW said:

Looking 👀 at GEFS 0z mean the last third of August could be bordering on or indeed autumnal?...of course we should remember that it’s not all about what the GEFS shows, it’s merely a cog in the wheel.😜

6317B1B4-0F4F-45E2-B85A-21B7C5F89674.thumb.png.cdcf32a40ec1aa388c6c3a43ae90baf7.pngECA9B764-C6C9-47B1-B583-685B0614F659.thumb.png.a5a403b0f2856f157bc048ae2bc3ef68.pngCB611C4D-6455-475C-B477-54A618A50F61.thumb.png.a8eae54a81fa488219eab12aa6144257.png400D2848-8940-4D05-BBC8-AB538E210A2E.thumb.png.e3123e4c71fdc283a4712f79fe5b19c1.png5311E7B7-AA13-496C-9983-FBF6DA908C54.thumb.png.9a57f35b391faf4a626ffa76ff5bddd1.pngAEE8BB6E-C734-4468-BE8C-82498C7CA8FF.thumb.png.29353aac70778a46443b4fdeaeda4171.png

 

Yes very much like we are going to suffer an early autumn. Im glad im off to Greece for a week on the 22nd to avoid this. Some major fluctuations in the GFS - last night they were showing high pressure in these time frames now low pressure!  Enjoy today as its the last day of the Tropical heat . 

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1 hour ago, mb018538 said:

Well - the last of the truly hot days today, with mid 30s again likely if the storms stay away in the SE.

Tomorrow could see 30c hit again across East Anglia/SE corner in between any storms and longer rainy periods. Friday and into the weekend we slowly drift towards a much more unsettled period of low pressure domination, with temperatures coming back down to normal along with spells of rain. Much more akin to what we've had for most of summer 2020, and probably quite likely to see us out until the end of the month.

well not sure everyone will agree but THANK GOD for that

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The ECM 0z op is something of a compromise / middle ground scenario, doesn’t rid us of summer, indeed it maintains some decent uppers (850’s) so it wouldn’t be to cool although it would still be a mixed outlook but you couldn’t rule out further very warm weather returning longer term.

09FBB28E-9FF4-4857-8A5C-1F4D0BB5F4BE.thumb.png.7dd1c156fb3101a4c703e1e34edaa676.pngA9136130-2039-4A7A-ADE6-BF657638953F.thumb.png.c0254e06bad9c70e280b092ca0e1899f.png6E4AB3EC-9B18-48B6-855D-A8D303E5897A.thumb.png.9110693e3ba0321e7131be25f08d1d69.png02C512D0-057C-4E9A-9549-16C417A4AF6B.thumb.png.7ca2ce584e21ddbb86c2a5b4aac5c32d.png

Edited by JON SNOW
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55 minutes ago, NApplewhite said:

Yes very much like we are going to suffer an early autumn. Im glad im off to Greece for a week on the 22nd to avoid this. Some major fluctuations in the GFS - last night they were showing high pressure in these time frames now low pressure!  Enjoy today as its the last day of the Tropical heat . 

I wouldn't be so sure about that, Napple... as there'll be a vast reservoir of very warm air, over southern Europe, well into meteorological autumn, IMO...? And I'll be very interested in seeing just how far south the 20C 850hPa isotherm retreats this winter... and, should it return before the end of January, next summer could be a rerun of the last three, in terms of heat spikes?🤔

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16 minutes ago, Daniel* said:

The last two runs from ECM have been extremely wet for southern areas. First the monstrous heat then the floods? 

7EA9347E-CD01-4492-9EC5-17F0884ACE71.thumb.jpeg.e0f247d6847b0bac064582850d0e43df.jpegBF673D44-11A6-4624-B34D-35157293A5AC.thumb.jpeg.e2e63cf011f2865ceaf8fbf1b9b0a1de.jpeg

bear in mind these are accumulated amounts up until those days not the days themselves

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Full update Wed 12 August

Ec-gfs and ec shows some changes to positions of ridges/+ve heights and troughs; gfs seems to have ‘dropped’ its ridge/+ve heights  off eastern seaboard, shape of trough different

NOAA and its Tuesday evening 6-10 is a mjor change from the day before, deep trough Iceland into uk, marked ridging/+ve height rises s Greenland, with atlantic flow beneath both these into Europe. It is unusual for Noaa to change so much in 24 hours so best wait for next 2 days to see what it does.

Overall with ec-gfs changes as well then little help for surface weather ideas from these 3 for 2-3 days at least!

Full update Wed 12 August

Ec-gfs and ec shows some changes to positions of ridges/+ve heights and troughs; gfs seems to have ‘dropped’ its ridge/+ve heights  off eastern seaboard, shape of trough different

NOAA and its Tuesday evening 6-10 is a mjor change from the day before, deep trough Iceland into uk, marked ridging/+ve height rises s Greenland, with atlantic flow beneath both these into Europe. It is unusual for Noaa to change so much in 24 hours so best wait for next 2 days to see what it does.

Overall with ec-gfs changes as well then little help for surface weather ideas from these 3 for 2-3 days at least!

http://mp1.met.psu.edu/~fxg1/ECMWF_0z/hgtcomp.html

 
 

 

Edited by johnholmes
also for double post just noticed!
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33 minutes ago, Daniel* said:

The last two runs from ECM have been extremely wet for southern areas. First the monstrous heat then the floods? 

7EA9347E-CD01-4492-9EC5-17F0884ACE71.thumb.jpeg.e0f247d6847b0bac064582850d0e43df.jpegBF673D44-11A6-4624-B34D-35157293A5AC.thumb.jpeg.e2e63cf011f2865ceaf8fbf1b9b0a1de.jpeg

A lot of that is predicted T/storm or shower activity though - very difficult to be accurate in this sort of set of. I suspect some areas will probably see 3-4 inches under that blob, but others nearby may see very little. such is the nature of the beast.

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2 hours ago, mb018538 said:

Much more akin to what we've had for most of summer 2020, and probably quite likely to see us out until the end of the month.

A more unsettled spell seems very likely, but interested to know how you can predict all the way to the end of the month?

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12 minutes ago, johnholmes said:

NOAA and its Tuesday evening 6-10 is a mjor change from the day before, deep trough Iceland into uk, marked ridging/+ve height rises s Greenland, with atlantic flow beneath both these into Europe. It is unusual for Noaa to change so much in 24 hours so best wait for next 2 days to see what it does.

Overall with ec-gfs changes as well then little help for surface weather ideas from these 3 for 2-3 days at least!

http://mp1.met.psu.edu/~fxg1/ECMWF_0z/hgtcomp.html

 
 

 

 

Yes this was my interpretation also. Unusually erratic output, although Tamara's posts from recent days predicted just such difficulties for the models (as well as potentially a less unsettled outcome than currently shown). Will be interesting to see how this resolves.

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Just now, Scorcher said:

A more unsettled spell seems very likely, but interested to know how you can predict all the way to the end of the month?

I can't - hence why I said 'probably quite likely'.

There is always a chance something more settled could arrive again (especially with hurricane activity expected to ramp up), but with all of the available data and shift in global patterns pointing back towards a very similar set-up that we had through June and July digging in, the form horse at the moment is mainly unsettled. 

image.thumb.png.d6f8f7cd8d362b69fbd96024329a28e8.pngimage.thumb.png.f59ecd56f40aa88b2ba2ea52786d47e1.pngimage.thumb.png.30ce24b02475c321986d59ac5c5a68ac.png

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11 hours ago, wellington boot said:

I understood your point the other day about successful interpretation of these charts requiring a good dose of experience, as well as your point about it being a moving average and needing to be understood in that context.

With that in mind, do today's charts not show a striking shift from yesterday's? Seems quite a dramatic shift North and East by that low pressure.

Separately, I wonder if you can shed any light on how these NOAA anomaly charts are actually produced? Is there another suite of model runs which is aggregated and summarised this way? Or is the underlying data/method completely different?

If i may put my tuppence worth in...

Yes they are prone to sudden changes, they re-align when the data changes, but John has always said "when they are consistent over a few runs" , and usually they are.
But i am a convert, im more then happy to produce a blog using these as the framework, i do find them to be extremely helpful in sorting out the reality from the more inaccurate whims of the ops..

for example... last week i was going on about the GFS and ECM not matching their predicted symoptic pattern closely to what id expect the then current NOAA charts were IMHO suggesting. The GFS in particular appeared to be playing down the heatwave potential that i read the noaa charts to suggest. The then GFS had the Azores high much closer and the  high to our east further East whilst the NOAA suggested it would be centred closer to Norway, with a shallow trough just west of northwestern Spain/Biscay.

The attatched charts show this mornings GFS (00z) for now... and the NOAA chart from a week ago, imho the GFS now pretty closely matches what i thought the NOAA chart was suggesting... for the first time! Yet again, when theres conflict between the GFS or ECM and the consistent NOAA, the NOAA end up being closer to the solution.

 

gfs right.png

610day.03 (2).gif

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Wow the 6z op has the stamp of autumnal written all over it during late August..they think it’s all over:shok:?..but wait, it’s only the 6z so maybe it isn’t?!😁😜

2C1CCC8D-4B89-413B-8C90-F474A8661502.thumb.png.824634f36882f06ff826a2cfe3e6ca38.png4DBB8740-DA31-4C5B-B60B-8CBCD722256F.thumb.png.e62d71e0ef39526abcacc6471846d218.png

Edited by JON SNOW
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19 minutes ago, JON SNOW said:

Wow the 6z op has the stamp of autumnal written all over it during late August..they think it’s all over:shok:?..but wait, it’s only the 6z so maybe it isn’t?!😁😜

2C1CCC8D-4B89-413B-8C90-F474A8661502.thumb.png.824634f36882f06ff826a2cfe3e6ca38.png4DBB8740-DA31-4C5B-B60B-8CBCD722256F.thumb.png.e62d71e0ef39526abcacc6471846d218.png

As mushy posts just above you JS, perhaps it is close to what may occur. I'll be more sure if the anomaly charts are showing similar to what mushy shows in 2-3 days time

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20 minutes ago, JON SNOW said:

Wow the 6z op has the stamp of autumnal written all over it during late August..they think it’s all over:shok:?..but wait, it’s only the 6z so maybe it isn’t?!😁😜

2C1CCC8D-4B89-413B-8C90-F474A8661502.thumb.png.824634f36882f06ff826a2cfe3e6ca38.png4DBB8740-DA31-4C5B-B60B-8CBCD722256F.thumb.png.e62d71e0ef39526abcacc6471846d218.png

Bring it on - give my sweaty underpants a break!

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Re this from wb

I understood your point the other day about successful interpretation of these charts requiring a good dose of experience, as well as your point about it being a moving average and needing to be understood in that context.

No reply needed and thank you

With that in mind, do today's charts not show a striking shift from yesterday's? Seems quite a dramatic shift North and East by that low pressure.

They do indeed which is why I urged caution in accepting it as being a definite change, let's see in 2-3 days. Mind you as infrequent as such large changes occur on the NOAA 6-10 it has an uncanny knack of being close to what actually happens, we will see this time how it copes.

Separately, I wonder if you can shed any light on how these NOAA anomaly charts are actually produced? Is there another suite of model runs which is aggregated and summarised this way? Or is the underlying data/method completely different?

 

I'm afraid I have no data to be able to honestly answer this. Not a cough out but try e mailing NOAA, they are usually quite good in responding I find. In terms perhaps of using them, then the overall outlook from a much wider perspective from Tamara is a good start point. Then the very helpful ones from MWB, on to the anomaly charts and from there to the synoptic outputs, as mushy suggests above, use a chart that fits what I've just mentioned if this exists.

Hope that is helpful.

John

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2 minutes ago, mb018538 said:

4B890776-7695-4307-87D7-B3680DA336D6.thumb.png.0f2c2ecf7912a3f7516ac259caa0e2e4.png243AF771-99DA-47B5-AA8C-49D82275D9FA.thumb.png.66729a159daf34fb085f09e620680bb7.png
 

00z vs 12z UKMO - keeping the low further away on the 12z. Not as unsettled.

It would take much tweaking to put us back in the furnace 

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