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Model output discussion - summer rolls on

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The ECM actually brings 15c 850’s into the S&SW on Wednesday, so in any sunshine in the south midweek it will get pretty warm.

 

1E82FEA9-A0E9-45CA-BDC6-CBD54DD2CA27.png

Edited by danm
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35 minutes ago, Alderc said:

Well on a fully Autumnal day where it started at just 7c and is currently raining heavily - remember even on Monday or Tuesday this week, the forecast was pretty much dry all week with just a front or two passing through at the weekend, well its rained almost every day now and Summer is 100% on hold. Scattergum ensembles are a tell tail sign the unsettled conditions will likely dominate. I would fully expect a mobile pattern to dominate for a least 10days, possibly until the end of the month and summer 2018 will likely exit with a whimper. 

Sunny days mixed with showery ones, T around the very pleasant 20C every day and even a touch warmer is showing on the models, leaves are on the trees, it is very much Summery in North Wales and further S and E. My glass more than half full. Enjoy Summer. 😊

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Anyway, cluster time. Yet again a whole heap of options on offer = uncertainty.

Day 7 very much trough dominated, with slight variations.

ec-ens_nat_z500scenarios_2018081000_168.

By day 10 we start to see things changing. Above average heights, though still westerly based. Improving weather for sure.

ec-ens_nat_z500scenarios_2018081000_240.

By day 15 it looks quite interesting:

ec-ens_nat_z500scenarios_2018081000_360.

The first 'proper' build of heights for a little while shown in cluster 4...odds still against though. NW/SE split looks like prevailing for a while yet.

Edited by Paul
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The models really don't have much of a light to guide them for next week. I can understand why they're so hesitant to kick off the MJO in the Pacific rather than west of there; the SSTs anomalies in the C and E Pac are mostly within a few tenths *C of zero, meaning a lot of the expectation is down to the tropical-extratropical interactions taking place, which the models have a harder time handling.

It also makes it harder for us humans to anticipate how fast or not things will progress. I think the GFS 00z and ECM 00z captured the soonest and latest 'reasonable' limits, though, in terms of how soon we start to see high pressure gaining more influence from the southwest.

I'm not convinced by how far east they're taking the Atlantic trough mid-late next week,  as the jet stream is being modelled to be unusually strong for a non-Nina base state, but I can see how it could be a result of the Atlantic SST anomaly pattern which has a lot of negatives northwest of positives, enhancing the temp gradient that the jet stream has to work with.

However, as long as the main trough moves north of east, we can still get the pressure rise from the southwest (GFS 06z getting all mixed-up at this stage; one for the bin).

 

No denying this is an irritating time if you were hoping for the 'lull' in Nino tropical cycles to be brief with a quick resumption of anomalously warm conditions. Back in late July, that was my anticipation, but that was  based on the tropical Pacific SSTs widely reaching the +0.5*C mark by around now. 

u.anom.30.5S-5N.gif

This should kick those anomalies up a bit in the C Pacific, but the fact we're waiting until almost mid-month for it is among the main reasons for this unfortunately lengthy 'lull'.

Sure, it still may turn out not too bad in the south, but I'm sparing thoughts for those up north who have had the cooler, changeable/unsettled weather for longer already, and look to be in the thick of it next week as well.

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Yet another very encouraging T+240 Ecm 00z ensemble mean showing the azores high ridging in for the last third of August.☺

EDM1-240.GIF

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1 hour ago, danm said:

Do you want a NW’erly?

Seems impossible to achieve now days in summer to get an air mass from a northerly or northwesterly, yes please! Recently glimpses at day 9 or 10 but then turns into a flat westerly in reality.

Edited by Froze were the Days

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The Gfs 6z operational is mostly vile away from the at times warmer SE corner, there's plenty of cool, changeable / unsettled weather for most of the uk.

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11 minutes ago, Frosty. said:

The Gfs 6z operational is mostly vile away from the at times warmer SE corner, there's plenty of cool, changeable / unsettled weather for most of the uk.

Fortunately it appears the GFS 06Z Ops was something of a cold/wet outlier in the south at least. 

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Just looking through the GEFS 6z I will be very surprised (and disappointed) if we don't get another warm / very warm anticyclonic spell during the second half of this month because currently there's plenty of support for it!

Looking at the latest mean, things do gradually improve.☺

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Edited by Frosty.
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Another good GFS run out to next Friday so far for the south, still looking mainly unsettled further north. We’re still looking odds on for a N/S split to develop from Tuesday onwards with high pressure to the SW ridging quite extensively at times across southern parts of England and Wales with some warm sunshine and lighter winds. Low pressure always close to northern Scotland with breezy, showery weather never far away. 

D51EA919-C1EF-4997-B236-F3E314CD86BA.png

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3276D11F-AC9A-44C9-BF76-767D5557E9A5.png

8ACE7ED8-CF51-44D5-9FD8-B29AE988A024.png

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h850t850eu.png

GFS is acting like an excited puppy; sure it makes a mess sometimes, but it keeps trying to find ways to please you in between.

Rukm1441.gif

UKMO the older, more restrained dog but willing to entertain the puppy's ideas at least a little bit...

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Similar UKMO to the GFS with the N/S split developing from Tuesday onwards: 

 

1A8127B7-EDDC-4E52-B331-E7E13318B7B4.png

057BF089-4056-4FD1-ADFA-276117E44F07.png

D857036F-24CF-44BD-B2C1-4367B23906C9.png

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22 minutes ago, Singularity said:

h850t850eu.png

GFS is acting like an excited puppy; sure it makes a mess sometimes, but it keeps trying to find ways to please you in between.

Rukm1441.gif

UKMO the older, more restrained dog but willing to entertain the puppy's ideas at least a little bit...

I've growing to the idea that if you want to be sure about a pattern change, you need the UKMO to be reasonably onside at T144 over the course of a couple of runs. It never seems to be wildly out. 

The GFS, though, can't really be trusted on this ridge coming in from the SW. So often it promises a more amplified pattern, only for one more low to magically appear at D5. 

With all this in mind, I think the guidance of short 2/3 day settled periods in between lows (shorter still in the north) presents the most sensible guidance out to D9 at least. 

Edited by Man With Beard

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Much warmer Gfs 12z operational compared to the 6z across most of england and wales with some very warm largely fine spells across southern uk, especially the east / southeast..most of the unsettled and cooler weather further n / nw.

Edited by Frosty.
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ECM follows a similar trend to the GFS and UKMO with the N/S split from Tuesday onwards, with signs of some very warm air from the continent infiltrating into the south again next Saturday. Until then, standard summer fare with the warmest, driest, sunniest conditions in the south whilst the north is more prone to cooler, wetter weather with LP anchored to the N/NW of Scotland. 

 

8F9E45F7-B9FF-4EB6-86B4-1CCFF8A8EED6.png

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24A58327-042E-443A-B5D1-92F7C3D8DA07.png

Edited by danm

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1 hour ago, Man With Beard said:

I've growing to the idea that if you want to be sure about a pattern change, you need the UKMO to be reasonably onside at T144 over the course of a couple of runs. It never seems to be wildly out. 

The GFS, though, can't really be trusted on this ridge coming in from the SW. So often it promises a more amplified pattern, only for one more low to magically appear at D5. 

With all this in mind, I think the guidance of short 2/3 day settled periods in between lows (shorter still in the north) presents the most sensible guidance out to D9 at least. 

144_mslp850.png?cb=890 168_mslp850.png?cb=890 192_mslp850.png?cb=890

Then again... here's where ECM goes from a very similar position to UKMO at +144 hours.

This being the subtle shift I spied in the UKMO 12z compared to the previous runs - the increased ridging to our SW with an alignment conducive to building across S UK.

Whether this adjustment will stick or not, remains to be seen; what you say just still remains the safer bet at the moment as we need persistence of something different before confidence can grow. As you well know, I'm sure 😎.


At this moment in time, though, I'll permit myself a smile at seeing the most stubborn of the models try out a warmer, less wet (still shower potential on this run!) outcome for next weekend.

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All things considered, the Ecm 12z would be a very good result for southern uk with predominantly higher pressure bringing some fine, very warm, even hot weather at times with impressive uppers, given any decent sunshine, temperatures would rocket with 850's generally +10 / 12 occasionally +15 / 16. Most of the unsettled weather and rather cooler conditions is further n / nw.. similar to the Gfs 12z.

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240_mslp500.png

Edited by Frosty.
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Uncertainty reigns tonight.  All models have a generally westerly flow for the foreseeable, then they start to differ. GEM is awful, GFS has higher pressure building intermittently, ECM looks good for more settled conditions at day 10.  

However, the 2 ensemble mean charts, actually look promising at T240:

image.thumb.jpg.560941831fc74346fd10906fa7bc23c6.jpg

image.thumb.jpg.0a404cdde11525b90931dbafbc18ff31.jpg

And FV3 12z heading for fine and settled, here for T252:

image.thumb.jpg.0fa41c37b48b5037d10a62ef04629971.jpg

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21 minutes ago, Mike Poole said:

Uncertainty reigns tonight.  All models have a generally westerly flow for the foreseeable, then they start to differ. GEM is awful, GFS has higher pressure building intermittently, ECM looks good for more settled conditions at day 10.  

However, the 2 ensemble mean charts, actually look promising at T240:

image.thumb.jpg.560941831fc74346fd10906fa7bc23c6.jpg

image.thumb.jpg.0a404cdde11525b90931dbafbc18ff31.jpg

And FV3 12z heading for fine and settled, here for T252:

image.thumb.jpg.0fa41c37b48b5037d10a62ef04629971.jpg

Yes most encouraging means for a while. I wouldn't be too certain we've seen the back of the lows until those heights appear a bit further north still. 

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Nothing substantially cool in the ten day range however the GFS18z (bar about 48 hours) has the Atlantic firmly in control and even tries building heights to the north around day 10.

GFSOPEU18_240_33.png 

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28 minutes ago, summer blizzard said:

Nothing substantially cool in the ten day range however the GFS18z (bar about 48 hours) has the Atlantic firmly in control and even tries building heights to the north around day 10.

GFSOPEU18_240_33.png 

Not quite true - yes LP is firmly in control across the north, but the 18z continues on from previous model runs showing a N/S split developing next week. The southern half of the UK actually sees plenty of fine weather, bar a blip on Thursday when the jet dips further south again for 24 hrs. Friday and into the weekend again shows higher pressure into the south. 

Edited by danm

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00z runs are all fairly flat without any substantial ridging....nothing to suggest anything major changing any time soon.

Also the noaa anomalies have finally caught up and show negative anomalies in the Iceland region which weren’t there over the last couple of days - flat pattern prevailing.

Edited by mb018538

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